replicant-frameworks_native/libs/utils/ObbFile.cpp

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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define LOG_TAG "ObbFile"
#include <utils/Compat.h>
#include <utils/Log.h>
#include <utils/ObbFile.h>
//#define DEBUG 1
#define kFooterTagSize 8 /* last two 32-bit integers */
#define kFooterMinSize 33 /* 32-bit signature version (4 bytes)
* 32-bit package version (4 bytes)
* 32-bit flags (4 bytes)
* 64-bit salt (8 bytes)
* 32-bit package name size (4 bytes)
* >=1-character package name (1 byte)
* 32-bit footer size (4 bytes)
* 32-bit footer marker (4 bytes)
*/
#define kMaxBufSize 32768 /* Maximum file read buffer */
#define kSignature 0x01059983U /* ObbFile signature */
#define kSigVersion 1 /* We only know about signature version 1 */
/* offsets in version 1 of the header */
#define kPackageVersionOffset 4
#define kFlagsOffset 8
#define kSaltOffset 12
#define kPackageNameLenOffset 20
#define kPackageNameOffset 24
/*
* TEMP_FAILURE_RETRY is defined by some, but not all, versions of
* <unistd.h>. (Alas, it is not as standard as we'd hoped!) So, if it's
* not already defined, then define it here.
*/
#ifndef TEMP_FAILURE_RETRY
/* Used to retry syscalls that can return EINTR. */
#define TEMP_FAILURE_RETRY(exp) ({ \
typeof (exp) _rc; \
do { \
_rc = (exp); \
} while (_rc == -1 && errno == EINTR); \
_rc; })
#endif
namespace android {
ObbFile::ObbFile()
: mPackageName("")
, mVersion(-1)
, mFlags(0)
{
memset(mSalt, 0, sizeof(mSalt));
}
ObbFile::~ObbFile() {
}
bool ObbFile::readFrom(const char* filename)
{
int fd;
bool success = false;
fd = ::open(filename, O_RDONLY);
if (fd < 0) {
ALOGW("couldn't open file %s: %s", filename, strerror(errno));
goto out;
}
success = readFrom(fd);
close(fd);
if (!success) {
ALOGW("failed to read from %s (fd=%d)\n", filename, fd);
}
out:
return success;
}
bool ObbFile::readFrom(int fd)
{
if (fd < 0) {
ALOGW("attempt to read from invalid fd\n");
return false;
}
return parseObbFile(fd);
}
bool ObbFile::parseObbFile(int fd)
{
off64_t fileLength = lseek64(fd, 0, SEEK_END);
if (fileLength < kFooterMinSize) {
if (fileLength < 0) {
ALOGW("error seeking in ObbFile: %s\n", strerror(errno));
} else {
ALOGW("file is only %lld (less than %d minimum)\n", fileLength, kFooterMinSize);
}
return false;
}
ssize_t actual;
size_t footerSize;
{
lseek64(fd, fileLength - kFooterTagSize, SEEK_SET);
char *footer = new char[kFooterTagSize];
actual = TEMP_FAILURE_RETRY(read(fd, footer, kFooterTagSize));
if (actual != kFooterTagSize) {
ALOGW("couldn't read footer signature: %s\n", strerror(errno));
return false;
}
unsigned int fileSig = get4LE((unsigned char*)footer + sizeof(int32_t));
if (fileSig != kSignature) {
ALOGW("footer didn't match magic string (expected 0x%08x; got 0x%08x)\n",
kSignature, fileSig);
return false;
}
footerSize = get4LE((unsigned char*)footer);
if (footerSize > (size_t)fileLength - kFooterTagSize
|| footerSize > kMaxBufSize) {
ALOGW("claimed footer size is too large (0x%08zx; file size is 0x%08llx)\n",
footerSize, fileLength);
return false;
}
if (footerSize < (kFooterMinSize - kFooterTagSize)) {
ALOGW("claimed footer size is too small (0x%zx; minimum size is 0x%x)\n",
footerSize, kFooterMinSize - kFooterTagSize);
return false;
}
}
off64_t fileOffset = fileLength - footerSize - kFooterTagSize;
if (lseek64(fd, fileOffset, SEEK_SET) != fileOffset) {
ALOGW("seek %lld failed: %s\n", fileOffset, strerror(errno));
return false;
}
mFooterStart = fileOffset;
char* scanBuf = (char*)malloc(footerSize);
if (scanBuf == NULL) {
ALOGW("couldn't allocate scanBuf: %s\n", strerror(errno));
return false;
}
actual = TEMP_FAILURE_RETRY(read(fd, scanBuf, footerSize));
// readAmount is guaranteed to be less than kMaxBufSize
if (actual != (ssize_t)footerSize) {
ALOGI("couldn't read ObbFile footer: %s\n", strerror(errno));
free(scanBuf);
return false;
}
#ifdef DEBUG
for (int i = 0; i < footerSize; ++i) {
ALOGI("char: 0x%02x\n", scanBuf[i]);
}
#endif
uint32_t sigVersion = get4LE((unsigned char*)scanBuf);
if (sigVersion != kSigVersion) {
ALOGW("Unsupported ObbFile version %d\n", sigVersion);
free(scanBuf);
return false;
}
mVersion = (int32_t) get4LE((unsigned char*)scanBuf + kPackageVersionOffset);
mFlags = (int32_t) get4LE((unsigned char*)scanBuf + kFlagsOffset);
memcpy(&mSalt, (unsigned char*)scanBuf + kSaltOffset, sizeof(mSalt));
size_t packageNameLen = get4LE((unsigned char*)scanBuf + kPackageNameLenOffset);
if (packageNameLen == 0
|| packageNameLen > (footerSize - kPackageNameOffset)) {
ALOGW("bad ObbFile package name length (0x%04zx; 0x%04zx possible)\n",
packageNameLen, footerSize - kPackageNameOffset);
free(scanBuf);
return false;
}
char* packageName = reinterpret_cast<char*>(scanBuf + kPackageNameOffset);
mPackageName = String8(const_cast<char*>(packageName), packageNameLen);
free(scanBuf);
#ifdef DEBUG
ALOGI("Obb scan succeeded: packageName=%s, version=%d\n", mPackageName.string(), mVersion);
#endif
return true;
}
bool ObbFile::writeTo(const char* filename)
{
int fd;
bool success = false;
fd = ::open(filename, O_WRONLY);
if (fd < 0) {
goto out;
}
success = writeTo(fd);
close(fd);
out:
if (!success) {
ALOGW("failed to write to %s: %s\n", filename, strerror(errno));
}
return success;
}
bool ObbFile::writeTo(int fd)
{
if (fd < 0) {
return false;
}
lseek64(fd, 0, SEEK_END);
if (mPackageName.size() == 0 || mVersion == -1) {
ALOGW("tried to write uninitialized ObbFile data\n");
return false;
}
unsigned char intBuf[sizeof(uint32_t)+1];
memset(&intBuf, 0, sizeof(intBuf));
put4LE(intBuf, kSigVersion);
if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
ALOGW("couldn't write signature version: %s\n", strerror(errno));
return false;
}
put4LE(intBuf, mVersion);
if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
ALOGW("couldn't write package version\n");
return false;
}
put4LE(intBuf, mFlags);
if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
ALOGW("couldn't write package version\n");
return false;
}
if (write(fd, mSalt, sizeof(mSalt)) != (ssize_t)sizeof(mSalt)) {
ALOGW("couldn't write salt: %s\n", strerror(errno));
return false;
}
size_t packageNameLen = mPackageName.size();
put4LE(intBuf, packageNameLen);
if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
ALOGW("couldn't write package name length: %s\n", strerror(errno));
return false;
}
if (write(fd, mPackageName.string(), packageNameLen) != (ssize_t)packageNameLen) {
ALOGW("couldn't write package name: %s\n", strerror(errno));
return false;
}
put4LE(intBuf, kPackageNameOffset + packageNameLen);
if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
ALOGW("couldn't write footer size: %s\n", strerror(errno));
return false;
}
put4LE(intBuf, kSignature);
if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
ALOGW("couldn't write footer magic signature: %s\n", strerror(errno));
return false;
}
return true;
}
bool ObbFile::removeFrom(const char* filename)
{
int fd;
bool success = false;
fd = ::open(filename, O_RDWR);
if (fd < 0) {
goto out;
}
success = removeFrom(fd);
close(fd);
out:
if (!success) {
ALOGW("failed to remove signature from %s: %s\n", filename, strerror(errno));
}
return success;
}
bool ObbFile::removeFrom(int fd)
{
if (fd < 0) {
return false;
}
if (!readFrom(fd)) {
return false;
}
ftruncate(fd, mFooterStart);
return true;
}
}