Don't error out writing a multibyte character to an unbuffered stream (bug 17522)

ChangeLog

@@ -1,3 +1,11 @@
+2014-11-03  Andreas Schwab  <schwab@suse.de>
+
+	[BZ #17522]
+	* libio/wfileops.c (_IO_wdo_write): If the file buffer has room
+	for less than MB_LEN_MAX use a local buffer of that size.
+	* libio/tst-fputws.c: New file.
+	* libio/Makefile (tests): Add tst-fputws.
+
 2014-11-01  Jose E. Marchesi  <jose.marchesi@oracle.com>
 
 	* sysdeps/unix/sysv/linux/sparc/sys/ucontext.h (struct fpu): fix

NEWS

@@ -10,7 +10,7 @@ Version 2.21
 * The following bugs are resolved with this release:
 
   6652, 12926, 14138, 14171, 15215, 15884, 17266, 17344, 17363, 17370,
-  17371, 17411, 17460, 17485, 17501, 17508.
+  17371, 17411, 17460, 17485, 17501, 17508, 17522.
 
 Version 2.20
 

libio/Makefile

@@ -61,7 +61,7 @@ tests = tst_swprintf tst_wprintf tst_swscanf tst_wscanf tst_getwc tst_putwc   \
 	bug-memstream1 bug-wmemstream1 \
 	tst-setvbuf1 tst-popen1 tst-fgetwc bug-wsetpos tst-fseek \
 	tst-fwrite-error tst-ftell-partial-wide tst-ftell-active-handler \
-	tst-ftell-append
+	tst-ftell-append tst-fputws
 ifeq (yes,$(build-shared))
 # Add test-fopenloc only if shared library is enabled since it depends on
 # shared localedata objects.

libio/tst-fputws.c

@@ -0,0 +1,39 @@
+/* Test that we can write a multibyte character to an unbuffered stream.
+   Copyright (C) 2014 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
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <locale.h>
+#include <stdio.h>
+#include <wchar.h>
+
+static int
+do_test (void)
+{
+  const wchar_t str[] = L"\xbe\n";
+
+  setlocale (LC_ALL, "en_US.UTF-8");
+  setvbuf (stdout, NULL, _IONBF, 0);
+
+  if (fputws (str, stdout) < 0)
+    return 1;
+
+  return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+
+#include <test-skeleton.c>

libio/wfileops.c

@@ -75,17 +75,32 @@ _IO_wdo_write (fp, data, to_do)
 	{
 	  enum __codecvt_result result;
 	  const wchar_t *new_data;
+	  char mb_buf[MB_LEN_MAX];
+	  char *write_base, *write_ptr, *buf_end;
+
+	  if (fp->_IO_write_ptr - fp->_IO_write_base < sizeof (mb_buf))
+	    {
+	      /* Make sure we have room for at least one multibyte
+		 character.  */
+	      write_ptr = write_base = mb_buf;
+	      buf_end = mb_buf + sizeof (mb_buf);
+	    }
+	  else
+	    {
+	      write_ptr = fp->_IO_write_ptr;
+	      write_base = fp->_IO_write_base;
+	      buf_end = fp->_IO_buf_end;
+	    }
 
 	  /* Now convert from the internal format into the external buffer.  */
 	  result = (*cc->__codecvt_do_out) (cc, &fp->_wide_data->_IO_state,
 					    data, data + to_do, &new_data,
-					    fp->_IO_write_ptr,
+					    write_ptr,
-					    fp->_IO_buf_end,
+					    buf_end,
-					    &fp->_IO_write_ptr);
+					    &write_ptr);
 
 	  /* Write out what we produced so far.  */
-	  if (_IO_new_do_write (fp, fp->_IO_write_base,
+	  if (_IO_new_do_write (fp, write_base, write_ptr - write_base) == EOF)
-				fp->_IO_write_ptr - fp->_IO_write_base) == EOF)
 	    /* Something went wrong.  */
 	    return WEOF;