David Sehr | 97c381e | 2017-02-01 15:09:58 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2011 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 "exec_utils.h" |
| 18 | |
| 19 | #include <sys/types.h> |
| 20 | #include <sys/wait.h> |
| 21 | #include <string> |
| 22 | #include <vector> |
| 23 | |
| 24 | #include "android-base/stringprintf.h" |
| 25 | #include "android-base/strings.h" |
| 26 | |
| 27 | #include "runtime.h" |
| 28 | |
| 29 | namespace art { |
| 30 | |
David Sehr | 97c381e | 2017-02-01 15:09:58 -0800 | [diff] [blame] | 31 | using android::base::StringPrintf; |
| 32 | |
Orion Hodson | dd732cc | 2021-01-15 16:31:30 +0000 | [diff] [blame] | 33 | namespace { |
David Sehr | 97c381e | 2017-02-01 15:09:58 -0800 | [diff] [blame] | 34 | |
Orion Hodson | dd732cc | 2021-01-15 16:31:30 +0000 | [diff] [blame] | 35 | std::string ToCommandLine(const std::vector<std::string>& args) { |
| 36 | return android::base::Join(args, ' '); |
| 37 | } |
| 38 | |
| 39 | // Fork and execute a command specified in a subprocess. |
| 40 | // If there is a runtime (Runtime::Current != nullptr) then the subprocess is created with the |
| 41 | // same environment that existed when the runtime was started. |
| 42 | // Returns the process id of the child process on success, -1 otherwise. |
| 43 | pid_t ExecWithoutWait(std::vector<std::string>& arg_vector) { |
David Sehr | 97c381e | 2017-02-01 15:09:58 -0800 | [diff] [blame] | 44 | // Convert the args to char pointers. |
| 45 | const char* program = arg_vector[0].c_str(); |
| 46 | std::vector<char*> args; |
Orion Hodson | dd732cc | 2021-01-15 16:31:30 +0000 | [diff] [blame] | 47 | for (const auto& arg : arg_vector) { |
| 48 | args.push_back(const_cast<char*>(arg.c_str())); |
David Sehr | 97c381e | 2017-02-01 15:09:58 -0800 | [diff] [blame] | 49 | } |
| 50 | args.push_back(nullptr); |
| 51 | |
| 52 | // fork and exec |
| 53 | pid_t pid = fork(); |
| 54 | if (pid == 0) { |
| 55 | // no allocation allowed between fork and exec |
| 56 | |
| 57 | // change process groups, so we don't get reaped by ProcessManager |
| 58 | setpgid(0, 0); |
| 59 | |
| 60 | // (b/30160149): protect subprocesses from modifications to LD_LIBRARY_PATH, etc. |
| 61 | // Use the snapshot of the environment from the time the runtime was created. |
| 62 | char** envp = (Runtime::Current() == nullptr) ? nullptr : Runtime::Current()->GetEnvSnapshot(); |
| 63 | if (envp == nullptr) { |
| 64 | execv(program, &args[0]); |
| 65 | } else { |
| 66 | execve(program, &args[0], envp); |
| 67 | } |
Orion Hodson | dd732cc | 2021-01-15 16:31:30 +0000 | [diff] [blame] | 68 | PLOG(ERROR) << "Failed to execve(" << ToCommandLine(arg_vector) << ")"; |
David Sehr | 97c381e | 2017-02-01 15:09:58 -0800 | [diff] [blame] | 69 | // _exit to avoid atexit handlers in child. |
| 70 | _exit(1); |
| 71 | } else { |
Orion Hodson | dd732cc | 2021-01-15 16:31:30 +0000 | [diff] [blame] | 72 | return pid; |
David Sehr | 97c381e | 2017-02-01 15:09:58 -0800 | [diff] [blame] | 73 | } |
| 74 | } |
| 75 | |
Orion Hodson | dd732cc | 2021-01-15 16:31:30 +0000 | [diff] [blame] | 76 | } // namespace |
| 77 | |
| 78 | int ExecAndReturnCode(std::vector<std::string>& arg_vector, std::string* error_msg) { |
| 79 | pid_t pid = ExecWithoutWait(arg_vector); |
| 80 | if (pid == -1) { |
| 81 | *error_msg = StringPrintf("Failed to execv(%s) because fork failed: %s", |
| 82 | ToCommandLine(arg_vector).c_str(), strerror(errno)); |
| 83 | return -1; |
| 84 | } |
| 85 | |
| 86 | // wait for subprocess to finish |
| 87 | int status = -1; |
| 88 | pid_t got_pid = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0)); |
| 89 | if (got_pid != pid) { |
| 90 | *error_msg = StringPrintf("Failed after fork for execv(%s) because waitpid failed: " |
| 91 | "wanted %d, got %d: %s", |
| 92 | ToCommandLine(arg_vector).c_str(), pid, got_pid, strerror(errno)); |
| 93 | return -1; |
| 94 | } |
| 95 | if (WIFEXITED(status)) { |
| 96 | return WEXITSTATUS(status); |
| 97 | } |
| 98 | return -1; |
| 99 | } |
| 100 | |
| 101 | int ExecAndReturnCode(std::vector<std::string>& arg_vector, |
| 102 | time_t timeout_secs, |
| 103 | bool* timed_out, |
| 104 | std::string* error_msg) { |
| 105 | *timed_out = false; |
| 106 | |
| 107 | // Start subprocess. |
| 108 | pid_t pid = ExecWithoutWait(arg_vector); |
| 109 | if (pid == -1) { |
| 110 | *error_msg = StringPrintf("Failed to execv(%s) because fork failed: %s", |
| 111 | ToCommandLine(arg_vector).c_str(), strerror(errno)); |
| 112 | return -1; |
| 113 | } |
| 114 | |
| 115 | // Add SIGCHLD to the signal set. |
| 116 | sigset_t child_mask, original_mask; |
| 117 | sigemptyset(&child_mask); |
| 118 | sigaddset(&child_mask, SIGCHLD); |
| 119 | if (sigprocmask(SIG_BLOCK, &child_mask, &original_mask) == -1) { |
| 120 | *error_msg = StringPrintf("Failed to set sigprocmask(): %s", strerror(errno)); |
| 121 | return -1; |
| 122 | } |
| 123 | |
| 124 | // Wait for a SIGCHLD notification. |
| 125 | errno = 0; |
| 126 | timespec ts = {timeout_secs, 0}; |
| 127 | int wait_result = TEMP_FAILURE_RETRY(sigtimedwait(&child_mask, nullptr, &ts)); |
| 128 | int wait_errno = errno; |
| 129 | |
| 130 | // Restore the original signal set. |
| 131 | if (sigprocmask(SIG_SETMASK, &original_mask, nullptr) == -1) { |
| 132 | *error_msg = StringPrintf("Fail to restore sigprocmask(): %s", strerror(errno)); |
| 133 | if (wait_result == 0) { |
| 134 | return -1; |
| 135 | } |
| 136 | } |
| 137 | |
| 138 | // Having restored the signal set, see if we need to terminate the subprocess. |
| 139 | if (wait_result == -1) { |
| 140 | if (wait_errno == EAGAIN) { |
| 141 | *error_msg = "Timed out."; |
| 142 | *timed_out = true; |
| 143 | } else { |
| 144 | *error_msg = StringPrintf("Failed to sigtimedwait(): %s", strerror(errno)); |
| 145 | } |
| 146 | if (kill(pid, SIGKILL) != 0) { |
| 147 | PLOG(ERROR) << "Failed to kill() subprocess: "; |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | // Wait for subprocess to finish. |
| 152 | int status = -1; |
| 153 | pid_t got_pid = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0)); |
| 154 | if (got_pid != pid) { |
| 155 | *error_msg = StringPrintf("Failed after fork for execv(%s) because waitpid failed: " |
| 156 | "wanted %d, got %d: %s", |
| 157 | ToCommandLine(arg_vector).c_str(), pid, got_pid, strerror(errno)); |
| 158 | return -1; |
| 159 | } |
| 160 | if (WIFEXITED(status)) { |
| 161 | return WEXITSTATUS(status); |
| 162 | } |
| 163 | return -1; |
| 164 | } |
| 165 | |
| 166 | |
David Sehr | 97c381e | 2017-02-01 15:09:58 -0800 | [diff] [blame] | 167 | bool Exec(std::vector<std::string>& arg_vector, std::string* error_msg) { |
| 168 | int status = ExecAndReturnCode(arg_vector, error_msg); |
| 169 | if (status != 0) { |
David Sehr | 97c381e | 2017-02-01 15:09:58 -0800 | [diff] [blame] | 170 | *error_msg = StringPrintf("Failed execv(%s) because non-0 exit status", |
Orion Hodson | dd732cc | 2021-01-15 16:31:30 +0000 | [diff] [blame] | 171 | ToCommandLine(arg_vector).c_str()); |
David Sehr | 97c381e | 2017-02-01 15:09:58 -0800 | [diff] [blame] | 172 | return false; |
| 173 | } |
| 174 | return true; |
| 175 | } |
| 176 | |
| 177 | } // namespace art |