osmocom
/
wireshark
14
0
Fork 1
Code Issues Pull Requests Projects Releases Wiki Activity

Expand comments. 

Change-Id: I92348f98cd04ff0e7fc05e472075315ca0fd260e
Reviewed-on: https://code.wireshark.org/review/4931
Reviewed-by: Guy Harris <guy@alum.mit.edu>
This commit is contained in:
Guy Harris 2014-10-25 16:08:02 -07:00
parent 6ebb50c67e
commit 30742dd7c8
1 changed files with 52 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
wiretap/file_wrappers.c
View File

@ -940,15 +940,27 @@ file_seek(FILE_T file, gint64 offset, int whence, int *err)
offset += file->skip;
file->seek_pending = FALSE;
/*
* Are we seeking backwards and, if so, do we have data in the buffer?
*/
if (offset < 0 && file->next) {
/*
* Yes.
*
* This is guaranteed to fit in an unsigned int.
* To squelch compiler warnings, we cast the
* result.
*/
guint had = (unsigned)(file->next - file->out);
/*
* Do we have enough data before the current position in
* the buffer that we can seek backwards within the buffer?
*/
if (-offset <= had) {
/*
* Yes.
*
* Offset is negative, so -offset is
* non-negative, and -offset is
* <= an unsigned and thus fits in an
@ -968,10 +980,21 @@ file_seek(FILE_T file, gint64 offset, int whence, int *err)
}
}
/* XXX, profile */
/*
* No. Do we have "fast seek" data for the location to which we
* will be seeking?
*
* XXX, profile
*/
if ((here = fast_seek_find(file, file->pos + offset)) && (offset < 0 || offset > SPAN || here->compression == UNCOMPRESSED)) {
gint64 off, off2;
/*
* Yes. Use that data to do the seek.
* Note that this will be true only if file_set_random_access()
* has been called on this file, which should never be the case
* for a pipe.
*/
#ifdef HAVE_LIBZ
if (here->compression == ZLIB) {
#ifdef HAVE_INFLATEPRIME
@ -1050,11 +1073,23 @@ file_seek(FILE_T file, gint64 offset, int whence, int *err)
return file->pos + offset;
}
/* if within raw area while reading, just go there */
/*
* Is this an uncompressed file, are we within the raw area,
* are we either seeking backwards or seeking past the end
* of the buffer, and are we set up for random access with
* file_set_random_access()?
*
* Again, note that this will never be true on a pipe, as
* file_set_random_access() should never be called if we're
* reading from a pipe.
*/
if (file->compression == UNCOMPRESSED && file->pos + offset >= file->raw
&& (offset < 0 || offset >= file->have) /* seek only when we don't have that offset in buffer */
&& (file->fast_seek) /* seek only when random access is supported */)
&& (offset < 0 || offset >= file->have)
&& (file->fast_seek))
{
/*
* Yes. Just seek there within the file.
*/
if (ws_lseek64(file->fd, offset - file->have, SEEK_CUR) == -1) {
*err = errno;
return -1;
@ -1070,8 +1105,15 @@ file_seek(FILE_T file, gint64 offset, int whence, int *err)
return file->pos;
}
/* calculate skip amount, rewinding if needed for back seek when reading */
/*
* Are we seeking backwards?
*/
if (offset < 0) {
/*
* Yes.
*
* Calculate the amount to skip forward after rewinding.
*/
offset += file->pos;
if (offset < 0) { /* before start of file! */
*err = EINVAL;
@ -1089,7 +1131,11 @@ file_seek(FILE_T file, gint64 offset, int whence, int *err)
gz_reset(file);
}
/* skip what's in output buffer (one less gzgetc() check) */
/*
* No, we're skipping forwards.
*
* Skip what's in output buffer (one less gzgetc() check).
*/
n = (gint64)file->have > offset ? (unsigned)offset : file->have;
file->have -= n;
file->next += n;