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.

1 files changed, 6 insertions, 25 deletions

diff --git a/newlib/libc/stdio64/fseeko64.c b/newlib/libc/stdio64/fseeko64.c
index 0672086..f380055 100644
--- a/newlib/libc/stdio64/fseeko64.c
+++ b/newlib/libc/stdio64/fseeko64.c
@@ -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;