Clean up process spawning.

runtime/bin/process_linux.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_LINUX)
 
 #include "bin/process.h"
 
 #include <errno.h>  // NOLINT
 #include <fcntl.h>  // NOLINT
 #include <poll.h>  // NOLINT
 #include <stdio.h>  // NOLINT
 #include <stdlib.h>  // NOLINT
 #include <string.h>  // NOLINT
 #include <sys/wait.h>  // NOLINT
 #include <unistd.h>  // NOLINT
 
 #include "platform/signal_blocker.h"
 #include "bin/fdutils.h"
 #include "bin/lockers.h"
 #include "bin/log.h"
 #include "bin/thread.h"
 
 
-extern char **environ;
-
-
 namespace dart {
 namespace bin {
 
 // ProcessInfo is used to map a process id to the file descriptor for
 // the pipe used to communicate the exit code of the process to Dart.
 // ProcessInfo objects are kept in the static singly-linked
 // ProcessInfoList.
 class ProcessInfo {
  public:
   ProcessInfo(pid_t pid, intptr_t fd) : pid_(pid), fd_(fd) { }
@@ skipping 107 matching lines @@
     if (!running_) {
       return;
     }
 
     // Set terminate_done_ to false, so we can use it as a guard for our
     // monitor.
     running_ = false;
 
     // Fork to wake up waitpid.
     if (TEMP_FAILURE_RETRY(fork()) == 0) {
-      exit(0);
+      _exit(0);
     }
 
     monitor_->Notify();
 
     while (!terminate_done_) {
       monitor_->Wait(Monitor::kNoTimeout);
     }
   }
 
  private:
@@ skipping 239 matching lines @@
     return 0;
   }
 
 
   void NewProcess() {
     // Wait for parent process before setting up the child process.
     char msg;
     int bytes_read = FDUtils::ReadFromBlocking(read_in_[0], &msg, sizeof(msg));
     if (bytes_read != sizeof(msg)) {
       perror("Failed receiving notification message");
-      exit(1);
+      _exit(1);
     }
     if (mode_ == kNormal) {
       ExecProcess();
     } else {
       ExecDetachedProcess();
     }
   }
 
 
   void ExecProcess() {
     if (TEMP_FAILURE_RETRY(dup2(write_out_[0], STDIN_FILENO)) == -1) {
       ReportChildError();
     }
 
     if (TEMP_FAILURE_RETRY(dup2(read_in_[1], STDOUT_FILENO)) == -1) {
       ReportChildError();
     }
 
     if (TEMP_FAILURE_RETRY(dup2(read_err_[1], STDERR_FILENO)) == -1) {
       ReportChildError();
     }
 
     if (working_directory_ != NULL &&
         TEMP_FAILURE_RETRY(chdir(working_directory_)) == -1) {
       ReportChildError();
     }
 
     if (program_environment_ != NULL) {
-      environ = program_environment_;
+      VOID_TEMP_FAILURE_RETRY(
+          execvpe(path_, const_cast<char* const*>(program_arguments_),
+                  program_environment_));
+    } else {
+      VOID_TEMP_FAILURE_RETRY(
+          execvp(path_, const_cast<char* const*>(program_arguments_)));
     }
 
-    VOID_TEMP_FAILURE_RETRY(
-        execvp(path_, const_cast<char* const*>(program_arguments_)));
-
     ReportChildError();
   }
 
 
   void ExecDetachedProcess() {
     if (mode_ == kDetached) {
       ASSERT(write_out_[0] == -1);
       ASSERT(write_out_[1] == -1);
       ASSERT(read_err_[0] == -1);
       ASSERT(read_err_[1] == -1);
@@ skipping 31 matching lines @@
               TEMP_FAILURE_RETRY(chdir(working_directory_)) == -1) {
             ReportChildError();
           }
 
           // Report the final PID and do the exec.
           ReportPid(getpid());  // getpid cannot fail.
           VOID_TEMP_FAILURE_RETRY(
               execvp(path_, const_cast<char* const*>(program_arguments_)));
           ReportChildError();
         } else {
-          // Exit the intermeiate process.
-          exit(0);
+          // Exit the intermediate process.
+          _exit(0);
         }
       }
     } else {
-      // Exit the intermeiate process.
-      exit(0);
+      // Exit the intermediate process.
+      _exit(0);
     }
   }
 
 
   int RegisterProcess(pid_t pid) {
     int result;
     int event_fds[2];
     result = TEMP_FAILURE_RETRY(pipe2(event_fds, O_CLOEXEC));
     if (result < 0) {
       return CleanupAndReturnError();
     }
 
     ProcessInfoList::AddProcess(pid, event_fds[1]);
     *exit_event_ = event_fds[0];
     FDUtils::SetNonBlocking(event_fds[0]);
     return 0;
   }
 
 
   int ReadExecResult() {
     int child_errno;
     int bytes_read = -1;
     // Read exec result from child. If no data is returned the exec was
     // successful and the exec call closed the pipe. Otherwise the errno
     // is written to the pipe.
     bytes_read =
         FDUtils::ReadFromBlocking(
             exec_control_[0], &child_errno, sizeof(child_errno));
     if (bytes_read == sizeof(child_errno)) {
-      ReadChildError();
+      SetOSErrorMessage(child_errno);
       return child_errno;
     } else if (bytes_read == -1) {
       return errno;
     }
     return 0;
   }
 
 
   int ReadDetachedExecResult(pid_t *pid) {
     int child_errno;
     int bytes_read = -1;
     // Read exec result from child. If only pid data is returned the exec was
     // successful and the exec call closed the pipe. Otherwise the errno
     // is written to the pipe as well.
     int result[2];
     bytes_read =
         FDUtils::ReadFromBlocking(
             exec_control_[0], result, sizeof(result));
     if (bytes_read == sizeof(int)) {
       *pid = result[0];
     } else if (bytes_read == 2 * sizeof(int)) {
       *pid = result[0];
       child_errno = result[1];
-      ReadChildError();
+      SetOSErrorMessage(child_errno);
       return child_errno;
     } else if (bytes_read == -1) {
       return errno;
     }
     return 0;
   }
 
 
   void SetupDetached() {
     ASSERT(mode_ == kDetached);
@@ skipping 68 matching lines @@
 
 
   void SetChildOsErrorMessage() {
     const int kBufferSize = 1024;
     char error_buf[kBufferSize];
     *os_error_message_ = strdup(strerror_r(errno, error_buf, kBufferSize));
   }
 
 
   void ReportChildError() {
-    // In the case of failure in the child process write the errno and
-    // the OS error message to the exec control pipe and exit.
+    // In the case of failure in the child process write the errno to the exec
+    // control pipe and exit.
     int child_errno = errno;
-    const int kBufferSize = 1024;
-    char error_buf[kBufferSize];
-    char* os_error_message = strerror_r(errno, error_buf, kBufferSize);
-    int bytes_written =
-        FDUtils::WriteToBlocking(
-            exec_control_[1], &child_errno, sizeof(child_errno));
-    if (bytes_written == sizeof(child_errno)) {
-      FDUtils::WriteToBlocking(
-          exec_control_[1], os_error_message, strlen(os_error_message) + 1);
-    }
-    VOID_TEMP_FAILURE_RETRY(close(exec_control_[1]));
-    exit(1);
+    FDUtils::WriteToBlocking(
+        exec_control_[1], &child_errno, sizeof(child_errno));
+    _exit(1);
   }
 
 
   void ReportPid(int pid) {
     // In the case of starting a detached process the actual pid of that process
     // is communicated using the exec control pipe.
     int bytes_written =
         FDUtils::WriteToBlocking(exec_control_[1], &pid, sizeof(pid));
     ASSERT(bytes_written == sizeof(int));
     USE(bytes_written);
   }
 
 
-  void ReadChildError() {
+  void SetOSErrorMessage(int child_errno) {
     const int kMaxMessageSize = 256;
-    char* message = static_cast<char*>(malloc(kMaxMessageSize));
-    if (message != NULL) {
-      FDUtils::ReadFromBlocking(exec_control_[0], message, kMaxMessageSize);
-      message[kMaxMessageSize - 1] = '\0';
+    char* message = static_cast<char*>(calloc(kMaxMessageSize, 0));
+    char* os_error_message = strerror_r(
+        child_errno, message, kMaxMessageSize - 1);
+    if (message == os_error_message) {
       *os_error_message_ = message;
     } else {
-      // Could not get error message. It will be NULL.
-      ASSERT(*os_error_message_ == NULL);
+      free(message);
+      *os_error_message_ = strdup(os_error_message);
     }
   }
 
 
   void ClosePipe(int* fds) {
     for (int i = 0; i < 2; i++) {
       if (fds[i] != -1) {
         VOID_TEMP_FAILURE_RETRY(close(fds[i]));
         fds[i] = -1;
       }
@@ skipping 294 matching lines @@
     bzero(&act, sizeof(act));
     act.sa_handler = SIG_DFL;
     sigaction(signal, &act, NULL);
   }
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_LINUX)