Fix string growth algorithm for XML presence bodies.

pjpidf_print() does not return < 0 if there is not enough
room for the document to be printed. Rather, it returns
39, the length of the XML prolog.

The algorithm also had a bug in that it would return if
it attempted to grow the string larger.
........

Merged revisions 416442 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@416444 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_pjsip_pidf_body_generator.c

@@ -80,6 +80,7 @@ static int pidf_generate_body_content(void *body, void *data)
 }
 
 #define MAX_STRING_GROWTHS 3
+#define XML_PROLOG 39
 
 static void pidf_to_string(void *body, struct ast_str **str)
 {
@@ -89,14 +90,13 @@ static void pidf_to_string(void *body, struct ast_str **str)
 
 	do {
 		size = pjpidf_print(pres, ast_str_buffer(*str), ast_str_size(*str) - 1);
-		if (size < 0) {
+		if (size == XML_PROLOG) {
 			ast_str_make_space(str, ast_str_size(*str) * 2);
 			++growths;
-			return;
 		}
-	} while (size < 0 && growths < MAX_STRING_GROWTHS);
+	} while (size == XML_PROLOG && growths < MAX_STRING_GROWTHS);
 
-	if (size < 0) {
+	if (size == XML_PROLOG) {
 		ast_log(LOG_WARNING, "PIDF body text too large\n");
 		return;
 	}

res/res_pjsip_xpidf_body_generator.c

@@ -97,6 +97,7 @@ static int xpidf_generate_body_content(void *body, void *data)
 }
 
 #define MAX_STRING_GROWTHS 3
+#define XML_PROLOG 39
 
 static void xpidf_to_string(void *body, struct ast_str **str)
 {
@@ -105,16 +106,14 @@ static void xpidf_to_string(void *body, struct ast_str **str)
 	int size;
 
 	do {
-
 		size = pjxpidf_print(pres, ast_str_buffer(*str), ast_str_size(*str));
-		if (size < 0) {
+		if (size == XML_PROLOG) {
 			ast_str_make_space(str, ast_str_size(*str) * 2);
 			++growths;
-			return;
 		}
-	} while (size < 0 && growths < MAX_STRING_GROWTHS);
+	} while (size == XML_PROLOG && growths < MAX_STRING_GROWTHS);
 
-	if (size < 0) {
+	if (size == XML_PROLOG) {
 		ast_log(LOG_WARNING, "XPIDF body text too large\n");
 		return;
 	}