glib/glib/gstdio.c

/* gstdio.c - wrappers for C library functions
 *
 * Copyright 2004 Tor Lillqvist
 *
 * GLib is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * GLib is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with GLib; see the file COPYING.LIB.  If not,
 * see <http://www.gnu.org/licenses/>.
 */

#include "config.h"
#include "glibconfig.h"

#define G_STDIO_NO_WRAP_ON_UNIX

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#ifdef G_OS_UNIX
#include <unistd.h>
#endif

#ifdef G_OS_WIN32
#include <windows.h>
#include <errno.h>
#include <wchar.h>
#include <direct.h>
#include <io.h>
#include <sys/utime.h>
#else
#include <utime.h>
#include <errno.h>
#endif

#include "gstdio.h"


#if !defined (G_OS_UNIX) && !defined (G_OS_WIN32)
#error Please port this to your operating system
#endif

#if defined (_MSC_VER) && !defined(_WIN64)
#undef _wstat
#define _wstat _wstat32
#endif

/**
 * g_access:
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 * @mode: as in access()
 *
 * A wrapper for the POSIX access() function. This function is used to
 * test a pathname for one or several of read, write or execute
 * permissions, or just existence.
 *
 * On Windows, the file protection mechanism is not at all POSIX-like,
 * and the underlying function in the C library only checks the
 * FAT-style READONLY attribute, and does not look at the ACL of a
 * file at all. This function is this in practise almost useless on
 * Windows. Software that needs to handle file permissions on Windows
 * more exactly should use the Win32 API.
 *
 * See your C library manual for more details about access().
 *
 * Returns: zero if the pathname refers to an existing file system
 *     object that has all the tested permissions, or -1 otherwise
 *     or on error.
 * 
 * Since: 2.8
 */
int
g_access (const gchar *filename,
	  int          mode)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;
    
  if (wfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }

#ifndef X_OK
#define X_OK 1
#endif

  retval = _waccess (wfilename, mode & ~X_OK);
  save_errno = errno;

  g_free (wfilename);

  errno = save_errno;
  return retval;
#else
  return access (filename, mode);
#endif
}

/**
 * g_chmod:
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 * @mode: as in chmod()
 *
 * A wrapper for the POSIX chmod() function. The chmod() function is
 * used to set the permissions of a file system object.
 * 
 * On Windows the file protection mechanism is not at all POSIX-like,
 * and the underlying chmod() function in the C library just sets or
 * clears the FAT-style READONLY attribute. It does not touch any
 * ACL. Software that needs to manage file permissions on Windows
 * exactly should use the Win32 API.
 *
 * See your C library manual for more details about chmod().
 *
 * Returns: 0 if the operation succeeded, -1 on error
 * 
 * Since: 2.8
 */
int
g_chmod (const gchar *filename,
	 int          mode)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;
    
  if (wfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  retval = _wchmod (wfilename, mode);
  save_errno = errno;

  g_free (wfilename);

  errno = save_errno;
  return retval;
#else
  return chmod (filename, mode);
#endif
}
/**
 * g_open:
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 * @flags: as in open()
 * @mode: as in open()
 *
 * A wrapper for the POSIX open() function. The open() function is
 * used to convert a pathname into a file descriptor.
 *
 * On POSIX systems file descriptors are implemented by the operating
 * system. On Windows, it's the C library that implements open() and
 * file descriptors. The actual Win32 API for opening files is quite
 * different, see MSDN documentation for CreateFile(). The Win32 API
 * uses file handles, which are more randomish integers, not small
 * integers like file descriptors.
 *
 * Because file descriptors are specific to the C library on Windows,
 * the file descriptor returned by this function makes sense only to
 * functions in the same C library. Thus if the GLib-using code uses a
 * different C library than GLib does, the file descriptor returned by
 * this function cannot be passed to C library functions like write()
 * or read().
 *
 * See your C library manual for more details about open().
 *
 * Returns: a new file descriptor, or -1 if an error occurred.
 *     The return value can be used exactly like the return value
 *     from open().
 * 
 * Since: 2.6
 */
int
g_open (const gchar *filename,
	int          flags,
	int          mode)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;
    
  if (wfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  retval = _wopen (wfilename, flags, mode);
  save_errno = errno;

  g_free (wfilename);

  errno = save_errno;
  return retval;
#else
  int fd;
  do
    fd = open (filename, flags, mode);
  while (G_UNLIKELY (fd == -1 && errno == EINTR));
  return fd;
#endif
}

/**
 * g_creat:
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 * @mode: as in creat()
 *
 * A wrapper for the POSIX creat() function. The creat() function is
 * used to convert a pathname into a file descriptor, creating a file
 * if necessary.

 * On POSIX systems file descriptors are implemented by the operating
 * system. On Windows, it's the C library that implements creat() and
 * file descriptors. The actual Windows API for opening files is
 * different, see MSDN documentation for CreateFile(). The Win32 API
 * uses file handles, which are more randomish integers, not small
 * integers like file descriptors.
 *
 * Because file descriptors are specific to the C library on Windows,
 * the file descriptor returned by this function makes sense only to
 * functions in the same C library. Thus if the GLib-using code uses a
 * different C library than GLib does, the file descriptor returned by
 * this function cannot be passed to C library functions like write()
 * or read().
 *
 * See your C library manual for more details about creat().
 *
 * Returns: a new file descriptor, or -1 if an error occurred.
 *     The return value can be used exactly like the return value
 *     from creat().
 * 
 * Since: 2.8
 */
int
g_creat (const gchar *filename,
	 int          mode)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;
    
  if (wfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  retval = _wcreat (wfilename, mode);
  save_errno = errno;

  g_free (wfilename);

  errno = save_errno;
  return retval;
#else
  return creat (filename, mode);
#endif
}

/**
 * g_rename:
 * @oldfilename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 * @newfilename: (type filename): a pathname in the GLib file name encoding
 *
 * A wrapper for the POSIX rename() function. The rename() function 
 * renames a file, moving it between directories if required.
 * 
 * See your C library manual for more details about how rename() works
 * on your system. It is not possible in general on Windows to rename
 * a file that is open to some process.
 *
 * Returns: 0 if the renaming succeeded, -1 if an error occurred
 * 
 * Since: 2.6
 */
int
g_rename (const gchar *oldfilename,
	  const gchar *newfilename)
{
#ifdef G_OS_WIN32
  wchar_t *woldfilename = g_utf8_to_utf16 (oldfilename, -1, NULL, NULL, NULL);
  wchar_t *wnewfilename;
  int retval;
  int save_errno = 0;

  if (woldfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  wnewfilename = g_utf8_to_utf16 (newfilename, -1, NULL, NULL, NULL);

  if (wnewfilename == NULL)
    {
      g_free (woldfilename);
      errno = EINVAL;
      return -1;
    }

  if (MoveFileExW (woldfilename, wnewfilename, MOVEFILE_REPLACE_EXISTING))
    retval = 0;
  else
    {
      retval = -1;
      switch (GetLastError ())
	{
#define CASE(a,b) case ERROR_##a: save_errno = b; break
	  CASE (FILE_NOT_FOUND, ENOENT);
	  CASE (PATH_NOT_FOUND, ENOENT);
	  CASE (ACCESS_DENIED, EACCES);
	  CASE (NOT_SAME_DEVICE, EXDEV);
	  CASE (LOCK_VIOLATION, EACCES);
	  CASE (SHARING_VIOLATION, EACCES);
	  CASE (FILE_EXISTS, EEXIST);
	  CASE (ALREADY_EXISTS, EEXIST);
#undef CASE
	default: save_errno = EIO;
	}
    }

  g_free (woldfilename);
  g_free (wnewfilename);
    
  errno = save_errno;
  return retval;
#else
  return rename (oldfilename, newfilename);
#endif
}

/**
 * g_mkdir: 
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 * @mode: permissions to use for the newly created directory
 *
 * A wrapper for the POSIX mkdir() function. The mkdir() function 
 * attempts to create a directory with the given name and permissions.
 * The mode argument is ignored on Windows.
 * 
 * See your C library manual for more details about mkdir().
 *
 * Returns: 0 if the directory was successfully created, -1 if an error 
 *    occurred
 * 
 * Since: 2.6
 */
int
g_mkdir (const gchar *filename,
	 int          mode)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;

  if (wfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  retval = _wmkdir (wfilename);
  save_errno = errno;

  g_free (wfilename);
    
  errno = save_errno;
  return retval;
#else
  return mkdir (filename, mode);
#endif
}

/**
 * g_chdir: 
 * @path: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 *
 * A wrapper for the POSIX chdir() function. The function changes the
 * current directory of the process to @path.
 * 
 * See your C library manual for more details about chdir().
 *
 * Returns: 0 on success, -1 if an error occurred.
 * 
 * Since: 2.8
 */
int
g_chdir (const gchar *path)
{
#ifdef G_OS_WIN32
  wchar_t *wpath = g_utf8_to_utf16 (path, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;

  if (wpath == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  retval = _wchdir (wpath);
  save_errno = errno;

  g_free (wpath);
    
  errno = save_errno;
  return retval;
#else
  return chdir (path);
#endif
}

/**
 * GStatBuf:
 *
 * A type corresponding to the appropriate struct type for the stat()
 * system call, depending on the platform and/or compiler being used.
 *
 * See g_stat() for more information.
 */
/**
 * g_stat: 
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 * @buf: a pointer to a stat struct, which will be filled with the file
 *     information
 *
 * A wrapper for the POSIX stat() function. The stat() function
 * returns information about a file. On Windows the stat() function in
 * the C library checks only the FAT-style READONLY attribute and does
 * not look at the ACL at all. Thus on Windows the protection bits in
 * the @st_mode field are a fabrication of little use.
 * 
 * On Windows the Microsoft C libraries have several variants of the
 * stat struct and stat() function with names like _stat(), _stat32(),
 * _stat32i64() and _stat64i32(). The one used here is for 32-bit code
 * the one with 32-bit size and time fields, specifically called _stat32().
 *
 * In Microsoft's compiler, by default struct stat means one with
 * 64-bit time fields while in MinGW struct stat is the legacy one
 * with 32-bit fields. To hopefully clear up this messs, the gstdio.h
 * header defines a type #GStatBuf which is the appropriate struct type
 * depending on the platform and/or compiler being used. On POSIX it
 * is just struct stat, but note that even on POSIX platforms, stat()
 * might be a macro.
 *
 * See your C library manual for more details about stat().
 *
 * Returns: 0 if the information was successfully retrieved,
 *     -1 if an error occurred
 * 
 * Since: 2.6
 */
int
g_stat (const gchar *filename,
	GStatBuf    *buf)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;
  int len;

  if (wfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  len = wcslen (wfilename);
  while (len > 0 && G_IS_DIR_SEPARATOR (wfilename[len-1]))
    len--;
  if (len > 0 &&
      (!g_path_is_absolute (filename) || len > g_path_skip_root (filename) - filename))
    wfilename[len] = '\0';

  retval = _wstat (wfilename, buf);
  save_errno = errno;

  g_free (wfilename);

  errno = save_errno;
  return retval;
#else
  return stat (filename, buf);
#endif
}

/**
 * g_lstat: 
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 * @buf: a pointer to a stat struct, which will be filled with the file
 *     information
 *
 * A wrapper for the POSIX lstat() function. The lstat() function is
 * like stat() except that in the case of symbolic links, it returns
 * information about the symbolic link itself and not the file that it
 * refers to. If the system does not support symbolic links g_lstat()
 * is identical to g_stat().
 * 
 * See your C library manual for more details about lstat().
 *
 * Returns: 0 if the information was successfully retrieved,
 *     -1 if an error occurred
 * 
 * Since: 2.6
 */
int
g_lstat (const gchar *filename,
	 GStatBuf    *buf)
{
#ifdef HAVE_LSTAT
  /* This can't be Win32, so don't do the widechar dance. */
  return lstat (filename, buf);
#else
  return g_stat (filename, buf);
#endif
}

/**
 * g_unlink:
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 *
 * A wrapper for the POSIX unlink() function. The unlink() function 
 * deletes a name from the filesystem. If this was the last link to the 
 * file and no processes have it opened, the diskspace occupied by the
 * file is freed.
 * 
 * See your C library manual for more details about unlink(). Note
 * that on Windows, it is in general not possible to delete files that
 * are open to some process, or mapped into memory.
 *
 * Returns: 0 if the name was successfully deleted, -1 if an error 
 *    occurred
 * 
 * Since: 2.6
 */
int
g_unlink (const gchar *filename)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;

  if (wfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  retval = _wunlink (wfilename);
  save_errno = errno;

  g_free (wfilename);

  errno = save_errno;
  return retval;
#else
  return unlink (filename);
#endif
}

/**
 * g_remove:
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 *
 * A wrapper for the POSIX remove() function. The remove() function
 * deletes a name from the filesystem.
 * 
 * See your C library manual for more details about how remove() works
 * on your system. On Unix, remove() removes also directories, as it
 * calls unlink() for files and rmdir() for directories. On Windows,
 * although remove() in the C library only works for files, this
 * function tries first remove() and then if that fails rmdir(), and
 * thus works for both files and directories. Note however, that on
 * Windows, it is in general not possible to remove a file that is
 * open to some process, or mapped into memory.
 *
 * If this function fails on Windows you can't infer too much from the
 * errno value. rmdir() is tried regardless of what caused remove() to
 * fail. Any errno value set by remove() will be overwritten by that
 * set by rmdir().
 *
 * Returns: 0 if the file was successfully removed, -1 if an error 
 *    occurred
 * 
 * Since: 2.6
 */
int
g_remove (const gchar *filename)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;

  if (wfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  retval = _wremove (wfilename);
  if (retval == -1)
    retval = _wrmdir (wfilename);
  save_errno = errno;

  g_free (wfilename);

  errno = save_errno;
  return retval;
#else
  return remove (filename);
#endif
}

/**
 * g_rmdir:
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 *
 * A wrapper for the POSIX rmdir() function. The rmdir() function
 * deletes a directory from the filesystem.
 * 
 * See your C library manual for more details about how rmdir() works
 * on your system.
 *
 * Returns: 0 if the directory was successfully removed, -1 if an error 
 *    occurred
 * 
 * Since: 2.6
 */
int
g_rmdir (const gchar *filename)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;

  if (wfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }
  
  retval = _wrmdir (wfilename);
  save_errno = errno;

  g_free (wfilename);

  errno = save_errno;
  return retval;
#else
  return rmdir (filename);
#endif
}

/**
 * g_fopen:
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 * @mode: a string describing the mode in which the file should be opened
 *
 * A wrapper for the stdio fopen() function. The fopen() function
 * opens a file and associates a new stream with it.
 * 
 * Because file descriptors are specific to the C library on Windows,
 * and a file descriptor is part of the FILE struct, the FILE* returned
 * by this function makes sense only to functions in the same C library.
 * Thus if the GLib-using code uses a different C library than GLib does,
 * the FILE* returned by this function cannot be passed to C library
 * functions like fprintf() or fread().
 *
 * See your C library manual for more details about fopen().
 *
 * Returns: A FILE* if the file was successfully opened, or %NULL if
 *     an error occurred
 * 
 * Since: 2.6
 */
FILE *
g_fopen (const gchar *filename,
	 const gchar *mode)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  wchar_t *wmode;
  FILE *retval;
  int save_errno;

  if (wfilename == NULL)
    {
      errno = EINVAL;
      return NULL;
    }

  wmode = g_utf8_to_utf16 (mode, -1, NULL, NULL, NULL);

  if (wmode == NULL)
    {
      g_free (wfilename);
      errno = EINVAL;
      return NULL;
    }

  retval = _wfopen (wfilename, wmode);
  save_errno = errno;

  g_free (wfilename);
  g_free (wmode);

  errno = save_errno;
  return retval;
#else
  return fopen (filename, mode);
#endif
}

/**
 * g_freopen:
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 * @mode: a string describing the mode in which the file should be  opened
 * @stream: (allow-none): an existing stream which will be reused, or %NULL
 *
 * A wrapper for the POSIX freopen() function. The freopen() function
 * opens a file and associates it with an existing stream.
 * 
 * See your C library manual for more details about freopen().
 *
 * Returns: A FILE* if the file was successfully opened, or %NULL if
 *     an error occurred.
 * 
 * Since: 2.6
 */
FILE *
g_freopen (const gchar *filename,
	   const gchar *mode,
	   FILE        *stream)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  wchar_t *wmode;
  FILE *retval;
  int save_errno;

  if (wfilename == NULL)
    {
      errno = EINVAL;
      return NULL;
    }
  
  wmode = g_utf8_to_utf16 (mode, -1, NULL, NULL, NULL);

  if (wmode == NULL)
    {
      g_free (wfilename);
      errno = EINVAL;
      return NULL;
    }
  
  retval = _wfreopen (wfilename, wmode, stream);
  save_errno = errno;

  g_free (wfilename);
  g_free (wmode);

  errno = save_errno;
  return retval;
#else
  return freopen (filename, mode, stream);
#endif
}

/**
 * g_utime:
 * @filename: (type filename): a pathname in the GLib file name encoding
 *     (UTF-8 on Windows)
 * @utb: a pointer to a struct utimbuf.
 *
 * A wrapper for the POSIX utime() function. The utime() function
 * sets the access and modification timestamps of a file.
 * 
 * See your C library manual for more details about how utime() works
 * on your system.
 *
 * Returns: 0 if the operation was successful, -1 if an error occurred
 * 
 * Since: 2.18
 */
int
g_utime (const gchar    *filename,
	 struct utimbuf *utb)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;

  if (wfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }
  
  retval = _wutime (wfilename, (struct _utimbuf*) utb);
  save_errno = errno;

  g_free (wfilename);

  errno = save_errno;
  return retval;
#else
  return utime (filename, utb);
#endif
}

/**
 * g_close:
 * @fd: A file descriptor
 * @error: a #GError
 *
 * This wraps the close() call; in case of error, %errno will be
 * preserved, but the error will also be stored as a #GError in @error.
 *
 * Besides using #GError, there is another major reason to prefer this
 * function over the call provided by the system; on Unix, it will
 * attempt to correctly handle %EINTR, which has platform-specific
 * semantics.
 *
 * Returns: %TRUE on success, %FALSE if there was an error.
 *
 * Since: 2.36
 */
gboolean
g_close (gint       fd,
         GError   **error)
{
  int res;
  res = close (fd);
  /* Just ignore EINTR for now; a retry loop is the wrong thing to do
   * on Linux at least.  Anyone who wants to add a conditional check
   * for e.g. HP-UX is welcome to do so later...
   *
   * http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html
   * https://bugzilla.gnome.org/show_bug.cgi?id=682819
   * http://utcc.utoronto.ca/~cks/space/blog/unix/CloseEINTR
   * https://sites.google.com/site/michaelsafyan/software-engineering/checkforeintrwheninvokingclosethinkagain
   */
  if (G_UNLIKELY (res == -1 && errno == EINTR))
    return TRUE;
  else if (res == -1)
    {
      int errsv = errno;
      g_set_error_literal (error, G_FILE_ERROR,
                           g_file_error_from_errno (errsv),
                           g_strerror (errsv));
      errno = errsv;
      return FALSE;
    }
  return TRUE;
}