Use strerror_r in safe_strerror if available

Also stores the result in a thread-local static variable and
changes the return value to a const char*.

This is already important because Guile creates threads and
Python can create threads, but with the patch series here:
https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/176
GDB itself will create threads, too.

gdb/ChangeLog:

2019-10-31  Christian Biesinger  <cbiesinger@google.com>

	* configure: Regenerate.
	* configure.ac: Check for strerror_r.
	* gdbsupport/common-utils.h (safe_strerror): Change return value
	to const char * and document that this function is now threadsafe.
	* gdbsupport/posix-strerror.c (safe_strerror): Make buf
	thread_local and call strerror_r, if available.
	* utils.c (perror_string): Update.
	(print_sys_errmsg): Update.

Change-Id: I81048fbaf148035c221c528727f7efe58ba528eb

1 files changed, 3 insertions, 8 deletions

diff --git a/gdb/utils.c b/gdb/utils.c
index 0c133d1..e06eedd 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -582,9 +582,7 @@ add_internal_problem_command (struct internal_problem *problem)
 static std::string
 perror_string (const char *prefix)
 {
-  char *err;
-
-  err = safe_strerror (errno);
+  const char *err = safe_strerror (errno);
   return std::string (prefix) + ": " + err;
 }
 
@@ -630,11 +628,8 @@ perror_warning_with_name (const char *string)
 void
 print_sys_errmsg (const char *string, int errcode)
 {
-  char *err;
-  char *combined;
-
-  err = safe_strerror (errcode);
-  combined = (char *) alloca (strlen (err) + strlen (string) + 3);
+  const char *err = safe_strerror (errcode);
+  char *combined = (char *) alloca (strlen (err) + strlen (string) + 3);
   strcpy (combined, string);
   strcat (combined, ": ");
   strcat (combined, err);