printf should return negative value on error

[BZ #11741]
Fixed bug where printf and family may return a spurious success when
printing padded formats.

4 files changed, 15 insertions, 14 deletions

diff --git a/libio/fileops.c b/libio/fileops.c
index 6aabadc644..fb6ac17b64 100644
--- a/libio/fileops.c
+++ b/libio/fileops.c
@@ -1253,12 +1253,13 @@ _IO_new_file_write (f, data, n)
      _IO_ssize_t n;
 {
   _IO_ssize_t to_do = n;
+  _IO_ssize_t count = 0;
   while (to_do > 0)
     {
-      _IO_ssize_t count = (__builtin_expect (f->_flags2
-					     & _IO_FLAGS2_NOTCANCEL, 0)
-			   ? write_not_cancel (f->_fileno, data, to_do)
-			   : write (f->_fileno, data, to_do));
+      count = (__builtin_expect (f->_flags2
+				 & _IO_FLAGS2_NOTCANCEL, 0)
+	       ? write_not_cancel (f->_fileno, data, to_do)
+	       : write (f->_fileno, data, to_do));
       if (count < 0)
 	{
 	  f->_flags |= _IO_ERR_SEEN;
@@ -1270,7 +1271,7 @@ _IO_new_file_write (f, data, n)
   n -= to_do;
   if (f->_offset >= 0)
     f->_offset += n;
-  return n;
+  return count < 0 ? count : n;
 }
 
 _IO_size_t
@@ -1330,9 +1331,10 @@ _IO_new_file_xsputn (f, data, n)
       _IO_size_t block_size, do_write;
       /* Next flush the (full) buffer. */
       if (_IO_OVERFLOW (f, EOF) == EOF)
-	/* If nothing else has to be written we must not signal the
-	   caller that everything has been written.  */
-	return to_do == 0 ? EOF : n - to_do;
+	/* If nothing else has to be written or nothing has been written, we
+	   must not signal the caller that the call was even partially
+	   successful.  */
+	return (to_do == 0 || to_do == n) ? EOF : n - to_do;
 
       /* Try to maintain alignment: write a whole number of blocks.
 	 dont_write is what gets left over. */
diff --git a/libio/iopadn.c b/libio/iopadn.c
index 7e374508f0..b7a4c5a739 100644
--- a/libio/iopadn.c
+++ b/libio/iopadn.c
@@ -59,7 +59,7 @@ _IO_padn (fp, pad, count)
       w = _IO_sputn (fp, padptr, PADSIZE);
       written += w;
       if (w != PADSIZE)
-	return written;
+	return w == EOF ? w : written;
     }
 
   if (i > 0)
diff --git a/libio/iowpadn.c b/libio/iowpadn.c
index 05632d5bf0..56e4b8ccb2 100644
--- a/libio/iowpadn.c
+++ b/libio/iowpadn.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1993, 1997, 1999 Free Software Foundation, Inc.
+/* Copyright (C) 1993-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -65,7 +65,7 @@ _IO_wpadn (fp, pad, count)
       w = _IO_sputn (fp, (char *) padptr, PADSIZE);
       written += w;
       if (w != PADSIZE)
-	return written;
+	return w == EOF ? w : written;
     }
 
   if (i > 0)
diff --git a/libio/libioP.h b/libio/libioP.h
index fe81115094..a402958b9c 100644
--- a/libio/libioP.h
+++ b/libio/libioP.h
@@ -1,5 +1,4 @@
-/* Copyright (C) 1993, 1997-2003,2004,2005,2006,2007,2012
-	Free Software Foundation, Inc.
+/* Copyright (C) 1993-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -167,7 +166,7 @@ typedef int (*_IO_pbackfail_t) (_IO_FILE *, int);
 #define _IO_WPBACKFAIL(FP, CH) WJUMP1 (__pbackfail, FP, CH)
 
 /* The 'xsputn' hook writes upto N characters from buffer DATA.
-   Returns the number of character actually written.
+   Returns EOF or the number of character actually written.
    It matches the streambuf::xsputn virtual function. */
 typedef _IO_size_t (*_IO_xsputn_t) (_IO_FILE *FP, const void *DATA,
 				    _IO_size_t N);