Clean up process spawning.

runtime/bin/process_macos.cc

Index: runtime/bin/process_macos.cc
diff --git a/runtime/bin/process_macos.cc b/runtime/bin/process_macos.cc
index 7ef89b1b3a91c0b97d23dcf4e698c605048183ae..f97737690bf65327cf197f68148d5d4aff64e5ef 100644
--- a/runtime/bin/process_macos.cc
+++ b/runtime/bin/process_macos.cc
@@ -25,7 +25,6 @@
 #include "platform/signal_blocker.h"
 
 
-
 namespace dart {
 namespace bin {
 
@@ -153,7 +152,7 @@ class ExitCodeHandler {
 
     // Fork to wake up waitpid.
     if (TEMP_FAILURE_RETRY(fork()) == 0) {
-      exit(0);
+      _exit(0);
     }
 
     monitor_->Notify();
@@ -421,7 +420,7 @@ class ProcessStarter {
     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();
@@ -450,15 +449,14 @@ class ProcessStarter {
     }
 
     if (program_environment_ != NULL) {
-      // On MacOS you have to do a bit of magic to get to the
-      // environment strings.
-      char*** environ = _NSGetEnviron();
-      *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();
   }
 
@@ -510,13 +508,13 @@ class ProcessStarter {
               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);
     }
   }
 
@@ -548,7 +546,7 @@ class ProcessStarter {
         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;
@@ -572,7 +570,7 @@ class ProcessStarter {
     } 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;
@@ -662,21 +660,12 @@ class ProcessStarter {
 
 
   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 os_error_message[kBufferSize];
-    strerror_r(errno, os_error_message, 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);
   }
 
 
@@ -690,16 +679,16 @@ class ProcessStarter {
   }
 
 
-  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);
     }
   }