This patch adds a new third-party library that implements an ELF dynamic linker.

third_party/crazy_linker/crazy_linker/src/crazy_linker_api.cpp

Index: third_party/crazy_linker/crazy_linker/src/crazy_linker_api.cpp
diff --git a/third_party/crazy_linker/crazy_linker/src/crazy_linker_api.cpp b/third_party/crazy_linker/crazy_linker/src/crazy_linker_api.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..89df02c55050c1181537a448ef46d9d18463bf24
--- /dev/null
+++ b/third_party/crazy_linker/crazy_linker/src/crazy_linker_api.cpp
@@ -0,0 +1,267 @@
+// Copyright (c) 2013 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.
+
+// Implements the crazy linker C-based API exposed by <crazy_linker.h>
+
+#include <crazy_linker.h>
+
+#include <string.h>
+
+#include "crazy_linker_error.h"
+#include "crazy_linker_globals.h"
+#include "crazy_linker_proc_maps.h"
+#include "crazy_linker_search_path_list.h"
+#include "crazy_linker_shared_library.h"
+#include "crazy_linker_thread.h"
+#include "crazy_linker_util.h"
+#include "crazy_linker_library_view.h"
+#include "crazy_linker_system.h"
+
+using crazy::Globals;
+using crazy::Error;
+using crazy::SearchPathList;
+using crazy::ScopedGlobalLock;
+using crazy::LibraryView;
+
+//
+// crazy_context_t
+//
+
+struct crazy_context_t {
+ public:
+  crazy_context_t()
+    : load_address(0),
+      file_offset(0),
+      error(),
+      search_paths() {
+    ResetSearchPaths();
+  }
+
+  void ResetSearchPaths();
+
+  size_t load_address;
+  size_t file_offset;
+  Error error;
+  SearchPathList search_paths;
+};
+
+void crazy_context_t::ResetSearchPaths() {
+  search_paths.Reset();
+  const char* env = crazy::GetEnv("LD_LIBRARY_PATH");
+  if (env && env[0])
+    search_paths.AddPaths(env);
+}
+
+//
+// API functions
+//
+
+extern "C" {
+
+crazy_context_t* crazy_context_create(void) {
+  return new crazy_context_t();
+}
+
+const char* crazy_context_get_error(crazy_context_t* context) {
+  const char* error = context->error.c_str();
+  return (error[0] != '\0') ? error : NULL;
+}
+
+// Clear error in a given context.
+void crazy_context_clear_error(crazy_context_t* context) {
+  context->error = "";
+}
+
+void crazy_context_set_load_address(crazy_context_t* context,
+                                    size_t load_address) {
+  context->load_address = load_address;
+}
+
+size_t crazy_context_get_load_address(crazy_context_t* context) {
+  return context->load_address;
+}
+
+void crazy_context_set_file_offset(crazy_context_t* context,
+                                   size_t file_offset) {
+  context->file_offset = file_offset;
+}
+
+size_t crazy_context_get_file_offset(crazy_context_t* context) {
+  return context->file_offset;
+}
+
+crazy_status_t crazy_context_add_search_path(crazy_context_t* context,
+                                             const char* file_path) {
+  context->search_paths.AddPaths(file_path);
+  return CRAZY_STATUS_OK;
+}
+
+crazy_status_t crazy_context_add_search_path_for_address(
+    crazy_context_t* context,
+    void* address) {
+  uintptr_t load_address;
+  char path[512];
+  char* p;
+
+  if (crazy::FindElfBinaryForAddress(
+          address, &load_address, path, sizeof(path)) &&
+      (p = strrchr(path, '/')) != NULL && p[1]) {
+    *p = '\0';
+    return crazy_context_add_search_path(context, path);
+  }
+
+  context->error.Format(
+      "Could not find ELF binary at address @%p", address);
+  return CRAZY_STATUS_KO;
+}
+
+void crazy_context_reset_search_paths(crazy_context_t* context) {
+  context->ResetSearchPaths();
+}
+
+void crazy_context_destroy(crazy_context_t* context) {
+  delete context;
+}
+
+crazy_status_t crazy_library_open(crazy_library_t** library,
+                                  const char* lib_name,
+                                  crazy_context_t* context) {
+  ScopedGlobalLock lock;
+  LibraryView* wrap =
+      crazy::Globals::GetLibraries()->LoadLibrary(lib_name,
+                                                  RTLD_NOW,
+                                                  context->load_address,
+                                                  context->file_offset,
+                                                  &context->search_paths,
+                                                  &context->error);
+  if (!wrap)
+    return CRAZY_STATUS_KO;
+
+  *library = reinterpret_cast<crazy_library_t*>(wrap);
+  return CRAZY_STATUS_OK;
+}
+
+crazy_status_t crazy_library_get_info(crazy_library_t* library,
+                                      crazy_context_t* context,
+                                      crazy_library_info_t* info) {
+  if (!library) {
+    context->error = "Invalid library file handle";
+    return CRAZY_STATUS_KO;
+  }
+
+  LibraryView* wrap = reinterpret_cast<LibraryView*>(library);
+  if (!wrap->GetInfo(&info->load_address,
+                     &info->load_size,
+                     &info->relro_start,
+                     &info->relro_size,
+                     &info->relro_fd,
+                     &context->error)) {
+    return CRAZY_STATUS_KO;
+  }
+
+  return CRAZY_STATUS_OK;
+}
+
+crazy_status_t crazy_library_enable_relro_sharing(
+    crazy_library_t* library,
+    crazy_context_t* context) {
+  LibraryView* wrap =
+      reinterpret_cast<LibraryView*>(library);
+
+  if (!library) {
+    context->error = "Invalid library file handle";
+    return CRAZY_STATUS_KO;
+  }
+
+  if (!wrap->EnableSharedRelro(&context->error))
+    return CRAZY_STATUS_KO;
+
+  return CRAZY_STATUS_OK;
+}
+
+crazy_status_t crazy_library_use_relro_sharing(
+    crazy_library_t* library,
+    size_t relro_start,
+    size_t relro_size,
+    int relro_fd,
+    crazy_context_t* context) {
+  LibraryView* wrap =
+      reinterpret_cast<LibraryView*>(library);
+
+  if (!library) {
+    context->error = "Invalid library file handle";
+    return CRAZY_STATUS_KO;
+  }
+
+  if (!wrap->UseSharedRelro(relro_start,
+                            relro_size,
+                            relro_fd,
+                            &context->error)) {
+    return CRAZY_STATUS_KO;
+  }
+
+  return CRAZY_STATUS_OK;
+}
+
+crazy_status_t crazy_library_find_by_name(const char* library_name,
+                                          crazy_library_t** library) {
+  {
+    ScopedGlobalLock lock;
+    LibraryView* wrap =
+        Globals::GetLibraries()->FindLibraryByName(library_name);
+    if (!wrap)
+      return CRAZY_STATUS_KO;
+
+    wrap->AddRef();
+    *library = reinterpret_cast<crazy_library_t*>(wrap);
+  }
+  return CRAZY_STATUS_OK;
+}
+
+crazy_status_t crazy_library_find_symbol(
+    crazy_library_t* library,
+    const char* symbol_name,
+    void** symbol_address) {
+  LibraryView* wrap =
+      reinterpret_cast<LibraryView*>(library);
+
+  // TODO(digit): Handle NULL symbols properly.
+  *symbol_address = wrap->LookupSymbol(symbol_name);
+  return (*symbol_address == NULL) ? CRAZY_STATUS_KO : CRAZY_STATUS_OK;
+}
+
+crazy_status_t crazy_linker_find_symbol(
+      const char* symbol_name,
+      void** symbol_address) {
+  // TODO(digit): Implement this.
+  return CRAZY_STATUS_KO;
+}
+
+crazy_status_t crazy_library_find_from_address(
+    void* address, crazy_library_t** library) {
+  {
+    ScopedGlobalLock lock;
+    LibraryView* wrap =
+        Globals::GetLibraries()->FindLibraryForAddress(address);
+    if (!wrap)
+      return CRAZY_STATUS_KO;
+
+    wrap->AddRef();
+
+    *library = reinterpret_cast<crazy_library_t*>(wrap);
+    return CRAZY_STATUS_OK;
+  }
+}
+
+void crazy_library_close(crazy_library_t* library) {
+  if (library) {
+    ScopedGlobalLock lock;
+    LibraryView* wrap =
+      reinterpret_cast<LibraryView*>(library);
+
+    Globals::GetLibraries()->UnloadLibrary(wrap);
+  }
+}
+
+}  // extern "C"