Landing https://codereview.chromium.org/1171223003/ for Chinmay.

BUG=

Review URL: https://codereview.chromium.org//1174343006.

Author: iposva-google

runtime/bin/BUILD.gn

@@ -208,7 +208,7 @@ source_set("embedded_dart_io") {
     "builtin.cc",
     "builtin_gen_snapshot.cc",
   ]
-  if (!is_mac) {
+  if (!is_mac && !is_ios) {
     # Dart tree uses *_macos.* instead of *_mac.*
     custom_sources_filter += [
       "*_macos.h",

runtime/bin/file_system_watcher_macos.cc

@@ -7,6 +7,8 @@
 
 #include "bin/file_system_watcher.h"
 
+#if !defined(TARGET_OS_IOS)
+
 #include <errno.h>  // NOLINT
 #include <fcntl.h>  // NOLINT
 #include <unistd.h>  // NOLINT
@@ -392,4 +394,44 @@ Dart_Handle FileSystemWatcher::ReadEvents(intptr_t id, intptr_t path_id) {
 }  // namespace bin
 }  // namespace dart
 
+#else  // !defined(TARGET_OS_IOS)
+
+namespace dart {
+namespace bin {
+
+// FSEvents are unavailable on iOS. Stub out related methods
+Dart_Handle FileSystemWatcher::ReadEvents(intptr_t id, intptr_t path_id) {
+  return DartUtils::NewDartOSError();
+}
+
+intptr_t FileSystemWatcher::GetSocketId(intptr_t id, intptr_t path_id) {
+  return -1;
+}
+
+bool FileSystemWatcher::IsSupported() {
+  return false;
+}
+
+void FileSystemWatcher::UnwatchPath(intptr_t id, intptr_t path_id) {
+}
+
+intptr_t FileSystemWatcher::Init() {
+  return -1;
+}
+
+void FileSystemWatcher::Close(intptr_t id) {
+}
+
+intptr_t FileSystemWatcher::WatchPath(intptr_t id,
+                                      const char* path,
+                                      int events,
+                                      bool recursive) {
+  return -1;
+}
+
+}  // namespace bin
+}  // namespace dart
+
+#endif  // !defined(TARGET_OS_IOS)
+
 #endif  // defined(TARGET_OS_MACOS)

runtime/bin/platform_macos.cc

@@ -57,6 +57,16 @@ bool Platform::LocalHostname(char *buffer, intptr_t buffer_length) {
 
 
 char** Platform::Environment(intptr_t* count) {
+#if defined(TARGET_OS_IOS)
+  // TODO(iposva): On Mac (desktop), _NSGetEnviron() is used to access the
+  // environ from shared libraries or bundles. This is present in crt_externs.h
+  // which is unavailable on iOS. On iOS, everything is statically linked for
+  // now. So arguably, accessing the environ directly with a "extern char
+  // **environ" will work. But this approach is brittle as the target with this
+  // CU could be a dynamic framework (introduced in iOS 8). A more elegant
+  // approach needs to be devised.
+  return NULL;
+#else
   // Using environ directly is only safe as long as we do not
   // provide access to modifying environment variables.
   // On MacOS you have to do a bit of magic to get to the
@@ -71,6 +81,7 @@ char** Platform::Environment(intptr_t* count) {
     result[current] = environ[current];
   }
   return result;
+#endif
 }
 
 

runtime/bin/process_macos.cc

@@ -7,7 +7,9 @@
 
 #include "bin/process.h"
 
+#if !defined(TARGET_OS_IOS)
 #include <crt_externs.h>  // NOLINT
+#endif
 #include <errno.h>  // NOLINT
 #include <fcntl.h>  // NOLINT
 #include <poll.h>  // NOLINT
@@ -451,12 +453,14 @@ class ProcessStarter {
       ReportChildError();
     }
 
+#if !defined(TARGET_OS_IOS)
     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_;
     }
+#endif
 
     VOID_TEMP_FAILURE_RETRY(
         execvp(path_, const_cast<char* const*>(program_arguments_)));