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..8c0fc8cf15eb84cbb66f9b0abcce2d5b39f776e4
--- /dev/null
+++ b/chrome/app/chrome_exe_main_mac.c
@@ -0,0 +1,90 @@
+// Copyright (c) 2015 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).

[brettw, 2015/11/04 05:37:04]

Just to clarify, this file is a C-only file to avoid linking the C++ libraries
into the (small) binary? Can you mention that at the top of this file if so?

If instead this is a .c to save the extern statements, I would prefer to keep it
.cc so we can have more flexibility.

+
+#include <dlfcn.h>
+#include <errno.h>
+#include <libgen.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 rv = _NSGetExecutablePath(NULL, &exec_path_size);
+  if (rv != -1) {
+    fprintf(stderr,
+            "_NSGetExecutablePath: get [length|path] failed.\n");
+    abort();
+  }
+
+  char* exec_path = malloc(exec_path_size);
+  if (!exec_path) {
+    fprintf(stderr, "malloc %u: %s\n", exec_path_size, strerror(errno));
+    abort();
+  }
+
+  rv = _NSGetExecutablePath(exec_path, &exec_path_size);
+  if (rv != 0) {
+    fprintf(stderr,
+            "_NSGetExecutablePath(): get [%d|path] failed.\n", exec_path_size);
+    abort();
+  }
+
+  // Slice off the last part of the main executable path, and append the
+  // version framework information.
+  char* parent_dir = dirname(exec_path);
+  if (!parent_dir) {
+    fprintf(stderr, "dirname %s: %s\n", exec_path, strerror(errno));
+    abort();
+  }
+  free(exec_path);
+
+  size_t parent_path_len = strlen(parent_dir);
+  size_t rel_path_len = strlen(rel_path);
+  // 2 accounts for a trailing NUL byte and the '/' in the middle of the paths.
+  size_t framework_path_size = parent_path_len + rel_path_len + 2;
+  char* framework_path = malloc(framework_path_size);
+  if (!framework_path) {
+    fprintf(stderr, "malloc %zu: %s\n", framework_path_size, strerror(errno));
+    abort();
+  }
+  snprintf(framework_path, framework_path_size, "%s/%s", parent_dir, rel_path);
+
+  void* library = dlopen(framework_path, RTLD_LAZY | RTLD_LOCAL | RTLD_FIRST);
+  if (!library) {
+    fprintf(stderr, "dlopen %s: %s\n", framework_path, dlerror());
+    abort();
+  }
+  free(framework_path);
+
+  ChromeMainPtr chrome_main = dlsym(library, "ChromeMain");
+  if (!chrome_main) {
+    fprintf(stderr, "dlsym ChromeMain: %s\n", dlerror());
+    abort();
+  }
+  rv = chrome_main(argc, argv);
+
+  // exit, don't return from main, to avoid the apparent removal of main from
+  // stack backtraces under tail call optimization.
+  exit(rv);
+}