Set up a interposing library for Carbon calls made by plugins.

chrome/plugin/plugin_main.cc

Index: chrome/plugin/plugin_main.cc
diff --git a/chrome/plugin/plugin_main.cc b/chrome/plugin/plugin_main.cc
index 63d295d15d0bf794005c8acc3563034f542f910e..afc83a5145e75388f6cdeaff785447b6db157641 100644
--- a/chrome/plugin/plugin_main.cc
+++ b/chrome/plugin/plugin_main.cc
@@ -25,8 +25,45 @@
 #elif defined(OS_LINUX)
 #include "base/global_descriptors_posix.h"
 #include "ipc/ipc_descriptors.h"
+#elif defined(OS_MACOSX)
+#include "chrome/common/plugin_carbon_interpose_constants_mac.h"
 #endif
 
+#if defined(OS_MACOSX)
+// Removes our Carbon library interposing from the environment so that it
+// doesn't carry into any processes that plugins might start.
+static void TrimInterposeEnvironment() {
+  const char* interpose_list =
+      getenv(plugin_interpose_strings::kDYLDInsertLibrariesKey);
+  if (!interpose_list) {
+    NOTREACHED() << "No interposing libraries set";
+    return;
+  }
+
+  // The list is a :-separated list of paths. Because we append our interpose
+  // library just before forking in plugin_process_host.cc, the only cases we
+  // need to handle are:
+  // 1) The whole string is "<kInterposeLibraryPath>", so just clear it, or
+  // 2) ":<kInterposeLibraryPath>" is the end of the string, so trim and re-set.
+  int suffix_offset = strlen(interpose_list) -
+      strlen(plugin_interpose_strings::kInterposeLibraryPath);
+  if (suffix_offset == 0 &&
+      strcmp(interpose_list,
+             plugin_interpose_strings::kInterposeLibraryPath) == 0) {
+    unsetenv(plugin_interpose_strings::kDYLDInsertLibrariesKey);
+  } else if (suffix_offset > 0 && interpose_list[suffix_offset - 1] == ':' &&
+             strcmp(interpose_list + suffix_offset,
+                    plugin_interpose_strings::kInterposeLibraryPath) == 0) {
+    std::string trimmed_list =
+        std::string(interpose_list).substr(0, suffix_offset - 1);
+    setenv(plugin_interpose_strings::kDYLDInsertLibrariesKey,
+           trimmed_list.c_str(), 1);
+  } else {
+    NOTREACHED() << "Missing Carbon interposing library";
+  }
+}
+#endif  // OS_MACOSX
+
 // main() routine for running as the plugin process.
 int PluginMain(const MainFunctionParams& parameters) {
   // The main thread of the plugin services UI.
@@ -37,6 +74,10 @@ int PluginMain(const MainFunctionParams& parameters) {
   // Initialize the SystemMonitor
   base::SystemMonitor::Start();
 
+#if defined(OS_MACOSX)
+  TrimInterposeEnvironment();
+#endif
+
   const CommandLine& parsed_command_line = parameters.command_line_;
 
 #if defined(OS_WIN)