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
158 lines
4.4 KiB
C
158 lines
4.4 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2008, Digium, Inc.
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*
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* Tilghman Lesher <tlesher@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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*
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* \brief String manipulation API
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*
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* \author Tilghman Lesher <tilghman@digium.com>
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*/
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/*** MAKEOPTS
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<category name="MENUSELECT_CFLAGS" displayname="Compiler Flags" positive_output="yes">
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<member name="DEBUG_OPAQUE" displayname="Change ast_str internals to detect improper usage" touch_on_change="include/asterisk/strings.h">
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<defaultenabled>yes</defaultenabled>
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</member>
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</category>
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***/
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#include "asterisk.h"
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ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
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#include "asterisk/strings.h"
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#include "asterisk/pbx.h"
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/*!
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* core handler for dynamic strings.
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* This is not meant to be called directly, but rather through the
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* various wrapper macros
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* ast_str_set(...)
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* ast_str_append(...)
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* ast_str_set_va(...)
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* ast_str_append_va(...)
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*/
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#if (defined(MALLOC_DEBUG) && !defined(STANDALONE))
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int __ast_debug_str_helper(struct ast_str **buf, ssize_t max_len,
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int append, const char *fmt, va_list ap, const char *file, int lineno, const char *function)
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#else
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int __ast_str_helper(struct ast_str **buf, ssize_t max_len,
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int append, const char *fmt, va_list ap)
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#endif
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{
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int res, need;
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int offset = (append && (*buf)->__AST_STR_LEN) ? (*buf)->__AST_STR_USED : 0;
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va_list aq;
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do {
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if (max_len < 0) {
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max_len = (*buf)->__AST_STR_LEN; /* don't exceed the allocated space */
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}
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/*
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* Ask vsnprintf how much space we need. Remember that vsnprintf
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* does not count the final <code>'\0'</code> so we must add 1.
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*/
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va_copy(aq, ap);
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res = vsnprintf((*buf)->__AST_STR_STR + offset, (*buf)->__AST_STR_LEN - offset, fmt, aq);
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need = res + offset + 1;
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/*
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* If there is not enough space and we are below the max length,
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* reallocate the buffer and return a message telling to retry.
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*/
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if (need > (*buf)->__AST_STR_LEN && (max_len == 0 || (*buf)->__AST_STR_LEN < max_len) ) {
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if (max_len && max_len < need) { /* truncate as needed */
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need = max_len;
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} else if (max_len == 0) { /* if unbounded, give more room for next time */
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need += 16 + need / 4;
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}
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if (0) { /* debugging */
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ast_verbose("extend from %d to %d\n", (int)(*buf)->__AST_STR_LEN, need);
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}
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if (
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#if (defined(MALLOC_DEBUG) && !defined(STANDALONE))
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_ast_str_make_space(buf, need, file, lineno, function)
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#else
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ast_str_make_space(buf, need)
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#endif
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) {
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ast_verbose("failed to extend from %d to %d\n", (int)(*buf)->__AST_STR_LEN, need);
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va_end(aq);
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return AST_DYNSTR_BUILD_FAILED;
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}
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(*buf)->__AST_STR_STR[offset] = '\0'; /* Truncate the partial write. */
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/* Restart va_copy before calling vsnprintf() again. */
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va_end(aq);
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continue;
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}
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va_end(aq);
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break;
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} while (1);
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/* update space used, keep in mind the truncation */
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(*buf)->__AST_STR_USED = (res + offset > (*buf)->__AST_STR_LEN) ? (*buf)->__AST_STR_LEN - 1: res + offset;
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return res;
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}
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char *__ast_str_helper2(struct ast_str **buf, ssize_t maxlen, const char *src, size_t maxsrc, int append, int escapecommas)
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{
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int dynamic = 0;
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char *ptr = append ? &((*buf)->__AST_STR_STR[(*buf)->__AST_STR_USED]) : (*buf)->__AST_STR_STR;
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if (maxlen < 1) {
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if (maxlen == 0) {
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dynamic = 1;
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}
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maxlen = (*buf)->__AST_STR_LEN;
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}
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while (*src && maxsrc && maxlen && (!escapecommas || (maxlen - 1))) {
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if (escapecommas && (*src == '\\' || *src == ',')) {
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*ptr++ = '\\';
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maxlen--;
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(*buf)->__AST_STR_USED++;
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}
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*ptr++ = *src++;
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maxsrc--;
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maxlen--;
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(*buf)->__AST_STR_USED++;
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if ((ptr >= (*buf)->__AST_STR_STR + (*buf)->__AST_STR_LEN - 3) ||
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(dynamic && (!maxlen || (escapecommas && !(maxlen - 1))))) {
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char *oldbase = (*buf)->__AST_STR_STR;
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size_t old = (*buf)->__AST_STR_LEN;
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if (ast_str_make_space(buf, (*buf)->__AST_STR_LEN * 2)) {
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/* If the buffer can't be extended, end it. */
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break;
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}
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/* What we extended the buffer by */
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maxlen = old;
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ptr += (*buf)->__AST_STR_STR - oldbase;
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}
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}
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if (__builtin_expect(!maxlen, 0)) {
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ptr--;
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}
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*ptr = '\0';
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return (*buf)->__AST_STR_STR;
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}
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