[fuchsia] Fix build. Build packages/ output. Add Directory::Exists().

runtime/bin/directory_fuchsia.cc

 // Copyright (c) 2016, 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_FUCHSIA)
 
 #include "bin/directory.h"
 
 #include <errno.h>  // NOLINT
 #include <stdlib.h>  // NOLINT
 #include <string.h>  // NOLINT
+#include <sys/stat.h>  // NOLINT
 #include <unistd.h>  // NOLINT
 
+#include "bin/dartutils.h"
+#include "bin/file.h"
+#include "bin/platform.h"
+#include "platform/signal_blocker.h"
+
 namespace dart {
 namespace bin {
 
 PathBuffer::PathBuffer() : length_(0) {
   data_ = calloc(PATH_MAX + 1, sizeof(char));  // NOLINT
 }
 
 
 PathBuffer::~PathBuffer() {
   free(data_);
@@ skipping 62 matching lines @@
   UNIMPLEMENTED();
 }
 
 
 void DirectoryListingEntry::ResetLink() {
   UNIMPLEMENTED();
 }
 
 
 Directory::ExistsResult Directory::Exists(const char* dir_name) {
-  UNIMPLEMENTED();
-  return UNKNOWN;
+  struct stat entry_info;
+  int success = NO_RETRY_EXPECTED(stat(dir_name, &entry_info));
+  if (success == 0) {
+    if (S_ISDIR(entry_info.st_mode)) {
+      return EXISTS;
+    } else {
+      return DOES_NOT_EXIST;
+    }
+  } else {
+    if ((errno == EACCES) ||
+        (errno == EBADF) ||
+        (errno == EFAULT) ||
+        (errno == ENOMEM) ||
+        (errno == EOVERFLOW)) {
+      // Search permissions denied for one of the directories in the
+      // path or a low level error occured. We do not know if the
+      // directory exists.
+      return UNKNOWN;
+    }
+    ASSERT((errno == ELOOP) ||
+           (errno == ENAMETOOLONG) ||
+           (errno == ENOENT) ||
+           (errno == ENOTDIR));
+    return DOES_NOT_EXIST;
+  }
 }
 
 
 char* Directory::CurrentNoScope() {
   return getcwd(NULL, 0);
 }
 
 
 const char* Directory::Current() {
   char buffer[PATH_MAX];
@@ skipping 36 matching lines @@
 
 bool Directory::Rename(const char* path, const char* new_path) {
   UNIMPLEMENTED();
   return false;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_LINUX)