1 files changed, 36 insertions, 28 deletions

diff --git a/main/utils.c b/main/utils.c
index 9a7a3acd4..0101d93ed 100644
--- a/main/utils.c
+++ b/main/utils.c
@@ -1667,37 +1667,45 @@ int __ast_str_helper(struct ast_str **buf, size_t max_len,
 {
 	int res, need;
 	int offset = (append && (*buf)->len) ? (*buf)->used : 0;
+	va_list aq;
 
-	if (max_len < 0)
-		max_len = (*buf)->len;	/* don't exceed the allocated space */
-	/*
-	 * Ask vsnprintf how much space we need. Remember that vsnprintf
-	 * does not count the final '\0' so we must add 1.
-	 */
-	res = vsnprintf((*buf)->str + offset, (*buf)->len - offset, fmt, ap);
-
-	need = res + offset + 1;
-	/*
-	 * If there is not enough space and we are below the max length,
-	 * reallocate the buffer and return a message telling to retry.
-	 */
-	if (need > (*buf)->len && (max_len == 0 || (*buf)->len < max_len) ) {
-		if (max_len && max_len < need)	/* truncate as needed */
-			need = max_len;
-		else if (max_len == 0)	/* if unbounded, give more room for next time */
-			need += 16 + need/4;
-		if (0)	/* debugging */
-			ast_verbose("extend from %d to %d\n", (int)(*buf)->len, need);
-		if (ast_str_make_space(buf, need)) {
-			ast_verbose("failed to extend from %d to %d\n", (int)(*buf)->len, need);
-			return AST_DYNSTR_BUILD_FAILED;
+	do {
+		if (max_len < 0) {
+			max_len = (*buf)->len;	/* don't exceed the allocated space */
 		}
-		(*buf)->str[offset] = '\0';	/* Truncate the partial write. */
+		/*
+		 * Ask vsnprintf how much space we need. Remember that vsnprintf
+		 * does not count the final '\0' so we must add 1.
+		 */
+		va_copy(aq, ap);
+		res = vsnprintf((*buf)->str + offset, (*buf)->len - offset, fmt, aq);
+
+		need = res + offset + 1;
+		/*
+		 * If there is not enough space and we are below the max length,
+		 * reallocate the buffer and return a message telling to retry.
+		 */
+		if (need > (*buf)->len && (max_len == 0 || (*buf)->len < max_len) ) {
+			if (max_len && max_len < need) {	/* truncate as needed */
+				need = max_len;
+			} else if (max_len == 0) {	/* if unbounded, give more room for next time */
+				need += 16 + need / 4;
+			}
+			if (0) {	/* debugging */
+				ast_verbose("extend from %d to %d\n", (int)(*buf)->len, need);
+			}
+			if (ast_str_make_space(buf, need)) {
+				ast_verbose("failed to extend from %d to %d\n", (int)(*buf)->len, need);
+				return AST_DYNSTR_BUILD_FAILED;
+			}
+			(*buf)->str[offset] = '\0';	/* Truncate the partial write. */
 
-		/* va_end() and va_start() must be done before calling
-		 * vsnprintf() again. */
-		return AST_DYNSTR_BUILD_RETRY;
-	}
+			/* Restart va_copy before calling vsnprintf() again. */
+			va_end(aq);
+			continue;
+		}
+		break;
+	} while (1);
 	/* update space used, keep in mind the truncation */
 	(*buf)->used = (res + offset > (*buf)->len) ? (*buf)->len : res + offset;