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, 27 insertions, 0 deletions

diff --git a/main/logger.c b/main/logger.c
index 90fb7f2c0..29122b514 100644
--- a/main/logger.c
+++ b/main/logger.c
@@ -102,6 +102,7 @@ static struct {
 } logfiles = { 1 };
 
 static char hostname[MAXHOSTNAMELEN];
+AST_THREADSTORAGE_RAW(in_safe_log);
 
 enum logtypes {
 	LOGTYPE_SYSLOG,
@@ -1719,6 +1720,32 @@ void ast_log(int level, const char *file, int line, const char *function, const
 	va_end(ap);
 }
 
+void ast_log_safe(int level, const char *file, int line, const char *function, const char *fmt, ...)
+{
+	va_list ap;
+	void *recursed = ast_threadstorage_get_ptr(&in_safe_log);
+	ast_callid callid;
+
+	if (recursed) {
+		return;
+	}
+
+	if (ast_threadstorage_set_ptr(&in_safe_log, (void*)1)) {
+		/* We've failed to set the flag that protects against
+		 * recursion, so bail. */
+		return;
+	}
+
+	callid = ast_read_threadstorage_callid();
+
+	va_start(ap, fmt);
+	ast_log_full(level, file, line, function, callid, fmt, ap);
+	va_end(ap);
+
+	/* Clear flag so the next allocation failure can be logged. */
+	ast_threadstorage_set_ptr(&in_safe_log, NULL);
+}
+
 void ast_log_callid(int level, const char *file, int line, const char *function, ast_callid callid, const char *fmt, ...)
 {
 	va_list ap;