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// Copyright (c) 2010 Google Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
// This file implements the google_breakpad::StabsReader class.
// See stabs_reader.h.
#include "common/stabs_reader.h"
#include <assert.h>
#include <stab.h>
#include <string.h>
#include <string>
#include "common/using_std_string.h"
using std::vector;
namespace google_breakpad {
StabsReader::EntryIterator::EntryIterator(const ByteBuffer* buffer,
bool big_endian, size_t value_size)
: value_size_(value_size), cursor_(buffer, big_endian) {
// Actually, we could handle weird sizes just fine, but they're
// probably mistakes --- expressed in bits, say.
assert(value_size == 4 || value_size == 8);
entry_.index = 0;
Fetch();
}
void StabsReader::EntryIterator::Fetch() {
cursor_
.Read(4, false, &entry_.name_offset)
.Read(1, false, &entry_.type)
.Read(1, false, &entry_.other)
.Read(2, false, &entry_.descriptor)
.Read(value_size_, false, &entry_.value);
entry_.at_end = !cursor_;
}
StabsReader::StabsReader(const uint8_t* stab, size_t stab_size,
const uint8_t* stabstr, size_t stabstr_size,
bool big_endian, size_t value_size, bool unitized,
StabsHandler* handler)
: entries_(stab, stab_size),
strings_(stabstr, stabstr_size),
iterator_(&entries_, big_endian, value_size),
unitized_(unitized),
handler_(handler),
string_offset_(0),
next_cu_string_offset_(0),
current_source_file_(NULL) { }
const char* StabsReader::SymbolString() {
ptrdiff_t offset = string_offset_ + iterator_->name_offset;
if (offset < 0 || (size_t) offset >= strings_.Size()) {
handler_->Warning("symbol %d: name offset outside the string section\n",
iterator_->index);
// Return our null string, to keep our promise about all names being
// taken from the string section.
offset = 0;
}
return reinterpret_cast<const char*>(strings_.start + offset);
}
bool StabsReader::Process() {
while (!iterator_->at_end) {
if (iterator_->type == N_SO) {
if (! ProcessCompilationUnit())
return false;
} else if (iterator_->type == N_UNDF && unitized_) {
// In unitized STABS (including Linux STABS, and pretty much anything
// else that puts STABS data in sections), at the head of each
// compilation unit's entries there is an N_UNDF stab giving the
// number of symbols in the compilation unit, and the number of bytes
// that compilation unit's strings take up in the .stabstr section.
// Each CU's strings are separate; the n_strx values are offsets
// within the current CU's portion of the .stabstr section.
//
// As an optimization, the GNU linker combines all the
// compilation units into one, with a single N_UNDF at the
// beginning. However, other linkers, like Gold, do not perform
// this optimization.
string_offset_ = next_cu_string_offset_;
next_cu_string_offset_ = iterator_->value;
++iterator_;
}
#if defined(HAVE_MACH_O_NLIST_H)
// Export symbols in Mach-O binaries look like this.
// This is necessary in order to be able to dump symbols
// from OS X system libraries.
else if ((iterator_->type & N_STAB) == 0 &&
(iterator_->type & N_TYPE) == N_SECT) {
ProcessExtern();
}
#endif
else {
++iterator_;
}
}
return true;
}
bool StabsReader::ProcessCompilationUnit() {
assert(!iterator_->at_end && iterator_->type == N_SO);
// There may be an N_SO entry whose name ends with a slash,
// indicating the directory in which the compilation occurred.
// The build directory defaults to NULL.
const char* build_directory = NULL;
{
const char* name = SymbolString();
if (name[0] && name[strlen(name) - 1] == '/') {
build_directory = name;
++iterator_;
}
}
// We expect to see an N_SO entry with a filename next, indicating
// the start of the compilation unit.
{
if (iterator_->at_end || iterator_->type != N_SO)
return true;
const char* name = SymbolString();
if (name[0] == '\0') {
// This seems to be a stray end-of-compilation-unit marker;
// consume it, but don't report the end, since we didn't see a
// beginning.
++iterator_;
return true;
}
current_source_file_ = name;
}
if (! handler_->StartCompilationUnit(current_source_file_,
iterator_->value,
build_directory))
return false;
++iterator_;
// The STABS documentation says that some compilers may emit
// additional N_SO entries with names immediately following the
// first, and that they should be ignored. However, the original
// Breakpad STABS reader doesn't ignore them, so we won't either.
// Process the body of the compilation unit, up to the next N_SO.
while (!iterator_->at_end && iterator_->type != N_SO) {
if (iterator_->type == N_FUN) {
if (! ProcessFunction())
return false;
} else if (iterator_->type == N_SLINE) {
// Mac OS X STABS place SLINE records before functions.
Line line;
// The value of an N_SLINE entry that appears outside a function is
// the absolute address of the line.
line.address = iterator_->value;
line.filename = current_source_file_;
// The n_desc of a N_SLINE entry is the line number. It's a
// signed 16-bit field; line numbers from 32768 to 65535 are
// stored as n-65536.
line.number = (uint16_t) iterator_->descriptor;
queued_lines_.push_back(line);
++iterator_;
} else if (iterator_->type == N_SOL) {
current_source_file_ = SymbolString();
++iterator_;
} else {
// Ignore anything else.
++iterator_;
}
}
// An N_SO with an empty name indicates the end of the compilation
// unit. Default to zero.
uint64_t ending_address = 0;
if (!iterator_->at_end) {
assert(iterator_->type == N_SO);
const char* name = SymbolString();
if (name[0] == '\0') {
ending_address = iterator_->value;
++iterator_;
}
}
if (! handler_->EndCompilationUnit(ending_address))
return false;
queued_lines_.clear();
return true;
}
bool StabsReader::ProcessFunction() {
assert(!iterator_->at_end && iterator_->type == N_FUN);
uint64_t function_address = iterator_->value;
// The STABS string for an N_FUN entry is the name of the function,
// followed by a colon, followed by type information for the
// function. We want to pass the name alone to StartFunction.
const char* stab_string = SymbolString();
const char* name_end = strchr(stab_string, ':');
if (! name_end)
name_end = stab_string + strlen(stab_string);
string name(stab_string, name_end - stab_string);
if (! handler_->StartFunction(name, function_address))
return false;
++iterator_;
// If there were any SLINE records given before the function, report them now.
for (vector<Line>::const_iterator it = queued_lines_.begin();
it != queued_lines_.end(); it++) {
if (!handler_->Line(it->address, it->filename, it->number))
return false;
}
queued_lines_.clear();
while (!iterator_->at_end) {
if (iterator_->type == N_SO || iterator_->type == N_FUN)
break;
else if (iterator_->type == N_SLINE) {
// The value of an N_SLINE entry is the offset of the line from
// the function's start address.
uint64_t line_address = function_address + iterator_->value;
// The n_desc of a N_SLINE entry is the line number. It's a
// signed 16-bit field; line numbers from 32768 to 65535 are
// stored as n-65536.
uint16_t line_number = iterator_->descriptor;
if (! handler_->Line(line_address, current_source_file_, line_number))
return false;
++iterator_;
} else if (iterator_->type == N_SOL) {
current_source_file_ = SymbolString();
++iterator_;
} else
// Ignore anything else.
++iterator_;
}
// We've reached the end of the function. See if we can figure out its
// ending address.
uint64_t ending_address = 0;
if (!iterator_->at_end) {
assert(iterator_->type == N_SO || iterator_->type == N_FUN);
if (iterator_->type == N_FUN) {
const char* symbol_name = SymbolString();
if (symbol_name[0] == '\0') {
// An N_FUN entry with no name is a terminator for this function;
// its value is the function's size.
ending_address = function_address + iterator_->value;
++iterator_;
} else {
// An N_FUN entry with a name is the next function, and we can take
// its value as our ending address. Don't advance the iterator, as
// we'll use this symbol to start the next function as well.
ending_address = iterator_->value;
}
} else {
// An N_SO entry could be an end-of-compilation-unit marker, or the
// start of the next compilation unit, but in either case, its value
// is our ending address. We don't advance the iterator;
// ProcessCompilationUnit will decide what to do with this symbol.
ending_address = iterator_->value;
}
}
if (! handler_->EndFunction(ending_address))
return false;
return true;
}
bool StabsReader::ProcessExtern() {
#if defined(HAVE_MACH_O_NLIST_H)
assert(!iterator_->at_end &&
(iterator_->type & N_STAB) == 0 &&
(iterator_->type & N_TYPE) == N_SECT);
#endif
// TODO(mark): only do symbols in the text section?
if (!handler_->Extern(SymbolString(), iterator_->value))
return false;
++iterator_;
return true;
}
} // namespace google_breakpad