Support passing an environment variable map to child processes.

runtime/bin/process.cc

Index: runtime/bin/process.cc
diff --git a/runtime/bin/process.cc b/runtime/bin/process.cc
index c7a0aec49cc4e209dc76904775e51cde4b20ed3c..e33ea613d9c6b99d669f7bf5fe4b1f173db54938 100644
--- a/runtime/bin/process.cc
+++ b/runtime/bin/process.cc
@@ -7,6 +7,37 @@
 
 #include "include/dart_api.h"
 
+// Extract an array of C strings from a list of Dart strings.
+static char** ExtractCStringList(Dart_Handle strings,
+                                 Dart_Handle status_handle,
+                                 const char* error_msg,
+                                 intptr_t* length) {
+  ASSERT(Dart_IsList(strings));
+  intptr_t len = 0;
+  Dart_Handle result = Dart_ListLength(strings, &len);
+  if (Dart_IsError(result)) {
+    Dart_PropagateError(result);
+  }
+  *length = len;
+  char** string_args = new char*[len];
+  for (int i = 0; i < len; i++) {
+    Dart_Handle arg = Dart_ListGetAt(strings, i);
+    if (Dart_IsError(arg)) {
+      delete[] string_args;
+      Dart_PropagateError(arg);
+    }
+    if (!Dart_IsString(arg)) {
+      DartUtils::SetIntegerField(status_handle, "_errorCode", 0);
+      DartUtils::SetStringField(
+          status_handle, "_errorMessage", error_msg);
+      delete[] string_args;
+      return NULL;
+    }
+    string_args[i] = const_cast<char *>(DartUtils::GetStringValue(arg));
+  }
+  return string_args;
+}
+
 void FUNCTION_NAME(Process_Start)(Dart_NativeArguments args) {
   Dart_EnterScope();
   Dart_Handle process =  Dart_GetNativeArgument(args, 0);
@@ -14,7 +45,7 @@ void FUNCTION_NAME(Process_Start)(Dart_NativeArguments args) {
   intptr_t out;
   intptr_t err;
   intptr_t exit_event;
-  Dart_Handle status_handle = Dart_GetNativeArgument(args, 8);
+  Dart_Handle status_handle = Dart_GetNativeArgument(args, 9);
   Dart_Handle path_handle = Dart_GetNativeArgument(args, 1);
   // The Dart code verifies that the path implements the String
   // interface. However, only builtin Strings are handled by
@@ -29,34 +60,16 @@ void FUNCTION_NAME(Process_Start)(Dart_NativeArguments args) {
   }
   const char* path = DartUtils::GetStringValue(path_handle);
   Dart_Handle arguments = Dart_GetNativeArgument(args, 2);
-  // The arguments are copied into a non-extensible array in the
-  // dart code so this should not fail.
-  ASSERT(Dart_IsList(arguments));
-  intptr_t length = 0;
-  Dart_Handle result = Dart_ListLength(arguments, &length);
-  if (Dart_IsError(result)) {
-    Dart_PropagateError(result);
-  }
-  char** string_args = new char*[length];
-  for (int i = 0; i < length; i++) {
-    Dart_Handle arg = Dart_ListGetAt(arguments, i);
-    if (Dart_IsError(arg)) {
-      delete[] string_args;
-      Dart_PropagateError(arg);
-    }
-    // The Dart code verifies that the arguments implement the String
-    // interface. However, only builtin Strings are handled by
-    // GetStringValue.
-    if (!Dart_IsString(arg)) {
-      DartUtils::SetIntegerField(status_handle, "_errorCode", 0);
-      DartUtils::SetStringField(
-          status_handle, "_errorMessage", "Arguments must be builtin strings");
-      delete[] string_args;
-      Dart_SetReturnValue(args, Dart_NewBoolean(false));
-      Dart_ExitScope();
-      return;
-    }
-    string_args[i] = const_cast<char *>(DartUtils::GetStringValue(arg));
+  intptr_t args_length = 0;
+  char** string_args =
+      ExtractCStringList(arguments,
+                         status_handle,
+                         "Arguments must be builtin strings",
+                         &args_length);
+  if (string_args == NULL) {
+    Dart_SetReturnValue(args, Dart_NewBoolean(false));
+    Dart_ExitScope();
+    return;
   }
   Dart_Handle working_directory_handle = Dart_GetNativeArgument(args, 3);
   // Defaults to the current working directoy.
@@ -73,18 +86,35 @@ void FUNCTION_NAME(Process_Start)(Dart_NativeArguments args) {
     Dart_ExitScope();
     return;
   }
-  Dart_Handle in_handle = Dart_GetNativeArgument(args, 4);
-  Dart_Handle out_handle = Dart_GetNativeArgument(args, 5);
-  Dart_Handle err_handle = Dart_GetNativeArgument(args, 6);
-  Dart_Handle exit_handle = Dart_GetNativeArgument(args, 7);
+  Dart_Handle environment = Dart_GetNativeArgument(args, 4);
+  intptr_t environment_length = 0;
+  char** string_environment = NULL;
+  if (!Dart_IsNull(environment)) {
+    string_environment =
+        ExtractCStringList(environment,
+                           status_handle,
+                           "Environment values must be builtin strings",
+                           &environment_length);
+    if (string_environment == NULL) {
+      Dart_SetReturnValue(args, Dart_NewBoolean(false));
+      Dart_ExitScope();
+      return;
+    }
+  }
+  Dart_Handle in_handle = Dart_GetNativeArgument(args, 5);
+  Dart_Handle out_handle = Dart_GetNativeArgument(args, 6);
+  Dart_Handle err_handle = Dart_GetNativeArgument(args, 7);
+  Dart_Handle exit_handle = Dart_GetNativeArgument(args, 8);
   intptr_t pid = -1;
   static const int kMaxChildOsErrorMessageLength = 256;
   char os_error_message[kMaxChildOsErrorMessageLength];
 
   int error_code = Process::Start(path,
                                   string_args,
-                                  length,
+                                  args_length,
                                   working_directory,
+                                  string_environment,
+                                  environment_length,
                                   &in,
                                   &out,
                                   &err,
@@ -107,6 +137,7 @@ void FUNCTION_NAME(Process_Start)(Dart_NativeArguments args) {
         status_handle, "_errorMessage", os_error_message);
   }
   delete[] string_args;
+  delete[] string_environment;
   Dart_SetReturnValue(args, Dart_NewBoolean(error_code == 0));
   Dart_ExitScope();
 }