| /* pngfix.c |
| * |
| * Copyright (c) 2014-2015 John Cunningham Bowler |
| * |
| * Last changed in libpng 1.6.20 [December 3, 2015] |
| * |
| * This code is released under the libpng license. |
| * For conditions of distribution and use, see the disclaimer |
| * and license in png.h |
| * |
| * Tool to check and fix the zlib inflate 'too far back' problem. |
| * See the usage message for more information. |
| */ |
| #include <stdlib.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <ctype.h> |
| #include <limits.h> |
| #include <errno.h> |
| #include <assert.h> |
| |
| #define implies(x,y) assert(!(x) || (y)) |
| |
| #ifdef __GNUC__ |
| /* This is used to fix the error: |
| * |
| * pngfix.c: |
| * In function 'zlib_advance': |
| * pngfix.c:181:13: error: assuming signed overflow does not |
| * occur when simplifying conditional to constant [-Werror=strict-overflow] |
| */ |
| # define FIX_GCC volatile |
| #else |
| # define FIX_GCC |
| #endif |
| |
| #define PROGRAM_NAME "pngfix" |
| |
| /* Define the following to use this program against your installed libpng, |
| * rather than the one being built here: |
| */ |
| #ifdef PNG_FREESTANDING_TESTS |
| # include <png.h> |
| #else |
| # include "../../png.h" |
| #endif |
| |
| #if PNG_LIBPNG_VER < 10603 /* 1.6.3 */ |
| # error "pngfix will not work with libpng prior to 1.6.3" |
| #endif |
| |
| #ifdef PNG_SETJMP_SUPPORTED |
| #include <setjmp.h> |
| |
| #if defined(PNG_READ_SUPPORTED) && defined(PNG_EASY_ACCESS_SUPPORTED) &&\ |
| (defined(PNG_READ_DEINTERLACE_SUPPORTED) ||\ |
| defined(PNG_READ_INTERLACING_SUPPORTED)) |
| |
| /* zlib.h defines the structure z_stream, an instance of which is included |
| * in this structure and is required for decompressing the LZ compressed |
| * data in PNG files. |
| */ |
| #ifndef ZLIB_CONST |
| /* We must ensure that zlib uses 'const' in declarations. */ |
| # define ZLIB_CONST |
| #endif |
| #include <zlib.h> |
| #ifdef const |
| /* zlib.h sometimes #defines const to nothing, undo this. */ |
| # undef const |
| #endif |
| |
| /* zlib.h has mediocre z_const use before 1.2.6, this stuff is for compatibility |
| * with older builds. |
| */ |
| #if ZLIB_VERNUM < 0x1260 |
| # define PNGZ_MSG_CAST(s) constcast(char*,s) |
| # define PNGZ_INPUT_CAST(b) constcast(png_bytep,b) |
| #else |
| # define PNGZ_MSG_CAST(s) (s) |
| # define PNGZ_INPUT_CAST(b) (b) |
| #endif |
| |
| #ifndef PNG_MAXIMUM_INFLATE_WINDOW |
| # error "pngfix not supported in this libpng version" |
| #endif |
| |
| #if ZLIB_VERNUM >= 0x1240 |
| |
| /* Copied from pngpriv.h */ |
| #ifdef __cplusplus |
| # define voidcast(type, value) static_cast<type>(value) |
| # define constcast(type, value) const_cast<type>(value) |
| # define aligncast(type, value) \ |
| static_cast<type>(static_cast<void*>(value)) |
| # define aligncastconst(type, value) \ |
| static_cast<type>(static_cast<const void*>(value)) |
| #else |
| # define voidcast(type, value) (value) |
| # define constcast(type, value) ((type)(value)) |
| # define aligncast(type, value) ((void*)(value)) |
| # define aligncastconst(type, value) ((const void*)(value)) |
| #endif /* __cplusplus */ |
| |
| #if PNG_LIBPNG_VER < 10700 |
| /* Chunk tags (copied from pngpriv.h) */ |
| #define PNG_32b(b,s) ((png_uint_32)(b) << (s)) |
| #define PNG_U32(b1,b2,b3,b4) \ |
| (PNG_32b(b1,24) | PNG_32b(b2,16) | PNG_32b(b3,8) | PNG_32b(b4,0)) |
| |
| /* Constants for known chunk types. */ |
| #define png_IDAT PNG_U32( 73, 68, 65, 84) |
| #define png_IEND PNG_U32( 73, 69, 78, 68) |
| #define png_IHDR PNG_U32( 73, 72, 68, 82) |
| #define png_PLTE PNG_U32( 80, 76, 84, 69) |
| #define png_bKGD PNG_U32( 98, 75, 71, 68) |
| #define png_cHRM PNG_U32( 99, 72, 82, 77) |
| #define png_fRAc PNG_U32(102, 82, 65, 99) /* registered, not defined */ |
| #define png_gAMA PNG_U32(103, 65, 77, 65) |
| #define png_gIFg PNG_U32(103, 73, 70, 103) |
| #define png_gIFt PNG_U32(103, 73, 70, 116) /* deprecated */ |
| #define png_gIFx PNG_U32(103, 73, 70, 120) |
| #define png_hIST PNG_U32(104, 73, 83, 84) |
| #define png_iCCP PNG_U32(105, 67, 67, 80) |
| #define png_iTXt PNG_U32(105, 84, 88, 116) |
| #define png_oFFs PNG_U32(111, 70, 70, 115) |
| #define png_pCAL PNG_U32(112, 67, 65, 76) |
| #define png_pHYs PNG_U32(112, 72, 89, 115) |
| #define png_sBIT PNG_U32(115, 66, 73, 84) |
| #define png_sCAL PNG_U32(115, 67, 65, 76) |
| #define png_sPLT PNG_U32(115, 80, 76, 84) |
| #define png_sRGB PNG_U32(115, 82, 71, 66) |
| #define png_sTER PNG_U32(115, 84, 69, 82) |
| #define png_tEXt PNG_U32(116, 69, 88, 116) |
| #define png_tIME PNG_U32(116, 73, 77, 69) |
| #define png_tRNS PNG_U32(116, 82, 78, 83) |
| #define png_zTXt PNG_U32(122, 84, 88, 116) |
| #endif |
| |
| /* The 8-byte signature as a pair of 32-bit quantities */ |
| #define sig1 PNG_U32(137, 80, 78, 71) |
| #define sig2 PNG_U32( 13, 10, 26, 10) |
| |
| /* Is the chunk critical? */ |
| #define CRITICAL(chunk) (((chunk) & PNG_U32(32,0,0,0)) == 0) |
| |
| /* Is it safe to copy? */ |
| #define SAFE_TO_COPY(chunk) (((chunk) & PNG_U32(0,0,0,32)) != 0) |
| |
| /* Fix ups for builds with limited read support */ |
| #ifndef PNG_ERROR_TEXT_SUPPORTED |
| # define png_error(a,b) png_err(a) |
| #endif |
| |
| /********************************* UTILITIES **********************************/ |
| /* UNREACHED is a value to cause an assert to fail. Because of the way the |
| * assert macro is written the string "UNREACHED" is produced in the error |
| * message. |
| */ |
| #define UNREACHED 0 |
| |
| /* 80-bit number handling - a PNG image can be up to (2^31-1)x(2^31-1) 8-byte |
| * (16-bit RGBA) pixels in size; that's less than 2^65 bytes or 2^68 bits, so |
| * arithmetic of 80-bit numbers is sufficient. This representation uses an |
| * arbitrary length array of png_uint_16 digits (0..65535). The representation |
| * is little endian. |
| * |
| * The arithmetic functions take zero to two uarb values together with the |
| * number of digits in those values and write the result to the given uarb |
| * (always the first argument) returning the number of digits in the result. |
| * If the result is negative the return value is also negative (this would |
| * normally be an error). |
| */ |
| typedef png_uint_16 udigit; /* A 'unum' is an array of these */ |
| typedef png_uint_16p uarb; |
| typedef png_const_uint_16p uarbc; |
| |
| #define UDIGITS(unum) ((sizeof unum)/(sizeof (udigit)) |
| /* IMPORTANT: only apply this to an array, applied to a pointer the result |
| * will typically be '2', which is not useful. |
| */ |
| |
| static int |
| uarb_set(uarb result, png_alloc_size_t val) |
| /* Set (initialize) 'result' to 'val'. The size required for 'result' must |
| * be determined by the caller from a knowledge of the maximum for 'val'. |
| */ |
| { |
| int ndigits = 0; |
| |
| while (val > 0) |
| { |
| result[ndigits++] = (png_uint_16)(val & 0xffff); |
| val >>= 16; |
| } |
| |
| return ndigits; |
| } |
| |
| static int |
| uarb_copy(uarb to, uarb from, int idigits) |
| /* Copy a uarb, may reduce the digit count */ |
| { |
| int d, odigits; |
| |
| for (d=odigits=0; d<idigits; ++d) |
| if ((to[d] = from[d]) != 0) |
| odigits = d+1; |
| |
| return odigits; |
| } |
| |
| static int |
| uarb_inc(uarb num, int in_digits, png_int_32 add) |
| /* This is a signed 32-bit add, except that to avoid overflow the value added |
| * or subtracted must be no more than 2^31-65536. A negative result |
| * indicates a negative number (which is an error below). The size of |
| * 'num' should be max(in_digits+1,2) for arbitrary 'add' but can be just |
| * in_digits+1 if add is known to be in the range -65535..65535. |
| */ |
| { |
| FIX_GCC int out_digits = 0; |
| |
| while (out_digits < in_digits) |
| { |
| add += num[out_digits]; |
| num[out_digits++] = (png_uint_16)(add & 0xffff); |
| add >>= 16; |
| } |
| |
| while (add != 0 && add != (-1)) |
| { |
| num[out_digits++] = (png_uint_16)(add & 0xffff); |
| add >>= 16; |
| } |
| |
| if (add == 0) |
| { |
| while (out_digits > 0 && num[out_digits-1] == 0) |
| --out_digits; |
| return out_digits; /* may be 0 */ |
| } |
| |
| else /* negative result */ |
| { |
| while (out_digits > 1 && num[out_digits-1] == 0xffff) |
| --out_digits; |
| |
| return -out_digits; |
| } |
| } |
| |
| static int |
| uarb_add32(uarb num, int in_digits, png_uint_32 add) |
| /* As above but this works with any 32-bit value and only does 'add' */ |
| { |
| if (in_digits > 0) |
| { |
| in_digits = uarb_inc(num, in_digits, add & 0xffff); |
| return uarb_inc(num+1, in_digits-1, add >> 16)+1; |
| } |
| |
| return uarb_set(num, add); |
| } |
| |
| static int |
| uarb_mult_digit(uarb acc, int a_digits, uarb num, FIX_GCC int n_digits, |
| png_uint_16 val) |
| /* Primitive one-digit multiply - 'val' must be 0..65535. Note that this |
| * primitive is a multiply and accumulate - the result of *num * val is added |
| * to *acc. |
| * |
| * This is a one-digit multiply, so the product may be up to one digit longer |
| * than 'num', however the add to 'acc' means that the caller must ensure |
| * that 'acc' is at least one digit longer than this *and* at least one digit |
| * longer than the current length of 'acc'. (Or the caller must otherwise |
| * ensure 'adigits' is adequate from knowledge of the values.) |
| */ |
| { |
| /* The digits in *acc, *num and val are in the range 0..65535, so the |
| * result below is at most (65535*65535)+2*65635 = 65535*(65535+2), which is |
| * exactly 0xffffffff. |
| */ |
| if (val > 0 && n_digits > 0) /* Else the product is 0 */ |
| { |
| png_uint_32 carry = 0; |
| int out_digits = 0; |
| |
| while (out_digits < n_digits || carry > 0) |
| { |
| if (out_digits < a_digits) |
| carry += acc[out_digits]; |
| |
| if (out_digits < n_digits) |
| carry += (png_uint_32)num[out_digits] * val; |
| |
| acc[out_digits++] = (png_uint_16)(carry & 0xffff); |
| carry >>= 16; |
| } |
| |
| /* So carry is 0 and all the input digits have been consumed. This means |
| * that it is possible to skip any remaining digits in acc. |
| */ |
| if (out_digits > a_digits) |
| return out_digits; |
| } |
| |
| return a_digits; |
| } |
| |
| static int |
| uarb_mult32(uarb acc, int a_digits, uarb num, int n_digits, png_uint_32 val) |
| /* calculate acc += num * val, 'val' may be any 32-bit value, 'acc' and 'num' |
| * may be any value, returns the number of digits in 'acc'. |
| */ |
| { |
| if (n_digits > 0 && val > 0) |
| { |
| a_digits = uarb_mult_digit(acc, a_digits, num, n_digits, |
| (png_uint_16)(val & 0xffff)); |
| |
| /* Because n_digits and val are >0 the following must be true: */ |
| assert(a_digits > 0); |
| |
| val >>= 16; |
| if (val > 0) |
| a_digits = uarb_mult_digit(acc+1, a_digits-1, num, n_digits, |
| (png_uint_16)val) + 1; |
| } |
| |
| return a_digits; |
| } |
| |
| static int |
| uarb_shift(uarb inout, int ndigits, unsigned int right_shift) |
| /* Shift inout right by right_shift bits, right_shift must be in the range |
| * 1..15 |
| */ |
| { |
| FIX_GCC int i = ndigits; |
| png_uint_16 carry = 0; |
| |
| assert(right_shift >= 1 && right_shift <= 15); |
| |
| while (--i >= 0) |
| { |
| png_uint_16 temp = (png_uint_16)(carry | (inout[i] >> right_shift)); |
| |
| /* Bottom bits to top bits of carry */ |
| carry = (png_uint_16)((inout[i] << (16-right_shift)) & 0xffff); |
| |
| inout[i] = temp; |
| |
| /* The shift may reduce ndigits */ |
| if (i == ndigits-1 && temp == 0) |
| ndigits = i; |
| } |
| |
| return ndigits; |
| } |
| |
| static int |
| uarb_cmp(uarb a, int adigits, uarb b, int bdigits) |
| /* Return -1/0/+1 according as a<b/a==b/a>b */ |
| { |
| if (adigits < bdigits) |
| return -1; |
| |
| if (adigits > bdigits) |
| return 1; |
| |
| while (adigits-- > 0) |
| if (a[adigits] < b[adigits]) |
| return -1; |
| |
| else if (a[adigits] > b[adigits]) |
| return 1; |
| |
| return 0; |
| } |
| |
| #if 0 /*UNUSED*/ |
| static int |
| uarb_eq32(uarb num, int digits, png_uint_32 val) |
| /* Return true if the uarb is equal to 'val' */ |
| { |
| switch (digits) |
| { |
| case 0: return val == 0; |
| case 1: return val == num[0]; |
| case 2: return (val & 0xffff) == num[0] && (val >> 16) == num[1]; |
| default: return 0; |
| } |
| } |
| #endif |
| |
| static void |
| uarb_printx(uarb num, int digits, FILE *out) |
| /* Print 'num' as a hexadecimal number (easier than decimal!) */ |
| { |
| while (digits > 0) |
| if (num[--digits] > 0) |
| { |
| fprintf(out, "0x%x", num[digits]); |
| |
| while (digits > 0) |
| fprintf(out, "%.4x", num[--digits]); |
| } |
| |
| else if (digits == 0) /* the number is 0 */ |
| fputs("0x0", out); |
| } |
| |
| static void |
| uarb_print(uarb num, int digits, FILE *out) |
| /* Prints 'num' as a decimal if it will fit in an unsigned long, else as a |
| * hexadecimal number. Notice that the results vary for images over 4GByte |
| * in a system dependent way, and the hexadecimal form doesn't work very well |
| * in awk script input. |
| * |
| * |
| * TODO: write uarb_div10 |
| */ |
| { |
| if (digits * sizeof (udigit) > sizeof (unsigned long)) |
| uarb_printx(num, digits, out); |
| |
| else |
| { |
| unsigned long n = 0; |
| |
| while (digits > 0) |
| n = (n << 16) + num[--digits]; |
| |
| fprintf(out, "%lu", n); |
| } |
| } |
| |
| /* Generate random bytes. This uses a boring repeatable algorithm and it |
| * is implemented here so that it gives the same set of numbers on every |
| * architecture. It's a linear congruential generator (Knuth or Sedgewick |
| * "Algorithms") but it comes from the 'feedback taps' table in Horowitz and |
| * Hill, "The Art of Electronics" (Pseudo-Random Bit Sequences and Noise |
| * Generation.) |
| * |
| * (Copied from contrib/libtests/pngvalid.c) |
| */ |
| static void |
| make_random_bytes(png_uint_32* seed, void* pv, size_t size) |
| { |
| png_uint_32 u0 = seed[0], u1 = seed[1]; |
| png_bytep bytes = voidcast(png_bytep, pv); |
| |
| /* There are thirty-three bits; the next bit in the sequence is bit-33 XOR |
| * bit-20. The top 1 bit is in u1, the bottom 32 are in u0. |
| */ |
| size_t i; |
| for (i=0; i<size; ++i) |
| { |
| /* First generate 8 new bits then shift them in at the end. */ |
| png_uint_32 u = ((u0 >> (20-8)) ^ ((u1 << 7) | (u0 >> (32-7)))) & 0xff; |
| u1 <<= 8; |
| u1 |= u0 >> 24; |
| u0 <<= 8; |
| u0 |= u; |
| *bytes++ = (png_byte)u; |
| } |
| |
| seed[0] = u0; |
| seed[1] = u1; |
| } |
| |
| /* Clear an object to a random value. */ |
| static void |
| clear(void *pv, size_t size) |
| { |
| static png_uint_32 clear_seed[2] = { 0x12345678, 0x9abcdef0 }; |
| make_random_bytes(clear_seed, pv, size); |
| } |
| |
| #define CLEAR(object) clear(&(object), sizeof (object)) |
| |
| /* Copied from unreleased 1.7 code. |
| * |
| * CRC checking uses a local pre-built implementation of the Ethernet CRC32. |
| * This is to avoid a function call to the zlib DLL and to optimize the |
| * byte-by-byte case. |
| */ |
| static png_uint_32 crc_table[256] = |
| { |
| 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, |
| 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, |
| 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, |
| 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, |
| 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, |
| 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, |
| 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, |
| 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, |
| 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, |
| 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, |
| 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, |
| 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, |
| 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, |
| 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, |
| 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, |
| 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, |
| 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, |
| 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, |
| 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, |
| 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, |
| 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, |
| 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, |
| 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, |
| 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, |
| 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, |
| 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, |
| 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, |
| 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, |
| 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, |
| 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, |
| 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, |
| 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, |
| 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, |
| 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, |
| 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, |
| 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, |
| 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, |
| 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, |
| 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, |
| 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, |
| 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, |
| 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, |
| 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, |
| 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, |
| 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, |
| 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, |
| 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, |
| 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, |
| 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, |
| 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, |
| 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, |
| 0x2d02ef8d |
| }; |
| |
| /* The CRC calculated here *IS* conditioned, the corresponding value used by |
| * zlib and the result value is obtained by XORing with CRC_INIT, which is also |
| * the first value that must be passed in (for the first byte) to crc_one_byte. |
| */ |
| #define CRC_INIT 0xffffffff |
| |
| static png_uint_32 |
| crc_one_byte(png_uint_32 crc, int b) |
| { |
| return crc_table[(crc ^ b) & 0xff] ^ (crc >> 8); |
| } |
| |
| static png_uint_32 |
| crc_init_4(png_uint_32 value) |
| { |
| /* This is an alternative to the algorithm used in zlib, which requires four |
| * separate tables to parallelize the four byte operations, it only works for |
| * a CRC of the first four bytes of the stream, but this is what happens in |
| * the parser below where length+chunk-name is read and chunk-name used to |
| * initialize the CRC. Notice that the calculation here avoids repeated |
| * conditioning (xor with 0xffffffff) by storing the conditioned value. |
| */ |
| png_uint_32 crc = crc_table[(~value >> 24)] ^ 0xffffff; |
| |
| crc = crc_table[(crc ^ (value >> 16)) & 0xff] ^ (crc >> 8); |
| crc = crc_table[(crc ^ (value >> 8)) & 0xff] ^ (crc >> 8); |
| return crc_table[(crc ^ value) & 0xff] ^ (crc >> 8); |
| } |
| |
| static int |
| chunk_type_valid(png_uint_32 c) |
| /* Bit whacking approach to chunk name validation that is intended to avoid |
| * branches. The cost is that it uses a lot of 32-bit constants, which might |
| * be bad on some architectures. |
| */ |
| { |
| png_uint_32 t; |
| |
| /* Remove bit 5 from all but the reserved byte; this means every |
| * 8-bit unit must be in the range 65-90 to be valid. So bit 5 |
| * must be zero, bit 6 must be set and bit 7 zero. |
| */ |
| c &= ~PNG_U32(32,32,0,32); |
| t = (c & ~0x1f1f1f1f) ^ 0x40404040; |
| |
| /* Subtract 65 for each 8-bit quantity, this must not overflow |
| * and each byte must then be in the range 0-25. |
| */ |
| c -= PNG_U32(65,65,65,65); |
| t |=c ; |
| |
| /* Subtract 26, handling the overflow which should set the top |
| * three bits of each byte. |
| */ |
| c -= PNG_U32(25,25,25,26); |
| t |= ~c; |
| |
| return (t & 0xe0e0e0e0) == 0; |
| } |
| |
| /**************************** CONTROL INFORMATION *****************************/ |
| |
| /* Information about a sequence of IDAT chunks, the chunks have been re-synced |
| * using sync_stream below and the new lengths are recorded here. Because the |
| * number of chunks is unlimited this is handled using a linked list of these |
| * structures. |
| */ |
| struct IDAT_list |
| { |
| struct IDAT_list *next; /* Linked list */ |
| unsigned int length; /* Actual length of the array below */ |
| unsigned int count; /* Number of entries that are valid */ |
| # define IDAT_INIT_LENGTH 16 |
| png_uint_32 lengths[IDAT_INIT_LENGTH]; |
| }; |
| |
| static void |
| IDAT_list_init(struct IDAT_list *list) |
| { |
| CLEAR(*list); |
| |
| list->next = NULL; |
| list->length = IDAT_INIT_LENGTH; |
| } |
| |
| static size_t |
| IDAT_list_size(struct IDAT_list *list, unsigned int length) |
| /* Return the size in bytes of an IDAT_list of the given length. */ |
| { |
| if (list != NULL) |
| length = list->length; |
| |
| return sizeof *list - sizeof list->lengths + |
| length * sizeof list->lengths[0]; |
| } |
| |
| static void |
| IDAT_list_end(struct IDAT_list *IDAT_list) |
| { |
| struct IDAT_list *list = IDAT_list->next; |
| |
| CLEAR(*IDAT_list); |
| |
| while (list != NULL) |
| { |
| struct IDAT_list *next = list->next; |
| |
| clear(list, IDAT_list_size(list, 0)); |
| free(list); |
| list = next; |
| } |
| } |
| |
| static struct IDAT_list * |
| IDAT_list_extend(struct IDAT_list *tail) |
| { |
| /* Use the previous cached value if available. */ |
| struct IDAT_list *next = tail->next; |
| |
| if (next == NULL) |
| { |
| /* Insert a new, malloc'ed, block of IDAT information buffers, this |
| * one twice as large as the previous one: |
| */ |
| unsigned int length = 2 * tail->length; |
| |
| if (length < tail->length) /* arithmetic overflow */ |
| length = tail->length; |
| |
| next = voidcast(IDAT_list*, malloc(IDAT_list_size(NULL, length))); |
| CLEAR(*next); |
| |
| /* The caller must handle this: */ |
| if (next == NULL) |
| return NULL; |
| |
| next->next = NULL; |
| next->length = length; |
| tail->next = next; |
| } |
| |
| return next; |
| } |
| |
| /* GLOBAL CONTROL STRUCTURE */ |
| struct global |
| { |
| /* PUBLIC GLOBAL VARIABLES: OWNER INITIALIZE */ |
| unsigned int errors :1; /* print file errors to stderr */ |
| unsigned int warnings :1; /* print libpng warnings to stderr */ |
| unsigned int optimize_zlib :1; /* Run optimization search */ |
| unsigned int quiet :2; /* don't output summaries */ |
| unsigned int verbose :3; /* various internal tracking */ |
| unsigned int skip :3; /* Non-critical chunks to skip */ |
| # define SKIP_NONE 0 |
| # define SKIP_BAD_CRC 1 /* Chunks with a bad CRC */ |
| # define SKIP_UNSAFE 2 /* Chunks not safe to copy */ |
| # define SKIP_UNUSED 3 /* Chunks not used by libpng */ |
| # define SKIP_TRANSFORM 4 /* Chunks only used in transforms */ |
| # define SKIP_COLOR 5 /* Everything but tRNS, sBIT, gAMA and sRGB */ |
| # define SKIP_ALL 6 /* Everything but tRNS and sBIT */ |
| |
| png_uint_32 idat_max; /* 0 to perform no re-chunking */ |
| |
| int status_code; /* Accumulated status code */ |
| # define TOO_FAR_BACK 0x01 /* found a too-far-back error */ |
| # define CRC_ERROR 0x02 /* fixed an invalid CRC */ |
| # define STREAM_ERROR 0x04 /* damaged PNG stream (may be fixable) */ |
| # define TRUNCATED 0x08 /* truncated but still readable */ |
| # define FILE_ERROR 0x10 /* could not read the file */ |
| # define WRITE_ERROR 0x20 /* write error (this terminates the read) */ |
| # define INTERNAL_ERROR 0x40 /* internal limits/errors encountered */ |
| |
| /* PUBLIC GLOBAL VARIABLES: USED INTERNALLY BY IDAT READ CODE */ |
| struct IDAT_list idat_cache; /* Cache of file IDAT information buffers */ |
| /* The structure is shared across all uses of this global control |
| * structure to avoid reallocation between IDAT streams. |
| */ |
| }; |
| |
| static int |
| global_end(struct global *global) |
| { |
| |
| int rc; |
| |
| IDAT_list_end(&global->idat_cache); |
| rc = global->status_code; |
| CLEAR(*global); |
| return rc; |
| } |
| |
| static void |
| global_init(struct global *global) |
| /* Call this once (and only once) to initialize the control */ |
| { |
| CLEAR(*global); |
| |
| /* Globals */ |
| global->errors = 0; |
| global->warnings = 0; |
| global->quiet = 0; |
| global->verbose = 0; |
| global->idat_max = 0; /* no re-chunking of IDAT */ |
| global->optimize_zlib = 0; |
| global->skip = SKIP_NONE; |
| global->status_code = 0; |
| |
| IDAT_list_init(&global->idat_cache); |
| } |
| |
| static int |
| skip_chunk_type(const struct global *global, png_uint_32 type) |
| /* Return true if this chunk is to be skipped according to the --strip |
| * option. This code needs to recognize all known ancillary chunks in order |
| * to handle the --strip=unsafe option. |
| */ |
| { |
| /* Never strip critical chunks: */ |
| if (CRITICAL(type)) |
| return 0; |
| |
| switch (type) |
| { |
| /* Chunks that are treated as, effectively, critical because they affect |
| * correct interpretation of the pixel values: |
| */ |
| case png_tRNS: case png_sBIT: |
| return 0; |
| |
| /* Chunks that specify gamma encoding which should therefore only be |
| * removed the the user insists: |
| */ |
| case png_gAMA: case png_sRGB: |
| if (global->skip >= SKIP_ALL) |
| return 1; |
| return 0; |
| |
| /* Chunks that affect color interpretation - not used by libpng and rarely |
| * used by applications, but technically still required for correct |
| * interpretation of the image data: |
| */ |
| case png_cHRM: case png_iCCP: |
| if (global->skip >= SKIP_COLOR) |
| return 1; |
| return 0; |
| |
| /* Other chunks that are used by libpng in image transformations (as |
| * opposed to known chunks that have get/set APIs but are not otherwise |
| * used.) |
| */ |
| case png_bKGD: |
| if (global->skip >= SKIP_TRANSFORM) |
| return 1; |
| return 0; |
| |
| /* All other chunks that libpng knows about and affect neither image |
| * interpretation nor libpng transforms - chunks that are effectively |
| * unused by libpng even though libpng might recognize and store them. |
| */ |
| case png_fRAc: case png_gIFg: case png_gIFt: case png_gIFx: case png_hIST: |
| case png_iTXt: case png_oFFs: case png_pCAL: case png_pHYs: case png_sCAL: |
| case png_sPLT: case png_sTER: case png_tEXt: case png_tIME: case png_zTXt: |
| if (global->skip >= SKIP_UNUSED) |
| return 1; |
| return 0; |
| |
| /* Chunks that libpng does not know about (notice that this depends on the |
| * list above including all known chunks!) The decision here depends on |
| * whether the safe-to-copy bit is set in the chunk type. |
| */ |
| default: |
| if (SAFE_TO_COPY(type)) |
| { |
| if (global->skip >= SKIP_UNUSED) /* as above */ |
| return 1; |
| } |
| |
| else if (global->skip >= SKIP_UNSAFE) |
| return 1; |
| |
| return 0; |
| } |
| } |
| |
| /* PER-FILE CONTROL STRUCTURE */ |
| struct chunk; |
| struct IDAT; |
| struct file |
| { |
| /* ANCESTORS */ |
| struct global *global; |
| |
| /* PUBLIC PER-FILE VARIABLES: CALLER INITIALIZE */ |
| const char * file_name; |
| const char * out_name; /* Name of output file (if required) */ |
| |
| /* PUBLIC PER-FILE VARIABLES: SET BY PNG READ CODE */ |
| /* File specific result codes */ |
| int status_code; /* Set to a bit mask of the following: */ |
| int read_errno; /* Records a read error errno */ |
| int write_errno; /* Records a write error errno */ |
| |
| /* IHDR information */ |
| png_uint_32 width; |
| png_uint_32 height; |
| png_byte bit_depth; |
| png_byte color_type; |
| png_byte compression_method; |
| png_byte filter_method; |
| png_byte interlace_method; |
| |
| udigit image_bytes[5]; |
| int image_digits; |
| |
| /* PROTECTED PER-FILE VARIABLES: USED BY THE READ CODE */ |
| FILE * file; /* Original PNG file */ |
| FILE * out; /* If a new one is being written */ |
| jmp_buf jmpbuf; /* Set while reading a PNG */ |
| |
| /* PROTECTED CHUNK SPECIFIC VARIABLES: USED BY CHUNK CODE */ |
| /* The following variables are used during reading to record the length, type |
| * and data position of the *next* chunk or, right at the start, the |
| * signature (in length,type). |
| * |
| * When a chunk control structure is instantiated these values are copied |
| * into the structure and can then be overritten with the data for the next |
| * chunk. |
| */ |
| fpos_t data_pos; /* Position of first byte of chunk data */ |
| png_uint_32 length; /* First word (length or signature start) */ |
| png_uint_32 type; /* Second word (type or signature end) */ |
| png_uint_32 crc; /* Running chunk CRC (used by read_chunk) */ |
| |
| /* These counts are maintained by the read and write routines below and are |
| * reset by the chunk handling code. They record the total number of bytes |
| * read or written for the chunk, including the header (length,type) bytes. |
| */ |
| png_uint_32 read_count; /* Count of bytes read (in the chunk) */ |
| png_uint_32 write_count; /* Count of bytes written (in the chunk) */ |
| int state; /* As defined here: */ |
| # define STATE_SIGNATURE 0 /* The signature is being written */ |
| # define STATE_CHUNKS 1 /* Non-IDAT chunks are being written */ |
| # define STATE_IDAT 2 /* An IDAT stream is being written */ |
| |
| /* Two pointers used to enable clean-up in the event of fatal errors and to |
| * hold state about the parser process (only one of each at present.) |
| */ |
| struct chunk * chunk; |
| struct IDAT * idat; |
| |
| /* Interface to allocate a new chunk or IDAT control structure. The result |
| * is returned by setting one or other of the above variables. Note that the |
| * relevant initializer is called by the allocator function. The alloc_ptr |
| * is used only by the implementation of the allocate function. |
| */ |
| void * alloc_ptr; |
| void (*alloc)(struct file*,int idat); |
| /* idat: allocate IDAT not chunk */ |
| }; |
| |
| /* Valid longjmp (stop) codes are: */ |
| #define LIBPNG_WARNING_CODE 1 /* generic png_error */ |
| #define LIBPNG_ERROR_CODE 2 /* generic png_error */ |
| #define ZLIB_ERROR_CODE 3 /* generic zlib error */ |
| #define INVALID_ERROR_CODE 4 /* detected an invalid PNG */ |
| #define READ_ERROR_CODE 5 /* read failed */ |
| #define WRITE_ERROR_CODE 6 /* error in write */ |
| #define UNEXPECTED_ERROR_CODE 7 /* unexpected (internal?) error */ |
| |
| static void |
| emit_string(const char *str, FILE *out) |
| /* Print a string with spaces replaced by '_' and non-printing characters by |
| * an octal escape. |
| */ |
| { |
| for (; *str; ++str) |
| if (isgraph(UCHAR_MAX & *str)) |
| putc(*str, out); |
| |
| else if (isspace(UCHAR_MAX & *str)) |
| putc('_', out); |
| |
| else |
| fprintf(out, "\\%.3o", *str); |
| } |
| |
| static const char * |
| strcode(int code) |
| { |
| switch (code) |
| { |
| case LIBPNG_WARNING_CODE: return "warning"; |
| case LIBPNG_ERROR_CODE: return "libpng"; |
| case ZLIB_ERROR_CODE: return "zlib"; |
| case INVALID_ERROR_CODE: return "invalid"; |
| case READ_ERROR_CODE: return "read"; |
| case WRITE_ERROR_CODE: return "write"; |
| case UNEXPECTED_ERROR_CODE: return "unexpected"; |
| default: return "INVALID"; |
| } |
| } |
| |
| static void |
| emit_error(struct file *file, int code, const char *what) |
| /* Generic error message routine, takes a 'stop' code but can be used |
| * elsewhere. Always outputs a message. |
| */ |
| { |
| const char *reason; |
| int err = 0; |
| |
| switch (code) |
| { |
| case LIBPNG_WARNING_CODE: reason = "libpng warning:"; break; |
| case LIBPNG_ERROR_CODE: reason = "libpng error:"; break; |
| case ZLIB_ERROR_CODE: reason = "zlib error:"; break; |
| case INVALID_ERROR_CODE: reason = "invalid"; break; |
| case READ_ERROR_CODE: reason = "read failure:"; |
| err = file->read_errno; |
| break; |
| case WRITE_ERROR_CODE: reason = "write error"; |
| err = file->write_errno; |
| break; |
| case UNEXPECTED_ERROR_CODE: reason = "unexpected error:"; |
| err = file->read_errno; |
| if (err == 0) |
| err = file->write_errno; |
| break; |
| default: reason = "INVALID (internal error):"; break; |
| } |
| |
| if (err != 0) |
| fprintf(stderr, "%s: %s %s [%s]\n", file->file_name, reason, what, |
| strerror(err)); |
| |
| else |
| fprintf(stderr, "%s: %s %s\n", file->file_name, reason, what); |
| } |
| |
| static void chunk_end(struct chunk **); |
| static void IDAT_end(struct IDAT **); |
| |
| static int |
| file_end(struct file *file) |
| { |
| int rc; |
| |
| /* If either of the chunk pointers are set end them here, the IDAT structure |
| * must be deallocated first as it may deallocate the chunk structure. |
| */ |
| if (file->idat != NULL) |
| IDAT_end(&file->idat); |
| |
| if (file->chunk != NULL) |
| chunk_end(&file->chunk); |
| |
| rc = file->status_code; |
| |
| if (file->file != NULL) |
| (void)fclose(file->file); |
| |
| if (file->out != NULL) |
| { |
| /* NOTE: this is bitwise |, all the following functions must execute and |
| * must succeed. |
| */ |
| if (ferror(file->out) | fflush(file->out) | fclose(file->out)) |
| { |
| perror(file->out_name); |
| emit_error(file, READ_ERROR_CODE, "output write error"); |
| rc |= WRITE_ERROR; |
| } |
| } |
| |
| /* Accumulate the result codes */ |
| file->global->status_code |= rc; |
| |
| CLEAR(*file); |
| |
| return rc; /* status code: non-zero on read or write error */ |
| } |
| |
| static int |
| file_init(struct file *file, struct global *global, const char *file_name, |
| const char *out_name, void *alloc_ptr, void (*alloc)(struct file*,int)) |
| /* Initialize a file control structure. This will open the given files as |
| * well. The status code returned is 0 on success, non zero (using the flags |
| * above) on a file open error. |
| */ |
| { |
| CLEAR(*file); |
| file->global = global; |
| |
| file->file_name = file_name; |
| file->out_name = out_name; |
| file->status_code = 0; |
| file->read_errno = 0; |
| file->write_errno = 0; |
| |
| file->file = NULL; |
| file->out = NULL; |
| /* jmpbuf is garbage: must be set by read_png */ |
| |
| file->read_count = 0; |
| file->state = STATE_SIGNATURE; |
| |
| file->chunk = NULL; |
| file->idat = NULL; |
| |
| file->alloc_ptr = alloc_ptr; |
| file->alloc = alloc; |
| |
| /* Open the files: */ |
| assert(file_name != NULL); |
| file->file = fopen(file_name, "rb"); |
| |
| if (file->file == NULL) |
| { |
| file->read_errno = errno; |
| file->status_code |= FILE_ERROR; |
| /* Always output: please give a readable file! */ |
| perror(file_name); |
| return FILE_ERROR; |
| } |
| |
| if (out_name != NULL) |
| { |
| file->out = fopen(out_name, "wb"); |
| |
| if (file->out == NULL) |
| { |
| file->write_errno = errno; |
| file->status_code |= WRITE_ERROR; |
| perror(out_name); |
| return WRITE_ERROR; |
| } |
| } |
| |
| return 0; |
| } |
| |
| static void |
| log_error(struct file *file, int code, const char *what) |
| /* Like emit_error but checks the global 'errors' flag */ |
| { |
| if (file->global->errors) |
| emit_error(file, code, what); |
| } |
| |
| static char |
| type_char(png_uint_32 v) |
| { |
| /* In fact because chunk::chunk_type is validated prior to any call to this |
| * function it will always return a-zA-Z, but the extra codes are just there |
| * to help in finding internal (programming) errors. Note that the code only |
| * ever considers the low 7 bits of the value (so it is not necessary for the |
| * type_name function to mask of the byte.) |
| */ |
| if (v & 32) |
| return "!abcdefghijklmnopqrstuvwxyz56789"[(v-96)&31]; |
| |
| else |
| return "@ABCDEFGHIJKLMNOPQRSTUVWXYZ01234"[(v-64)&31]; |
| } |
| |
| static void |
| type_name(png_uint_32 type, FILE *out) |
| { |
| putc(type_char(type >> 24), out); |
| putc(type_char(type >> 16), out); |
| putc(type_char(type >> 8), out); |
| putc(type_char(type ), out); |
| } |
| |
| static void |
| type_sep(FILE *out) |
| { |
| putc(':', out); |
| putc(' ', out); |
| } |
| |
| static png_uint_32 current_type(struct file *file, int code); |
| |
| PNG_NORETURN static void |
| stop(struct file *file, int code, const char *what) |
| /* Return control when a PNG file cannot be read. This outputs an 'ERR' |
| * summary line too. |
| */ |
| { |
| log_error(file, code, what); |
| |
| /* The chunk being read is typically identified by file->chunk or, if this is |
| * NULL, by file->type. This may be wrong if libpng reads ahead, but this |
| * only happens with IDAT where libpng reads the header then jumps around |
| * finding errors in the previous chunks. We know that is happening because |
| * we are at the start of the IDAT (i.e. no IDAT data has yet been written.) |
| * |
| * SUMMARY FORMAT (stop): |
| * |
| * IDAT ERR status code read-errno write-errno message file |
| * |
| * 'uncompressed' will be 0 if there was a problem in the IHDR. The errno |
| * values are emit_string(strerror(errno)). |
| */ |
| if (file->global->quiet < 2) /* need two quiets to stop this. */ |
| { |
| png_uint_32 type; |
| |
| if (file->chunk != NULL) |
| type = current_type(file, code); /* Gropes in struct chunk and IDAT */ |
| |
| else |
| type = file->type; |
| |
| if (type) |
| type_name(type, stdout); |
| |
| else /* magic: an IDAT header, produces bogons for too many IDATs */ |
| fputs("HEAD", stdout); /* not a registered chunk! */ |
| |
| printf(" ERR %.2x %s ", file->status_code, strcode(code)); |
| /* This only works one strerror at a time, because of the way strerror is |
| * implemented. |
| */ |
| emit_string(strerror(file->read_errno), stdout); |
| putc(' ', stdout); |
| emit_string(strerror(file->write_errno), stdout); |
| putc(' ', stdout); |
| emit_string(what, stdout); |
| putc(' ', stdout); |
| fputs(file->file_name, stdout); |
| putc('\n', stdout); |
| } |
| |
| file->status_code |= FILE_ERROR; |
| longjmp(file->jmpbuf, code); |
| } |
| |
| PNG_NORETURN static void |
| stop_invalid(struct file *file, const char *what) |
| { |
| stop(file, INVALID_ERROR_CODE, what); |
| } |
| |
| static void |
| type_message(struct file *file, png_uint_32 type, const char *what) |
| /* Error message for a chunk; the chunk name comes from 'type' */ |
| { |
| if (file->global->errors) |
| { |
| fputs(file->file_name, stderr); |
| type_sep(stderr); |
| type_name(type, stderr); |
| type_sep(stderr); |
| fputs(what, stderr); |
| putc('\n', stderr); |
| } |
| } |
| |
| /* Input file positioning - we jump around in the input file while reading |
| * stuff, these wrappers deal with the error handling. |
| */ |
| static void |
| file_getpos(struct file *file, fpos_t *pos) |
| { |
| if (fgetpos(file->file, pos)) |
| { |
| /* This is unexpected, so perror it */ |
| perror(file->file_name); |
| stop(file, READ_ERROR_CODE, "fgetpos"); |
| } |
| } |
| |
| static void |
| file_setpos(struct file *file, const fpos_t *pos) |
| { |
| if (fsetpos(file->file, pos)) |
| { |
| perror(file->file_name); |
| stop(file, READ_ERROR_CODE, "fsetpos"); |
| } |
| } |
| |
| static void |
| getpos(struct file *file) |
| /* Get the current position and store it in 'data_pos'. The corresponding |
| * setpos() function is chunk specific because it uses the copy of the |
| * position for the specific chunk. |
| */ |
| { |
| file_getpos(file, &file->data_pos); |
| } |
| |
| |
| /* Read utility - read a single byte, returns a value in the range 0..255 or EOF |
| * on a read error. In the latter case status_code and read_errno are updated |
| * appropriately. |
| */ |
| static int |
| read_byte(struct file *file) |
| { |
| int ch = getc(file->file); |
| |
| if (ch >= 0 && ch <= 255) |
| { |
| ++(file->read_count); |
| return ch; |
| } |
| |
| else if (ch != EOF) |
| { |
| file->status_code |= INTERNAL_ERROR; |
| file->read_errno = ERANGE; /* out of range character */ |
| |
| /* This is very unexpected; an error message is always output: */ |
| emit_error(file, UNEXPECTED_ERROR_CODE, "file read"); |
| } |
| |
| # ifdef EINTR |
| else if (errno == EINTR) /* Interrupted, try again */ |
| { |
| errno = 0; |
| return read_byte(file); |
| } |
| # endif |
| |
| else |
| { |
| /* An error, it doesn't really matter what the error is but it gets |
| * recorded anyway. |
| */ |
| if (ferror(file->file)) |
| file->read_errno = errno; |
| |
| else if (feof(file->file)) |
| file->read_errno = 0; /* I.e. a regular EOF, no error */ |
| |
| else /* unexpected */ |
| file->read_errno = EDOM; |
| } |
| |
| /* 'TRUNCATED' is used for all cases of failure to read a byte, because of |
| * the way libpng works a byte read is never attempted unless the byte is |
| * expected to be there, so EOF should not occur. |
| */ |
| file->status_code |= TRUNCATED; |
| return EOF; |
| } |
| |
| static png_byte |
| reread_byte(struct file *file) |
| /* Read a byte when an error is not expected to happen because the byte has |
| * been read before without error. |
| */ |
| { |
| int ch = getc(file->file); |
| |
| if (errno != 0) |
| file->read_errno = errno; |
| |
| if (ch < 0 || ch > 255) |
| stop(file, UNEXPECTED_ERROR_CODE, "reread"); |
| |
| return (png_byte)ch; |
| } |
| |
| static png_uint_32 |
| reread_4(struct file *file) |
| /* The same but for a four byte quantity */ |
| { |
| png_uint_32 result = 0; |
| int i = 0; |
| |
| while (++i <= 4) |
| result = (result << 8) + reread_byte(file); |
| |
| return result; |
| } |
| |
| static void |
| skip_12(struct file *file) |
| /* Skip exactly 12 bytes in the input stream - used to skip a CRC and chunk |
| * header that has been read before. |
| */ |
| { |
| /* Since the chunks were read before this shouldn't fail: */ |
| if (fseek(file->file, 12, SEEK_CUR) != 0) |
| { |
| if (errno != 0) |
| file->read_errno = errno; |
| |
| stop(file, UNEXPECTED_ERROR_CODE, "reskip"); |
| } |
| } |
| |
| static void |
| write_byte(struct file *file, int b) |
| /* Write one byte to the output - this causes a fatal error if the write |
| * fails and the read of this PNG file immediately terminates. Just |
| * increments the write count if there is no output file. |
| */ |
| { |
| if (file->out != NULL) |
| { |
| if (putc(b, file->out) != b) |
| { |
| file->write_errno = errno; |
| file->status_code |= WRITE_ERROR; |
| stop(file, WRITE_ERROR_CODE, "write byte"); |
| } |
| } |
| |
| ++(file->write_count); |
| } |
| |
| /* Derivatives of the read/write functions. */ |
| static unsigned int |
| read_4(struct file *file, png_uint_32 *pu) |
| /* Read four bytes, returns the number of bytes read successfully and, if all |
| * four bytes are read, assigns the result to *pu. |
| */ |
| { |
| unsigned int i = 0; |
| png_uint_32 val = 0; |
| |
| do |
| { |
| int ch = read_byte(file); |
| |
| if (ch == EOF) |
| return i; |
| |
| val = (val << 8) + ch; |
| } while (++i < 4); |
| |
| *pu = val; |
| return i; |
| } |
| |
| /* CRC handling - read but calculate the CRC while doing so. */ |
| static int |
| crc_read_many(struct file *file, png_uint_32 length) |
| /* Reads 'length' bytes and updates the CRC, returns true on success, false |
| * if the input is truncated. |
| */ |
| { |
| if (length > 0) |
| { |
| png_uint_32 crc = file->crc; |
| |
| do |
| { |
| int ch = read_byte(file); |
| |
| if (ch == EOF) |
| return 0; /* Truncated */ |
| |
| crc = crc_one_byte(crc, ch); |
| } |
| while (--length > 0); |
| |
| file->crc = crc; |
| } |
| |
| return 1; /* OK */ |
| } |
| |
| static int |
| calc_image_size(struct file *file) |
| /* Fill in the image_bytes field given the IHDR information, calls stop on |
| * error. |
| */ |
| { |
| png_uint_16 pd = file->bit_depth; |
| |
| switch (file->color_type) |
| { |
| default: |
| stop_invalid(file, "IHDR: colour type"); |
| |
| invalid_bit_depth: |
| stop_invalid(file, "IHDR: bit depth"); |
| |
| case 0: /* g */ |
| if (pd != 1 && pd != 2 && pd != 4 && pd != 8 && pd != 16) |
| goto invalid_bit_depth; |
| break; |
| |
| case 3: |
| if (pd != 1 && pd != 2 && pd != 4 && pd != 8) |
| goto invalid_bit_depth; |
| break; |
| |
| case 2: /* rgb */ |
| if (pd != 8 && pd != 16) |
| goto invalid_bit_depth; |
| |
| pd = (png_uint_16)(pd * 3); |
| break; |
| |
| case 4: /* ga */ |
| if (pd != 8 && pd != 16) |
| goto invalid_bit_depth; |
| |
| pd = (png_uint_16)(pd * 2); |
| break; |
| |
| case 6: /* rgba */ |
| if (pd != 8 && pd != 16) |
| goto invalid_bit_depth; |
| |
| pd = (png_uint_16)(pd * 4); |
| break; |
| } |
| |
| if (file->width < 1 || file->width > 0x7fffffff) |
| stop_invalid(file, "IHDR: width"); |
| |
| else if (file->height < 1 || file->height > 0x7fffffff) |
| stop_invalid(file, "IHDR: height"); |
| |
| else if (file->compression_method != 0) |
| stop_invalid(file, "IHDR: compression method"); |
| |
| else if (file->filter_method != 0) |
| stop_invalid(file, "IHDR: filter method"); |
| |
| else switch (file->interlace_method) |
| { |
| case PNG_INTERLACE_ADAM7: |
| /* Interlacing makes the image larger because of the replication of |
| * both the filter byte and the padding to a byte boundary. |
| */ |
| { |
| int pass; |
| int image_digits = 0; |
| udigit row_width[2], row_bytes[3]; |
| |
| for (pass=0; pass<=6; ++pass) |
| { |
| png_uint_32 pw = PNG_PASS_COLS(file->width, pass); |
| |
| if (pw > 0) |
| { |
| int digits; |
| |
| /* calculate 1+((pw*pd+7)>>3) in row_bytes */ |
| digits = uarb_mult_digit(row_bytes, uarb_set(row_bytes, 7), |
| row_width, uarb_set(row_width, pw), pd); |
| digits = uarb_shift(row_bytes, digits, 3); |
| digits = uarb_inc(row_bytes, digits, 1); |
| |
| /* Add row_bytes * pass-height to the file image_bytes field |
| */ |
| image_digits = uarb_mult32(file->image_bytes, image_digits, |
| row_bytes, digits, |
| PNG_PASS_ROWS(file->height, pass)); |
| } |
| } |
| |
| file->image_digits = image_digits; |
| } |
| break; |
| |
| case PNG_INTERLACE_NONE: |
| { |
| int digits; |
| udigit row_width[2], row_bytes[3]; |
| |
| /* As above, but use image_width in place of the pass width: */ |
| digits = uarb_mult_digit(row_bytes, uarb_set(row_bytes, 7), |
| row_width, uarb_set(row_width, file->width), pd); |
| digits = uarb_shift(row_bytes, digits, 3); |
| digits = uarb_inc(row_bytes, digits, 1); |
| |
| /* Set row_bytes * image-height to the file image_bytes field */ |
| file->image_digits = uarb_mult32(file->image_bytes, 0, |
| row_bytes, digits, file->height); |
| } |
| break; |
| |
| default: |
| stop_invalid(file, "IHDR: interlace method"); |
| } |
| |
| assert(file->image_digits >= 1 && file->image_digits <= 5); |
| return 1; |
| } |
| |
| /* PER-CHUNK CONTROL STRUCTURE |
| * This structure is instantiated for each chunk, except for the IDAT chunks |
| * where one chunk control structure is used for the whole of a single stream of |
| * IDAT chunks (see the IDAT control structure below). |
| */ |
| struct chunk |
| { |
| /* ANCESTORS */ |
| struct file * file; |
| struct global * global; |
| |
| /* PUBLIC IDAT INFORMATION: SET BY THE ZLIB CODE */ |
| udigit uncompressed_bytes[5]; |
| int uncompressed_digits; |
| udigit compressed_bytes[5]; |
| int compressed_digits; |
| |
| /* PUBLIC PER-CHUNK INFORMATION: USED BY CHUNK READ CODE */ |
| /* This information is filled in by chunk_init from the data in the file |
| * control structure, but chunk_length may be changed later. |
| */ |
| fpos_t chunk_data_pos; /* Position of first byte of chunk data */ |
| png_uint_32 chunk_length; /* From header (or modified below) */ |
| png_uint_32 chunk_type; /* From header */ |
| |
| /* PUBLIC PER-CHUNK INFORMATION: FOR THE CHUNK WRITE CODE */ |
| png_uint_32 write_crc; /* Output CRC (may differ from read_crc) */ |
| png_uint_32 rewrite_offset; /* Count of bytes before rewrite. */ |
| int rewrite_length; /* Number of bytes left to change */ |
| png_byte rewrite_buffer[2]; /* Buffer of new byte values */ |
| }; |
| |
| static void |
| chunk_message(struct chunk *chunk, const char *message) |
| { |
| type_message(chunk->file, chunk->chunk_type, message); |
| } |
| |
| static void |
| chunk_end(struct chunk **chunk_var) |
| { |
| struct chunk *chunk = *chunk_var; |
| |
| *chunk_var = NULL; |
| CLEAR(*chunk); |
| } |
| |
| static void |
| chunk_init(struct chunk * const chunk, struct file * const file) |
| /* When a chunk is initialized the file length/type/pos are copied into the |
| * corresponding chunk fields and the new chunk is registered in the file |
| * structure. There can only be one chunk at a time. |
| * |
| * NOTE: this routine must onely be called from the file alloc routine! |
| */ |
| { |
| assert(file->chunk == NULL); |
| |
| CLEAR(*chunk); |
| |
| chunk->file = file; |
| chunk->global = file->global; |
| |
| chunk->chunk_data_pos = file->data_pos; |
| chunk->chunk_length = file->length; |
| chunk->chunk_type = file->type; |
| |
| /* Compresssed/uncompressed size information (from the zlib control structure |
| * that is used to check the compressed data in a chunk.) |
| */ |
| chunk->uncompressed_digits = 0; |
| chunk->compressed_digits = 0; |
| |
| file->chunk = chunk; |
| } |
| |
| static png_uint_32 |
| current_type(struct file *file, int code) |
| /* Guess the actual chunk type that causes a stop() */ |
| { |
| /* This may return png_IDAT for errors detected (late) in the header; that |
| * includes any inter-chunk consistency check that libpng performs. Assume |
| * that if the chunk_type is png_IDAT and the file write count is 8 this is |
| * what is happening. |
| */ |
| if (file->chunk != NULL) |
| { |
| png_uint_32 type = file->chunk->chunk_type; |
| |
| /* This is probably wrong for the excess IDATs case, because then libpng |
| * whines about too many of them (apparently in some cases erroneously) |
| * when the header is read. |
| */ |
| if (code <= LIBPNG_ERROR_CODE && type == png_IDAT && |
| file->write_count == 8) |
| type = 0; /* magic */ |
| |
| return type; |
| } |
| |
| else |
| return file->type; |
| } |
| |
| static void |
| setpos(struct chunk *chunk) |
| /* Reset the position to 'chunk_data_pos' - the start of the data for this |
| * chunk. As a side effect the read_count in the file is reset to 8, just |
| * after the length/type header. |
| */ |
| { |
| chunk->file->read_count = 8; |
| file_setpos(chunk->file, &chunk->chunk_data_pos); |
| } |
| |
| /* Specific chunk handling - called for each chunk header, all special chunk |
| * processing is initiated in these functions. |
| */ |
| /* The next functions handle special processing for those chunks with LZ data, |
| * the data is identified and checked for validity. If there are problems which |
| * cannot be corrected the routines return false, otherwise true (although |
| * modification to the zlib header may be required.) |
| * |
| * The compressed data is in zlib format (RFC1950) and consequently has a |
| * minimum length of 7 bytes. |
| */ |
| static int zlib_check(struct file *file, png_uint_32 offset); |
| |
| static int |
| process_zTXt_iCCP(struct file *file) |
| /* zTXt and iCCP have exactly the same form - keyword, null, compression |
| * method then compressed data. |
| */ |
| { |
| struct chunk *chunk = file->chunk; |
| png_uint_32 length; |
| png_uint_32 index = 0; |
| |
| assert(chunk != NULL && file->idat == NULL); |
| length = chunk->chunk_length; |
| setpos(chunk); |
| |
| while (length >= 9) |
| { |
| --length; |
| ++index; |
| if (reread_byte(file) == 0) /* keyword null terminator */ |
| { |
| --length; |
| ++index; |
| (void)reread_byte(file); /* compression method */ |
| return zlib_check(file, index); |
| } |
| } |
| |
| chunk_message(chunk, "too short"); |
| return 0; /* skip */ |
| } |
| |
| static int |
| process_iTXt(struct file *file) |
| { |
| /* Like zTXt but more fields. */ |
| struct chunk *chunk = file->chunk; |
| png_uint_32 length; |
| png_uint_32 index = 0; |
| |
| assert(chunk != NULL && file->idat == NULL); |
| length = chunk->chunk_length; |
| setpos(chunk); |
| |
| while (length >= 5) |
| { |
| --length; |
| ++index; |
| if (reread_byte(file) == 0) /* keyword null terminator */ |
| { |
| --length; |
| ++index; |
| if (reread_byte(file) == 0) /* uncompressed text */ |
| return 1; /* nothing to check */ |
| |
| --length; |
| ++index; |
| (void)reread_byte(file); /* compression method */ |
| |
| /* Skip the language tag (null terminated). */ |
| while (length >= 9) |
| { |
| --length; |
| ++index; |
| if (reread_byte(file) == 0) /* terminator */ |
| { |
| /* Skip the translated keyword */ |
| while (length >= 8) |
| { |
| --length; |
| ++index; |
| if (reread_byte(file) == 0) /* terminator */ |
| return zlib_check(file, index); |
| } |
| } |
| } |
| |
| /* Ran out of bytes in the compressed case. */ |
| break; |
| } |
| } |
| |
| log_error(file, INVALID_ERROR_CODE, "iTXt chunk length"); |
| |
| return 0; /* skip */ |
| } |
| |
| /* IDAT READ/WRITE CONTROL STRUCTURE */ |
| struct IDAT |
| { |
| /* ANCESTORS */ |
| struct file * file; |
| struct global * global; |
| |
| /* PROTECTED IDAT INFORMATION: SET BY THE IDAT READ CODE */ |
| struct IDAT_list *idat_list_head; /* START of the list of IDAT information */ |
| struct IDAT_list *idat_list_tail; /* *END* of the list of IDAT information */ |
| |
| /* PROTECTED IDAT INFORMATION: USED BY THE IDAT WRITE CODE */ |
| struct IDAT_list *idat_cur; /* Current list entry */ |
| unsigned int idat_count; /* And the *current* index into the list */ |
| png_uint_32 idat_index; /* Index of *next* input byte to write */ |
| png_uint_32 idat_length; /* Cache of current chunk length */ |
| }; |
| |
| /* NOTE: there is currently no IDAT_reset, so a stream cannot contain more than |
| * one IDAT sequence (i.e. MNG is not supported). |
| */ |
| |
| static void |
| IDAT_end(struct IDAT **idat_var) |
| { |
| struct IDAT *idat = *idat_var; |
| struct file *file = idat->file; |
| |
| *idat_var = NULL; |
| |
| CLEAR(*idat); |
| |
| assert(file->chunk != NULL); |
| chunk_end(&file->chunk); |
| |
| /* Regardless of why the IDAT was killed set the state back to CHUNKS (it may |
| * already be CHUNKS because the state isn't changed until process_IDAT |
| * returns; a stop will cause IDAT_end to be entered in state CHUNKS!) |
| */ |
| file->state = STATE_CHUNKS; |
| } |
| |
| static void |
| IDAT_init(struct IDAT * const idat, struct file * const file) |
| /* When the chunk is png_IDAT instantiate an IDAT control structure in place |
| * of a chunk control structure. The IDAT will instantiate a chunk control |
| * structure using the file alloc routine. |
| * |
| * NOTE: this routine must only be called from the file alloc routine! |
| */ |
| { |
| assert(file->chunk == NULL); |
| assert(file->idat == NULL); |
| |
| CLEAR(*idat); |
| |
| idat->file = file; |
| idat->global = file->global; |
| |
| /* Initialize the tail to the pre-allocated buffer and set the count to 0 |
| * (empty.) |
| */ |
| idat->global->idat_cache.count = 0; |
| idat->idat_list_head = idat->idat_list_tail = &idat->global->idat_cache; |
| |
| /* Now the chunk. The allocator calls the initializer of the new chunk and |
| * stores the result in file->chunk: |
| */ |
| file->alloc(file, 0/*chunk*/); |
| assert(file->chunk != NULL); |
| |
| /* And store this for cleanup (and to check for double alloc or failure to |
| * free.) |
| */ |
| file->idat = idat; |
| } |
| |
| static png_uint_32 |
| rechunk_length(struct IDAT *idat) |
| /* Return the length for the next IDAT chunk, taking into account |
| * rechunking. |
| */ |
| { |
| png_uint_32 len = idat->global->idat_max; |
| |
| if (len == 0) /* use original chunk lengths */ |
| { |
| const struct IDAT_list *cur; |
| unsigned int count; |
| |
| if (idat->idat_index == 0) /* at the new chunk (first time) */ |
| return idat->idat_length; /* use the cache */ |
| |
| /* Otherwise rechunk_length is called at the end of a chunk for the length |
| * of the next one. |
| */ |
| cur = idat->idat_cur; |
| count = idat->idat_count; |
| |
| assert(idat->idat_index == idat->idat_length && |
| idat->idat_length == cur->lengths[count]); |
| |
| /* Return length of the *next* chunk */ |
| if (++count < cur->count) |
| return cur->lengths[count]; |
| |
| /* End of this list */ |
| assert(cur != idat->idat_list_tail); |
| cur = cur->next; |
| assert(cur != NULL && cur->count > 0); |
| return cur->lengths[0]; |
| } |
| |
| else /* rechunking */ |
| { |
| /* The chunk size is the lesser of file->idat_max and the number |
| * of remaining bytes. |
| */ |
| png_uint_32 have = idat->idat_length - idat->idat_index; |
| |
| if (len > have) |
| { |
| struct IDAT_list *cur = idat->idat_cur; |
| unsigned int j = idat->idat_count+1; /* the next IDAT in the list */ |
| |
| do |
| { |
| /* Add up the remaining bytes. This can't overflow because the |
| * individual lengths are always <= 0x7fffffff, so when we add two |
| * of them overflow is not possible. |
| */ |
| assert(cur != NULL); |
| |
| for (;;) |
| { |
| /* NOTE: IDAT_list::count here, not IDAT_list::length */ |
| for (; j < cur->count; ++j) |
| { |
| have += cur->lengths[j]; |
| if (len <= have) |
| return len; |
| } |
| |
| /* If this was the end return the count of the available bytes */ |
| if (cur == idat->idat_list_tail) |
| return have; |
| |
| cur = cur->next; |
| j = 0; |
| } |
| } |
| while (len > have); |
| } |
| |
| return len; |
| } |
| } |
| |
| static int |
| process_IDAT(struct file *file) |
| /* Process the IDAT stream, this is the more complex than the preceding |
| * cases because the compressed data is spread across multiple IDAT chunks |
| * (typically). Rechunking of the data is not handled here; all this |
| * function does is establish whether the zlib header needs to be modified. |
| * |
| * Initially the function returns false, indicating that the chunk should not |
| * be written. It does this until the last IDAT chunk is passed in, then it |
| * checks the zlib data and returns true. |
| * |
| * It does not return false on a fatal error; it calls stop instead. |
| * |
| * The caller must have an instantiated (IDAT) control structure and it must |
| * have extent over the whole read of the IDAT stream. For a PNG this means |
| * the whole PNG read, for MNG it could have lesser extent. |
| */ |
| { |
| struct IDAT_list *list; |
| |
| assert(file->idat != NULL && file->chunk != NULL); |
| |
| /* We need to first check the entire sequence of IDAT chunks to ensure the |
| * stream is in sync. Do this by building a list of all the chunks and |
| * recording the length of each because the length may have been fixed up by |
| * sync_stream below. |
| * |
| * At the end of the list of chunks, where the type of the next chunk is not |
| * png_IDAT, process the whole stream using the list data to check validity |
| * then return control to the start and rewrite everything. |
| */ |
| list = file->idat->idat_list_tail; |
| |
| if (list->count == list->length) |
| { |
| list = IDAT_list_extend(list); |
| |
| if (list == NULL) |
| stop(file, READ_ERROR_CODE, "out of memory"); |
| |
| /* Move to the next block */ |
| list->count = 0; |
| file->idat->idat_list_tail = list; |
| } |
| |
| /* And fill in the next IDAT information buffer. */ |
| list->lengths[(list->count)++] = file->chunk->chunk_length; |
| |
| /* The type of the next chunk was recorded in the file control structure by |
| * the caller, if this is png_IDAT return 'skip' to the caller. |
| */ |
| if (file->type == png_IDAT) |
| return 0; /* skip this for the moment */ |
| |
| /* This is the final IDAT chunk, so run the tests to check for the too far |
| * back error and possibly optimize the window bits. This means going back |
| * to the start of the first chunk data, which is stored in the original |
| * chunk allocation. |
| */ |
| setpos(file->chunk); |
| |
| if (zlib_check(file, 0)) |
| { |
| struct IDAT *idat; |
| int cmp; |
| |
| /* The IDAT stream was successfully uncompressed; see whether it |
| * contained the correct number of bytes of image data. |
| */ |
| cmp = uarb_cmp(file->image_bytes, file->image_digits, |
| file->chunk->uncompressed_bytes, file->chunk->uncompressed_digits); |
| |
| if (cmp < 0) |
| type_message(file, png_IDAT, "extra uncompressed data"); |
| |
| else if (cmp > 0) |
| stop(file, LIBPNG_ERROR_CODE, "IDAT: uncompressed data too small"); |
| |
| /* Return the stream to the start of the first IDAT chunk; the length |
| * is set in the write case below but the input chunk variables must be |
| * set (once) here: |
| */ |
| setpos(file->chunk); |
| |
| idat = file->idat; |
| idat->idat_cur = idat->idat_list_head; |
| idat->idat_length = idat->idat_cur->lengths[0]; |
| idat->idat_count = 0; /* Count of chunks read in current list */ |
| idat->idat_index = 0; /* Index into chunk data */ |
| |
| /* Update the chunk length to the correct value for the IDAT chunk: */ |
| file->chunk->chunk_length = rechunk_length(idat); |
| |
| /* Change the state to writing IDAT chunks */ |
| file->state = STATE_IDAT; |
| |
| return 1; |
| } |
| |
| else /* Failure to decompress the IDAT stream; give up. */ |
| stop(file, ZLIB_ERROR_CODE, "could not uncompress IDAT"); |
| } |
| |
| /* ZLIB CONTROL STRUCTURE */ |
| struct zlib |
| { |
| /* ANCESTORS */ |
| struct IDAT * idat; /* NOTE: May be NULL */ |
| struct chunk * chunk; |
| struct file * file; |
| struct global *global; |
| |
| /* GLOBAL ZLIB INFORMATION: SET BY THE CALLER */ |
| png_uint_32 rewrite_offset; |
| |
| /* GLOBAL ZLIB INFORMATION: SET BY THE ZLIB READ CODE */ |
| udigit compressed_bytes[5]; |
| int compressed_digits; |
| udigit uncompressed_bytes[5]; |
| int uncompressed_digits; |
| int file_bits; /* window bits from the file */ |
| int ok_bits; /* Set <16 on a successful read */ |
| int cksum; /* Set on a checksum error */ |
| |
| /* PROTECTED ZLIB INFORMATION: USED BY THE ZLIB ROUTINES */ |
| z_stream z; |
| png_uint_32 extra_bytes; /* Count of extra compressed bytes */ |
| int state; |
| int rc; /* Last return code */ |
| int window_bits; /* 0 if no change */ |
| png_byte header[2]; |
| }; |
| |
| static const char * |
| zlib_flevel(struct zlib *zlib) |
| { |
| switch (zlib->header[1] >> 6) |
| { |
| case 0: return "supfast"; |
| case 1: return "stdfast"; |
| case 2: return "default"; |
| case 3: return "maximum"; |
| default: assert(UNREACHED); |
| } |
| |
| return "COMPILER BUG"; |
| } |
| |
| static const char * |
| zlib_rc(struct zlib *zlib) |
| /* Return a string for the zlib return code */ |
| { |
| switch (zlib->rc) |
| { |
| case Z_OK: return "Z_OK"; |
| case Z_STREAM_END: return "Z_STREAM_END"; |
| case Z_NEED_DICT: return "Z_NEED_DICT"; |
| case Z_ERRNO: return "Z_ERRNO"; |
| case Z_STREAM_ERROR: return "Z_STREAM_ERROR"; |
| case Z_DATA_ERROR: return "Z_DATA_ERROR"; |
| case Z_MEM_ERROR: return "Z_MEM_ERROR"; |
| case Z_BUF_ERROR: return "Z_BUF_ERROR"; |
| case Z_VERSION_ERROR: return "Z_VERSION_ERROR"; |
| default: return "Z_*INVALID_RC*"; |
| } |
| } |
| |
| static void |
| zlib_message(struct zlib *zlib, int unexpected) |
| /* Output a message given a zlib rc */ |
| { |
| if (zlib->global->errors) |
| { |
| const char *reason = zlib->z.msg; |
| |
| if (reason == NULL) |
| reason = "[no message]"; |
| |
| fputs(zlib->file->file_name, stderr); |
| type_sep(stderr); |
| type_name(zlib->chunk->chunk_type, stderr); |
| fprintf(stderr, ": %szlib error: %d (%s) (%s)\n", |
| unexpected ? "unexpected " : "", zlib->rc, zlib_rc(zlib), reason); |
| } |
| } |
| |
| static void |
| zlib_end(struct zlib *zlib) |
| { |
| /* Output the summary line now; this ensures a summary line always gets |
| * output regardless of the manner of exit. |
| */ |
| if (!zlib->global->quiet) |
| { |
| if (zlib->ok_bits < 16) /* stream was read ok */ |
| { |
| const char *reason; |
| |
| if (zlib->cksum) |
| reason = "CHK"; /* checksum error */ |
| |
| else if (zlib->ok_bits > zlib->file_bits) |
| reason = "TFB"; /* fixing a too-far-back error */ |
| |
| else if (zlib->ok_bits == zlib->file_bits) |
| reason = "OK "; |
| |
| else |
| reason = "OPT"; /* optimizing window bits */ |
| |
| /* SUMMARY FORMAT (for a successful zlib inflate): |
| * |
| * IDAT reason flevel file-bits ok-bits compressed uncompressed file |
| */ |
| type_name(zlib->chunk->chunk_type, stdout); |
| printf(" %s %s %d %d ", reason, zlib_flevel(zlib), zlib->file_bits, |
| zlib->ok_bits); |
| uarb_print(zlib->compressed_bytes, zlib->compressed_digits, stdout); |
| putc(' ', stdout); |
| uarb_print(zlib->uncompressed_bytes, zlib->uncompressed_digits, |
| stdout); |
| putc(' ', stdout); |
| fputs(zlib->file->file_name, stdout); |
| putc('\n', stdout); |
| } |
| |
| else |
| { |
| /* This is a zlib read error; the chunk will be skipped. For an IDAT |
| * stream this will also cause a fatal read error (via stop()). |
| * |
| * SUMMARY FORMAT: |
| * |
| * IDAT SKP flevel file-bits z-rc compressed message file |
| * |
| * z-rc is the zlib failure code; message is the error message with |
| * spaces replaced by '-'. The compressed byte count indicates where |
| * in the zlib stream the error occurred. |
| */ |
| type_name(zlib->chunk->chunk_type, stdout); |
| printf(" SKP %s %d %s ", zlib_flevel(zlib), zlib->file_bits, |
| zlib_rc(zlib)); |
| uarb_print(zlib->compressed_bytes, zlib->compressed_digits, stdout); |
| putc(' ', stdout); |
| emit_string(zlib->z.msg ? zlib->z.msg : "[no_message]", stdout); |
| putc(' ', stdout); |
| fputs(zlib->file->file_name, stdout); |
| putc('\n', stdout); |
| } |
| } |
| |
| if (zlib->state >= 0) |
| { |
| zlib->rc = inflateEnd(&zlib->z); |
| |
| if (zlib->rc != Z_OK) |
| zlib_message(zlib, 1/*unexpected*/); |
| } |
| |
| CLEAR(*zlib); |
| } |
| |
| static int |
| zlib_reset(struct zlib *zlib, int window_bits) |
| /* Reinitializes a zlib with a different window_bits */ |
| { |
| assert(zlib->state >= 0); /* initialized by zlib_init */ |
| |
| zlib->z.next_in = Z_NULL; |
| zlib->z.avail_in = 0; |
| zlib->z.next_out = Z_NULL; |
| zlib->z.avail_out = 0; |
| |
| zlib->window_bits = window_bits; |
| zlib->compressed_digits = 0; |
| zlib->uncompressed_digits = 0; |
| |
| zlib->state = 0; /* initialized, once */ |
| zlib->rc = inflateReset2(&zlib->z, 0); |
| if (zlib->rc != Z_OK) |
| { |
| zlib_message(zlib, 1/*unexpected*/); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static int |
| zlib_init(struct zlib *zlib, struct IDAT *idat, struct chunk *chunk, |
| int window_bits, png_uint_32 offset) |
| /* Initialize a zlib_control; the result is true/false */ |
| { |
| CLEAR(*zlib); |
| |
| zlib->idat = idat; |
| zlib->chunk = chunk; |
| zlib->file = chunk->file; |
| zlib->global = chunk->global; |
| zlib->rewrite_offset = offset; /* never changed for this zlib */ |
| |
| /* *_out does not need to be set: */ |
| zlib->z.next_in = Z_NULL; |
| zlib->z.avail_in = 0; |
| zlib->z.zalloc = Z_NULL; |
| zlib->z.zfree = Z_NULL; |
| zlib->z.opaque = Z_NULL; |
| |
| zlib->state = -1; |
| zlib->window_bits = window_bits; |
| |
| zlib->compressed_digits = 0; |
| zlib->uncompressed_digits = 0; |
| |
| /* These values are sticky across reset (in addition to the stuff in the |
| * first block, which is actually constant.) |
| */ |
| zlib->file_bits = 24; |
| zlib->ok_bits = 16; /* unset */ |
| zlib->cksum = 0; /* set when a checksum error is detected */ |
| |
| /* '0' means use the header; inflateInit2 should always succeed because it |
| * does nothing apart from allocating the internal zstate. |
| */ |
| zlib->rc = inflateInit2(&zlib->z, 0); |
| if (zlib->rc != Z_OK) |
| { |
| zlib_message(zlib, 1/*unexpected*/); |
| return 0; |
| } |
| |
| else |
| { |
| zlib->state = 0; /* initialized */ |
| return 1; |
| } |
| } |
| |
| static int |
| max_window_bits(uarbc size, int ndigits) |
| /* Return the zlib stream window bits required for data of the given size. */ |
| { |
| png_uint_16 cb; |
| |
| if (ndigits > 1) |
| return 15; |
| |
| cb = size[0]; |
| |
| if (cb > 16384) return 15; |
| if (cb > 8192) return 14; |
| if (cb > 4096) return 13; |
| if (cb > 2048) return 12; |
| if (cb > 1024) return 11; |
| if (cb > 512) return 10; |
| if (cb > 256) return 9; |
| return 8; |
| } |
| |
| static int |
| zlib_advance(struct zlib *zlib, png_uint_32 nbytes) |
| /* Read nbytes compressed bytes; the stream will be initialized if required. |
| * Bytes are always being reread and errors are fatal. The return code is as |
| * follows: |
| * |
| * -1: saw the "too far back" error |
| * 0: ok, keep going |
| * 1: saw Z_STREAM_END (zlib->extra_bytes indicates too much data) |
| * 2: a zlib error that cannot be corrected (error message already |
| * output if required.) |
| */ |
| # define ZLIB_TOO_FAR_BACK (-1) |
| # define ZLIB_OK 0 |
| # define ZLIB_STREAM_END 1 |
| # define ZLIB_FATAL 2 |
| { |
| int state = zlib->state; |
| int endrc = ZLIB_OK; |
| png_uint_32 in_bytes = 0; |
| struct file *file = zlib->file; |
| |
| assert(state >= 0); |
| |
| while (in_bytes < nbytes && endrc == ZLIB_OK) |
| { |
| png_uint_32 out_bytes; |
| int flush; |
| png_byte bIn = reread_byte(file); |
| png_byte bOut; |
| |
| switch (state) |
| { |
| case 0: /* first header byte */ |
| { |
| int file_bits = 8+(bIn >> 4); |
| int new_bits = zlib->window_bits; |
| |
| zlib->file_bits = file_bits; |
| |
| /* Check against the existing value - it may not need to be |
| * changed. Note that a bogus file_bits is allowed through once, |
| * to see if it works, but the window_bits value is set to 15, |
| * the maximum. |
| */ |
| if (new_bits == 0) /* no change */ |
| zlib->window_bits = ((file_bits > 15) ? 15 : file_bits); |
| |
| else if (new_bits != file_bits) /* rewrite required */ |
| bIn = (png_byte)((bIn & 0xf) + ((new_bits-8) << 4)); |
| } |
| |
| zlib->header[0] = bIn; |
| zlib->state = state = 1; |
| break; |
| |
| case 1: /* second header byte */ |
| { |
| int b2 = bIn & 0xe0; /* top 3 bits */ |
| |
| /* The checksum calculation, on the first 11 bits: */ |
| b2 += 0x1f - ((zlib->header[0] << 8) + b2) % 0x1f; |
| |
| /* Update the checksum byte if required: */ |
| if (bIn != b2) |
| { |
| /* If the first byte wasn't changed this indicates an error in |
| * the checksum calculation; signal this by setting 'cksum'. |
| */ |
| if (zlib->file_bits == zlib->window_bits) |
| zlib->cksum = 1; |
| |
| bIn = (png_byte)b2; |
| } |
| } |
| |
| zlib->header[1] = bIn; |
| zlib->state = state = 2; |
| break; |
| |
| default: /* After the header bytes */ |
| break; |
| } |
| |
| /* For some streams, perhaps only those compressed with 'superfast |
| * compression' (which results in a lot of copying) Z_BUF_ERROR can happen |
| * immediately after all output has been flushed on the next input byte. |
| * This is handled below when Z_BUF_ERROR is detected by adding an output |
| * byte. |
| */ |
| zlib->z.next_in = &bIn; |
| zlib->z.avail_in = 1; |
| zlib->z.next_out = &bOut; |
| zlib->z.avail_out = 0; /* Initially */ |
| |
| /* Initially use Z_NO_FLUSH in an attempt to persuade zlib to look at this |
| * byte without confusing what is going on with output. |
| */ |
| flush = Z_NO_FLUSH; |
| out_bytes = 0; |
| |
| /* NOTE: expression 3 is only evaluted on 'continue', because of the |
| * 'break' at the end of this loop below. |
| */ |
| for (;endrc == ZLIB_OK; |
| flush = Z_SYNC_FLUSH, |
| zlib->z.next_out = &bOut, |
| zlib->z.avail_out = 1, |
| ++out_bytes) |
| { |
| zlib->rc = inflate(&zlib->z, flush); |
| out_bytes -= zlib->z.avail_out; |
| |
| switch (zlib->rc) |
| { |
| case Z_BUF_ERROR: |
| if (zlib->z.avail_out == 0) |
| continue; /* Try another output byte. */ |
| |
| if (zlib->z.avail_in == 0) |
| break; /* Try another input byte */ |
| |
| /* Both avail_out and avail_in are 1 yet zlib returned a code |
| * indicating no progress was possible. This is unexpected. |
| */ |
| zlib_message(zlib, 1/*unexpected*/); |
| endrc = ZLIB_FATAL; /* stop processing */ |
| break; |
| |
| case Z_OK: |
| /* Zlib is supposed to have made progress: */ |
| assert(zlib->z.avail_out == 0 || zlib->z.avail_in == 0); |
| continue; |
| |
| case Z_STREAM_END: |
| /* This is the successful end. */ |
| zlib->state = 3; /* end of stream */ |
| endrc = ZLIB_STREAM_END; |
| break; |
| |
| case Z_NEED_DICT: |
| zlib_message(zlib, 0/*stream error*/); |
| endrc = ZLIB_FATAL; |
| break; |
| |
| case Z_DATA_ERROR: |
| /* The too far back error can be corrected, others cannot: */ |
| if (zlib->z.msg != NULL && |
| strcmp(zlib->z.msg, "invalid distance too far back") == 0) |
| { |
| endrc = ZLIB_TOO_FAR_BACK; |
| break; |
| } |
| /* FALL THROUGH */ |
| |
| default: |
| zlib_message(zlib, 0/*stream error*/); |
| endrc = ZLIB_FATAL; |
| break; |
| } /* switch (inflate rc) */ |
| |
| /* Control gets here when further output is not possible; endrc may |
| * still be ZLIB_OK if more input is required. |
| */ |
| break; |
| } /* for (output bytes) */ |
| |
| /* Keep a running count of output byte produced: */ |
| zlib->uncompressed_digits = uarb_add32(zlib->uncompressed_bytes, |
| zlib->uncompressed_digits, out_bytes); |
| |
| /* Keep going, the loop will terminate when endrc is no longer set to |
| * ZLIB_OK or all the input bytes have been consumed; meanwhile keep |
| * adding input bytes. |
| */ |
| assert(zlib->z.avail_in == 0 || endrc != ZLIB_OK); |
| |
| in_bytes += 1 - zlib->z.avail_in; |
| } /* while (input bytes) */ |
| |
| assert(in_bytes == nbytes || endrc != ZLIB_OK); |
| |
| /* Update the running total of input bytes consumed */ |
| zlib->compressed_digits = uarb_add32(zlib->compressed_bytes, |
| zlib->compressed_digits, in_bytes - zlib->z.avail_in); |
| |
| /* At the end of the stream update the chunk with the accumulated |
| * information if it is an improvement: |
| */ |
| if (endrc == ZLIB_STREAM_END && zlib->window_bits < zlib->ok_bits) |
| { |
| struct chunk *chunk = zlib->chunk; |
| |
| chunk->uncompressed_digits = uarb_copy(chunk->uncompressed_bytes, |
| zlib->uncompressed_bytes, zlib->uncompressed_digits); |
| chunk->compressed_digits = uarb_copy(chunk->compressed_bytes, |
| zlib->compressed_bytes, zlib->compressed_digits); |
| chunk->rewrite_buffer[0] = zlib->header[0]; |
| chunk->rewrite_buffer[1] = zlib->header[1]; |
| |
| if (zlib->window_bits != zlib->file_bits || zlib->cksum) |
| { |
| /* A rewrite is required */ |
| chunk->rewrite_offset = zlib->rewrite_offset; |
| chunk->rewrite_length = 2; |
| } |
| |
| else |
| { |
| chunk->rewrite_offset = 0; |
| chunk->rewrite_length = 0; |
| } |
| |
| if (in_bytes < nbytes) |
| chunk_message(chunk, "extra compressed data"); |
| |
| zlib->extra_bytes = nbytes - in_bytes; |
| zlib->ok_bits = zlib->window_bits; |
| } |
| |
| return endrc; |
| } |
| |
| static int |
| zlib_run(struct zlib *zlib) |
| /* Like zlib_advance but also handles a stream of IDAT chunks. */ |
| { |
| /* The 'extra_bytes' field is set by zlib_advance if there is extra |
| * compressed data in the chunk it handles (if it sees Z_STREAM_END before |
| * all the input data has been used.) This function uses the value to update |
| * the correct chunk length, so the problem should only ever be detected once |
| * for each chunk. zlib_advance outputs the error message, though see the |
| * IDAT specific check below. |
| */ |
| zlib->extra_bytes = 0; |
| |
| if (zlib->idat != NULL) |
| { |
| struct IDAT_list *list = zlib->idat->idat_list_head; |
| struct IDAT_list *last = zlib->idat->idat_list_tail; |
| int skip = 0; |
| |
| /* 'rewrite_offset' is the offset of the LZ data within the chunk, for |
| * IDAT it should be 0: |
| */ |
| assert(zlib->rewrite_offset == 0); |
| |
| /* Process each IDAT_list in turn; the caller has left the stream |
| * positioned at the start of the first IDAT chunk data. |
| */ |
| for (;;) |
| { |
| const unsigned int count = list->count; |
| unsigned int i; |
| |
| for (i = 0; i<count; ++i) |
| { |
| int rc; |
| |
| if (skip > 0) /* Skip CRC and next IDAT header */ |
| skip_12(zlib->file); |
| |
| skip = 12; /* for the next time */ |
| |
| rc = zlib_advance(zlib, list->lengths[i]); |
| |
| switch (rc) |
| { |
| case ZLIB_OK: /* keep going */ |
| break; |
| |
| case ZLIB_STREAM_END: /* stop */ |
| /* There may be extra chunks; if there are and one of them is |
| * not zero length output the 'extra data' message. Only do |
| * this check if errors are being output. |
| */ |
| if (zlib->global->errors && zlib->extra_bytes == 0) |
| { |
| struct IDAT_list *check = list; |
| int j = i+1, jcount = count; |
| |
| for (;;) |
| { |
| for (; j<jcount; ++j) |
| if (check->lengths[j] > 0) |
| { |
| chunk_message(zlib->chunk, |
| "extra compressed data"); |
| goto end_check; |
| } |
| |
| if (check == last) |
| break; |
| |
| check = check->next; |
| jcount = check->count; |
| j = 0; |
| } |
| } |
| |
| end_check: |
| /* Terminate the list at the current position, reducing the |
| * length of the last IDAT too if required. |
| */ |
| list->lengths[i] -= zlib->extra_bytes; |
| list->count = i+1; |
| zlib->idat->idat_list_tail = list; |
| /* FALL THROUGH */ |
| |
| default: |
| return rc; |
| } |
| } |
| |
| /* At the end of the compressed data and Z_STREAM_END was not seen. */ |
| if (list == last) |
| return ZLIB_OK; |
| |
| list = list->next; |
| } |
| } |
| |
| else |
| { |
| struct chunk *chunk = zlib->chunk; |
| int rc; |
| |
| assert(zlib->rewrite_offset < chunk->chunk_length); |
| |
| rc = zlib_advance(zlib, chunk->chunk_length - zlib->rewrite_offset); |
| |
| /* The extra bytes in the chunk are handled now by adjusting the chunk |
| * length to exclude them; the zlib data is always stored at the end of |
| * the PNG chunk (although clearly this is not necessary.) zlib_advance |
| * has already output a warning message. |
| */ |
| chunk->chunk_length -= zlib->extra_bytes; |
| return rc; |
| } |
| } |
| |
| static int /* global function; not a member function */ |
| zlib_check(struct file *file, png_uint_32 offset) |
| /* Check the stream of zlib compressed data in either idat (if given) or (if |
| * not) chunk. In fact it is zlib_run that handles the difference in reading |
| * a single chunk and a list of IDAT chunks. |
| * |
| * In either case the input file must be positioned at the first byte of zlib |
| * compressed data (the first header byte). |
| * |
| * The return value is true on success, including the case where the zlib |
| * header may need to be rewritten, and false on an unrecoverable error. |
| * |
| * In the case of IDAT chunks 'offset' should be 0. |
| */ |
| { |
| fpos_t start_pos; |
| struct zlib zlib; |
| |
| /* Record the start of the LZ data to allow a re-read. */ |
| file_getpos(file, &start_pos); |
| |
| /* First test the existing (file) window bits: */ |
| if (zlib_init(&zlib, file->idat, file->chunk, 0/*window bits*/, offset)) |
| { |
| int min_bits, max_bits, rc; |
| |
| /* The first run using the existing window bits. */ |
| rc = zlib_run(&zlib); |
| |
| switch (rc) |
| { |
| case ZLIB_TOO_FAR_BACK: |
| /* too far back error */ |
| file->status_code |= TOO_FAR_BACK; |
| min_bits = zlib.window_bits + 1; |
| max_bits = 15; |
| break; |
| |
| case ZLIB_STREAM_END: |
| if (!zlib.global->optimize_zlib && |
| zlib.window_bits == zlib.file_bits && !zlib.cksum) |
| { |
| /* The trivial case where the stream is ok and optimization was |
| * not requested. |
| */ |
| zlib_end(&zlib); |
| return 1; |
| } |
| |
| max_bits = max_window_bits(zlib.uncompressed_bytes, |
| zlib.uncompressed_digits); |
| if (zlib.ok_bits < max_bits) |
| max_bits = zlib.ok_bits; |
| min_bits = 8; |
| |
| /* cksum is set if there is an error in the zlib header checksum |
| * calculation in the original file (and this may be the only reason |
| * a rewrite is required). We can't rely on the file window bits in |
| * this case, so do the optimization anyway. |
| */ |
| if (zlib.cksum) |
| chunk_message(zlib.chunk, "zlib checkum"); |
| break; |
| |
| |
| case ZLIB_OK: |
| /* Truncated stream; unrecoverable, gets converted to ZLIB_FATAL */ |
| zlib.z.msg = PNGZ_MSG_CAST("[truncated]"); |
| zlib_message(&zlib, 0/*expected*/); |
| /* FALL THROUGH */ |
| |
| default: |
| /* Unrecoverable error; skip the chunk; a zlib_message has already |
| * been output. |
| */ |
| zlib_end(&zlib); |
| return 0; |
| } |
| |
| /* Optimize window bits or fix a too-far-back error. min_bits and |
| * max_bits have been set appropriately, ok_bits records the bit value |
| * known to work. |
| */ |
| while (min_bits < max_bits || max_bits < zlib.ok_bits/*if 16*/) |
| { |
| int test_bits = (min_bits + max_bits) >> 1; |
| |
| if (zlib_reset(&zlib, test_bits)) |
| { |
| file_setpos(file, &start_pos); |
| rc = zlib_run(&zlib); |
| |
| switch (rc) |
| { |
| case ZLIB_TOO_FAR_BACK: |
| min_bits = test_bits+1; |
| if (min_bits > max_bits) |
| { |
| /* This happens when the stream really is damaged and it |
| * contains a distance code that addresses bytes before |
| * the start of the uncompressed data. |
| */ |
| assert(test_bits == 15); |
| |
| /* Output the error that wasn't output before: */ |
| if (zlib.z.msg == NULL) |
| zlib.z.msg = PNGZ_MSG_CAST( |
| "invalid distance too far back"); |
| zlib_message(&zlib, 0/*stream error*/); |
| zlib_end(&zlib); |
| return 0; |
| } |
| break; |
| |
| case ZLIB_STREAM_END: /* success */ |
| max_bits = test_bits; |
| break; |
| |
| default: |
| /* A fatal error; this happens if a too-far-back error was |
| * hiding a more serious error, zlib_advance has already |
| * output a zlib_message. |
| */ |
| zlib_end(&zlib); |
| return 0; |
| } |
| } |
| |
| else /* inflateReset2 failed */ |
| { |
| zlib_end(&zlib); |
| return 0; |
| } |
| } |
| |
| /* The loop guarantees this */ |
| assert(zlib.ok_bits == max_bits); |
| zlib_end(&zlib); |
| return 1; |
| } |
| |
| else /* zlib initialization failed - skip the chunk */ |
| { |
| zlib_end(&zlib); |
| return 0; |
| } |
| } |
| |
| /***************************** LIBPNG CALLBACKS *******************************/ |
| /* The strategy here is to run a regular libpng PNG file read but examine the |
| * input data (from the file) before passing it to libpng so as to be aware of |
| * the state we expect libpng to be in. Warning and error callbacks are also |
| * intercepted so that they can be quieted and interpreted. Interpretation |
| * depends on a somewhat risky string match for known error messages; let us |
| * hope that this can be fixed in the next version of libpng. |
| * |
| * The control structure is pointed to by the libpng error pointer. It contains |
| * that set of structures which must persist across multiple read callbacks, |
| * which is pretty much everything except the 'zlib' control structure. |
| * |
| * The file structure is instantiated in the caller of the per-file routine, but |
| * the per-file routine contains the chunk and IDAT control structures. |
| */ |
| /* The three routines read_chunk, process_chunk and sync_stream can only be |
| * called via a call to read_chunk and only exit at a return from process_chunk. |
| * These routines could have been written as one confusing large routine, |
| * instead this code relies on the compiler to do tail call elimination. The |
| * possible calls are as follows: |
| * |
| * read_chunk |
| * -> sync_stream |
| * -> process_chunk |
| * -> process_chunk |
| * -> read_chunk |
| * returns |
| */ |
| static void read_chunk(struct file *file); |
| static void |
| process_chunk(struct file *file, png_uint_32 file_crc, png_uint_32 next_length, |
| png_uint_32 next_type) |
| /* Called when the chunk data has been read, next_length and next_type |
| * will be set for the next chunk (or 0 if this is IEND). |
| * |
| * When this routine returns, chunk_length and chunk_type will be set for the |
| * next chunk to write because if a chunk is skipped this return calls back |
| * to read_chunk. |
| */ |
| { |
| const png_uint_32 type = file->type; |
| |
| if (file->global->verbose > 1) |
| { |
| fputs(" ", stderr); |
| type_name(file->type, stderr); |
| fprintf(stderr, " %lu 0x%.8x 0x%.8x\n", (unsigned long)file->length, |
| file->crc ^ 0xffffffff, file_crc); |
| } |
| |
| /* The basic structure seems correct but the CRC may not match, in this |
| * case assume that it is simply a bad CRC, either wrongly calculated or |
| * because of damaged stream data. |
| */ |
| if ((file->crc ^ 0xffffffff) != file_crc) |
| { |
| /* The behavior is set by the 'skip' setting; if it is anything other |
| * than SKIP_BAD_CRC ignore the bad CRC and return the chunk, with a |
| * corrected CRC and possibly processed, to libpng. Otherwise skip the |
| * chunk, which will result in a fatal error if the chunk is critical. |
| */ |
| file->status_code |= CRC_ERROR; |
| |
| /* Ignore the bad CRC */ |
| if (file->global->skip != SKIP_BAD_CRC) |
| type_message(file, type, "bad CRC"); |
| |
| /* This will cause an IEND with a bad CRC to stop */ |
| else if (CRITICAL(type)) |
| stop(file, READ_ERROR_CODE, "bad CRC in critical chunk"); |
| |
| else |
| { |
| type_message(file, type, "skipped: bad CRC"); |
| |
| /* NOTE: this cannot be reached for IEND because it is critical. */ |
| goto skip_chunk; |
| } |
| } |
| |
| /* Check for other 'skip' cases and handle these; these only apply to |
| * ancillary chunks (and not tRNS, which should probably have been a critical |
| * chunk.) |
| */ |
| if (skip_chunk_type(file->global, type)) |
| goto skip_chunk; |
| |
| /* The chunk may still be skipped if problems are detected in the LZ data, |
| * however the LZ data check requires a chunk. Handle this by instantiating |
| * a chunk unless an IDAT is already instantiated (IDAT control structures |
| * instantiate their own chunk.) |
| */ |
| if (type != png_IDAT) |
| file->alloc(file, 0/*chunk*/); |
| |
| else if (file->idat == NULL) |
| file->alloc(file, 1/*IDAT*/); |
| |
| else |
| { |
| /* The chunk length must be updated for process_IDAT */ |
| assert(file->chunk != NULL); |
| assert(file->chunk->chunk_type == png_IDAT); |
| file->chunk->chunk_length = file->length; |
| } |
| |
| /* Record the 'next' information too, now that the original values for |
| * this chunk have been copied. Notice that the IDAT chunks only make a |
| * copy of the position of the first chunk, this is fine - process_IDAT does |
| * not need the position of this chunk. |
| */ |
| file->length = next_length; |
| file->type = next_type; |
| getpos(file); |
| |
| /* Do per-type processing, note that if this code does not return from the |
| * function the chunk will be skipped. The rewrite is cancelled here so that |
| * it can be set in the per-chunk processing. |
| */ |
| file->chunk->rewrite_length = 0; |
| file->chunk->rewrite_offset = 0; |
| switch (type) |
| { |
| default: |
| return; |
| |
| case png_IHDR: |
| /* Read this now and update the control structure with the information |
| * it contains. The header is validated completely to ensure this is a |
| * PNG. |
| */ |
| { |
| struct chunk *chunk = file->chunk; |
| |
| if (chunk->chunk_length != 13) |
| stop_invalid(file, "IHDR length"); |
| |
| /* Read all the IHDR information and validate it. */ |
| setpos(chunk); |
| file->width = reread_4(file); |
| file->height = reread_4(file); |
| file->bit_depth = reread_byte(file); |
| file->color_type = reread_byte(file); |
| file->compression_method = reread_byte(file); |
| file->filter_method = reread_byte(file); |
| file->interlace_method = reread_byte(file); |
| |
| /* This validates all the fields, and calls stop_invalid if |
| * there is a problem. |
| */ |
| calc_image_size(file); |
| } |
| return; |
| |
| /* Ancillary chunks that require further processing: */ |
| case png_zTXt: case png_iCCP: |
| if (process_zTXt_iCCP(file)) |
| return; |
| chunk_end(&file->chunk); |
| file_setpos(file, &file->data_pos); |
| break; |
| |
| case png_iTXt: |
| if (process_iTXt(file)) |
| return; |
| chunk_end(&file->chunk); |
| file_setpos(file, &file->data_pos); |
| break; |
| |
| case png_IDAT: |
| if (process_IDAT(file)) |
| return; |
| /* First pass: */ |
| assert(next_type == png_IDAT); |
| break; |
| } |
| |
| /* Control reaches this point if the chunk must be skipped. For chunks other |
| * than IDAT this means that the zlib compressed data is fatally damanged and |
| * the chunk will not be passed to libpng. For IDAT it means that the end of |
| * the IDAT stream has not yet been reached and we must handle the next |
| * (IDAT) chunk. If the LZ data in an IDAT stream cannot be read 'stop' must |
| * be used to halt parsing of the PNG. |
| */ |
| read_chunk(file); |
| return; |
| |
| /* This is the generic code to skip the current chunk; simply jump to the |
| * next one. |
| */ |
| skip_chunk: |
| file->length = next_length; |
| file->type = next_type; |
| getpos(file); |
| read_chunk(file); |
| } |
| |
| static png_uint_32 |
| get32(png_bytep buffer, int offset) |
| /* Read a 32-bit value from an 8-byte circular buffer (used only below). |
| */ |
| { |
| return |
| (buffer[ offset & 7] << 24) + |
| (buffer[(offset+1) & 7] << 16) + |
| (buffer[(offset+2) & 7] << 8) + |
| (buffer[(offset+3) & 7] ); |
| } |
| |
| static void |
| sync_stream(struct file *file) |
| /* The stream seems to be messed up, attempt to resync from the current chunk |
| * header. Executes stop on a fatal error, otherwise calls process_chunk. |
| */ |
| { |
| png_uint_32 file_crc; |
| |
| file->status_code |= STREAM_ERROR; |
| |
| if (file->global->verbose) |
| { |
| fputs(" SYNC ", stderr); |
| type_name(file->type, stderr); |
| putc('\n', stderr); |
| } |
| |
| /* Return to the start of the chunk data */ |
| file_setpos(file, &file->data_pos); |
| file->read_count = 8; |
| |
| if (read_4(file, &file_crc) == 4) /* else completely truncated */ |
| { |
| /* Ignore the recorded chunk length, proceed through the data looking for |
| * a leading sequence of bytes that match the CRC in the following four |
| * bytes. Each time a match is found check the next 8 bytes for a valid |
| * length, chunk-type pair. |
| */ |
| png_uint_32 length; |
| png_uint_32 type = file->type; |
| png_uint_32 crc = crc_init_4(type); |
| png_byte buffer[8]; |
| unsigned int nread = 0, nused = 0; |
| |
| for (length=0; length <= 0x7fffffff; ++length) |
| { |
| int ch; |
| |
| if ((crc ^ 0xffffffff) == file_crc) |
| { |
| /* A match on the CRC; for IEND this is sufficient, but for anything |
| * else expect a following chunk header. |
| */ |
| if (type == png_IEND) |
| { |
| file->length = length; |
| process_chunk(file, file_crc, 0, 0); |
| return; |
| } |
| |
| else |
| { |
| /* Need 8 bytes */ |
| while (nread < 8+nused) |
| { |
| ch = read_byte(file); |
| if (ch == EOF) |
| goto truncated; |
| buffer[(nread++) & 7] = (png_byte)ch; |
| } |
| |
| /* Prevent overflow */ |
| nread -= nused & ~7; |
| nused -= nused & ~7; /* or, nused &= 7 ;-) */ |
| |
| /* Examine the 8 bytes for a valid chunk header. */ |
| { |
| png_uint_32 next_length = get32(buffer, nused); |
| |
| if (next_length < 0x7fffffff) |
| { |
| png_uint_32 next_type = get32(buffer, nused+4); |
| |
| if (chunk_type_valid(next_type)) |
| { |
| file->read_count -= 8; |
| process_chunk(file, file_crc, next_length, next_type); |
| return; |
| } |
| } |
| |
| /* Not valid, keep going. */ |
| } |
| } |
| } |
| |
| /* This catches up with the circular buffer which gets filled above |
| * while checking a chunk header. This code is slightly tricky - if |
| * the chunk_type is IEND the buffer will never be used, if it is not |
| * the code will always read ahead exactly 8 bytes and pass this on to |
| * process_chunk. So the invariant that IEND leaves the file position |
| * after the IEND CRC and other chunk leave it after the *next* chunk |
| * header is not broken. |
| */ |
| if (nread <= nused) |
| { |
| ch = read_byte(file); |
| |
| if (ch == EOF) |
| goto truncated; |
| } |
| |
| else |
| ch = buffer[(++nused) & 7]; |
| |
| crc = crc_one_byte(crc, file_crc >> 24); |
| file_crc = (file_crc << 8) + ch; |
| } |
| |
| /* Control gets to here if when 0x7fffffff bytes (plus 8) have been read, |
| * ok, treat this as a damaged stream too: |
| */ |
| } |
| |
| truncated: |
| stop(file, READ_ERROR_CODE, "damaged PNG stream"); |
| } |
| |
| static void |
| read_chunk(struct file *file) |
| /* On entry file::data_pos must be set to the position of the first byte |
| * of the chunk data *and* the input file must be at this position. This |
| * routine (via process_chunk) instantiates a chunk or IDAT control structure |
| * based on file::length and file::type and also resets these fields and |
| * file::data_pos for the chunk after this one. For an IDAT chunk the whole |
| * stream of IDATs will be read, until something other than an IDAT is |
| * encountered, and the file fields will be set for the chunk after the end |
| * of the stream of IDATs. |
| * |
| * For IEND the file::type field will be set to 0, and nothing beyond the end |
| * of the IEND chunk will have been read. |
| */ |
| { |
| png_uint_32 length = file->length; |
| png_uint_32 type = file->type; |
| |
| /* After IEND file::type is set to 0, if libpng attempts to read |
| * more data at this point this is a bug in libpng. |
| */ |
| if (type == 0) |
| stop(file, UNEXPECTED_ERROR_CODE, "read beyond IEND"); |
| |
| if (file->global->verbose > 2) |
| { |
| fputs(" ", stderr); |
| type_name(type, stderr); |
| fprintf(stderr, " %lu\n", (unsigned long)length); |
| } |
| |
| /* Start the read_crc calculation with the chunk type, then read to the end |
| * of the chunk data (without processing it in any way) to check that it is |
| * all there and calculate the CRC. |
| */ |
| file->crc = crc_init_4(type); |
| if (crc_read_many(file, length)) /* else it was truncated */ |
| { |
| png_uint_32 file_crc; /* CRC read from file */ |
| unsigned int nread = read_4(file, &file_crc); |
| |
| if (nread == 4) |
| { |
| if (type != png_IEND) /* do not read beyond IEND */ |
| { |
| png_uint_32 next_length; |
| |
| nread += read_4(file, &next_length); |
| if (nread == 8 && next_length <= 0x7fffffff) |
| { |
| png_uint_32 next_type; |
| |
| nread += read_4(file, &next_type); |
| |
| if (nread == 12 && chunk_type_valid(next_type)) |
| { |
| /* Adjust the read count back to the correct value for this |
| * chunk. |
| */ |
| file->read_count -= 8; |
| process_chunk(file, file_crc, next_length, next_type); |
| return; |
| } |
| } |
| } |
| |
| else /* IEND */ |
| { |
| process_chunk(file, file_crc, 0, 0); |
| return; |
| } |
| } |
| } |
| |
| /* Control gets to here if the the stream seems invalid or damaged in some |
| * way. Either there was a problem reading all the expected data (this |
| * chunk's data, its CRC and the length and type of the next chunk) or the |
| * next chunk length/type are invalid. Notice that the cases that end up |
| * here all correspond to cases that would otherwise terminate the read of |
| * the PNG file. |
| */ |
| sync_stream(file); |
| } |
| |
| /* This returns a file* from a png_struct in an implementation specific way. */ |
| static struct file *get_control(png_const_structrp png_ptr); |
| |
| static void PNGCBAPI |
| error_handler(png_structp png_ptr, png_const_charp message) |
| { |
| stop(get_control(png_ptr), LIBPNG_ERROR_CODE, message); |
| } |
| |
| static void PNGCBAPI |
| warning_handler(png_structp png_ptr, png_const_charp message) |
| { |
| struct file *file = get_control(png_ptr); |
| |
| if (file->global->warnings) |
| emit_error(file, LIBPNG_WARNING_CODE, message); |
| } |
| |
| /* Read callback - this is where the work gets done to check the stream before |
| * passing it to libpng |
| */ |
| static void PNGCBAPI |
| read_callback(png_structp png_ptr, png_bytep buffer, size_t count) |
| /* Return 'count' bytes to libpng in 'buffer' */ |
| { |
| struct file *file = get_control(png_ptr); |
| png_uint_32 type, length; /* For the chunk be *WRITTEN* */ |
| struct chunk *chunk; |
| |
| /* libpng should always ask for at least one byte */ |
| if (count == 0) |
| stop(file, UNEXPECTED_ERROR_CODE, "read callback for 0 bytes"); |
| |
| |