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From: "Juan Manuel Guerrero" <ST001906 AT HRZ1 DOT HRZ DOT TU-Darmstadt DOT De>
Organization: Darmstadt University of Technology
To: djgpp-workers AT delorie DOT com
Date: Wed, 20 Feb 2002 11:42:39 +0100
Subject: SIGSEGV and strlwr/strupr
X-mailer: Pegasus Mail for Windows (v2.54DE)
Message-ID: <271CA283011@HRZ1.hrz.tu-darmstadt.de>
Reply-To: djgpp-workers AT delorie DOT com

The following code is part of the command-line parsing code of bison 1.32/33.

/* Under plain DOS, there is no difference on the case.  This can be
   troublesome when looking for `.tab' etc.  */
#ifdef MSDOS
# if defined (__DJGPP__)
/* Windows 9X and successors are case sensitive. */
#  define AS_FILE_NAME(File) ((pathconf ((File), _PC_NAME_MAX) > 12) ? (File) : (strlwr (File), (File)))
# else
#  define AS_FILE_NAME(File) (strlwr (File), (File))
# endif
#else
# define AS_FILE_NAME(File) (File)
#endif

It works OK as long as some kind of windows is used as dpmi server.
As soon as cwsdpmi is used, bison dies with an error=0004.
The reason is that strlwr() does not check if the passed pointer
is a NULL pointer. In this case the while-loop derefences a NULL pointer
producing the SIGSEGV. This is the reason why for certain combinations
of command-line options bison 1.32/33 breaks on plain dos.
The small patch below will fix this for strlwr and strupr (suffers from the
same bug).

Regards,
Guerrero, Juan Manuel


diff -auprNU3 djgpp.orig/src/libc/compat/string/strlwr.c djgpp/src/libc/compat/string/strlwr.c
--- djgpp.orig/src/libc/compat/string/strlwr.c	Thu Jun  3 19:27:34 1999
+++ djgpp/src/libc/compat/string/strlwr.c	Wed Feb 20 11:17:34 2002
@@ -7,6 +7,8 @@ char *
 strlwr(char *_s)
 {
   char *rv = _s;
+  if (!_s)
+    return rv;
   while (*_s)
   {
     *_s = tolower((unsigned char)*_s);
diff -auprNU3 djgpp.orig/src/libc/compat/string/strlwr.txh djgpp/src/libc/compat/string/strlwr.txh
--- djgpp.orig/src/libc/compat/string/strlwr.txh	Sun Sep 27 17:21:10 1998
+++ djgpp/src/libc/compat/string/strlwr.txh	Wed Feb 20 10:15:38 2002
@@ -14,7 +14,7 @@ case letters. 
 
 @subheading Return Value
 
-The string.
+@var{string}
 
 @subheading Portability
 
diff -auprNU3 djgpp.orig/src/libc/compat/string/strupr.c djgpp/src/libc/compat/string/strupr.c
--- djgpp.orig/src/libc/compat/string/strupr.c	Thu Jun  3 19:27:34 1999
+++ djgpp/src/libc/compat/string/strupr.c	Wed Feb 20 11:17:34 2002
@@ -7,6 +7,8 @@ char *
 strupr(char *_s)
 {
   char *rv = _s;
+  if (!_s)
+    return rv;
   while (*_s)
   {
     *_s = toupper((unsigned char)*_s);