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      1 /*
      2  ** Copyright 2016, The Android Open Source Project
      3  **
      4  ** Licensed under the Apache License, Version 2.0 (the "License");
      5  ** you may not use this file except in compliance with the License.
      6  ** You may obtain a copy of the License at
      7  **
      8  **     http://www.apache.org/licenses/LICENSE-2.0
      9  **
     10  ** Unless required by applicable law or agreed to in writing, software
     11  ** distributed under the License is distributed on an "AS IS" BASIS,
     12  ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  ** See the License for the specific language governing permissions and
     14  ** limitations under the License.
     15  */
     16 
     17 #include <algorithm>
     18 #include <inttypes.h>
     19 #include <random>
     20 #include <regex>
     21 #include <selinux/android.h>
     22 #include <selinux/avc.h>
     23 #include <stdlib.h>
     24 #include <string.h>
     25 #include <sys/capability.h>
     26 #include <sys/prctl.h>
     27 #include <sys/stat.h>
     28 #include <sys/wait.h>
     29 
     30 #include <android-base/logging.h>
     31 #include <android-base/macros.h>
     32 #include <android-base/stringprintf.h>
     33 #include <android-base/strings.h>
     34 #include <cutils/fs.h>
     35 #include <cutils/log.h>
     36 #include <cutils/properties.h>
     37 #include <private/android_filesystem_config.h>
     38 
     39 #include <commands.h>
     40 #include <file_parsing.h>
     41 #include <globals.h>
     42 #include <installd_deps.h>  // Need to fill in requirements of commands.
     43 #include <otapreopt_utils.h>
     44 #include <system_properties.h>
     45 #include <utils.h>
     46 
     47 #ifndef LOG_TAG
     48 #define LOG_TAG "otapreopt"
     49 #endif
     50 
     51 #define BUFFER_MAX    1024  /* input buffer for commands */
     52 #define TOKEN_MAX     16    /* max number of arguments in buffer */
     53 #define REPLY_MAX     256   /* largest reply allowed */
     54 
     55 using android::base::EndsWith;
     56 using android::base::Join;
     57 using android::base::Split;
     58 using android::base::StartsWith;
     59 using android::base::StringPrintf;
     60 
     61 namespace android {
     62 namespace installd {
     63 
     64 template<typename T>
     65 static constexpr T RoundDown(T x, typename std::decay<T>::type n) {
     66     return DCHECK_CONSTEXPR(IsPowerOfTwo(n), , T(0))(x & -n);
     67 }
     68 
     69 template<typename T>
     70 static constexpr T RoundUp(T x, typename std::remove_reference<T>::type n) {
     71     return RoundDown(x + n - 1, n);
     72 }
     73 
     74 class OTAPreoptService {
     75  public:
     76     // Main driver. Performs the following steps.
     77     //
     78     // 1) Parse options (read system properties etc from B partition).
     79     //
     80     // 2) Read in package data.
     81     //
     82     // 3) Prepare environment variables.
     83     //
     84     // 4) Prepare(compile) boot image, if necessary.
     85     //
     86     // 5) Run update.
     87     int Main(int argc, char** argv) {
     88         if (!ReadArguments(argc, argv)) {
     89             LOG(ERROR) << "Failed reading command line.";
     90             return 1;
     91         }
     92 
     93         if (!ReadSystemProperties()) {
     94             LOG(ERROR)<< "Failed reading system properties.";
     95             return 2;
     96         }
     97 
     98         if (!ReadEnvironment()) {
     99             LOG(ERROR) << "Failed reading environment properties.";
    100             return 3;
    101         }
    102 
    103         if (!CheckAndInitializeInstalldGlobals()) {
    104             LOG(ERROR) << "Failed initializing globals.";
    105             return 4;
    106         }
    107 
    108         PrepareEnvironment();
    109 
    110         if (!PrepareBootImage(/* force */ false)) {
    111             LOG(ERROR) << "Failed preparing boot image.";
    112             return 5;
    113         }
    114 
    115         int dexopt_retcode = RunPreopt();
    116 
    117         return dexopt_retcode;
    118     }
    119 
    120     int GetProperty(const char* key, char* value, const char* default_value) const {
    121         const std::string* prop_value = system_properties_.GetProperty(key);
    122         if (prop_value == nullptr) {
    123             if (default_value == nullptr) {
    124                 return 0;
    125             }
    126             // Copy in the default value.
    127             strncpy(value, default_value, kPropertyValueMax - 1);
    128             value[kPropertyValueMax - 1] = 0;
    129             return strlen(default_value);// TODO: Need to truncate?
    130         }
    131         size_t size = std::min(kPropertyValueMax - 1, prop_value->length());
    132         strncpy(value, prop_value->data(), size);
    133         value[size] = 0;
    134         return static_cast<int>(size);
    135     }
    136 
    137     std::string GetOTADataDirectory() const {
    138         return StringPrintf("%s/%s", GetOtaDirectoryPrefix().c_str(), target_slot_.c_str());
    139     }
    140 
    141     const std::string& GetTargetSlot() const {
    142         return target_slot_;
    143     }
    144 
    145 private:
    146 
    147     bool ReadSystemProperties() {
    148         static constexpr const char* kPropertyFiles[] = {
    149                 "/default.prop", "/system/build.prop"
    150         };
    151 
    152         for (size_t i = 0; i < arraysize(kPropertyFiles); ++i) {
    153             if (!system_properties_.Load(kPropertyFiles[i])) {
    154                 return false;
    155             }
    156         }
    157 
    158         return true;
    159     }
    160 
    161     bool ReadEnvironment() {
    162         // Parse the environment variables from init.environ.rc, which have the form
    163         //   export NAME VALUE
    164         // For simplicity, don't respect string quotation. The values we are interested in can be
    165         // encoded without them.
    166         std::regex export_regex("\\s*export\\s+(\\S+)\\s+(\\S+)");
    167         bool parse_result = ParseFile("/init.environ.rc", [&](const std::string& line) {
    168             std::smatch export_match;
    169             if (!std::regex_match(line, export_match, export_regex)) {
    170                 return true;
    171             }
    172 
    173             if (export_match.size() != 3) {
    174                 return true;
    175             }
    176 
    177             std::string name = export_match[1].str();
    178             std::string value = export_match[2].str();
    179 
    180             system_properties_.SetProperty(name, value);
    181 
    182             return true;
    183         });
    184         if (!parse_result) {
    185             return false;
    186         }
    187 
    188         if (system_properties_.GetProperty(kAndroidDataPathPropertyName) == nullptr) {
    189             return false;
    190         }
    191         android_data_ = *system_properties_.GetProperty(kAndroidDataPathPropertyName);
    192 
    193         if (system_properties_.GetProperty(kAndroidRootPathPropertyName) == nullptr) {
    194             return false;
    195         }
    196         android_root_ = *system_properties_.GetProperty(kAndroidRootPathPropertyName);
    197 
    198         if (system_properties_.GetProperty(kBootClassPathPropertyName) == nullptr) {
    199             return false;
    200         }
    201         boot_classpath_ = *system_properties_.GetProperty(kBootClassPathPropertyName);
    202 
    203         if (system_properties_.GetProperty(ASEC_MOUNTPOINT_ENV_NAME) == nullptr) {
    204             return false;
    205         }
    206         asec_mountpoint_ = *system_properties_.GetProperty(ASEC_MOUNTPOINT_ENV_NAME);
    207 
    208         return true;
    209     }
    210 
    211     const std::string& GetAndroidData() const {
    212         return android_data_;
    213     }
    214 
    215     const std::string& GetAndroidRoot() const {
    216         return android_root_;
    217     }
    218 
    219     const std::string GetOtaDirectoryPrefix() const {
    220         return GetAndroidData() + "/ota";
    221     }
    222 
    223     bool CheckAndInitializeInstalldGlobals() {
    224         // init_globals_from_data_and_root requires "ASEC_MOUNTPOINT" in the environment. We
    225         // do not use any datapath that includes this, but we'll still have to set it.
    226         CHECK(system_properties_.GetProperty(ASEC_MOUNTPOINT_ENV_NAME) != nullptr);
    227         int result = setenv(ASEC_MOUNTPOINT_ENV_NAME, asec_mountpoint_.c_str(), 0);
    228         if (result != 0) {
    229             LOG(ERROR) << "Could not set ASEC_MOUNTPOINT environment variable";
    230             return false;
    231         }
    232 
    233         if (!init_globals_from_data_and_root(GetAndroidData().c_str(), GetAndroidRoot().c_str())) {
    234             LOG(ERROR) << "Could not initialize globals; exiting.";
    235             return false;
    236         }
    237 
    238         // This is different from the normal installd. We only do the base
    239         // directory, the rest will be created on demand when each app is compiled.
    240         if (access(GetOtaDirectoryPrefix().c_str(), R_OK) < 0) {
    241             LOG(ERROR) << "Could not access " << GetOtaDirectoryPrefix();
    242             return false;
    243         }
    244 
    245         return true;
    246     }
    247 
    248     bool ReadArguments(int argc ATTRIBUTE_UNUSED, char** argv) {
    249         // Expected command line:
    250         //   target-slot dexopt {DEXOPT_PARAMETERS}
    251         // The DEXOPT_PARAMETERS are passed on to dexopt(), so we expect DEXOPT_PARAM_COUNT
    252         // of them. We store them in package_parameters_ (size checks are done when
    253         // parsing the special parameters and when copying into package_parameters_.
    254 
    255         static_assert(DEXOPT_PARAM_COUNT == ARRAY_SIZE(package_parameters_),
    256                       "Unexpected dexopt param count");
    257 
    258         const char* target_slot_arg = argv[1];
    259         if (target_slot_arg == nullptr) {
    260             LOG(ERROR) << "Missing parameters";
    261             return false;
    262         }
    263         // Sanitize value. Only allow (a-zA-Z0-9_)+.
    264         target_slot_ = target_slot_arg;
    265         if (!ValidateTargetSlotSuffix(target_slot_)) {
    266             LOG(ERROR) << "Target slot suffix not legal: " << target_slot_;
    267             return false;
    268         }
    269 
    270         // Check for "dexopt" next.
    271         if (argv[2] == nullptr) {
    272             LOG(ERROR) << "Missing parameters";
    273             return false;
    274         }
    275         if (std::string("dexopt").compare(argv[2]) != 0) {
    276             LOG(ERROR) << "Second parameter not dexopt: " << argv[2];
    277             return false;
    278         }
    279 
    280         // Copy the rest into package_parameters_, but be careful about over- and underflow.
    281         size_t index = 0;
    282         while (index < DEXOPT_PARAM_COUNT &&
    283                 argv[index + 3] != nullptr) {
    284             package_parameters_[index] = argv[index + 3];
    285             index++;
    286         }
    287         if (index != ARRAY_SIZE(package_parameters_) || argv[index + 3] != nullptr) {
    288             LOG(ERROR) << "Wrong number of parameters";
    289             return false;
    290         }
    291 
    292         return true;
    293     }
    294 
    295     void PrepareEnvironment() {
    296         environ_.push_back(StringPrintf("BOOTCLASSPATH=%s", boot_classpath_.c_str()));
    297         environ_.push_back(StringPrintf("ANDROID_DATA=%s", GetOTADataDirectory().c_str()));
    298         environ_.push_back(StringPrintf("ANDROID_ROOT=%s", android_root_.c_str()));
    299 
    300         for (const std::string& e : environ_) {
    301             putenv(const_cast<char*>(e.c_str()));
    302         }
    303     }
    304 
    305     // Ensure that we have the right boot image. The first time any app is
    306     // compiled, we'll try to generate it.
    307     bool PrepareBootImage(bool force) const {
    308         if (package_parameters_[kISAIndex] == nullptr) {
    309             LOG(ERROR) << "Instruction set missing.";
    310             return false;
    311         }
    312         const char* isa = package_parameters_[kISAIndex];
    313 
    314         // Check whether the file exists where expected.
    315         std::string dalvik_cache = GetOTADataDirectory() + "/" + DALVIK_CACHE;
    316         std::string isa_path = dalvik_cache + "/" + isa;
    317         std::string art_path = isa_path + "/system@framework (at) boot.art";
    318         std::string oat_path = isa_path + "/system@framework (at) boot.oat";
    319         bool cleared = false;
    320         if (access(art_path.c_str(), F_OK) == 0 && access(oat_path.c_str(), F_OK) == 0) {
    321             // Files exist, assume everything is alright if not forced. Otherwise clean up.
    322             if (!force) {
    323                 return true;
    324             }
    325             ClearDirectory(isa_path);
    326             cleared = true;
    327         }
    328 
    329         // Reset umask in otapreopt, so that we control the the access for the files we create.
    330         umask(0);
    331 
    332         // Create the directories, if necessary.
    333         if (access(dalvik_cache.c_str(), F_OK) != 0) {
    334             if (!CreatePath(dalvik_cache)) {
    335                 PLOG(ERROR) << "Could not create dalvik-cache dir " << dalvik_cache;
    336                 return false;
    337             }
    338         }
    339         if (access(isa_path.c_str(), F_OK) != 0) {
    340             if (!CreatePath(isa_path)) {
    341                 PLOG(ERROR) << "Could not create dalvik-cache isa dir";
    342                 return false;
    343             }
    344         }
    345 
    346         // Prepare to create.
    347         if (!cleared) {
    348             ClearDirectory(isa_path);
    349         }
    350 
    351         std::string preopted_boot_art_path = StringPrintf("/system/framework/%s/boot.art", isa);
    352         if (access(preopted_boot_art_path.c_str(), F_OK) == 0) {
    353           return PatchoatBootImage(art_path, isa);
    354         } else {
    355           // No preopted boot image. Try to compile.
    356           return Dex2oatBootImage(boot_classpath_, art_path, oat_path, isa);
    357         }
    358     }
    359 
    360     static bool CreatePath(const std::string& path) {
    361         // Create the given path. Use string processing instead of dirname, as dirname's need for
    362         // a writable char buffer is painful.
    363 
    364         // First, try to use the full path.
    365         if (mkdir(path.c_str(), 0711) == 0) {
    366             return true;
    367         }
    368         if (errno != ENOENT) {
    369             PLOG(ERROR) << "Could not create path " << path;
    370             return false;
    371         }
    372 
    373         // Now find the parent and try that first.
    374         size_t last_slash = path.find_last_of('/');
    375         if (last_slash == std::string::npos || last_slash == 0) {
    376             PLOG(ERROR) << "Could not create " << path;
    377             return false;
    378         }
    379 
    380         if (!CreatePath(path.substr(0, last_slash))) {
    381             return false;
    382         }
    383 
    384         if (mkdir(path.c_str(), 0711) == 0) {
    385             return true;
    386         }
    387         PLOG(ERROR) << "Could not create " << path;
    388         return false;
    389     }
    390 
    391     static void ClearDirectory(const std::string& dir) {
    392         DIR* c_dir = opendir(dir.c_str());
    393         if (c_dir == nullptr) {
    394             PLOG(WARNING) << "Unable to open " << dir << " to delete it's contents";
    395             return;
    396         }
    397 
    398         for (struct dirent* de = readdir(c_dir); de != nullptr; de = readdir(c_dir)) {
    399             const char* name = de->d_name;
    400             if (strcmp(name, ".") == 0 || strcmp(name, "..") == 0) {
    401                 continue;
    402             }
    403             // We only want to delete regular files and symbolic links.
    404             std::string file = StringPrintf("%s/%s", dir.c_str(), name);
    405             if (de->d_type != DT_REG && de->d_type != DT_LNK) {
    406                 LOG(WARNING) << "Unexpected file "
    407                              << file
    408                              << " of type "
    409                              << std::hex
    410                              << de->d_type
    411                              << " encountered.";
    412             } else {
    413                 // Try to unlink the file.
    414                 if (unlink(file.c_str()) != 0) {
    415                     PLOG(ERROR) << "Unable to unlink " << file;
    416                 }
    417             }
    418         }
    419         CHECK_EQ(0, closedir(c_dir)) << "Unable to close directory.";
    420     }
    421 
    422     bool PatchoatBootImage(const std::string& art_path, const char* isa) const {
    423         // This needs to be kept in sync with ART, see art/runtime/gc/space/image_space.cc.
    424 
    425         std::vector<std::string> cmd;
    426         cmd.push_back("/system/bin/patchoat");
    427 
    428         cmd.push_back("--input-image-location=/system/framework/boot.art");
    429         cmd.push_back(StringPrintf("--output-image-file=%s", art_path.c_str()));
    430 
    431         cmd.push_back(StringPrintf("--instruction-set=%s", isa));
    432 
    433         int32_t base_offset = ChooseRelocationOffsetDelta(ART_BASE_ADDRESS_MIN_DELTA,
    434                                                           ART_BASE_ADDRESS_MAX_DELTA);
    435         cmd.push_back(StringPrintf("--base-offset-delta=%d", base_offset));
    436 
    437         std::string error_msg;
    438         bool result = Exec(cmd, &error_msg);
    439         if (!result) {
    440             LOG(ERROR) << "Could not generate boot image: " << error_msg;
    441         }
    442         return result;
    443     }
    444 
    445     bool Dex2oatBootImage(const std::string& boot_cp,
    446                           const std::string& art_path,
    447                           const std::string& oat_path,
    448                           const char* isa) const {
    449         // This needs to be kept in sync with ART, see art/runtime/gc/space/image_space.cc.
    450         std::vector<std::string> cmd;
    451         cmd.push_back("/system/bin/dex2oat");
    452         cmd.push_back(StringPrintf("--image=%s", art_path.c_str()));
    453         for (const std::string& boot_part : Split(boot_cp, ":")) {
    454             cmd.push_back(StringPrintf("--dex-file=%s", boot_part.c_str()));
    455         }
    456         cmd.push_back(StringPrintf("--oat-file=%s", oat_path.c_str()));
    457 
    458         int32_t base_offset = ChooseRelocationOffsetDelta(ART_BASE_ADDRESS_MIN_DELTA,
    459                 ART_BASE_ADDRESS_MAX_DELTA);
    460         cmd.push_back(StringPrintf("--base=0x%x", ART_BASE_ADDRESS + base_offset));
    461 
    462         cmd.push_back(StringPrintf("--instruction-set=%s", isa));
    463 
    464         // These things are pushed by AndroidRuntime, see frameworks/base/core/jni/AndroidRuntime.cpp.
    465         AddCompilerOptionFromSystemProperty("dalvik.vm.image-dex2oat-Xms",
    466                 "-Xms",
    467                 true,
    468                 cmd);
    469         AddCompilerOptionFromSystemProperty("dalvik.vm.image-dex2oat-Xmx",
    470                 "-Xmx",
    471                 true,
    472                 cmd);
    473         AddCompilerOptionFromSystemProperty("dalvik.vm.image-dex2oat-filter",
    474                 "--compiler-filter=",
    475                 false,
    476                 cmd);
    477         cmd.push_back("--image-classes=/system/etc/preloaded-classes");
    478         // TODO: Compiled-classes.
    479         const std::string* extra_opts =
    480                 system_properties_.GetProperty("dalvik.vm.image-dex2oat-flags");
    481         if (extra_opts != nullptr) {
    482             std::vector<std::string> extra_vals = Split(*extra_opts, " ");
    483             cmd.insert(cmd.end(), extra_vals.begin(), extra_vals.end());
    484         }
    485         // TODO: Should we lower this? It's usually set close to max, because
    486         //       normally there's not much else going on at boot.
    487         AddCompilerOptionFromSystemProperty("dalvik.vm.image-dex2oat-threads",
    488                 "-j",
    489                 false,
    490                 cmd);
    491         AddCompilerOptionFromSystemProperty(
    492                 StringPrintf("dalvik.vm.isa.%s.variant", isa).c_str(),
    493                 "--instruction-set-variant=",
    494                 false,
    495                 cmd);
    496         AddCompilerOptionFromSystemProperty(
    497                 StringPrintf("dalvik.vm.isa.%s.features", isa).c_str(),
    498                 "--instruction-set-features=",
    499                 false,
    500                 cmd);
    501 
    502         std::string error_msg;
    503         bool result = Exec(cmd, &error_msg);
    504         if (!result) {
    505             LOG(ERROR) << "Could not generate boot image: " << error_msg;
    506         }
    507         return result;
    508     }
    509 
    510     static const char* ParseNull(const char* arg) {
    511         return (strcmp(arg, "!") == 0) ? nullptr : arg;
    512     }
    513 
    514     bool ShouldSkipPreopt() const {
    515         // There's one thing we have to be careful about: we may/will be asked to compile an app
    516         // living in the system image. This may be a valid request - if the app wasn't compiled,
    517         // e.g., if the system image wasn't large enough to include preopted files. However, the
    518         // data we have is from the old system, so the driver (the OTA service) can't actually
    519         // know. Thus, we will get requests for apps that have preopted components. To avoid
    520         // duplication (we'd generate files that are not used and are *not* cleaned up), do two
    521         // simple checks:
    522         //
    523         // 1) Does the apk_path start with the value of ANDROID_ROOT? (~in the system image)
    524         //    (For simplicity, assume the value of ANDROID_ROOT does not contain a symlink.)
    525         //
    526         // 2) If you replace the name in the apk_path with "oat," does the path exist?
    527         //    (=have a subdirectory for preopted files)
    528         //
    529         // If the answer to both is yes, skip the dexopt.
    530         //
    531         // Note: while one may think it's OK to call dexopt and it will fail (because APKs should
    532         //       be stripped), that's not true for APKs signed outside the build system (so the
    533         //       jar content must be exactly the same).
    534 
    535         //       (This is ugly as it's the only thing where we need to understand the contents
    536         //        of package_parameters_, but it beats postponing the decision or using the call-
    537         //        backs to do weird things.)
    538         constexpr size_t kApkPathIndex = 0;
    539         CHECK_GT(DEXOPT_PARAM_COUNT, kApkPathIndex);
    540         CHECK(package_parameters_[kApkPathIndex] != nullptr);
    541         if (StartsWith(package_parameters_[kApkPathIndex], android_root_.c_str())) {
    542             const char* last_slash = strrchr(package_parameters_[kApkPathIndex], '/');
    543             if (last_slash != nullptr) {
    544                 std::string path(package_parameters_[kApkPathIndex],
    545                                  last_slash - package_parameters_[kApkPathIndex] + 1);
    546                 CHECK(EndsWith(path, "/"));
    547                 path = path + "oat";
    548                 if (access(path.c_str(), F_OK) == 0) {
    549                     return true;
    550                 }
    551             }
    552         }
    553 
    554         // Another issue is unavailability of files in the new system. If the partition
    555         // layout changes, otapreopt_chroot may not know about this. Then files from that
    556         // partition will not be available and fail to build. This is problematic, as
    557         // this tool will wipe the OTA artifact cache and try again (for robustness after
    558         // a failed OTA with remaining cache artifacts).
    559         if (access(package_parameters_[kApkPathIndex], F_OK) != 0) {
    560             LOG(WARNING) << "Skipping preopt of non-existing package "
    561                          << package_parameters_[kApkPathIndex];
    562             return true;
    563         }
    564 
    565         return false;
    566     }
    567 
    568     int RunPreopt() {
    569         if (ShouldSkipPreopt()) {
    570             return 0;
    571         }
    572 
    573         int dexopt_result = dexopt(package_parameters_);
    574         if (dexopt_result == 0) {
    575             return 0;
    576         }
    577 
    578         // If the dexopt failed, we may have a stale boot image from a previous OTA run.
    579         // Try to delete and retry.
    580 
    581         if (!PrepareBootImage(/* force */ true)) {
    582             LOG(ERROR) << "Forced boot image creating failed. Original error return was "
    583                          << dexopt_result;
    584             return dexopt_result;
    585         }
    586 
    587         LOG(WARNING) << "Original dexopt failed, re-trying after boot image was regenerated.";
    588         return dexopt(package_parameters_);
    589     }
    590 
    591     ////////////////////////////////////
    592     // Helpers, mostly taken from ART //
    593     ////////////////////////////////////
    594 
    595     // Wrapper on fork/execv to run a command in a subprocess.
    596     static bool Exec(const std::vector<std::string>& arg_vector, std::string* error_msg) {
    597         const std::string command_line = Join(arg_vector, ' ');
    598 
    599         CHECK_GE(arg_vector.size(), 1U) << command_line;
    600 
    601         // Convert the args to char pointers.
    602         const char* program = arg_vector[0].c_str();
    603         std::vector<char*> args;
    604         for (size_t i = 0; i < arg_vector.size(); ++i) {
    605             const std::string& arg = arg_vector[i];
    606             char* arg_str = const_cast<char*>(arg.c_str());
    607             CHECK(arg_str != nullptr) << i;
    608             args.push_back(arg_str);
    609         }
    610         args.push_back(nullptr);
    611 
    612         // Fork and exec.
    613         pid_t pid = fork();
    614         if (pid == 0) {
    615             // No allocation allowed between fork and exec.
    616 
    617             // Change process groups, so we don't get reaped by ProcessManager.
    618             setpgid(0, 0);
    619 
    620             execv(program, &args[0]);
    621 
    622             PLOG(ERROR) << "Failed to execv(" << command_line << ")";
    623             // _exit to avoid atexit handlers in child.
    624             _exit(1);
    625         } else {
    626             if (pid == -1) {
    627                 *error_msg = StringPrintf("Failed to execv(%s) because fork failed: %s",
    628                         command_line.c_str(), strerror(errno));
    629                 return false;
    630             }
    631 
    632             // wait for subprocess to finish
    633             int status;
    634             pid_t got_pid = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0));
    635             if (got_pid != pid) {
    636                 *error_msg = StringPrintf("Failed after fork for execv(%s) because waitpid failed: "
    637                         "wanted %d, got %d: %s",
    638                         command_line.c_str(), pid, got_pid, strerror(errno));
    639                 return false;
    640             }
    641             if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
    642                 *error_msg = StringPrintf("Failed execv(%s) because non-0 exit status",
    643                         command_line.c_str());
    644                 return false;
    645             }
    646         }
    647         return true;
    648     }
    649 
    650     // Choose a random relocation offset. Taken from art/runtime/gc/image_space.cc.
    651     static int32_t ChooseRelocationOffsetDelta(int32_t min_delta, int32_t max_delta) {
    652         constexpr size_t kPageSize = PAGE_SIZE;
    653         CHECK_EQ(min_delta % kPageSize, 0u);
    654         CHECK_EQ(max_delta % kPageSize, 0u);
    655         CHECK_LT(min_delta, max_delta);
    656 
    657         std::default_random_engine generator;
    658         generator.seed(GetSeed());
    659         std::uniform_int_distribution<int32_t> distribution(min_delta, max_delta);
    660         int32_t r = distribution(generator);
    661         if (r % 2 == 0) {
    662             r = RoundUp(r, kPageSize);
    663         } else {
    664             r = RoundDown(r, kPageSize);
    665         }
    666         CHECK_LE(min_delta, r);
    667         CHECK_GE(max_delta, r);
    668         CHECK_EQ(r % kPageSize, 0u);
    669         return r;
    670     }
    671 
    672     static uint64_t GetSeed() {
    673 #ifdef __BIONIC__
    674         // Bionic exposes arc4random, use it.
    675         uint64_t random_data;
    676         arc4random_buf(&random_data, sizeof(random_data));
    677         return random_data;
    678 #else
    679 #error "This is only supposed to run with bionic. Otherwise, implement..."
    680 #endif
    681     }
    682 
    683     void AddCompilerOptionFromSystemProperty(const char* system_property,
    684             const char* prefix,
    685             bool runtime,
    686             std::vector<std::string>& out) const {
    687         const std::string* value = system_properties_.GetProperty(system_property);
    688         if (value != nullptr) {
    689             if (runtime) {
    690                 out.push_back("--runtime-arg");
    691             }
    692             if (prefix != nullptr) {
    693                 out.push_back(StringPrintf("%s%s", prefix, value->c_str()));
    694             } else {
    695                 out.push_back(*value);
    696             }
    697         }
    698     }
    699 
    700     static constexpr const char* kBootClassPathPropertyName = "BOOTCLASSPATH";
    701     static constexpr const char* kAndroidRootPathPropertyName = "ANDROID_ROOT";
    702     static constexpr const char* kAndroidDataPathPropertyName = "ANDROID_DATA";
    703     // The index of the instruction-set string inside the package parameters. Needed for
    704     // some special-casing that requires knowledge of the instruction-set.
    705     static constexpr size_t kISAIndex = 3;
    706 
    707     // Stores the system properties read out of the B partition. We need to use these properties
    708     // to compile, instead of the A properties we could get from init/get_property.
    709     SystemProperties system_properties_;
    710 
    711     // Some select properties that are always needed.
    712     std::string target_slot_;
    713     std::string android_root_;
    714     std::string android_data_;
    715     std::string boot_classpath_;
    716     std::string asec_mountpoint_;
    717 
    718     const char* package_parameters_[DEXOPT_PARAM_COUNT];
    719 
    720     // Store environment values we need to set.
    721     std::vector<std::string> environ_;
    722 };
    723 
    724 OTAPreoptService gOps;
    725 
    726 ////////////////////////
    727 // Plug-in functions. //
    728 ////////////////////////
    729 
    730 int get_property(const char *key, char *value, const char *default_value) {
    731     return gOps.GetProperty(key, value, default_value);
    732 }
    733 
    734 // Compute the output path of
    735 bool calculate_oat_file_path(char path[PKG_PATH_MAX], const char *oat_dir,
    736                              const char *apk_path,
    737                              const char *instruction_set) {
    738     const char *file_name_start;
    739     const char *file_name_end;
    740 
    741     file_name_start = strrchr(apk_path, '/');
    742     if (file_name_start == nullptr) {
    743         ALOGE("apk_path '%s' has no '/'s in it\n", apk_path);
    744         return false;
    745     }
    746     file_name_end = strrchr(file_name_start, '.');
    747     if (file_name_end == nullptr) {
    748         ALOGE("apk_path '%s' has no extension\n", apk_path);
    749         return false;
    750     }
    751 
    752     // Calculate file_name
    753     file_name_start++;  // Move past '/', is valid as file_name_end is valid.
    754     size_t file_name_len = file_name_end - file_name_start;
    755     std::string file_name(file_name_start, file_name_len);
    756 
    757     // <apk_parent_dir>/oat/<isa>/<file_name>.odex.b
    758     snprintf(path,
    759              PKG_PATH_MAX,
    760              "%s/%s/%s.odex.%s",
    761              oat_dir,
    762              instruction_set,
    763              file_name.c_str(),
    764              gOps.GetTargetSlot().c_str());
    765     return true;
    766 }
    767 
    768 /*
    769  * Computes the odex file for the given apk_path and instruction_set.
    770  * /system/framework/whatever.jar -> /system/framework/oat/<isa>/whatever.odex
    771  *
    772  * Returns false if it failed to determine the odex file path.
    773  */
    774 bool calculate_odex_file_path(char path[PKG_PATH_MAX], const char *apk_path,
    775                               const char *instruction_set) {
    776     const char *path_end = strrchr(apk_path, '/');
    777     if (path_end == nullptr) {
    778         ALOGE("apk_path '%s' has no '/'s in it?!\n", apk_path);
    779         return false;
    780     }
    781     std::string path_component(apk_path, path_end - apk_path);
    782 
    783     const char *name_begin = path_end + 1;
    784     const char *extension_start = strrchr(name_begin, '.');
    785     if (extension_start == nullptr) {
    786         ALOGE("apk_path '%s' has no extension.\n", apk_path);
    787         return false;
    788     }
    789     std::string name_component(name_begin, extension_start - name_begin);
    790 
    791     std::string new_path = StringPrintf("%s/oat/%s/%s.odex.%s",
    792                                         path_component.c_str(),
    793                                         instruction_set,
    794                                         name_component.c_str(),
    795                                         gOps.GetTargetSlot().c_str());
    796     if (new_path.length() >= PKG_PATH_MAX) {
    797         LOG(ERROR) << "apk_path of " << apk_path << " is too long: " << new_path;
    798         return false;
    799     }
    800     strcpy(path, new_path.c_str());
    801     return true;
    802 }
    803 
    804 bool create_cache_path(char path[PKG_PATH_MAX],
    805                        const char *src,
    806                        const char *instruction_set) {
    807     size_t srclen = strlen(src);
    808 
    809         /* demand that we are an absolute path */
    810     if ((src == 0) || (src[0] != '/') || strstr(src,"..")) {
    811         return false;
    812     }
    813 
    814     if (srclen > PKG_PATH_MAX) {        // XXX: PKG_NAME_MAX?
    815         return false;
    816     }
    817 
    818     std::string from_src = std::string(src + 1);
    819     std::replace(from_src.begin(), from_src.end(), '/', '@');
    820 
    821     std::string assembled_path = StringPrintf("%s/%s/%s/%s%s",
    822                                               gOps.GetOTADataDirectory().c_str(),
    823                                               DALVIK_CACHE,
    824                                               instruction_set,
    825                                               from_src.c_str(),
    826                                               DALVIK_CACHE_POSTFIX2);
    827 
    828     if (assembled_path.length() + 1 > PKG_PATH_MAX) {
    829         return false;
    830     }
    831     strcpy(path, assembled_path.c_str());
    832 
    833     return true;
    834 }
    835 
    836 static int log_callback(int type, const char *fmt, ...) {
    837     va_list ap;
    838     int priority;
    839 
    840     switch (type) {
    841         case SELINUX_WARNING:
    842             priority = ANDROID_LOG_WARN;
    843             break;
    844         case SELINUX_INFO:
    845             priority = ANDROID_LOG_INFO;
    846             break;
    847         default:
    848             priority = ANDROID_LOG_ERROR;
    849             break;
    850     }
    851     va_start(ap, fmt);
    852     LOG_PRI_VA(priority, "SELinux", fmt, ap);
    853     va_end(ap);
    854     return 0;
    855 }
    856 
    857 static int otapreopt_main(const int argc, char *argv[]) {
    858     int selinux_enabled = (is_selinux_enabled() > 0);
    859 
    860     setenv("ANDROID_LOG_TAGS", "*:v", 1);
    861     android::base::InitLogging(argv);
    862 
    863     if (argc < 2) {
    864         ALOGE("Expecting parameters");
    865         exit(1);
    866     }
    867 
    868     union selinux_callback cb;
    869     cb.func_log = log_callback;
    870     selinux_set_callback(SELINUX_CB_LOG, cb);
    871 
    872     if (selinux_enabled && selinux_status_open(true) < 0) {
    873         ALOGE("Could not open selinux status; exiting.\n");
    874         exit(1);
    875     }
    876 
    877     int ret = android::installd::gOps.Main(argc, argv);
    878 
    879     return ret;
    880 }
    881 
    882 }  // namespace installd
    883 }  // namespace android
    884 
    885 int main(const int argc, char *argv[]) {
    886     return android::installd::otapreopt_main(argc, argv);
    887 }
    888