Fix two problems in ast_str functions found while writing a unit test.

1. The documentation for ast_str_set and ast_str_append state that
the max_len parameter may be -1 in order to limit the size of the
ast_str to its current allocated size. The problem was that the max_len
parameter in all cases was a size_t, which is unsigned. Thus a -1 was
interpreted as UINT_MAX instead of -1. Changing the max_len parameter
to be ssize_t fixed this issue.

2. Once issue 1 was fixed, there was an off-by-one error in the case
where we attempted to write a string larger than the current allotted
size to a string when -1 was passed as the max_len parameter. When trying
to write more than the allotted size, the ast_str's __AST_STR_USED was
set to 1 higher than it should have been. Thanks to Tilghman for quickly
spotting the offending line of code.

Oh, and the unit test that I referenced in the top line of this commit
will be added to reviewboard shortly. Sit tight...



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@247335 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 4 insertions, 4 deletions

diff --git a/main/strings.c b/main/strings.c
index 040372449..6167e9b08 100644
--- a/main/strings.c
+++ b/main/strings.c
@@ -49,10 +49,10 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  */
 
 #if (defined(MALLOC_DEBUG) && !defined(STANDALONE))
-int __ast_debug_str_helper(struct ast_str **buf, size_t max_len,
+int __ast_debug_str_helper(struct ast_str **buf, ssize_t max_len,
 	int append, const char *fmt, va_list ap, const char *file, int lineno, const char *function)
 #else
-int __ast_str_helper(struct ast_str **buf, size_t max_len,
+int __ast_str_helper(struct ast_str **buf, ssize_t max_len,
 	int append, const char *fmt, va_list ap)
 #endif
 {
@@ -106,12 +106,12 @@ int __ast_str_helper(struct ast_str **buf, size_t max_len,
 		break;
 	} while (1);
 	/* update space used, keep in mind the truncation */
-	(*buf)->__AST_STR_USED = (res + offset > (*buf)->__AST_STR_LEN) ? (*buf)->__AST_STR_LEN : res + offset;
+	(*buf)->__AST_STR_USED = (res + offset > (*buf)->__AST_STR_LEN) ? (*buf)->__AST_STR_LEN - 1: res + offset;
 
 	return res;
 }
 
-char *__ast_str_helper2(struct ast_str **buf, size_t maxlen, const char *src, size_t maxsrc, int append, int escapecommas)
+char *__ast_str_helper2(struct ast_str **buf, ssize_t maxlen, const char *src, size_t maxsrc, int append, int escapecommas)
 {
 	int dynamic = 0;
 	char *ptr = append ? &((*buf)->__AST_STR_STR[(*buf)->__AST_STR_USED]) : (*buf)->__AST_STR_STR;