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newlib: fix fseek optimization with SEEK_CUR 

The call to fflush was invalidating the read buffer, preventing relative
seeks to positions that would have been inside the read buffer from
being optimized. The call to srefill would then re-read mostly the same
data that was initially in the read buffer.
This commit is contained in:
Bastien Bouclet 2019-11-09 17:28:04 +01:00 committed by Corinna Vinschen
parent 1626569222
commit 59362c80e3
2 changed files with 12 additions and 50 deletions
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31
newlib/libc/stdio/fseeko.c
View File

@ -141,31 +141,12 @@ _fseeko_r (struct _reent *ptr,
switch (whence)
{
case SEEK_CUR:
/*
* In order to seek relative to the current stream offset,
* we have to first find the current stream offset a la
* ftell (see ftell for details).
*/
_fflush_r (ptr, fp); /* may adjust seek offset on append stream */
if (fp->_flags & __SOFF)
curoff = fp->_offset;
else
{
curoff = seekfn (ptr, fp->_cookie, (_fpos_t) 0, SEEK_CUR);
if (curoff == -1L)
{
_newlib_flockfile_exit (fp);
return EOF;
}
}
if (fp->_flags & __SRD)
{
curoff -= fp->_r;
if (HASUB (fp))
curoff -= fp->_ur;
}
else if (fp->_flags & __SWR && fp->_p != NULL)
curoff += fp->_p - fp->_bf._base;
curoff = _ftello_r(ptr, fp);
if (curoff == -1L)
{
_newlib_flockfile_exit (fp);
return EOF;
}
offset += curoff;
whence = SEEK_SET;

31
newlib/libc/stdio64/fseeko64.c
View File

@ -142,31 +142,12 @@ _fseeko64_r (struct _reent *ptr,
switch (whence)
{
case SEEK_CUR:
/*
* In order to seek relative to the current stream offset,
* we have to first find the current stream offset a la
* ftell (see ftell for details).
*/
_fflush_r (ptr, fp); /* may adjust seek offset on append stream */
if (fp->_flags & __SOFF)
curoff = fp->_offset;
else
{
curoff = seekfn (ptr, fp->_cookie, (_fpos64_t) 0, SEEK_CUR);
if (curoff == -1L)
{
_newlib_flockfile_exit(fp);
return EOF;
}
}
if (fp->_flags & __SRD)
{
curoff -= fp->_r;
if (HASUB (fp))
curoff -= fp->_ur;
}
else if (fp->_flags & __SWR && fp->_p != NULL)
curoff += fp->_p - fp->_bf._base;
curoff = _ftello64_r(ptr, fp);
if (curoff == -1L)
{
_newlib_flockfile_exit (fp);
return EOF;
}
offset += curoff;
whence = SEEK_SET;