mpd/src/tag/ApeLoader.cxx

109 lines
2.7 KiB
C++

/*
* Copyright 2003-2017 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include "ApeLoader.hxx"
#include "system/ByteOrder.hxx"
#include "input/InputStream.hxx"
#include "util/StringView.hxx"
#include <memory>
#include <stdint.h>
#include <assert.h>
#include <string.h>
struct ApeFooter {
unsigned char id[8];
uint32_t version;
uint32_t length;
uint32_t count;
unsigned char flags[4];
unsigned char reserved[8];
};
bool
tag_ape_scan(InputStream &is, ApeTagCallback callback)
try {
const std::lock_guard<Mutex> protect(is.mutex);
if (!is.KnownSize() || !is.CheapSeeking())
return false;
/* determine if file has an apeV2 tag */
ApeFooter footer;
is.Seek(is.GetSize() - sizeof(footer));
is.ReadFull(&footer, sizeof(footer));
if (memcmp(footer.id, "APETAGEX", sizeof(footer.id)) != 0 ||
FromLE32(footer.version) != 2000)
return false;
/* find beginning of ape tag */
size_t remaining = FromLE32(footer.length);
if (remaining <= sizeof(footer) + 10 ||
/* refuse to load more than one megabyte of tag data */
remaining > 1024 * 1024)
return false;
is.Seek(is.GetSize() - remaining);
/* read tag into buffer */
remaining -= sizeof(footer);
assert(remaining > 10);
std::unique_ptr<char[]> buffer(new char[remaining]);
is.ReadFull(buffer.get(), remaining);
/* read tags */
unsigned n = FromLE32(footer.count);
const char *p = buffer.get();
while (n-- && remaining > 10) {
size_t size = FromLE32(*(const uint32_t *)p);
p += 4;
remaining -= 4;
unsigned long flags = FromLE32(*(const uint32_t *)p);
p += 4;
remaining -= 4;
/* get the key */
const char *key = p;
const char *key_end = (const char *)memchr(p, '\0', remaining);
if (key_end == nullptr)
break;
p = key_end + 1;
remaining -= p - key;
/* get the value */
if (remaining < size)
break;
if (!callback(flags, key, {p, size}))
break;
p += size;
remaining -= size;
}
return true;
} catch (...) {
return false;
}