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* decompress.c: Fix bugs with large buffers and weird inputs.

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Tune a bit.  Reindent as per usual Emacs style.
(BUFFER_SIZE): Remove.
(Fdecompress_gzipped_region): Do not mishandle input buffers with
more than UINT_MAX bytes.  Decompress into the gap instead of into
an auto buffer, as this should avoid copying.  Return nil if
'inflate' returns Z_NEED_DICT, as we have no dictionary.  Do not
set immediate_quit; we shouldn't trust zlib code that much.
This commit is contained in:
Paul Eggert 2013-08-11 16:09:26 -07:00
parent 8d28d0ac2a
commit d0e615c324
2 changed files with 63 additions and 46 deletions
Download patch file Download diff file Expand all files Collapse all files

11
src/ChangeLog
View file

@ -1,3 +1,14 @@
2013-08-11 Paul Eggert <eggert@cs.ucla.edu>
* decompress.c: Fix bugs with large buffers and weird inputs.
Tune a bit. Reindent as per usual Emacs style.
(BUFFER_SIZE): Remove.
(Fdecompress_gzipped_region): Do not mishandle input buffers with
more than UINT_MAX bytes. Decompress into the gap instead of into
an auto buffer, as this should avoid copying. Return nil if
'inflate' returns Z_NEED_DICT, as we have no dictionary. Do not
set immediate_quit; we shouldn't trust zlib code that much.
2013-08-11 Lars Magne Ingebrigtsen <larsi@gnus.org>
* decompress.c (Fdecompress_gzipped_region): Respect all zlib

98
src/decompress.c
View file

@ -27,48 +27,48 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
#include "buffer.h"
#define BUFFER_SIZE 16384
struct decompress_unwind_data {
struct decompress_unwind_data
{
ptrdiff_t old_point, start;
z_stream *stream;
};
static void
unwind_decompress (void *ddata) {
unwind_decompress (void *ddata)
{
struct decompress_unwind_data *data = ddata;
inflateEnd (data->stream);
/* Delete any uncompressed data already inserted and restore
point. */
if (data->start) {
del_range (data->start, PT);
SET_PT (data->old_point);
}
/* Delete any uncompressed data already inserted and restore point. */
if (data->start)
{
del_range (data->start, PT);
SET_PT (data->old_point);
}
}
DEFUN ("decompress-gzipped-region", Fdecompress_gzipped_region,
Sdecompress_gzipped_region,
2, 2, 0,
doc: /* Decompress a gzip-compressed region.
The text in the region will be replaced by the decompressed data.
On failure, nil is returned and the data is left in place.
This function can only be called in unibyte buffers.*/)
Replace the text in the region by the decompressed data.
On failure, return nil and leave the data in place.
This function can be called only in unibyte buffers. */)
(Lisp_Object start, Lisp_Object end)
{
ptrdiff_t istart, iend, point = PT;
ptrdiff_t istart, iend, pos_byte;
z_stream stream;
int decompressed;
char out[16384];
int inflate_status;
struct decompress_unwind_data unwind_data;
ptrdiff_t count = SPECPDL_INDEX ();
validate_region (&start, &end);
if (! NILP (BVAR (current_buffer, enable_multibyte_characters)))
error ("This function can only be called in unibyte buffers");
error ("This function can be called only in unibyte buffers");
/* This is a unibyte buffer, so character positions and bytes are
the same. */
the same. */
istart = XINT (start);
iend = XINT (end);
move_gap_both (iend, iend);
@ -79,49 +79,55 @@ This function can only be called in unibyte buffers.*/)
stream.avail_in = 0;
stream.next_in = Z_NULL;
/* This magic number apparently means "this is gzip". */
/* This magic number apparently means "this is gzip". */
if (inflateInit2 (&stream, 16 + MAX_WBITS) != Z_OK)
return Qnil;
/* We're inserting the decompressed data at the end of the
compressed data. */
SET_PT (iend);
stream.avail_in = iend - istart;
stream.next_in = (char *) BYTE_POS_ADDR (istart);
unwind_data.start = iend;
unwind_data.stream = &stream;
unwind_data.old_point = point;
unwind_data.old_point = PT;
record_unwind_protect_ptr (unwind_decompress, &unwind_data);
immediate_quit = 1;
/* Insert the decompressed data at the end of the compressed data. */
SET_PT (iend);
/* Run inflate() on input until the output buffer isn't full. */
do {
int result;
stream.avail_out = BUFFER_SIZE;
stream.next_out = out;
result = inflate (&stream, Z_NO_FLUSH);
if (result < 0) {
unbind_to (count, Qnil);
return Qnil;
pos_byte = istart;
/* Keep calling 'inflate' until it reports an error or end-of-input. */
do
{
/* Maximum number of bytes that one 'inflate' call should read and write.
zlib requires that these values not exceed UINT_MAX.
Do not make avail_out too large, as that might unduly delay C-g. */
ptrdiff_t avail_in = min (iend - pos_byte, UINT_MAX);
ptrdiff_t avail_out = min (1 << 14, UINT_MAX);
ptrdiff_t decompressed;
if (GAP_SIZE < avail_out)
make_gap (avail_out - GAP_SIZE);
stream.next_in = BYTE_POS_ADDR (pos_byte);
stream.avail_in = avail_in;
stream.next_out = GPT_ADDR;
stream.avail_out = avail_out;
inflate_status = inflate (&stream, Z_NO_FLUSH);
pos_byte += avail_in - stream.avail_in;
decompressed = avail_out - stream.avail_out;
insert_from_gap (decompressed, decompressed, 0);
QUIT;
}
while (inflate_status == Z_OK);
decompressed = BUFFER_SIZE - stream.avail_out;
insert_1_both (out, decompressed, decompressed, 0, 0, 0);
QUIT;
} while (stream.avail_out == 0);
immediate_quit = 0;
if (inflate_status != Z_STREAM_END)
return unbind_to (count, Qnil);
unwind_data.start = 0;
unbind_to (count, Qnil);
/* Delete the compressed data. */
/* Delete the compressed data. */
del_range (istart, iend);
return Qt;
return unbind_to (count, Qt);
}