Re: perror() changes the orientation of stderr to byte-oriented mode if stderr is not oriented yet.

Takashi Yano <[email protected]> Thu, 28 Jun 2018 20:14:21 +0900

Newsgroups	gmane.comp.lib.newlib
Message-ID	<[email protected]>

Hi Corinna,

On Wed, 27 Jun 2018 14:55:03 +0200
Corinna Vinschen wrote:
> again, please send patches related to newlib to the newlib mailing list.
> Newlib patches affect more targets than just Cygwin.  I redirected this
> mail to the newlib list and attached your original attachments.  Thank
> you.

Next time I will. Sorry for my inadequate understanding about newlib.

> I'm not sure exactly.  It may be nice to keep the writes buffered
> if the original stderr stream is buffered as well.
> 
> What about duplicating the non-_FVWRITE_IN_STREAMIO part of _fputs_r,
> just without calling ORIENT?

Thank you for your suggestion.

I tried this but it failed because __sputc_r() called from _fputs_r also
sets orientation. So I have borrowed the codes from __swbuf_r() in wbuf.c
so that the strings are pushed directly into the buffer.

Could you please have a look?

-- 
Takashi Yano <[email protected]>

0001-Fix-a-bug-of-perror-which-changes-the-orientation-of.patch (application/octet-stream, 2.3 KB)

From a0932c39db0ae2a199b5238c0f65cae5e69e016c Mon Sep 17 00:00:00 2001
From: Takashi Yano <[email protected]>
Date: Thu, 28 Jun 2018 19:46:21 +0900
Subject: [PATCH] Fix a bug of perror() which changes the orientation of
 stderr.

* perror.c: Fix the problem that perror() changes the orientation
  of stderr to byte-oriented mode if stderr is not oriented yet.
---
 newlib/libc/stdio/perror.c | 54 +++++++++++++++++++++++++++++++++++---
 1 file changed, 50 insertions(+), 4 deletions(-)

diff --git a/newlib/libc/stdio/perror.c b/newlib/libc/stdio/perror.c
index d98e17e19..d3a3413c7 100644
--- a/newlib/libc/stdio/perror.c
+++ b/newlib/libc/stdio/perror.c
@@ -56,8 +56,54 @@ Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
 #include <reent.h>
 #include <stdio.h>
 #include <string.h>
+#include "fvwrite.h"
 #include "local.h"
 
+/* Use static int _fputs_r_loc() instead of fputs()/fputc()
+   to prevent the orientation from being set. */
+static int
+_fputs_r_loc (struct _reent * ptr,
+       char const *__restrict s,
+       FILE *__restrict fp)
+{
+  register int n;
+  const char *p = s;
+
+  /* Ensure stdio has been initialized.  */
+  CHECK_INIT(ptr, fp);
+
+  _newlib_flockfile_start (fp);
+
+  if (cantwrite (ptr, fp))
+    goto error;
+
+  n = fp->_p - fp->_bf._base;
+  if (n >= fp->_bf._size)
+    {
+      if (_fflush_r (ptr, fp))
+	goto error;
+      n = 0;
+    }
+  while (*p)
+    {
+      fp->_w--;
+      *fp->_p++ = *p;
+      if (++n == fp->_bf._size || (fp->_flags & __SLBF && *p == '\n'))
+	{
+	  if (_fflush_r (ptr, fp))
+	    goto error;
+	  n = 0;
+	}
+      p++;
+    }
+  _newlib_flockfile_exit (fp);
+  return 0;
+
+error:
+  _newlib_flockfile_end (fp);
+  return EOF;
+}
+
 void
 _perror_r (struct _reent *ptr,
        const char *s)
@@ -68,14 +114,14 @@ _perror_r (struct _reent *ptr,
   _REENT_SMALL_CHECK_INIT (ptr);
   if (s != NULL && *s != '\0')
     {
-      fputs (s, _stderr_r (ptr));
-      fputs (": ", _stderr_r (ptr));
+      _fputs_r_loc (ptr, s, _stderr_r (ptr));
+      _fputs_r_loc (ptr, ": ", _stderr_r (ptr));
     }
 
   if ((error = _strerror_r (ptr, ptr->_errno, 1, &dummy)) != NULL)
-    fputs (error, _stderr_r (ptr));
+    _fputs_r_loc (ptr, error, _stderr_r (ptr));
 
-  fputc ('\n', _stderr_r (ptr));
+  _fputs_r_loc (ptr, "\n", _stderr_r (ptr));
 }
 
 #ifndef _REENT_ONLY
-- 
2.17.0