GFileOutputStream *
_g_local_file_output_stream_replace (const char *filename,
const char *etag,
gboolean create_backup,
GFileCreateFlags flags,
GCancellable *cancellable,
GError **error)
{
GLocalFileOutputStream *stream;
int mode;
int fd;
char *temp_file;
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return NULL;
temp_file = NULL;
if (flags & G_FILE_CREATE_PRIVATE)
mode = 0600;
else
mode = 0666;
/* If the file doesn't exist, create it */
fd = g_open (filename, O_CREAT | O_EXCL | O_WRONLY | O_BINARY, mode);
if (fd == -1 && errno == EEXIST)
{
/* The file already exists */
fd = handle_overwrite_open (filename, etag, create_backup, &temp_file,
cancellable, error);
if (fd == -1)
return NULL;
}
else if (fd == -1)
{
int errsv = errno;
if (errsv == EINVAL)
/* This must be an invalid filename, on e.g. FAT */
g_set_error_literal (error, G_IO_ERROR,
G_IO_ERROR_INVALID_FILENAME,
_("Invalid filename"));
else
{
char *display_name = g_filename_display_name (filename);
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error opening file '%s': %s"),
display_name, g_strerror (errsv));
g_free (display_name);
}
return NULL;
}
stream = g_object_new (G_TYPE_LOCAL_FILE_OUTPUT_STREAM, NULL);
stream->priv->fd = fd;
stream->priv->tmp_filename = temp_file;
if (create_backup)
stream->priv->backup_filename = create_backup_filename (filename);
stream->priv->original_filename = g_strdup (filename);
return G_FILE_OUTPUT_STREAM (stream);
}
GFileOutputStream *
_g_local_file_output_stream_replace (const char *filename,
gboolean readable,
const char *etag,
gboolean create_backup,
GFileCreateFlags flags,
GFileInfo *reference_info,
GCancellable *cancellable,
GError **error)
{
GLocalFileOutputStream *stream;
int mode;
int fd;
char *temp_file;
gboolean sync_on_close;
int open_flags;
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return NULL;
temp_file = NULL;
mode = mode_from_flags_or_info (flags, reference_info);
sync_on_close = FALSE;
/* If the file doesn't exist, create it */
open_flags = O_CREAT | O_EXCL | O_BINARY;
if (readable)
open_flags |= O_RDWR;
else
open_flags |= O_WRONLY;
fd = g_open (filename, open_flags, mode);
if (fd == -1 && errno == EEXIST)
{
/* The file already exists */
fd = handle_overwrite_open (filename, readable, etag,
create_backup, &temp_file,
flags, reference_info,
cancellable, error);
if (fd == -1)
return NULL;
/* If the final destination exists, we want to sync the newly written
* file to ensure the data is on disk when we rename over the destination.
* otherwise if we get a system crash we can lose both the new and the
* old file on some filesystems. (I.E. those that don't guarantee the
* data is written to the disk before the metadata.)
*/
sync_on_close = TRUE;
}
else if (fd == -1)
{
set_error_from_open_errno (filename, error);
return NULL;
}
stream = g_object_new (G_TYPE_LOCAL_FILE_OUTPUT_STREAM, NULL);
stream->priv->fd = fd;
stream->priv->sync_on_close = sync_on_close;
stream->priv->tmp_filename = temp_file;
if (create_backup)
stream->priv->backup_filename = create_backup_filename (filename);
stream->priv->original_filename = g_strdup (filename);
return G_FILE_OUTPUT_STREAM (stream);
}
static int
handle_overwrite_open (const char *filename,
const char *etag,
gboolean create_backup,
char **temp_filename,
GCancellable *cancellable,
GError **error)
{
int fd = -1;
GLocalFileStat original_stat;
char *current_etag;
gboolean is_symlink;
int open_flags;
int res;
/* We only need read access to the original file if we are creating a backup.
* We also add O_CREATE to avoid a race if the file was just removed */
if (create_backup)
open_flags = O_RDWR | O_CREAT | O_BINARY;
else
open_flags = O_WRONLY | O_CREAT | O_BINARY;
/* Some systems have O_NOFOLLOW, which lets us avoid some races
* when finding out if the file we opened was a symlink */
#ifdef O_NOFOLLOW
is_symlink = FALSE;
fd = g_open (filename, open_flags | O_NOFOLLOW, 0666);
if (fd == -1 && errno == ELOOP)
{
/* Could be a symlink, or it could be a regular ELOOP error,
* but then the next open will fail too. */
is_symlink = TRUE;
fd = g_open (filename, open_flags, 0666);
}
#else
fd = g_open (filename, open_flags, 0666);
/* This is racy, but we do it as soon as possible to minimize the race */
is_symlink = g_file_test (filename, G_FILE_TEST_IS_SYMLINK);
#endif
if (fd == -1)
{
int errsv = errno;
char *display_name = g_filename_display_name (filename);
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error opening file '%s': %s"),
display_name, g_strerror (errsv));
g_free (display_name);
return -1;
}
#ifdef G_OS_WIN32
res = _fstati64 (fd, &original_stat);
#else
res = fstat (fd, &original_stat);
#endif
if (res != 0)
{
int errsv = errno;
char *display_name = g_filename_display_name (filename);
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error stating file '%s': %s"),
display_name, g_strerror (errsv));
g_free (display_name);
goto err_out;
}
/* not a regular file */
if (!S_ISREG (original_stat.st_mode))
{
if (S_ISDIR (original_stat.st_mode))
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_IS_DIRECTORY,
_("Target file is a directory"));
else
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_NOT_REGULAR_FILE,
_("Target file is not a regular file"));
goto err_out;
}
if (etag != NULL)
{
current_etag = _g_local_file_info_create_etag (&original_stat);
if (strcmp (etag, current_etag) != 0)
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_WRONG_ETAG,
_("The file was externally modified"));
g_free (current_etag);
goto err_out;
}
g_free (current_etag);
}
/* We use two backup strategies.
* The first one (which is faster) consist in saving to a
* tmp file then rename the original file to the backup and the
* tmp file to the original name. This is fast but doesn't work
* when the file is a link (hard or symbolic) or when we can't
* write to the current dir or can't set the permissions on the
* new file.
* The second strategy consist simply in copying the old file
* to a backup file and rewrite the contents of the file.
*/
if (!(original_stat.st_nlink > 1) && !is_symlink)
{
char *dirname, *tmp_filename;
int tmpfd;
dirname = g_path_get_dirname (filename);
tmp_filename = g_build_filename (dirname, ".goutputstream-XXXXXX", NULL);
g_free (dirname);
tmpfd = g_mkstemp (tmp_filename);
if (tmpfd == -1)
{
g_free (tmp_filename);
goto fallback_strategy;
}
/* try to keep permissions */
if (
#ifdef HAVE_FCHOWN
fchown (tmpfd, original_stat.st_uid, original_stat.st_gid) == -1 ||
#endif
#ifdef HAVE_FCHMOD
fchmod (tmpfd, original_stat.st_mode) == -1 ||
#endif
0
)
{
struct stat tmp_statbuf;
/* Check that we really needed to change something */
if (fstat (tmpfd, &tmp_statbuf) != 0 ||
original_stat.st_uid != tmp_statbuf.st_uid ||
original_stat.st_gid != tmp_statbuf.st_gid ||
original_stat.st_mode != tmp_statbuf.st_mode)
{
close (tmpfd);
g_unlink (tmp_filename);
g_free (tmp_filename);
goto fallback_strategy;
}
}
close (fd);
*temp_filename = tmp_filename;
return tmpfd;
}
fallback_strategy:
if (create_backup)
{
#if defined(HAVE_FCHOWN) && defined(HAVE_FCHMOD)
struct stat tmp_statbuf;
#endif
char *backup_filename;
int bfd;
backup_filename = create_backup_filename (filename);
if (g_unlink (backup_filename) == -1 && errno != ENOENT)
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_CANT_CREATE_BACKUP,
_("Backup file creation failed"));
g_free (backup_filename);
goto err_out;
}
bfd = g_open (backup_filename,
O_WRONLY | O_CREAT | O_EXCL | O_BINARY,
original_stat.st_mode & 0777);
if (bfd == -1)
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_CANT_CREATE_BACKUP,
_("Backup file creation failed"));
g_free (backup_filename);
goto err_out;
}
/* If needed, Try to set the group of the backup same as the
* original file. If this fails, set the protection
* bits for the group same as the protection bits for
* others. */
#if defined(HAVE_FCHOWN) && defined(HAVE_FCHMOD)
if (fstat (bfd, &tmp_statbuf) != 0)
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_CANT_CREATE_BACKUP,
_("Backup file creation failed"));
g_unlink (backup_filename);
g_free (backup_filename);
goto err_out;
}
if ((original_stat.st_gid != tmp_statbuf.st_gid) &&
fchown (bfd, (uid_t) -1, original_stat.st_gid) != 0)
{
if (fchmod (bfd,
(original_stat.st_mode & 0707) |
((original_stat.st_mode & 07) << 3)) != 0)
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_CANT_CREATE_BACKUP,
_("Backup file creation failed"));
g_unlink (backup_filename);
close (bfd);
g_free (backup_filename);
goto err_out;
}
}
#endif
if (!copy_file_data (fd, bfd, NULL))
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_CANT_CREATE_BACKUP,
_("Backup file creation failed"));
g_unlink (backup_filename);
close (bfd);
g_free (backup_filename);
goto err_out;
}
close (bfd);
g_free (backup_filename);
/* Seek back to the start of the file after the backup copy */
if (lseek (fd, 0, SEEK_SET) == -1)
{
int errsv = errno;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error seeking in file: %s"),
g_strerror (errsv));
goto err_out;
}
}
/* Truncate the file at the start */
#ifdef G_OS_WIN32
if (g_win32_ftruncate (fd, 0) == -1)
#else
if (ftruncate (fd, 0) == -1)
#endif
{
int errsv = errno;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error truncating file: %s"),
g_strerror (errsv));
goto err_out;
}
return fd;
err_out:
close (fd);
return -1;
}
GFileOutputStream *
_g_local_file_output_stream_replace (const char *filename,
gboolean readable,
const char *etag,
gboolean create_backup,
GFileCreateFlags flags,
GCancellable *cancellable,
GError **error)
{
GLocalFileOutputStream *stream;
int mode;
int fd;
char *temp_file;
gboolean sync_on_close;
int open_flags;
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return NULL;
temp_file = NULL;
if (flags & G_FILE_CREATE_PRIVATE)
mode = 0600;
else
mode = 0666;
sync_on_close = FALSE;
/* If the file doesn't exist, create it */
open_flags = O_CREAT | O_EXCL | O_BINARY;
if (readable)
open_flags |= O_RDWR;
else
open_flags |= O_WRONLY;
fd = g_open (filename, open_flags, mode);
if (fd == -1 && errno == EEXIST)
{
/* The file already exists */
fd = handle_overwrite_open (filename, readable, etag,
create_backup, &temp_file,
flags, cancellable, error);
if (fd == -1)
return NULL;
/* If the final destination exists, we want to sync the newly written
* file to ensure the data is on disk when we rename over the destination.
* otherwise if we get a system crash we can lose both the new and the
* old file on some filesystems. (I.E. those that don't guarantee the
* data is written to the disk before the metadata.)
*/
sync_on_close = TRUE;
}
else if (fd == -1)
{
int errsv = errno;
if (errsv == EINVAL)
/* This must be an invalid filename, on e.g. FAT */
g_set_error_literal (error, G_IO_ERROR,
G_IO_ERROR_INVALID_FILENAME,
_("Invalid filename"));
else
{
char *display_name = g_filename_display_name (filename);
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error opening file '%s': %s"),
display_name, g_strerror (errsv));
g_free (display_name);
}
return NULL;
}
stream = g_object_new (G_TYPE_LOCAL_FILE_OUTPUT_STREAM, NULL);
stream->priv->fd = fd;
stream->priv->sync_on_close = sync_on_close;
stream->priv->tmp_filename = temp_file;
if (create_backup)
stream->priv->backup_filename = create_backup_filename (filename);
stream->priv->original_filename = g_strdup (filename);
return G_FILE_OUTPUT_STREAM (stream);
}
