diff -Nru a/include/asterisk/utils.h b/include/asterisk/utils.h
--- a/include/asterisk/utils.h	2005-03-20 10:54:15 -07:00
+++ b/include/asterisk/utils.h	2005-03-20 10:54:15 -07:00
@@ -172,4 +172,17 @@
 extern char *ast_strcasestr(const char *, const char *);
 #endif /* __linux__ */
 extern int ast_pthread_create_stack(pthread_t *thread, pthread_attr_t *attr, void *(*start_routine)(void *), void *data, size_t stacksize);
-#endif
+
+/*! Build a string in a buffer, designed to be called repeatedly */
+/*!
+ * This is a wrapper for snprintf, that properly handles the buffer pointer
+ * and buffer space available.
+ * Returns 0 on success, -1 on failure.
+ *
+ * \param buffer current position in buffer to place string into (will be updated on return)
+ * \param space remaining space in buffer (will be updated on return)
+ * \param fmt printf-style format string
+ */
+extern int ast_build_string(char **buffer, size_t *space, const char *fmt, ...) __attribute__ ((format (printf, 3, 4)));
+
+#endif /* _ASTERISK_UTIL_H */
diff -Nru a/utils.c b/utils.c
--- a/utils.c	2005-03-20 10:54:15 -07:00
+++ b/utils.c	2005-03-20 10:54:15 -07:00
@@ -17,6 +17,7 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include <errno.h>
+#include <stdarg.h>
 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -458,3 +459,25 @@
 	}
 }
 #endif
+
+int ast_build_string(char **buffer, size_t *space, const char *fmt, ...)
+{
+	va_list ap;
+	int result;
+
+	if (!buffer || !*buffer || !space || !*space)
+		return -1;
+
+	va_start(ap, fmt);
+	result = vsnprintf(*buffer, *space, fmt, ap);
+	va_end(ap);
+
+	if (result < 0)
+		return -1;
+	else if (result > *space)
+		result = *space;
+
+	*buffer += result;
+	*space -= result;
+	return 0;
+}