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      1 /*
      2  ** Copyright 2019, 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 "otapreopt_utils.h"
     18 
     19 #include <sys/types.h>
     20 #include <sys/wait.h>
     21 #include <unistd.h>
     22 
     23 #include <android-base/logging.h>
     24 #include <android-base/stringprintf.h>
     25 #include <android-base/strings.h>
     26 
     27 using android::base::Join;
     28 using android::base::StringPrintf;
     29 
     30 namespace android {
     31 namespace installd {
     32 
     33 bool Exec(const std::vector<std::string>& arg_vector, std::string* error_msg) {
     34     const std::string command_line = Join(arg_vector, ' ');
     35 
     36     CHECK_GE(arg_vector.size(), 1U) << command_line;
     37 
     38     // Convert the args to char pointers.
     39     const char* program = arg_vector[0].c_str();
     40     std::vector<char*> args;
     41     for (size_t i = 0; i < arg_vector.size(); ++i) {
     42         const std::string& arg = arg_vector[i];
     43         char* arg_str = const_cast<char*>(arg.c_str());
     44         CHECK(arg_str != nullptr) << i;
     45         args.push_back(arg_str);
     46     }
     47     args.push_back(nullptr);
     48 
     49     // Fork and exec.
     50     pid_t pid = fork();
     51     if (pid == 0) {
     52         // No allocation allowed between fork and exec.
     53 
     54         // Change process groups, so we don't get reaped by ProcessManager.
     55         setpgid(0, 0);
     56 
     57         execv(program, &args[0]);
     58 
     59         PLOG(ERROR) << "Failed to execv(" << command_line << ")";
     60         // _exit to avoid atexit handlers in child.
     61         _exit(1);
     62     } else {
     63         if (pid == -1) {
     64             *error_msg = StringPrintf("Failed to execv(%s) because fork failed: %s",
     65                     command_line.c_str(), strerror(errno));
     66             return false;
     67         }
     68 
     69         // wait for subprocess to finish
     70         int status;
     71         pid_t got_pid = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0));
     72         if (got_pid != pid) {
     73             *error_msg = StringPrintf("Failed after fork for execv(%s) because waitpid failed: "
     74                     "wanted %d, got %d: %s",
     75                     command_line.c_str(), pid, got_pid, strerror(errno));
     76             return false;
     77         }
     78         if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
     79             *error_msg = StringPrintf("Failed execv(%s) because non-0 exit status",
     80                     command_line.c_str());
     81             return false;
     82         }
     83     }
     84     return true;
     85 }
     86 
     87 }  // namespace installd
     88 }  // namespace android
     89