fix a flaw in the ast_string_field_build() family of API calls; these functions made...

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@176216 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/main/utils.c b/main/utils.c
index d7863198be49400b8967ecd669df291ff65987b4..84d53e182e135b238891f8bebabc5c453e8acd24 100644 (file)
--- a/main/utils.c
+++ b/main/utils.c
@@ -1256,24 +1256,49 @@ void __ast_string_field_index_build_va(struct ast_string_field_mgr *mgr,
                                       int index, const char *format, va_list ap1, va_list ap2)
 {
        size_t needed;
+       size_t available;
+       char *target;
 
-       needed = vsnprintf(mgr->pool->base + mgr->used, mgr->space, format, ap1) + 1;
-
-       va_end(ap1);
+       /* if the field already has space allocated, try to reuse it;
+          otherwise, use the empty space at the end of the current
+          pool
+       */
+       if (fields[index][0] != '0') {
+               target = (char *) fields[index];
+               available = strlen(fields[index]);
+       } else {
+               target = mgr->pool->base + mgr->used;
+               available = mgr->space;
+       }
 
-       if (needed > mgr->space) {
-               size_t new_size = mgr->size * 2;
+       needed = vsnprintf(target, available, format, ap1) + 1;
 
-               while (new_size < needed)
-                       new_size *= 2;
+       va_end(ap1);
 
-               if (add_string_pool(mgr, new_size))
-                       return;
+       if (needed > available) {
+               /* if the space needed can be satisfied by using the current
+                  pool (which could only occur if we tried to use the field's
+                  allocated space and failed), then use that space; otherwise
+                  allocate a new pool
+               */
+               if (needed <= mgr->space) {
+                       target = mgr->pool->base + mgr->used;
+               } else {
+                       size_t new_size = mgr->size * 2;
+
+                       while (new_size < needed)
+                               new_size *= 2;
+                       
+                       if (add_string_pool(mgr, new_size))
+                               return;
+                       
+                       target = mgr->pool->base + mgr->used;
+               }
 
-               vsprintf(mgr->pool->base + mgr->used, format, ap2);
+               vsprintf(target, format, ap2);
        }
 
-       fields[index] = mgr->pool->base + mgr->used;
+       fields[index] = target;
        mgr->used += needed;
        mgr->space -= needed;
 }