[patch] Fixed occasional failure to load a custom shared library

[Jan Kratochvil <lace@jankratochvil.net>]

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Hi,

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=146810

Inferior ENV{"LD_LIBRARY_PATH"} and/or ENV{"PATH"} may get ignored by
solib_open() resulting in
	Error while mapping shared library sections:
	libc++test4dl.so: Success.
and afterwards while calling a function from the shared library it crashes:
	(gdb) call randomthing()
	Program received signal SIGSEGV, Segmentation fault.
	randomthing () at c++test4dl.cxx:3
	3       void randomthing()
	The program being debugged was signaled while in a function called from GDB.

Trivia NULL vs. "" check issue.


Regards,
Jan Kratochvil

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https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=146810

Bug is still present in 2006-06-21 GDB CVS. The segfault is just a consequence of earlier failure to properly load the custom shared library:
Error while mapping shared library sections:
libc++test4dl.so: Success.


Index: solib.c
===================================================================
RCS file: /cvs/src/src/gdb/solib.c,v
retrieving revision 1.84
diff -u -p -r1.84 solib.c
--- solib.c	25 Feb 2006 04:36:39 -0000	1.84
+++ solib.c	22 Jun 2006 11:24:40 -0000
@@ -146,13 +146,17 @@ solib_open (char *in_pathname, char **fo
   int found_file = -1;
   char *temp_pathname = NULL;
   char *p = in_pathname;
+  int solib_absolute_prefix_is_empty;
+
+  solib_absolute_prefix_is_empty = (!solib_absolute_prefix
+                                    || !*solib_absolute_prefix);
 
   while (*p && !IS_DIR_SEPARATOR (*p))
     p++;
 
   if (*p)
     {
-      if (! IS_ABSOLUTE_PATH (in_pathname) || solib_absolute_prefix == NULL)
+      if (! IS_ABSOLUTE_PATH (in_pathname) || solib_absolute_prefix_is_empty)
         temp_pathname = in_pathname;
       else
 	{
@@ -208,14 +212,14 @@ solib_open (char *in_pathname, char **fo
 					   &temp_pathname);
 
   /* If not found, next search the inferior's $PATH environment variable. */
-  if (found_file < 0 && solib_absolute_prefix == NULL)
+  if (found_file < 0 && solib_absolute_prefix_is_empty)
     found_file = openp (get_in_environ (inferior_environ, "PATH"),
 			OPF_TRY_CWD_FIRST, in_pathname, O_RDONLY | O_BINARY, 0,
 			&temp_pathname);
 
   /* If not found, next search the inferior's $LD_LIBRARY_PATH 
      environment variable. */
-  if (found_file < 0 && solib_absolute_prefix == NULL)
+  if (found_file < 0 && solib_absolute_prefix_is_empty)
     found_file = openp (get_in_environ (inferior_environ, "LD_LIBRARY_PATH"),
 			OPF_TRY_CWD_FIRST, in_pathname, O_RDONLY | O_BINARY, 0,
 			&temp_pathname);