a19954ab37
See https://android-git.corp.google.com/g/156801 Bug: 5449033 Change-Id: Ib08fe86d23db91ee153e9f91a99a35c42b9208ea
346 lines
9.3 KiB
C++
346 lines
9.3 KiB
C++
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#define LOG_TAG "ObbFile"
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#include <utils/Compat.h>
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#include <utils/Log.h>
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#include <utils/ObbFile.h>
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//#define DEBUG 1
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#define kFooterTagSize 8 /* last two 32-bit integers */
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#define kFooterMinSize 33 /* 32-bit signature version (4 bytes)
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* 32-bit package version (4 bytes)
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* 32-bit flags (4 bytes)
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* 64-bit salt (8 bytes)
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* 32-bit package name size (4 bytes)
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* >=1-character package name (1 byte)
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* 32-bit footer size (4 bytes)
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* 32-bit footer marker (4 bytes)
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*/
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#define kMaxBufSize 32768 /* Maximum file read buffer */
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#define kSignature 0x01059983U /* ObbFile signature */
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#define kSigVersion 1 /* We only know about signature version 1 */
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/* offsets in version 1 of the header */
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#define kPackageVersionOffset 4
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#define kFlagsOffset 8
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#define kSaltOffset 12
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#define kPackageNameLenOffset 20
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#define kPackageNameOffset 24
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/*
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* TEMP_FAILURE_RETRY is defined by some, but not all, versions of
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* <unistd.h>. (Alas, it is not as standard as we'd hoped!) So, if it's
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* not already defined, then define it here.
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*/
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#ifndef TEMP_FAILURE_RETRY
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/* Used to retry syscalls that can return EINTR. */
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#define TEMP_FAILURE_RETRY(exp) ({ \
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typeof (exp) _rc; \
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do { \
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_rc = (exp); \
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} while (_rc == -1 && errno == EINTR); \
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_rc; })
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#endif
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namespace android {
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ObbFile::ObbFile()
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: mPackageName("")
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, mVersion(-1)
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, mFlags(0)
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{
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memset(mSalt, 0, sizeof(mSalt));
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}
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ObbFile::~ObbFile() {
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}
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bool ObbFile::readFrom(const char* filename)
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{
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int fd;
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bool success = false;
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fd = ::open(filename, O_RDONLY);
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if (fd < 0) {
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LOGW("couldn't open file %s: %s", filename, strerror(errno));
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goto out;
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}
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success = readFrom(fd);
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close(fd);
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if (!success) {
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LOGW("failed to read from %s (fd=%d)\n", filename, fd);
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}
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out:
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return success;
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}
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bool ObbFile::readFrom(int fd)
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{
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if (fd < 0) {
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LOGW("attempt to read from invalid fd\n");
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return false;
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}
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return parseObbFile(fd);
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}
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bool ObbFile::parseObbFile(int fd)
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{
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off64_t fileLength = lseek64(fd, 0, SEEK_END);
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if (fileLength < kFooterMinSize) {
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if (fileLength < 0) {
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LOGW("error seeking in ObbFile: %s\n", strerror(errno));
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} else {
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LOGW("file is only %lld (less than %d minimum)\n", fileLength, kFooterMinSize);
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}
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return false;
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}
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ssize_t actual;
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size_t footerSize;
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{
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lseek64(fd, fileLength - kFooterTagSize, SEEK_SET);
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char *footer = new char[kFooterTagSize];
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actual = TEMP_FAILURE_RETRY(read(fd, footer, kFooterTagSize));
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if (actual != kFooterTagSize) {
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LOGW("couldn't read footer signature: %s\n", strerror(errno));
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return false;
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}
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unsigned int fileSig = get4LE((unsigned char*)footer + sizeof(int32_t));
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if (fileSig != kSignature) {
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LOGW("footer didn't match magic string (expected 0x%08x; got 0x%08x)\n",
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kSignature, fileSig);
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return false;
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}
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footerSize = get4LE((unsigned char*)footer);
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if (footerSize > (size_t)fileLength - kFooterTagSize
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|| footerSize > kMaxBufSize) {
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LOGW("claimed footer size is too large (0x%08zx; file size is 0x%08llx)\n",
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footerSize, fileLength);
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return false;
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}
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if (footerSize < (kFooterMinSize - kFooterTagSize)) {
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LOGW("claimed footer size is too small (0x%zx; minimum size is 0x%x)\n",
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footerSize, kFooterMinSize - kFooterTagSize);
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return false;
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}
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}
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off64_t fileOffset = fileLength - footerSize - kFooterTagSize;
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if (lseek64(fd, fileOffset, SEEK_SET) != fileOffset) {
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LOGW("seek %lld failed: %s\n", fileOffset, strerror(errno));
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return false;
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}
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mFooterStart = fileOffset;
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char* scanBuf = (char*)malloc(footerSize);
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if (scanBuf == NULL) {
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LOGW("couldn't allocate scanBuf: %s\n", strerror(errno));
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return false;
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}
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actual = TEMP_FAILURE_RETRY(read(fd, scanBuf, footerSize));
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// readAmount is guaranteed to be less than kMaxBufSize
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if (actual != (ssize_t)footerSize) {
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ALOGI("couldn't read ObbFile footer: %s\n", strerror(errno));
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free(scanBuf);
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return false;
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}
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#ifdef DEBUG
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for (int i = 0; i < footerSize; ++i) {
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ALOGI("char: 0x%02x\n", scanBuf[i]);
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}
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#endif
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uint32_t sigVersion = get4LE((unsigned char*)scanBuf);
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if (sigVersion != kSigVersion) {
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LOGW("Unsupported ObbFile version %d\n", sigVersion);
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free(scanBuf);
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return false;
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}
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mVersion = (int32_t) get4LE((unsigned char*)scanBuf + kPackageVersionOffset);
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mFlags = (int32_t) get4LE((unsigned char*)scanBuf + kFlagsOffset);
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memcpy(&mSalt, (unsigned char*)scanBuf + kSaltOffset, sizeof(mSalt));
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size_t packageNameLen = get4LE((unsigned char*)scanBuf + kPackageNameLenOffset);
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if (packageNameLen == 0
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|| packageNameLen > (footerSize - kPackageNameOffset)) {
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LOGW("bad ObbFile package name length (0x%04zx; 0x%04zx possible)\n",
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packageNameLen, footerSize - kPackageNameOffset);
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free(scanBuf);
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return false;
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}
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char* packageName = reinterpret_cast<char*>(scanBuf + kPackageNameOffset);
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mPackageName = String8(const_cast<char*>(packageName), packageNameLen);
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free(scanBuf);
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#ifdef DEBUG
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ALOGI("Obb scan succeeded: packageName=%s, version=%d\n", mPackageName.string(), mVersion);
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#endif
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return true;
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}
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bool ObbFile::writeTo(const char* filename)
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{
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int fd;
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bool success = false;
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fd = ::open(filename, O_WRONLY);
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if (fd < 0) {
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goto out;
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}
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success = writeTo(fd);
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close(fd);
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out:
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if (!success) {
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LOGW("failed to write to %s: %s\n", filename, strerror(errno));
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}
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return success;
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}
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bool ObbFile::writeTo(int fd)
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{
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if (fd < 0) {
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return false;
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}
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lseek64(fd, 0, SEEK_END);
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if (mPackageName.size() == 0 || mVersion == -1) {
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LOGW("tried to write uninitialized ObbFile data\n");
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return false;
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}
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unsigned char intBuf[sizeof(uint32_t)+1];
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memset(&intBuf, 0, sizeof(intBuf));
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put4LE(intBuf, kSigVersion);
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if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
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LOGW("couldn't write signature version: %s\n", strerror(errno));
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return false;
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}
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put4LE(intBuf, mVersion);
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if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
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LOGW("couldn't write package version\n");
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return false;
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}
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put4LE(intBuf, mFlags);
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if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
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LOGW("couldn't write package version\n");
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return false;
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}
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if (write(fd, mSalt, sizeof(mSalt)) != (ssize_t)sizeof(mSalt)) {
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LOGW("couldn't write salt: %s\n", strerror(errno));
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return false;
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}
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size_t packageNameLen = mPackageName.size();
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put4LE(intBuf, packageNameLen);
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if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
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LOGW("couldn't write package name length: %s\n", strerror(errno));
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return false;
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}
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if (write(fd, mPackageName.string(), packageNameLen) != (ssize_t)packageNameLen) {
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LOGW("couldn't write package name: %s\n", strerror(errno));
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return false;
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}
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put4LE(intBuf, kPackageNameOffset + packageNameLen);
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if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
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LOGW("couldn't write footer size: %s\n", strerror(errno));
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return false;
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}
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put4LE(intBuf, kSignature);
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if (write(fd, &intBuf, sizeof(uint32_t)) != (ssize_t)sizeof(uint32_t)) {
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LOGW("couldn't write footer magic signature: %s\n", strerror(errno));
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return false;
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}
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return true;
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}
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bool ObbFile::removeFrom(const char* filename)
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{
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int fd;
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bool success = false;
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fd = ::open(filename, O_RDWR);
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if (fd < 0) {
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goto out;
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}
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success = removeFrom(fd);
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close(fd);
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out:
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if (!success) {
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LOGW("failed to remove signature from %s: %s\n", filename, strerror(errno));
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}
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return success;
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}
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bool ObbFile::removeFrom(int fd)
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{
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if (fd < 0) {
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return false;
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}
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if (!readFrom(fd)) {
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return false;
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}
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ftruncate(fd, mFooterStart);
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return true;
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}
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}
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