Resolve the executable path on Mac OS when sym-linked

runtime/bin/platform_macos.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_MACOS)
 
 #include <mach-o/dyld.h>
 
+#include "bin/file.h"
 #include "bin/platform.h"
 
 #include <crt_externs.h>  // NOLINT
 #include <signal.h>  // NOLINT
 #include <string.h>  // NOLINT
 #include <unistd.h>  // NOLINT
 
 #include "bin/fdutils.h"
 
 
@@ skipping 64 matching lines @@
   char* path = NULL;
   if (_NSGetExecutablePath(path, &path_size) == 0) {
     return NULL;
   }
   // Allocate buffer and get executable path.
   path = reinterpret_cast<char*>(malloc(path_size));
   if (_NSGetExecutablePath(path, &path_size) != 0) {
     free(path);
     return NULL;
   }
+  // If the path is a symbolic link resolve that link.
+  File::Type type = File::GetType(path, false);
+  if (type == File::kIsLink) {
+    char* target_path = File::LinkTarget(path);
+    free(path);
+    return target_path;
+  }
+  // If the directory of the executable is a symbolic link resolve that link.
+  char* last_slash = strrchr(path, '/');
+  if (last_slash != NULL && last_slash != path) {
+    // Split off the last slash and the executable.
+    *last_slash = '\0';
+    File::Type type = File::GetType(path, false);
+    if (type == File::kIsLink) {
+      // Resolve the directory and append the executable.
+      char* target_path = File::LinkTarget(path);
+      *last_slash = '/';
+      size_t new_path_len = strlen(target_path) + strlen(last_slash) + 1;
+      char* new_path = reinterpret_cast<char*>(malloc(new_path_len));
+      snprintf(new_path, new_path_len, "%s%s", target_path, last_slash);
+      free(path);
+      free(target_path);
+      return new_path;
+    } else {
+      // Directory was not a symbolic link re-construct the path.
+      *last_slash = '/';
+    }

[kustermann, 2015/06/08 08:22:25]

So this only handles symlinks to the binary itself or it's directory (which is
bin), but not to the sdk directory?

Furthermore it doesn't seem to handle symlinks to symlinks to actual binaries if
I see this correctly.

Can't you just use the File::GetCanonicalPath() function defined in this file?
The manpage indicates that it will resolve all '.' '..' and symlinks.

[Søren Gjesse, 2015/06/09 10:46:48]

Thanks Martin. This was a really crappy attempt to partly implement realpath.

+  }
   return path;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)