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glib/gio/glocalfileoutputstream.c
Maciej S. Szmigiero 8f8ebb1bd0 g_mkstemp: Use O_CLOEXEC for race-free setting of the close-on-exec flag 
mkstemp-like family of functions also use g_open () under the hood so
they should pass the O_CLOEXEC flag there for race-free setting of the
close-on-exec flag.
2023-02-22 00:38:13 +01:00

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/* GIO - GLib Input, Output and Streaming Library
*
* Copyright (C) 2006-2007 Red Hat, Inc.
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* 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 | O_CLOEXEC;
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 | O_CLOEXEC;
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 | O_CLOEXEC, 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 = 0;
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 | O_CLOEXEC;
else
open_flags = O_WRONLY | O_CREAT | O_BINARY | O_CLOEXEC;
/* 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 | O_CLOEXEC, 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 | O_CLOEXEC,
_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)
{
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);
fd = -1;
if (g_unlink (filename) != 0)
{
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 | O_CLOEXEC;
else
open_flags = O_WRONLY | O_CREAT | O_BINARY | O_CLOEXEC;
fd = g_open (filename, open_flags, mode);
if (fd == -1)
{
char *display_name;
errsv = errno;
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
{
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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