Switch Chrome to dlopen() the Google Chrome Framework.framework.

chrome/app/chrome_exe_main_mac.c

Index: chrome/app/chrome_exe_main_mac.c
diff --git a/chrome/app/chrome_exe_main_mac.c b/chrome/app/chrome_exe_main_mac.c
new file mode 100644
index 0000000000000000000000000000000000000000..93eee9f1ba2abb49f592b7e4deade4c19af79234
--- /dev/null
+++ b/chrome/app/chrome_exe_main_mac.c
@@ -0,0 +1,95 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// The entry point for all Mac Chromium processes, including the outer app
+// bundle (browser) and helper app (renderer, plugin, and friends).
+
+#include <dlfcn.h>
+#include <mach-o/dyld.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "chrome/common/chrome_version.h"
+
+typedef int (*ChromeMainPtr)(int, char**);
+
+__attribute__((visibility("default"))) int main(int argc, char* argv[]) {
+#if defined(HELPER_EXECUTABLE)
+  const char* const rel_path =
+      "../../../" PRODUCT_FULLNAME_STRING
+      " Framework.framework/" PRODUCT_FULLNAME_STRING " Framework";
+#else
+  const char* const rel_path =
+      "../Versions/" CHROME_VERSION_STRING "/" PRODUCT_FULLNAME_STRING
+      " Framework.framework/" PRODUCT_FULLNAME_STRING " Framework";
+#endif  // defined(HELPER_EXECUTABLE)
+
+  uint32_t exec_path_size = 0;
+  int rc = _NSGetExecutablePath(NULL, &exec_path_size);
+  if (rc != -1) {
+    fprintf(stderr,
+            "Unexpected return condition from _NSGetExecutablePath().\n");
+    abort();
+  }
+
+  char* exec_path = malloc(exec_path_size);

[Mark Mentovai, 2015/10/22 23:15:11]

fprintf(stderr, "malloc %zu: %s\n", framework_path_size, strerror(errno));

[Greg K, 2015/10/23 19:12:49]

Done.

+  if (!exec_path) {
+    fprintf(stderr, "Failed to allocate memory.\n");
+    abort();
+  }
+
+  rc = _NSGetExecutablePath(exec_path, &exec_path_size);
+  if (rc != 0) {
+    fprintf(stderr,
+            "_NSGetExecutablePath() call failed, "
+            "cannot calculate framework path.\n");
+    abort();
+  }
+
+  // Slice off the last part of the main executable path, and append the
+  // version framework information.
+  char* last_slash = strrchr(exec_path, '/');

[Mark Mentovai, 2015/10/22 23:15:11]

Hmm, this will be messed-up with valid but stupid paths like “Google
Chrome.app/Contents/MacOS/////Google Chrome”. You can #include <libgen.h> and
use dirname() instead. Then you can free() the executable path. dirname()
doesn’t give you a trailing /, but you can deal with that later.

[Greg K, 2015/10/23 19:12:48]

Done.

+  if (last_slash) {
+    *(last_slash + 1) = '\0';
+  } else {
+    fprintf(stderr, "Unexpected executable path.\n");
+    abort();
+  }
+
+  size_t exec_path_len = strlen(exec_path);
+  size_t rel_path_len = strlen(rel_path);
+  size_t framework_path_size = exec_path_len + rel_path_len + 1;
+  char* framework_path = malloc(framework_path_size);
+  if (!framework_path) {
+    fprintf(stderr, "Failed to allocate memory.\n");
+    abort();
+  }
+
+  memcpy(framework_path, exec_path, exec_path_len);
+  memcpy(framework_path + exec_path_len, rel_path, rel_path_len);
+  framework_path[exec_path_len + rel_path_len] = '\0';

[Mark Mentovai, 2015/10/22 23:15:12]

snprintf(framework_path, framework_path_size, "%s/%s", exec_path, rel_path);

[Greg K, 2015/10/23 19:12:49]

Done.

+
+  void* library = dlopen(framework_path, RTLD_LAZY);

[Mark Mentovai, 2015/10/22 23:15:11]

| RTLD_LOCAL | RTLD_FIRST

[Greg K, 2015/10/23 19:12:48]

Done.

+  if (!library) {
+    fprintf(stderr, "Unable to dlopen() the framework.\n");

[Mark Mentovai, 2015/10/22 23:15:11]

Say the framework name dlerror(). Something like

  fprintf(stderr, "dlopen %s: %s\n", framework_path, dlerror());

for brevity

[Greg K, 2015/10/23 19:12:48]

Done.

+    abort();
+  }

[Mark Mentovai, 2015/10/22 23:15:11]

free() framework_path now.

[Greg K, 2015/10/23 19:12:48]

Done.

+
+  ChromeMainPtr ChromeMain = dlsym(library, "ChromeMain");

[Mark Mentovai, 2015/10/22 23:15:11]

It’s still a variable, call it chrome_main

[Greg K, 2015/10/23 19:12:48]

Done.

+  if (!ChromeMain) {
+    fprintf(stderr, "Could not resolve the ChromeMain symbol.\n");

[Mark Mentovai, 2015/10/22 23:15:11]

Similarly, fprintf(stderr, "dlopen ChromeMain: %s\n", dlerror());

[Greg K, 2015/10/23 19:12:49]

Done.

+    abort();
+  }
+  int rv = ChromeMain(argc, argv);
+
+  // Free all resources here.

[Mark Mentovai, 2015/10/22 23:15:11]

Technically the library handle is a freeable resource too, but you shouldn’t
bother freeing it. But you’ll have moved any frees up above, so this will go
away.

[Greg K, 2015/10/23 19:12:48]

Done.

+  free(exec_path);
+  free(framework_path);
+
+  // exit, don't return from main, to avoid the apparent removal of main from
+  // stack backtraces under tail call optimization.
+  exit(rv);
+}