Improved and portable ast_log recursion avoidance

This introduces a new logger routine ast_log_safe.  This routine should be
used for all error messages in code that can be run as a result of ast_log.
ast_log_safe does nothing if run recursively.  All error logging in
astobj2.c, strings.c and utils.h have been switched to ast_log_safe.

This required adding support for raw threadstorage.  This provides direct
access to the void* pointer in threadstorage.  In ast_log_safe, NULL is used
to signify that this thread is not already running ast_log_safe, (void*)1 when
it is already running.  This was done since it's critical that ast_log_safe
do nothing that could log during recursion checking.

ASTERISK-24155 #close
Reported by: Timo Teräs
Review: https://reviewboard.asterisk.org/r/4502/
........

Merged revisions 433522 from http://svn.asterisk.org/svn/asterisk/branches/11
........

Merged revisions 433523 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@433524 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 11 insertions, 0 deletions

diff --git a/include/asterisk/logger.h b/include/asterisk/logger.h
index feb9c7eda..efaac4887 100644
--- a/include/asterisk/logger.h
+++ b/include/asterisk/logger.h
@@ -62,6 +62,17 @@ extern "C" {
 void ast_log(int level, const char *file, int line, const char *function, const char *fmt, ...)
 	__attribute__((format(printf, 5, 6)));
 
+/*!
+ * \brief Used for sending a log message with protection against recursion.
+ *
+ * \note This function should be used by all error messages that might be directly
+ * or indirectly caused by logging.
+ *
+ * \see ast_log for documentation on the parameters.
+ */
+void ast_log_safe(int level, const char *file, int line, const char *function, const char *fmt, ...)
+	__attribute__((format(printf, 5, 6)));
+
 /* XXX needs documentation */
 typedef unsigned int ast_callid;