temporarily revert substring fix pending the result of the discussion in issue #6271

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.2@8414 65c4cc65-6c06-0410-ace0-fbb531ad65f3

pbx.c

@@ -927,34 +927,40 @@ pvn_endfor:
 	}
 }
 
-/*! \brief takes a substring. It is ok to call with value == workspace.
+static char *substring(char *value, int offset, int length, char *workspace, size_t workspace_len)
- *
- * offset < 0 means start from the end of the string.
- * length is the length of the substring, -1 means unlimited
- * (we take any negative value).
- * Always return a copy in workspace.
- */
-static char *substring(const char *value, int offset, int length, char *workspace, size_t workspace_len)
 {
 	char *ret = workspace;
-	int lr;	/* length of the input string after the copy */
 
-	ast_copy_string(workspace, value, workspace_len); /* always make a copy */
+	/* No need to do anything */
+	if (offset == 0 && length==-1) {
+		return value;
+	}
 
-	if (offset == 0 && length < 0)	/* take the whole string */
+	ast_copy_string(workspace, value, workspace_len);
-		return ret;
 
-	lr = strlen(ret); /* compute length after copy, so we never go out of the workspace */
+	if (abs(offset) > strlen(ret)) {	/* Offset beyond string */
+		if (offset >= 0) 
+			offset = strlen(ret);
+		else 
+			offset =- strlen(ret);	
+	}
 
-	if (offset < 0)		/* translate negative offset into positive ones */
+	/* Detect too-long length */
-		offset = lr - offset;
+	if ((offset < 0 && length > -offset) || (offset >= 0 && offset+length > strlen(ret))) {
+		if (offset >= 0) 
+			length = strlen(ret)-offset;
+		else 
+			length = strlen(ret)+offset;
+	}
 
-	/* too large offset result in empty string so we know what to return */
+	/* Bounce up to the right offset */
-	if (offset >= lr)
+	if (offset >= 0)
-		return ret + lr;	/* the final '\0' */
+		ret += offset;
+	else
+		ret += strlen(ret)+offset;
 
-	ret += offset;		/* move to the start position */
+	/* Chop off at the requisite length */
-	if (length >= 0 && length < lr - offset)	/* truncate if necessary */
+	if (length >= 0)
 		ret[length] = '\0';
 
 	return ret;