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glib/gio/glocalfileoutputstream.c
Philip Withnall b1ebb72522 glocalfileoutputstream: Fix ETag check when replacing through a symlink 
Since commit 87e19535fe, the ETag check when writing out a file through
a symlink (following the symlink) has been incorrectly using the ETag
value of the symlink, rather than the target file. This is incorrect
because the ETag should represent the file content, not its metadata or
links to it.

Fix that, and add a unit test.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Fixes: #2417
2021-06-07 12:44:52 +01:00

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/* GIO - GLib Input, Output and Streaming Library
*
* Copyright (C) 2006-2007 Red Hat, Inc.
*
* This library 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 2.1 of the License, or (at your option) any later version.
*
* This library 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 this library; if not, see <http://www.gnu.org/licenses/>.
*
* Author: Alexander Larsson <alexl@redhat.com>
*/
/* Needed for the statx() calls in inline functions in glocalfileinfo.h */
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include "config.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <glib.h>
#include <glib/gstdio.h>
#include "glibintl.h"
#include "gioerror.h"
#include "gcancellable.h"
#include "glocalfileoutputstream.h"
#include "gfileinfo.h"
#include "glocalfileinfo.h"
#ifdef G_OS_UNIX
#include <unistd.h>
#include "gfiledescriptorbased.h"
#include <sys/uio.h>
#endif
#include "glib-private.h"
#include "gioprivate.h"
#ifdef G_OS_WIN32
#include <io.h>
#ifndef S_ISDIR
#define S_ISDIR(m) (((m) & _S_IFMT) == _S_IFDIR)
#endif
#ifndef S_ISREG
#define S_ISREG(m) (((m) & _S_IFMT) == _S_IFREG)
#endif
#endif
#ifndef O_BINARY
#define O_BINARY 0
#endif
#ifndef O_CLOEXEC
#define O_CLOEXEC 0
#else
#define HAVE_O_CLOEXEC 1
#endif
struct _GLocalFileOutputStreamPrivate {
char *tmp_filename;
char *original_filename;
char *backup_filename;
char *etag;
guint sync_on_close : 1;
guint do_close : 1;
int fd;
};
#ifdef G_OS_UNIX
static void g_file_descriptor_based_iface_init (GFileDescriptorBasedIface *iface);
#endif
#define g_local_file_output_stream_get_type _g_local_file_output_stream_get_type
#ifdef G_OS_UNIX
G_DEFINE_TYPE_WITH_CODE (GLocalFileOutputStream, g_local_file_output_stream, G_TYPE_FILE_OUTPUT_STREAM,
G_ADD_PRIVATE (GLocalFileOutputStream)
G_IMPLEMENT_INTERFACE (G_TYPE_FILE_DESCRIPTOR_BASED,
g_file_descriptor_based_iface_init))
#else
G_DEFINE_TYPE_WITH_CODE (GLocalFileOutputStream, g_local_file_output_stream, G_TYPE_FILE_OUTPUT_STREAM,
G_ADD_PRIVATE (GLocalFileOutputStream))
#endif
/* Some of the file replacement code was based on the code from gedit,
* relicenced to LGPL with permissions from the authors.
*/
#define BACKUP_EXTENSION "~"
static gssize g_local_file_output_stream_write (GOutputStream *stream,
const void *buffer,
gsize count,
GCancellable *cancellable,
GError **error);
#ifdef G_OS_UNIX
static gboolean g_local_file_output_stream_writev (GOutputStream *stream,
const GOutputVector *vectors,
gsize n_vectors,
gsize *bytes_written,
GCancellable *cancellable,
GError **error);
#endif
static gboolean g_local_file_output_stream_close (GOutputStream *stream,
GCancellable *cancellable,
GError **error);
static GFileInfo *g_local_file_output_stream_query_info (GFileOutputStream *stream,
const char *attributes,
GCancellable *cancellable,
GError **error);
static char * g_local_file_output_stream_get_etag (GFileOutputStream *stream);
static goffset g_local_file_output_stream_tell (GFileOutputStream *stream);
static gboolean g_local_file_output_stream_can_seek (GFileOutputStream *stream);
static gboolean g_local_file_output_stream_seek (GFileOutputStream *stream,
goffset offset,
GSeekType type,
GCancellable *cancellable,
GError **error);
static gboolean g_local_file_output_stream_can_truncate (GFileOutputStream *stream);
static gboolean g_local_file_output_stream_truncate (GFileOutputStream *stream,
goffset size,
GCancellable *cancellable,
GError **error);
#ifdef G_OS_UNIX
static int g_local_file_output_stream_get_fd (GFileDescriptorBased *stream);
#endif
static void
g_local_file_output_stream_finalize (GObject *object)
{
GLocalFileOutputStream *file;
file = G_LOCAL_FILE_OUTPUT_STREAM (object);
g_free (file->priv->tmp_filename);
g_free (file->priv->original_filename);
g_free (file->priv->backup_filename);
g_free (file->priv->etag);
G_OBJECT_CLASS (g_local_file_output_stream_parent_class)->finalize (object);
}
static void
g_local_file_output_stream_class_init (GLocalFileOutputStreamClass *klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
GOutputStreamClass *stream_class = G_OUTPUT_STREAM_CLASS (klass);
GFileOutputStreamClass *file_stream_class = G_FILE_OUTPUT_STREAM_CLASS (klass);
gobject_class->finalize = g_local_file_output_stream_finalize;
stream_class->write_fn = g_local_file_output_stream_write;
#ifdef G_OS_UNIX
stream_class->writev_fn = g_local_file_output_stream_writev;
#endif
stream_class->close_fn = g_local_file_output_stream_close;
file_stream_class->query_info = g_local_file_output_stream_query_info;
file_stream_class->get_etag = g_local_file_output_stream_get_etag;
file_stream_class->tell = g_local_file_output_stream_tell;
file_stream_class->can_seek = g_local_file_output_stream_can_seek;
file_stream_class->seek = g_local_file_output_stream_seek;
file_stream_class->can_truncate = g_local_file_output_stream_can_truncate;
file_stream_class->truncate_fn = g_local_file_output_stream_truncate;
}
#ifdef G_OS_UNIX
static void
g_file_descriptor_based_iface_init (GFileDescriptorBasedIface *iface)
{
iface->get_fd = g_local_file_output_stream_get_fd;
}
#endif
static void
g_local_file_output_stream_init (GLocalFileOutputStream *stream)
{
stream->priv = g_local_file_output_stream_get_instance_private (stream);
stream->priv->do_close = TRUE;
}
static gssize
g_local_file_output_stream_write (GOutputStream *stream,
const void *buffer,
gsize count,
GCancellable *cancellable,
GError **error)
{
GLocalFileOutputStream *file;
gssize res;
file = G_LOCAL_FILE_OUTPUT_STREAM (stream);
while (1)
{
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return -1;
res = write (file->priv->fd, buffer, count);
if (res == -1)
{
int errsv = errno;
if (errsv == EINTR)
continue;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error writing to file: %s"),
g_strerror (errsv));
}
break;
}
return res;
}
/* On Windows there is no equivalent API for files. The closest API to that is
* WriteFileGather() but it is useless in general: it requires, among other
* things, that each chunk is the size of a whole page and in memory aligned
* to a page. We can't possibly guarantee that in GLib.
*/
#ifdef G_OS_UNIX
/* Macro to check if struct iovec and GOutputVector have the same ABI */
#define G_OUTPUT_VECTOR_IS_IOVEC (sizeof (struct iovec) == sizeof (GOutputVector) && \
G_SIZEOF_MEMBER (struct iovec, iov_base) == G_SIZEOF_MEMBER (GOutputVector, buffer) && \
G_STRUCT_OFFSET (struct iovec, iov_base) == G_STRUCT_OFFSET (GOutputVector, buffer) && \
G_SIZEOF_MEMBER (struct iovec, iov_len) == G_SIZEOF_MEMBER (GOutputVector, size) && \
G_STRUCT_OFFSET (struct iovec, iov_len) == G_STRUCT_OFFSET (GOutputVector, size))
static gboolean
g_local_file_output_stream_writev (GOutputStream *stream,
const GOutputVector *vectors,
gsize n_vectors,
gsize *bytes_written,
GCancellable *cancellable,
GError **error)
{
GLocalFileOutputStream *file;
gssize res;
struct iovec *iov;
if (bytes_written)
*bytes_written = 0;
/* Clamp the number of vectors if more given than we can write in one go.
* The caller has to handle short writes anyway.
*/
if (n_vectors > G_IOV_MAX)
n_vectors = G_IOV_MAX;
file = G_LOCAL_FILE_OUTPUT_STREAM (stream);
if (G_OUTPUT_VECTOR_IS_IOVEC)
{
/* ABI is compatible */
iov = (struct iovec *) vectors;
}
else
{
gsize i;
/* ABI is incompatible */
iov = g_newa (struct iovec, n_vectors);
for (i = 0; i < n_vectors; i++)
{
iov[i].iov_base = (void *)vectors[i].buffer;
iov[i].iov_len = vectors[i].size;
}
}
while (1)
{
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return FALSE;
res = writev (file->priv->fd, iov, n_vectors);
if (res == -1)
{
int errsv = errno;
if (errsv == EINTR)
continue;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error writing to file: %s"),
g_strerror (errsv));
}
else if (bytes_written)
{
*bytes_written = res;
}
break;
}
return res != -1;
}
#endif
void
_g_local_file_output_stream_set_do_close (GLocalFileOutputStream *out,
gboolean do_close)
{
out->priv->do_close = do_close;
}
gboolean
_g_local_file_output_stream_really_close (GLocalFileOutputStream *file,
GCancellable *cancellable,
GError **error)
{
GLocalFileStat final_stat;
if (file->priv->sync_on_close &&
g_fsync (file->priv->fd) != 0)
{
int errsv = errno;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error writing to file: %s"),
g_strerror (errsv));
goto err_out;
}
#ifdef G_OS_WIN32
/* Must close before renaming on Windows, so just do the close first
* in all cases for now.
*/
if (GLIB_PRIVATE_CALL (g_win32_fstat) (file->priv->fd, &final_stat) == 0)
file->priv->etag = _g_local_file_info_create_etag (&final_stat);
if (!g_close (file->priv->fd, NULL))
{
int errsv = errno;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error closing file: %s"),
g_strerror (errsv));
return FALSE;
}
#endif
if (file->priv->tmp_filename)
{
/* We need to move the temp file to its final place,
* and possibly create the backup file
*/
if (file->priv->backup_filename)
{
if (g_cancellable_set_error_if_cancelled (cancellable, error))
goto err_out;
#ifdef G_OS_UNIX
/* create original -> backup link, the original is then renamed over */
if (g_unlink (file->priv->backup_filename) != 0 &&
errno != ENOENT)
{
int errsv = errno;
g_set_error (error, G_IO_ERROR,
G_IO_ERROR_CANT_CREATE_BACKUP,
_("Error removing old backup link: %s"),
g_strerror (errsv));
goto err_out;
}
if (link (file->priv->original_filename, file->priv->backup_filename) != 0)
{
/* link failed or is not supported, try rename */
if (g_rename (file->priv->original_filename, file->priv->backup_filename) != 0)
{
int errsv = errno;
g_set_error (error, G_IO_ERROR,
G_IO_ERROR_CANT_CREATE_BACKUP,
_("Error creating backup copy: %s"),
g_strerror (errsv));
goto err_out;
}
}
#else
/* If link not supported, just rename... */
if (g_rename (file->priv->original_filename, file->priv->backup_filename) != 0)
{
int errsv = errno;
g_set_error (error, G_IO_ERROR,
G_IO_ERROR_CANT_CREATE_BACKUP,
_("Error creating backup copy: %s"),
g_strerror (errsv));
goto err_out;
}
#endif
}
if (g_cancellable_set_error_if_cancelled (cancellable, error))
goto err_out;
/* tmp -> original */
if (g_rename (file->priv->tmp_filename, file->priv->original_filename) != 0)
{
int errsv = errno;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error renaming temporary file: %s"),
g_strerror (errsv));
goto err_out;
}
g_clear_pointer (&file->priv->tmp_filename, g_free);
}
if (g_cancellable_set_error_if_cancelled (cancellable, error))
goto err_out;
#ifndef G_OS_WIN32 /* Already did the fstat() and close() above on Win32 */
if (g_local_file_fstat (file->priv->fd, G_LOCAL_FILE_STAT_FIELD_MTIME, G_LOCAL_FILE_STAT_FIELD_ALL, &final_stat) == 0)
file->priv->etag = _g_local_file_info_create_etag (&final_stat);
if (!g_close (file->priv->fd, NULL))
{
int errsv = errno;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error closing file: %s"),
g_strerror (errsv));
goto err_out;
}
#endif
return TRUE;
err_out:
#ifndef G_OS_WIN32
/* A simple try to close the fd in case we fail before the actual close */
g_close (file->priv->fd, NULL);
#endif
if (file->priv->tmp_filename)
g_unlink (file->priv->tmp_filename);
return FALSE;
}
static gboolean
g_local_file_output_stream_close (GOutputStream *stream,
GCancellable *cancellable,
GError **error)
{
GLocalFileOutputStream *file;
file = G_LOCAL_FILE_OUTPUT_STREAM (stream);
if (file->priv->do_close)
return _g_local_file_output_stream_really_close (file,
cancellable,
error);
return TRUE;
}
static char *
g_local_file_output_stream_get_etag (GFileOutputStream *stream)
{
GLocalFileOutputStream *file;
file = G_LOCAL_FILE_OUTPUT_STREAM (stream);
return g_strdup (file->priv->etag);
}
static goffset
g_local_file_output_stream_tell (GFileOutputStream *stream)
{
GLocalFileOutputStream *file;
off_t pos;
file = G_LOCAL_FILE_OUTPUT_STREAM (stream);
pos = lseek (file->priv->fd, 0, SEEK_CUR);
if (pos == (off_t)-1)
return 0;
return pos;
}
static gboolean
g_local_file_output_stream_can_seek (GFileOutputStream *stream)
{
GLocalFileOutputStream *file;
off_t pos;
file = G_LOCAL_FILE_OUTPUT_STREAM (stream);
pos = lseek (file->priv->fd, 0, SEEK_CUR);
if (pos == (off_t)-1 && errno == ESPIPE)
return FALSE;
return TRUE;
}
static int
seek_type_to_lseek (GSeekType type)
{
switch (type)
{
default:
case G_SEEK_CUR:
return SEEK_CUR;
case G_SEEK_SET:
return SEEK_SET;
case G_SEEK_END:
return SEEK_END;
}
}
static gboolean
g_local_file_output_stream_seek (GFileOutputStream *stream,
goffset offset,
GSeekType type,
GCancellable *cancellable,
GError **error)
{
GLocalFileOutputStream *file;
off_t pos;
file = G_LOCAL_FILE_OUTPUT_STREAM (stream);
pos = lseek (file->priv->fd, offset, seek_type_to_lseek (type));
if (pos == (off_t)-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));
return FALSE;
}
return TRUE;
}
static gboolean
g_local_file_output_stream_can_truncate (GFileOutputStream *stream)
{
/* We can't truncate pipes and stuff where we can't seek */
return g_local_file_output_stream_can_seek (stream);
}
static gboolean
g_local_file_output_stream_truncate (GFileOutputStream *stream,
goffset size,
GCancellable *cancellable,
GError **error)
{
GLocalFileOutputStream *file;
int res;
file = G_LOCAL_FILE_OUTPUT_STREAM (stream);
restart:
#ifdef G_OS_WIN32
res = g_win32_ftruncate (file->priv->fd, size);
#else
res = ftruncate (file->priv->fd, size);
#endif
if (res == -1)
{
int errsv = errno;
if (errsv == EINTR)
{
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return FALSE;
goto restart;
}
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error truncating file: %s"),
g_strerror (errsv));
return FALSE;
}
return TRUE;
}
static GFileInfo *
g_local_file_output_stream_query_info (GFileOutputStream *stream,
const char *attributes,
GCancellable *cancellable,
GError **error)
{
GLocalFileOutputStream *file;
file = G_LOCAL_FILE_OUTPUT_STREAM (stream);
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return NULL;
return _g_local_file_info_get_from_fd (file->priv->fd,
attributes,
error);
}
GFileOutputStream *
_g_local_file_output_stream_new (int fd)
{
GLocalFileOutputStream *stream;
stream = g_object_new (G_TYPE_LOCAL_FILE_OUTPUT_STREAM, NULL);
stream->priv->fd = fd;
return G_FILE_OUTPUT_STREAM (stream);
}
static void
set_error_from_open_errno (const char *filename,
GError **error)
{
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);
}
}
static GFileOutputStream *
output_stream_open (const char *filename,
gint open_flags,
guint mode,
GCancellable *cancellable,
GError **error)
{
GLocalFileOutputStream *stream;
gint fd;
fd = g_open (filename, open_flags, mode);
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;
return G_FILE_OUTPUT_STREAM (stream);
}
GFileOutputStream *
_g_local_file_output_stream_open (const char *filename,
gboolean readable,
GCancellable *cancellable,
GError **error)
{
int open_flags;
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return NULL;
open_flags = O_BINARY;
if (readable)
open_flags |= O_RDWR;
else
open_flags |= O_WRONLY;
return output_stream_open (filename, open_flags, 0666, cancellable, error);
}
static gint
mode_from_flags_or_info (GFileCreateFlags flags,
GFileInfo *reference_info)
{
if (flags & G_FILE_CREATE_PRIVATE)
return 0600;
else if (reference_info && g_file_info_has_attribute (reference_info, "unix::mode"))
return g_file_info_get_attribute_uint32 (reference_info, "unix::mode") & (~S_IFMT);
else
return 0666;
}
GFileOutputStream *
_g_local_file_output_stream_create (const char *filename,
gboolean readable,
GFileCreateFlags flags,
GFileInfo *reference_info,
GCancellable *cancellable,
GError **error)
{
int mode;
int open_flags;
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return NULL;
mode = mode_from_flags_or_info (flags, reference_info);
open_flags = O_CREAT | O_EXCL | O_BINARY;
if (readable)
open_flags |= O_RDWR;
else
open_flags |= O_WRONLY;
return output_stream_open (filename, open_flags, mode, cancellable, error);
}
GFileOutputStream *
_g_local_file_output_stream_append (const char *filename,
GFileCreateFlags flags,
GCancellable *cancellable,
GError **error)
{
int mode;
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return NULL;
if (flags & G_FILE_CREATE_PRIVATE)
mode = 0600;
else
mode = 0666;
return output_stream_open (filename, O_CREAT | O_APPEND | O_WRONLY | O_BINARY, mode,
cancellable, error);
}
static char *
create_backup_filename (const char *filename)
{
return g_strconcat (filename, BACKUP_EXTENSION, NULL);
}
#define BUFSIZE 8192 /* size of normal write buffer */
static gboolean
copy_file_data (gint sfd,
gint dfd,
GError **error)
{
gboolean ret = TRUE;
gpointer buffer;
const gchar *write_buffer;
gssize bytes_read;
gssize bytes_to_write;
gssize bytes_written;
buffer = g_malloc (BUFSIZE);
do
{
bytes_read = read (sfd, buffer, BUFSIZE);
if (bytes_read == -1)
{
int errsv = errno;
if (errsv == EINTR)
continue;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error reading from file: %s"),
g_strerror (errsv));
ret = FALSE;
break;
}
bytes_to_write = bytes_read;
write_buffer = buffer;
do
{
bytes_written = write (dfd, write_buffer, bytes_to_write);
if (bytes_written == -1)
{
int errsv = errno;
if (errsv == EINTR)
continue;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error writing to file: %s"),
g_strerror (errsv));
ret = FALSE;
break;
}
bytes_to_write -= bytes_written;
write_buffer += bytes_written;
}
while (bytes_to_write > 0);
} while ((bytes_read != 0) && (ret == TRUE));
g_free (buffer);
return ret;
}
static int
handle_overwrite_open (const char *filename,
gboolean readable,
const char *etag,
gboolean create_backup,
char **temp_filename,
GFileCreateFlags flags,
GFileInfo *reference_info,
GCancellable *cancellable,
GError **error)
{
int fd = -1;
GLocalFileStat original_stat;
char *current_etag;
gboolean is_symlink;
int open_flags;
int res;
int mode;
int errsv;
gboolean replace_destination_set = (flags & G_FILE_CREATE_REPLACE_DESTINATION);
mode = mode_from_flags_or_info (flags, reference_info);
/* We only need read access to the original file if we are creating a backup.
* We also add O_CREAT to avoid a race if the file was just removed */
if (create_backup || readable)
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, mode);
errsv = errno;
#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
if (fd == -1 && errsv == EMLINK)
#elif defined(__NetBSD__)
if (fd == -1 && errsv == EFTYPE)
#else
if (fd == -1 && errsv == ELOOP)
#endif
{
/* Could be a symlink, or it could be a regular ELOOP error,
* but then the next open will fail too. */
is_symlink = TRUE;
if (!replace_destination_set)
fd = g_open (filename, open_flags, mode);
}
#else /* if !O_NOFOLLOW */
/* 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);
if (!is_symlink || !replace_destination_set)
{
fd = g_open (filename, open_flags, mode);
errsv = errno;
}
#endif
if (fd == -1 &&
(!is_symlink || !replace_destination_set))
{
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;
}
if (!is_symlink)
{
res = g_local_file_fstat (fd,
G_LOCAL_FILE_STAT_FIELD_TYPE |
G_LOCAL_FILE_STAT_FIELD_MODE |
G_LOCAL_FILE_STAT_FIELD_UID |
G_LOCAL_FILE_STAT_FIELD_GID |
G_LOCAL_FILE_STAT_FIELD_MTIME |
G_LOCAL_FILE_STAT_FIELD_NLINK,
G_LOCAL_FILE_STAT_FIELD_ALL, &original_stat);
errsv = errno;
}
else
{
res = g_local_file_lstat (filename,
G_LOCAL_FILE_STAT_FIELD_TYPE |
G_LOCAL_FILE_STAT_FIELD_MODE |
G_LOCAL_FILE_STAT_FIELD_UID |
G_LOCAL_FILE_STAT_FIELD_GID |
G_LOCAL_FILE_STAT_FIELD_MTIME |
G_LOCAL_FILE_STAT_FIELD_NLINK,
G_LOCAL_FILE_STAT_FIELD_ALL, &original_stat);
errsv = errno;
}
if (res != 0)
{
char *display_name = g_filename_display_name (filename);
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error when getting information for file “%s”: %s"),
display_name, g_strerror (errsv));
g_free (display_name);
goto error;
}
/* not a regular file */
if (!S_ISREG (_g_stat_mode (&original_stat)))
{
if (S_ISDIR (_g_stat_mode (&original_stat)))
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_IS_DIRECTORY,
_("Target file is a directory"));
goto error;
}
else if (!is_symlink ||
#ifdef S_ISLNK
!S_ISLNK (_g_stat_mode (&original_stat))
#else
FALSE
#endif
)
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_NOT_REGULAR_FILE,
_("Target file is not a regular file"));
goto error;
}
}
if (etag != NULL)
{
GLocalFileStat etag_stat;
GLocalFileStat *etag_stat_pointer;
/* The ETag is calculated on the details of the target file, for symlinks,
* so we might need to stat() again. */
if (is_symlink)
{
res = g_local_file_stat (filename,
G_LOCAL_FILE_STAT_FIELD_MTIME,
G_LOCAL_FILE_STAT_FIELD_ALL, &etag_stat);
errsv = errno;
if (res != 0)
{
char *display_name = g_filename_display_name (filename);
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error when getting information for file “%s”: %s"),
display_name, g_strerror (errsv));
g_free (display_name);
goto error;
}
etag_stat_pointer = &etag_stat;
}
else
etag_stat_pointer = &original_stat;
/* Compare the ETags */
current_etag = _g_local_file_info_create_etag (etag_stat_pointer);
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 error;
}
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 (replace_destination_set ||
(!(_g_stat_nlink (&original_stat) > 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_full (tmp_filename, (readable ? O_RDWR : O_WRONLY) | O_BINARY, mode);
if (tmpfd == -1)
{
g_free (tmp_filename);
goto fallback_strategy;
}
/* try to keep permissions (unless replacing) */
if (!replace_destination_set &&
(
#ifdef HAVE_FCHOWN
fchown (tmpfd, _g_stat_uid (&original_stat), _g_stat_gid (&original_stat)) == -1 ||
#endif
#ifdef HAVE_FCHMOD
fchmod (tmpfd, _g_stat_mode (&original_stat) & ~S_IFMT) == -1 ||
#endif
0
)
)
{
GLocalFileStat tmp_statbuf;
int tres;
tres = g_local_file_fstat (tmpfd,
G_LOCAL_FILE_STAT_FIELD_TYPE |
G_LOCAL_FILE_STAT_FIELD_MODE |
G_LOCAL_FILE_STAT_FIELD_UID |
G_LOCAL_FILE_STAT_FIELD_GID,
G_LOCAL_FILE_STAT_FIELD_ALL, &tmp_statbuf);
/* Check that we really needed to change something */
if (tres != 0 ||
_g_stat_uid (&original_stat) != _g_stat_uid (&tmp_statbuf) ||
_g_stat_gid (&original_stat) != _g_stat_gid (&tmp_statbuf) ||
_g_stat_mode (&original_stat) != _g_stat_mode (&tmp_statbuf))
{
g_close (tmpfd, NULL);
g_unlink (tmp_filename);
g_free (tmp_filename);
goto fallback_strategy;
}
}
if (fd >= 0)
g_close (fd, NULL);
*temp_filename = tmp_filename;
return tmpfd;
}
fallback_strategy:
if (create_backup)
{
#if defined(HAVE_FCHOWN) && defined(HAVE_FCHMOD)
GLocalFileStat 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 error;
}
bfd = g_open (backup_filename,
O_WRONLY | O_CREAT | O_EXCL | O_BINARY,
_g_stat_mode (&original_stat) & 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 error;
}
/* 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 (g_local_file_fstat (bfd, G_LOCAL_FILE_STAT_FIELD_GID, G_LOCAL_FILE_STAT_FIELD_ALL, &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_close (bfd, NULL);
g_free (backup_filename);
goto error;
}
if ((_g_stat_gid (&original_stat) != _g_stat_gid (&tmp_statbuf)) &&
fchown (bfd, (uid_t) -1, _g_stat_gid (&original_stat)) != 0)
{
if (fchmod (bfd,
(_g_stat_mode (&original_stat) & 0707) |
((_g_stat_mode (&original_stat) & 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);
g_close (bfd, NULL);
g_free (backup_filename);
goto error;
}
}
#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);
g_close (bfd, NULL);
g_free (backup_filename);
goto error;
}
g_close (bfd, NULL);
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 error;
}
}
if (replace_destination_set)
{
g_close (fd, NULL);
if (g_unlink (filename) != 0)
{
int errsv = errno;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error removing old file: %s"),
g_strerror (errsv));
goto error;
}
if (readable)
open_flags = O_RDWR | O_CREAT | O_BINARY;
else
open_flags = O_WRONLY | O_CREAT | O_BINARY;
fd = g_open (filename, open_flags, mode);
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);
goto error;
}
}
else
{
/* 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 error;
}
}
return fd;
error:
if (fd >= 0)
g_close (fd, NULL);
return -1;
}
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 | O_CLOEXEC;
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;
}
#if !defined(HAVE_O_CLOEXEC) && defined(F_SETFD)
else
fcntl (fd, F_SETFD, FD_CLOEXEC);
#endif
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);
}
gint
_g_local_file_output_stream_get_fd (GLocalFileOutputStream *stream)
{
g_return_val_if_fail (G_IS_LOCAL_FILE_OUTPUT_STREAM (stream), -1);
return stream->priv->fd;
}
#ifdef G_OS_UNIX
static int
g_local_file_output_stream_get_fd (GFileDescriptorBased *fd_based)
{
GLocalFileOutputStream *stream = G_LOCAL_FILE_OUTPUT_STREAM (fd_based);
return _g_local_file_output_stream_get_fd (stream);
}
#endif
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