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Bug 738329 - xcf_seek_pos() can cause unexpected OS behavior 

Change XCF saving to never seek past the end of the partially written
file. The only places where we still did this was when skipping the
offset tables for layers, channels, levels and tiles.

Now we write an all-zero offset table first, and then only seek around
in areas of the file that already exist. This also simplifies the code
a bit. Changed comments to make it clear what happens.
This commit is contained in:
Michael Natterer 2014-10-17 19:12:05 +02:00
parent 0d435f11b7
commit 5a4d865358
3 changed files with 109 additions and 75 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

130
app/xcf/xcf-save.c
View File

@ -139,6 +139,15 @@ static gboolean xcf_save_vectors (XcfInfo *info,
} \ } \
} G_STMT_END } G_STMT_END
#define xcf_write_zero_int32_check_error(info, count) G_STMT_START { \
info->cp += xcf_write_zero_int32 (info->output, count, &tmp_error); \
if (tmp_error) \
{ \
g_propagate_error (error, tmp_error); \
return FALSE; \
} \
} G_STMT_END
#define xcf_write_int8_check_error(info, data, count) G_STMT_START { \ #define xcf_write_int8_check_error(info, data, count) G_STMT_START { \
info->cp += xcf_write_int8 (info->output, data, count, &tmp_error); \ info->cp += xcf_write_int8 (info->output, data, count, &tmp_error); \
if (tmp_error) \ if (tmp_error) \
@ -185,9 +194,6 @@ static gboolean xcf_save_vectors (XcfInfo *info,
} G_STMT_END } G_STMT_END
static const guint32 zero = 0;
gboolean gboolean
xcf_save_image (XcfInfo *info, xcf_save_image (XcfInfo *info,
GimpImage *image, GimpImage *image,
@ -258,19 +264,26 @@ xcf_save_image (XcfInfo *info,
xcf_progress_update (info); xcf_progress_update (info);
/* 'offset' is where we will write the next layer or channel, which /* 'saved_pos' is the next slot in the offset table */
* is after the offset table saved_pos = info->cp;
*/
offset = info->cp + (n_layers + n_channels + 2) * 4; /* write an empty offset table */
xcf_write_zero_int32_check_error (info, n_layers + n_channels + 2);
/* 'offset' is where we will write the next layer or channel */
offset = info->cp;
for (list = all_layers; list; list = g_list_next (list)) for (list = all_layers; list; list = g_list_next (list))
{ {
GimpLayer *layer = list->data; GimpLayer *layer = list->data;
/* write the offset of the layer */ /* seek back to the next slot in the offset table and write the
* offset of the layer
*/
xcf_check_error (xcf_seek_pos (info, saved_pos, error));
xcf_write_int32_check_error (info, &offset, 1); xcf_write_int32_check_error (info, &offset, 1);
/* 'saved_pos' is the next slot in the layer offset table */ /* remember the next slot in the offset table */
saved_pos = info->cp; saved_pos = info->cp;
/* seek to the layer offset and save the layer */ /* seek to the layer offset and save the layer */
@ -280,40 +293,40 @@ xcf_save_image (XcfInfo *info,
/* the next layer's offset is after the layer we just wrote */ /* the next layer's offset is after the layer we just wrote */
offset = info->cp; offset = info->cp;
/* seek back to the next slot in the offset table */
xcf_check_error (xcf_seek_pos (info, saved_pos, error));
xcf_progress_update (info); xcf_progress_update (info);
} }
/* write out a '0' offset to indicate the end of the layer offsets */ /* skip a '0' in the offset table to indicate the end of the layer
xcf_write_int32_check_error (info, &zero, 1); * offsets
*/
saved_pos += 4;
for (list = all_channels; list; list = g_list_next (list)) for (list = all_channels; list; list = g_list_next (list))
{ {
GimpChannel *channel = list->data; GimpChannel *channel = list->data;
/* write the offset of the channel */ /* seek back to the next slot in the offset table and write the
* offset of the channel
*/
xcf_check_error (xcf_seek_pos (info, saved_pos, error));
xcf_write_int32_check_error (info, &offset, 1); xcf_write_int32_check_error (info, &offset, 1);
/* 'saved_pos' is the next slot in the channel offset table */ /* remember the next slot in the offset table */
saved_pos = info->cp; saved_pos = info->cp;
/* seek to the channel offset and save the channel */ /* seek to the channel offset and save the channel */
xcf_check_error (xcf_seek_pos (info, offset, error)); xcf_check_error (xcf_seek_pos (info, offset, error));
xcf_check_error (xcf_save_channel (info, image, channel, error)); xcf_check_error (xcf_save_channel (info, image, channel, error));
/* the next channels's offset is after the layer we just wrote */ /* the next channels's offset is after the channel we just wrote */
offset = info->cp; offset = info->cp;
/* seek back to the next slot in the offset table */
xcf_check_error (xcf_seek_pos (info, saved_pos, error));
xcf_progress_update (info); xcf_progress_update (info);
} }
/* write out a '0' offset to indicate the end of the channel offsets */ /* there is already a '0' at the end of the offset table to indicate
xcf_write_int32_check_error (info, &zero, 1); * the end of the channel offsets
*/
g_list_free (all_layers); g_list_free (all_layers);
g_list_free (all_channels); g_list_free (all_channels);
@ -1166,31 +1179,28 @@ xcf_save_layer (XcfInfo *info,
xcf_write_int32_check_error (info, &offset, 1); xcf_write_int32_check_error (info, &offset, 1);
saved_pos = info->cp; saved_pos = info->cp;
xcf_check_error (xcf_seek_pos (info, offset, error));
/* write a zero layer mask offset */
xcf_write_zero_int32_check_error (info, 1);
xcf_check_error (xcf_save_buffer (info, xcf_check_error (xcf_save_buffer (info,
gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)), gimp_drawable_get_buffer (GIMP_DRAWABLE (layer)),
error)); error));
offset = info->cp; offset = info->cp;
xcf_check_error (xcf_seek_pos (info, saved_pos, error));
/* write out the layer mask */ /* write out the layer mask */
if (gimp_layer_get_mask (layer)) if (gimp_layer_get_mask (layer))
{ {
GimpLayerMask *mask = gimp_layer_get_mask (layer); GimpLayerMask *mask = gimp_layer_get_mask (layer);
xcf_check_error (xcf_seek_pos (info, saved_pos, error));
xcf_write_int32_check_error (info, &offset, 1); xcf_write_int32_check_error (info, &offset, 1);
xcf_check_error (xcf_seek_pos (info, offset, error));
xcf_check_error (xcf_seek_pos (info, offset, error));
xcf_check_error (xcf_save_channel (info, image, GIMP_CHANNEL (mask), xcf_check_error (xcf_save_channel (info, image, GIMP_CHANNEL (mask),
error)); error));
} }
else
{
xcf_write_int32_check_error (info, &zero, 1);
xcf_check_error (xcf_seek_pos (info, offset, error));
}
return TRUE; return TRUE;
} }
@ -1292,17 +1302,24 @@ xcf_save_buffer (XcfInfo *info,
tmp2 = xcf_calc_levels (height, XCF_TILE_HEIGHT); tmp2 = xcf_calc_levels (height, XCF_TILE_HEIGHT);
nlevels = MAX (tmp1, tmp2); nlevels = MAX (tmp1, tmp2);
/* 'offset' is where we will save the next level, which is after the /* 'saved_pos' is the next slot in the offset table */
* level offset table saved_pos = info->cp;
*/
offset = info->cp + (1 + nlevels) * 4; /* write an empty offset table */
xcf_write_zero_int32_check_error (info, nlevels + 1);
/* 'offset' is where we will write the next level */
offset = info->cp;
for (i = 0; i < nlevels; i++) for (i = 0; i < nlevels; i++)
{ {
/* write the offset of the level */ /* seek back to the next slot in the offset table and write the
* offset of the level
*/
xcf_check_error (xcf_seek_pos (info, saved_pos, error));
xcf_write_int32_check_error (info, &offset, 1); xcf_write_int32_check_error (info, &offset, 1);
/* 'saved_pos' is the next slot in the level offset table */ /* remember the next slot in the offset table */
saved_pos = info->cp; saved_pos = info->cp;
/* seek to the level offset and save the level */ /* seek to the level offset and save the level */
@ -1326,16 +1343,11 @@ xcf_save_buffer (XcfInfo *info,
/* the next level's offset if after the level we just wrote */ /* the next level's offset if after the level we just wrote */
offset = info->cp; offset = info->cp;
/* seek back to the next slot in the offset table */
xcf_check_error (xcf_seek_pos (info, saved_pos, error));
} }
/* write out a '0' offset to indicate the end of the level offsets */ /* there is already a '0' at the end of the offset table to indicate
xcf_write_int32_check_error (info, &zero, 1); * the end of the level offsets
*/
/* seek to after the last level we just wrote */
xcf_check_error (xcf_seek_pos (info, offset, error));
return TRUE; return TRUE;
} }
@ -1380,19 +1392,26 @@ xcf_save_level (XcfInfo *info,
ntiles = n_tile_rows * n_tile_cols; ntiles = n_tile_rows * n_tile_cols;
/* 'offset' is where we will write the next tile, which is after the /* 'saved_pos' is the next slot in the offset table */
* tile offset table saved_pos = info->cp;
*/
offset = info->cp + (ntiles + 1) * 4; /* write an empty offset table */
xcf_write_zero_int32_check_error (info, ntiles + 1);
/* 'offset' is where we will write the next tile */
offset = info->cp;
for (i = 0; i < ntiles; i++) for (i = 0; i < ntiles; i++)
{ {
GeglRectangle rect; GeglRectangle rect;
/* write the offset of the tile */ /* seek back to the next slot in the offset table and write the
* offset of the tile
*/
xcf_check_error (xcf_seek_pos (info, saved_pos, error));
xcf_write_int32_check_error (info, &offset, 1); xcf_write_int32_check_error (info, &offset, 1);
/* 'saved_pos' is the next slot in the tile offset table */ /* remember the next slot in the offset table */
saved_pos = info->cp; saved_pos = info->cp;
/* seek to the tile offset and save the tile */ /* seek to the tile offset and save the tile */
@ -1424,16 +1443,11 @@ xcf_save_level (XcfInfo *info,
/* the next tile's offset is after the tile we just wrote */ /* the next tile's offset is after the tile we just wrote */
offset = info->cp; offset = info->cp;
/* seek back to the next slot in the offset table */
xcf_check_error (xcf_seek_pos (info, saved_pos, error));
} }
/* write out a '0' offset to indicate the end of the tile offsets */ /* there is already a '0' at the end of the offset table to indicate
xcf_write_int32_check_error (info, &zero, 1); * the end of the tile offsets
*/
/* seek to after the last tile we just wrote */
xcf_check_error (xcf_seek_pos (info, offset, error));
return TRUE; return TRUE;
} }

17
app/xcf/xcf-write.c
View File

@ -55,6 +55,23 @@ xcf_write_int32 (GOutputStream *output,
return count * 4; return count * 4;
} }
guint
xcf_write_zero_int32 (GOutputStream *output,
gint count,
GError **error)
{
if (count > 0)
{
guint32 *tmp = g_alloca (count * 4);
memset (tmp, 0, count * 4);
return xcf_write_int8 (output, (const guint8 *) tmp, count * 4, error);
}
return 0;
}
guint guint
xcf_write_float (GOutputStream *output, xcf_write_float (GOutputStream *output,
const gfloat *data, const gfloat *data,

3
app/xcf/xcf-write.h
View File

@ -23,6 +23,9 @@ guint xcf_write_int32 (GOutputStream *output,
const guint32 *data, const guint32 *data,
gint count, gint count,
GError **error); GError **error);
guint xcf_write_zero_int32 (GOutputStream *output,
gint count,
GError **error);
guint xcf_write_float (GOutputStream *output, guint xcf_write_float (GOutputStream *output,
const gfloat *data, const gfloat *data,
gint count, gint count,