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Re: fseek064 calling fflush on Cygwin


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According to Eric Blake on 6/22/2007 2:26 PM:
>> So, it would seem that fflush is not 64 bit safe and fseeko64 should not
>> be calling it, but I'm not sure how to fix it.
>>
> In environments with large files, fflush needs to check for __SL64, in which
> case it should call fp->_seek64, not fp->_seek.  That clinches it - I need to
> complete my patch to make fflush reentrant and 64-bit safe.  I'll hopefully
> have something by early next week.

So much for 'early next week'.  Here's the full patch - okay to apply?

2007-07-13  Eric Blake  <ebb9@byu.net>

	Fix fflush issues.
	* libc/stdio/fflush.c (_fflush_r): New function.
	(fflush): Fix reentrancy and large offset behavior.
	* libc/include/stdio.h (_fflush_r): Add prototype.
	* libc/stdio/fclose.c (_fclose_r): All fflush callers changed.
	* libc/stdio/freopen.c (_freopen_r): Likewise.
	* libc/stdio/fseek.c (_fseek_r): Likewise.
	* libc/stdio/ftell.c (_ftell_r): Likewise.
	* libc/stdio/fvwrite.c (__sfvwrite_r): Likewise.
	* libc/stdio/refill.c (__srefill_r): Likewise.
	* libc/stdio/setvbuf.c (setvbuf): Likewise.
	* libc/stdio/ungetc.c (_ungetc_r): Likewise.
	* libc/stdio/vfprintf.c (__sbprintf): Likewise.
	* libc/stdio/wbuf.c (__swbuf_r): Likewise.
	* libc/stdio64/freopen64.c (_freopen64_r): Likewise.
	* libc/stdio64/fseeko64.c (_fseeko64_r): Likewise.  Defer to
	32-bit version if not large file.
	* libc/stdio64/ftello64.c (_ftello64_r): Likewise.
	* libc/stdio64/tmpfile64.c (_tmpfile64_r): Avoid compile warning.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             ebb9@byu.net
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Index: libc/stdio/fflush.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/fflush.c,v
retrieving revision 1.10
diff -u -p -r1.10 fflush.c
--- libc/stdio/fflush.c	4 Jun 2007 18:10:17 -0000	1.10
+++ libc/stdio/fflush.c	13 Jul 2007 15:42:31 -0000
@@ -26,10 +26,7 @@ ANSI_SYNOPSIS
 	#include <stdio.h>
 	int fflush(FILE *<[fp]>);
 
-TRAD_SYNOPSIS
-	#include <stdio.h>
-	int fflush(<[fp]>)
-	FILE *<[fp]>;
+	int _fflush_r(struct _reent *<[reent]>, FILE *<[fp]>);
 
 DESCRIPTION
 The <<stdio>> output functions can buffer output before delivering it
@@ -41,32 +38,41 @@ or stream identified by <[fp]>) to the h
 If <[fp]> is <<NULL>>, <<fflush>> delivers pending output from all
 open files.
 
+Additionally, if <[fp]> is a seekable input stream visiting a file
+descriptor, set the position of the file descriptor to match next
+unread byte, useful for obeying POSIX semantics when ending a process
+without consuming all input from the stream.
+
+The alternate function <<_fflush_r>> is a reentrant version, where the
+extra argument <[reent]> is a pointer to a reentrancy structure, and
+<[fp]> must not be NULL.
+
 RETURNS
 <<fflush>> returns <<0>> unless it encounters a write error; in that
 situation, it returns <<EOF>>.
 
 PORTABILITY
-ANSI C requires <<fflush>>.
+ANSI C requires <<fflush>>.  The behavior on input streams is only
+specified by POSIX, and not all implementations follow POSIX rules.
 
 No supporting OS subroutines are required.
 */
 
 #include <_ansi.h>
 #include <stdio.h>
+#include <errno.h>
 #include "local.h"
 
 /* Flush a single file, or (if fp is NULL) all files.  */
 
 int
-_DEFUN(fflush, (fp),
+_DEFUN(_fflush_r, (ptr, fp),
+       struct _reent *ptr _AND
        register FILE * fp)
 {
   register unsigned char *p;
   register int n, t;
 
-  if (fp == NULL)
-    return _fwalk (_GLOBAL_REENT, fflush);
-
 #ifdef _REENT_SMALL
   /* For REENT_SMALL platforms, it is possible we are being
      called for the first time on a std stream.  This std
@@ -83,15 +89,13 @@ _DEFUN(fflush, (fp),
     return 0;
 #endif /* _REENT_SMALL  */
 
-  CHECK_INIT (_REENT, fp);
+  CHECK_INIT (ptr, fp);
 
   _flockfile (fp);
 
   t = fp->_flags;
   if ((t & __SWR) == 0)
     {
-      _fpos_t _EXFUN((*seekfn), (struct _reent *, _PTR, _fpos_t, int));
-
       /* For a read stream, an fflush causes the next seek to be
          unoptimized (i.e. forces a system-level seek).  This conforms
          to the POSIX and SUSv3 standards.  */
@@ -104,21 +108,35 @@ _DEFUN(fflush, (fp),
          this seek to be deferred until necessary, but we choose to do it here
          to make the change simpler, more contained, and less likely
          to miss a code scenario.  */
-      if ((fp->_r > 0 || fp->_ur > 0) && (seekfn = fp->_seek) != NULL)
+      if ((fp->_r > 0 || fp->_ur > 0) && fp->_seek != NULL)
         {
-          _fpos_t curoff;
+	  int tmp;
+#ifdef __LARGE64_FILES
+	  _fpos64_t curoff;
+#else
+	  _fpos_t curoff;
+#endif
 
           /* Get the physical position we are at in the file.  */
           if (fp->_flags & __SOFF)
             curoff = fp->_offset;
           else
             {
-              /* We don't know current physical offset, so ask for it.  */
-              curoff = seekfn (_REENT, fp->_cookie, (_fpos_t) 0, SEEK_CUR);
+              /* We don't know current physical offset, so ask for it.
+		 Only ESPIPE is ignorable.  */
+#ifdef __LARGE64_FILES
+	      if (fp->_flags & __SL64)
+		curoff = fp->_seek64 (ptr, fp->_cookie, 0, SEEK_CUR);
+	      else
+#endif
+		curoff = fp->_seek (ptr, fp->_cookie, 0, SEEK_CUR);
               if (curoff == -1L)
                 {
                   _funlockfile (fp);
-                  return 0;
+		  if (ptr->_errno == ESPIPE)
+		    return 0;
+		  fp->_flags |= __SERR;
+		  return EOF;
                 }
             }
           if (fp->_flags & __SRD)
@@ -130,7 +148,13 @@ _DEFUN(fflush, (fp),
                 curoff -= fp->_ur;
             }
           /* Now physically seek to after byte last read.  */
-          if (seekfn (_REENT, fp->_cookie, curoff, SEEK_SET) != -1)
+#ifdef __LARGE64_FILES
+	  if (fp->_flags & __SL64)
+	    tmp = fp->_seek64 (ptr, fp->_cookie, curoff, SEEK_SET);
+	  else
+#endif
+	    tmp = fp->_seek (ptr, fp->_cookie, curoff, SEEK_SET);
+	  if (tmp == 0)
             {
               /* Seek successful.  We can clear read buffer now.  */
               fp->_flags &= ~__SNPT;
@@ -139,6 +163,12 @@ _DEFUN(fflush, (fp),
               if (fp->_flags & __SOFF)
                 fp->_offset = curoff;
             }
+	  else
+	    {
+	      _funlockfile (fp);
+	      fp->_flags |= __SERR;
+	      return EOF;
+	    }
         }
       _funlockfile (fp);
       return 0;
@@ -161,7 +191,7 @@ _DEFUN(fflush, (fp),
 
   while (n > 0)
     {
-      t = fp->_write (_REENT, fp->_cookie, (char *) p, n);
+      t = fp->_write (ptr, fp->_cookie, (char *) p, n);
       if (t <= 0)
 	{
           fp->_flags |= __SERR;
@@ -174,3 +204,17 @@ _DEFUN(fflush, (fp),
   _funlockfile (fp);
   return 0;
 }
+
+#ifndef _REENT_ONLY
+
+int
+_DEFUN(fflush, (fp),
+       register FILE * fp)
+{
+  if (fp == NULL)
+    return _fwalk_reent (_GLOBAL_REENT, _fflush_r);
+
+  return _fflush_r (_REENT, fp);
+}
+
+#endif /* _REENT_ONLY */
Index: libc/stdio/fclose.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/fclose.c,v
retrieving revision 1.14
diff -u -p -r1.14 fclose.c
--- libc/stdio/fclose.c	4 Jun 2007 18:10:17 -0000	1.14
+++ libc/stdio/fclose.c	13 Jul 2007 15:30:44 -0000
@@ -89,7 +89,7 @@ _DEFUN(_fclose_r, (rptr, fp),
   /* Unconditionally flush to allow special handling for seekable read
      files to reposition file to last byte processed as opposed to
      last byte read ahead into the buffer.  */
-  r = fflush (fp);
+  r = _fflush_r (rptr, fp);
   if (fp->_close != NULL && fp->_close (rptr, fp->_cookie) < 0)
     r = EOF;
   if (fp->_flags & __SMBF)
Index: libc/stdio/freopen.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/freopen.c,v
retrieving revision 1.20
diff -u -p -r1.20 freopen.c
--- libc/stdio/freopen.c	4 Jun 2007 18:10:17 -0000	1.20
+++ libc/stdio/freopen.c	13 Jul 2007 15:30:44 -0000
@@ -124,7 +124,7 @@ _DEFUN(_freopen_r, (ptr, file, mode, fp)
   else
     {
       if (fp->_flags & __SWR)
-	fflush (fp);
+	_fflush_r (ptr, fp);
       /*
        * If close is NULL, closing is a no-op, hence pointless.
        * If file is NULL, the file should not be closed.
Index: libc/stdio/fseek.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/fseek.c,v
retrieving revision 1.17
diff -u -p -r1.17 fseek.c
--- libc/stdio/fseek.c	4 Jun 2007 18:10:17 -0000	1.17
+++ libc/stdio/fseek.c	13 Jul 2007 15:30:49 -0000
@@ -145,7 +145,7 @@ _DEFUN(_fseek_r, (ptr, fp, offset, whenc
   if (fp->_flags & __SAPP && fp->_flags & __SWR)
     {
       /* So flush the buffer and seek to the end.  */
-      fflush (fp);
+      _fflush_r (ptr, fp);
     }
 
   /* Have to be able to seek.  */
@@ -170,7 +170,7 @@ _DEFUN(_fseek_r, (ptr, fp, offset, whenc
        * we have to first find the current stream offset a la
        * ftell (see ftell for details).
        */
-      fflush (fp);   /* may adjust seek offset on append stream */
+      _fflush_r (ptr, fp);   /* may adjust seek offset on append stream */
       if (fp->_flags & __SOFF)
 	curoff = fp->_offset;
       else
@@ -356,7 +356,8 @@ _DEFUN(_fseek_r, (ptr, fp, offset, whenc
    */
 
 dumb:
-  if (fflush (fp) || seekfn (ptr, fp->_cookie, offset, whence) == POS_ERR)
+  if (_fflush_r (ptr, fp)
+      || seekfn (ptr, fp->_cookie, offset, whence) == POS_ERR)
     {
       _funlockfile (fp);
       return EOF;
Index: libc/stdio/ftell.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/ftell.c,v
retrieving revision 1.11
diff -u -p -r1.11 ftell.c
--- libc/stdio/ftell.c	4 Jun 2007 18:10:17 -0000	1.11
+++ libc/stdio/ftell.c	13 Jul 2007 15:30:49 -0000
@@ -120,7 +120,7 @@ _DEFUN(_ftell_r, (ptr, fp),
 
   /* Find offset of underlying I/O object, then
      adjust for buffered bytes.  */
-  fflush(fp);           /* may adjust seek offset on append stream */
+  _fflush_r (ptr, fp);           /* may adjust seek offset on append stream */
   if (fp->_flags & __SOFF)
     pos = fp->_offset;
   else
Index: libc/stdio/fvwrite.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/fvwrite.c,v
retrieving revision 1.13
diff -u -p -r1.13 fvwrite.c
--- libc/stdio/fvwrite.c	4 Jun 2007 18:10:17 -0000	1.13
+++ libc/stdio/fvwrite.c	13 Jul 2007 15:30:49 -0000
@@ -185,7 +185,7 @@ _DEFUN(__sfvwrite_r, (ptr, fp, uio),
 	      COPY (w);
 	      /* fp->_w -= w; *//* unneeded */
 	      fp->_p += w;
-	      if (fflush (fp))
+	      if (_fflush_r (ptr, fp))
 		goto err;
 	    }
 	  else if (len >= (w = fp->_bf._size))
@@ -235,7 +235,7 @@ _DEFUN(__sfvwrite_r, (ptr, fp, uio),
 	      COPY (w);
 	      /* fp->_w -= w; */
 	      fp->_p += w;
-	      if (fflush (fp))
+	      if (_fflush_r (ptr, fp))
 		goto err;
 	    }
 	  else if (s >= (w = fp->_bf._size))
@@ -254,7 +254,7 @@ _DEFUN(__sfvwrite_r, (ptr, fp, uio),
 	  if ((nldist -= w) == 0)
 	    {
 	      /* copied the newline: flush and forget */
-	      if (fflush (fp))
+	      if (_fflush_r (ptr, fp))
 		goto err;
 	      nlknown = 0;
 	    }
Index: libc/stdio/refill.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/refill.c,v
retrieving revision 1.10
diff -u -p -r1.10 refill.c
--- libc/stdio/refill.c	4 Jun 2007 18:10:17 -0000	1.10
+++ libc/stdio/refill.c	13 Jul 2007 15:30:49 -0000
@@ -65,7 +65,7 @@ _DEFUN(__srefill_r, (ptr, fp),
       /* switch to reading */
       if (fp->_flags & __SWR)
 	{
-	  if (fflush (fp))
+	  if (_fflush_r (ptr, fp))
 	    return EOF;
 	  fp->_flags &= ~__SWR;
 	  fp->_w = 0;
Index: libc/stdio/setvbuf.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/setvbuf.c,v
retrieving revision 1.6
diff -u -p -r1.6 setvbuf.c
--- libc/stdio/setvbuf.c	26 Sep 2006 21:22:19 -0000	1.6
+++ libc/stdio/setvbuf.c	13 Jul 2007 15:30:49 -0000
@@ -126,7 +126,7 @@ _DEFUN(setvbuf, (fp, buf, mode, size),
    * non buffer flags, and clear malloc flag.
    */
 
-  _CAST_VOID fflush (fp);
+  _fflush_r (_REENT, fp);
   fp->_r = 0;
   fp->_lbfsize = 0;
   if (fp->_flags & __SMBF)
Index: libc/stdio/ungetc.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/ungetc.c,v
retrieving revision 1.7
diff -u -p -r1.7 ungetc.c
--- libc/stdio/ungetc.c	26 Sep 2006 21:22:19 -0000	1.7
+++ libc/stdio/ungetc.c	13 Jul 2007 15:30:49 -0000
@@ -101,7 +101,7 @@ _DEFUN(_ungetc_r, (rptr, c, fp),
         }
       if (fp->_flags & __SWR)
 	{
-	  if (fflush (fp))
+	  if (_fflush_r (rptr, fp))
             {
               _funlockfile (fp);
               return EOF;
Index: libc/stdio/vfprintf.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/vfprintf.c,v
retrieving revision 1.63
diff -u -p -r1.63 vfprintf.c
--- libc/stdio/vfprintf.c	27 May 2007 14:19:15 -0000	1.63
+++ libc/stdio/vfprintf.c	13 Jul 2007 15:30:52 -0000
@@ -212,7 +212,7 @@ _DEFUN(__sbprintf, (rptr, fp, fmt, ap),
 
 	/* do the work, then copy any error status */
 	ret = _VFPRINTF_R (rptr, &fake, fmt, ap);
-	if (ret >= 0 && fflush(&fake))
+	if (ret >= 0 && _fflush_r (rptr, &fake))
 		ret = EOF;
 	if (fake._flags & __SERR)
 		fp->_flags |= __SERR;
Index: libc/stdio/wbuf.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/wbuf.c,v
retrieving revision 1.7
diff -u -p -r1.7 wbuf.c
--- libc/stdio/wbuf.c	15 Mar 2007 18:40:48 -0000	1.7
+++ libc/stdio/wbuf.c	13 Jul 2007 15:30:52 -0000
@@ -74,14 +74,14 @@ _DEFUN(__swbuf_r, (ptr, c, fp),
   n = fp->_p - fp->_bf._base;
   if (n >= fp->_bf._size)
     {
-      if (fflush (fp))
+      if (_fflush_r (ptr, fp))
 	return EOF;
       n = 0;
     }
   fp->_w--;
   *fp->_p++ = c;
   if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
-    if (fflush (fp))
+    if (_fflush_r (ptr, fp))
       return EOF;
   return c;
 }
Index: libc/stdio64/freopen64.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio64/freopen64.c,v
retrieving revision 1.16
diff -u -p -r1.16 freopen64.c
--- libc/stdio64/freopen64.c	4 Jun 2007 18:10:17 -0000	1.16
+++ libc/stdio64/freopen64.c	13 Jul 2007 15:30:52 -0000
@@ -124,7 +124,7 @@ _DEFUN (_freopen64_r, (ptr, file, mode, 
   else
     {
       if (fp->_flags & __SWR)
-	 fflush (fp);
+	_fflush_r (ptr, fp);
       /*
        * If close is NULL, closing is a no-op, hence pointless.
        * If file is NULL, the file should not be closed.
Index: libc/stdio64/fseeko64.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio64/fseeko64.c,v
retrieving revision 1.11
diff -u -p -r1.11 fseeko64.c
--- libc/stdio64/fseeko64.c	4 Jun 2007 18:10:17 -0000	1.11
+++ libc/stdio64/fseeko64.c	13 Jul 2007 15:30:52 -0000
@@ -111,11 +111,22 @@ _DEFUN (_fseeko64_r, (ptr, fp, offset, w
   struct stat64 st;
   int havepos;
 
+  /* Only do 64-bit seek on large file.  */
+  if (!(fp->_flags & __SL64))
+    {
+      if ((_off_t) offset != offset)
+	{
+	  ptr->_errno = EOVERFLOW;
+	  return EOF;
+	}
+      return (_off64_t) _fseeko_r (ptr, fp, offset, whence);
+    }
+
   /* Make sure stdio is set up.  */
 
   CHECK_INIT (ptr, fp);
 
-  _flockfile(fp);
+  _flockfile (fp);
 
   curoff = fp->_offset;
 
@@ -125,12 +136,12 @@ _DEFUN (_fseeko64_r, (ptr, fp, offset, w
   if (fp->_flags & __SAPP && fp->_flags & __SWR)
     {
       /* So flush the buffer and seek to the end.  */
-      fflush (fp);
+      _fflush_r (ptr, fp);
     }
 
   /* Have to be able to seek.  */
 
-  if ((seekfn = fp->_seek64) == NULL || !(fp->_flags & __SL64))
+  if ((seekfn = fp->_seek64) == NULL)
     {
       ptr->_errno = ESPIPE;	/* ??? */
       _funlockfile(fp);
@@ -150,7 +161,7 @@ _DEFUN (_fseeko64_r, (ptr, fp, offset, w
        * we have to first find the current stream offset a la
        * ftell (see ftell for details).
        */
-      fflush(fp);   /* may adjust seek offset on append stream */
+      _fflush_r (ptr, fp);   /* may adjust seek offset on append stream */
       if (fp->_flags & __SOFF)
 	curoff = fp->_offset;
       else
@@ -323,7 +334,8 @@ _DEFUN (_fseeko64_r, (ptr, fp, offset, w
    */
 
 dumb:
-  if (fflush (fp) || seekfn (ptr, fp->_cookie, offset, whence) == POS_ERR)
+  if (_fflush_r (ptr, fp)
+      || seekfn (ptr, fp->_cookie, offset, whence) == POS_ERR)
     {
       _funlockfile(fp);
       return EOF;
Index: libc/stdio64/ftello64.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio64/ftello64.c,v
retrieving revision 1.7
diff -u -p -r1.7 ftello64.c
--- libc/stdio64/ftello64.c	4 Jun 2007 18:10:17 -0000	1.7
+++ libc/stdio64/ftello64.c	13 Jul 2007 15:30:52 -0000
@@ -91,6 +91,10 @@ _DEFUN (_ftello64_r, (ptr, fp),
 {
   _fpos64_t pos;
 
+  /* Only do 64-bit tell on large file.  */
+  if (!(fp->_flags & __SL64))
+    return (_off64_t) _ftello_r (ptr, fp);
+
   /* Ensure stdio is set up.  */
 
   CHECK_INIT (ptr, fp);
@@ -106,7 +110,7 @@ _DEFUN (_ftello64_r, (ptr, fp),
 
   /* Find offset of underlying I/O object, then
      adjust for buffered bytes.  */
-  fflush(fp);           /* may adjust seek offset on append stream */
+  _fflush_r (ptr, fp);           /* may adjust seek offset on append stream */
   if (fp->_flags & __SOFF)
     pos = fp->_offset;
   else
Index: libc/stdio64/tmpfile64.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio64/tmpfile64.c,v
retrieving revision 1.5
diff -u -p -r1.5 tmpfile64.c
--- libc/stdio64/tmpfile64.c	17 May 2007 12:10:29 -0000	1.5
+++ libc/stdio64/tmpfile64.c	13 Jul 2007 15:30:52 -0000
@@ -48,6 +48,7 @@ Supporting OS subroutines required: <<cl
 */
 
 #include <stdio.h>
+#include <reent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>

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