Fork of the Android NDK crazy linker.

third_party/android_crazy_linker/src/src/crazy_linker_shared_library.cpp

Index: third_party/android_crazy_linker/src/src/crazy_linker_shared_library.cpp
diff --git a/third_party/android_crazy_linker/src/src/crazy_linker_shared_library.cpp b/third_party/android_crazy_linker/src/src/crazy_linker_shared_library.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..406346e6696f0d6ed35d4ec783d47429969522f8
--- /dev/null
+++ b/third_party/android_crazy_linker/src/src/crazy_linker_shared_library.cpp
@@ -0,0 +1,451 @@
+// 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.
+
+#include "crazy_linker_shared_library.h"
+
+#include <dlfcn.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <elf.h>
+#include <sys/exec_elf.h>
+
+#include "crazy_linker_ashmem.h"
+#include "crazy_linker_debug.h"
+#include "crazy_linker_elf_loader.h"
+#include "crazy_linker_elf_relocations.h"
+#include "crazy_linker_library_list.h"
+#include "crazy_linker_library_view.h"
+#include "crazy_linker_globals.h"
+#include "crazy_linker_memory_mapping.h"
+#include "crazy_linker_thread.h"
+#include "crazy_linker_util.h"
+#include "crazy_linker_wrappers.h"
+#include "linker_phdr.h"
+
+#ifndef DF_SYMBOLIC
+#define DF_SYMBOLIC 2
+#endif
+
+#ifndef DF_TEXTREL
+#define DF_TEXTREL 4
+#endif
+
+#ifndef DT_INIT_ARRAY
+#define DT_INIT_ARRAY 25
+#endif
+
+#ifndef DT_INIT_ARRAYSZ
+#define DT_INIT_ARRAYSZ 27
+#endif
+
+#ifndef DT_FINI_ARRAY
+#define DT_FINI_ARRAY 26
+#endif
+
+#ifndef DT_FINI_ARRAYSZ
+#define DT_FINI_ARRAYSZ 28
+#endif
+
+#ifndef DT_FLAGS
+#define DT_FLAGS 30
+#endif
+
+#ifndef DT_PREINIT_ARRAY
+#define DT_PREINIT_ARRAY 32
+#endif
+
+#ifndef DT_PREINIT_ARRAYSZ
+#define DT_PREINIT_ARRAYSZ 33
+#endif
+
+namespace crazy {
+
+namespace {
+
+typedef SharedLibrary::linker_function_t linker_function_t;
+typedef int (*JNI_OnLoadFunctionPtr)(void* vm, void* reserved);
+typedef void (*JNI_OnUnloadFunctionPtr)(void* vm, void* reserved);
+
+// Call a constructor or destructor function pointer. Ignore
+// NULL and -1 values intentionally. They correspond to markers
+// in the tables, or deleted values.
+// |func_type| corresponds to the type of the function, and is only
+// used for debugging (examples are "DT_INIT", "DT_INIT_ARRAY", etc...).
+void CallFunction(linker_function_t func, const char* func_type) {
+  uintptr_t func_address = reinterpret_cast<uintptr_t>(func);
+
+  LOG("%s: %p %s\n", __FUNCTION__, func, func_type);
+  if (func_address != 0 && func_address != uintptr_t(-1))
+    func();
+}
+
+// An instance of ElfRelocator::SymbolResolver that can be used
+// to resolve symbols in a shared library being loaded by
+// LibraryList::LoadLibrary.
+class SharedLibraryResolver : public ElfRelocations::SymbolResolver {
+ public:
+  SharedLibraryResolver(SharedLibrary* lib,
+                        LibraryList* lib_list,
+                        Vector<LibraryView*>* dependencies)
+      : lib_(lib), dependencies_(dependencies) {}
+
+  virtual void* Lookup(const char* symbol_name) {
+    // TODO(digit): Add the ability to lookup inside the main executable.
+
+    // First, look inside the current library.
+    const ELF::Sym* entry = lib_->LookupSymbolEntry(symbol_name);
+    if (entry)
+      return reinterpret_cast<void*>(lib_->load_bias() + entry->st_value);
+
+    // Special case: redirect the dynamic linker symbols to our wrappers.
+    // This ensures that loaded libraries can call dlopen() / dlsym()
+    // and transparently use the crazy linker to perform their duty.
+    void* address = WrapLinkerSymbol(symbol_name);
+    if (address)
+      return address;
+
+    // Then look inside the dependencies.
+    for (size_t n = 0; n < dependencies_->GetCount(); ++n) {
+      LibraryView* wrap = (*dependencies_)[n];
+      // LOG("%s: Looking into dependency %p (%s)\n", __FUNCTION__, wrap,
+      // wrap->GetName());
+      if (wrap->IsSystem()) {
+        address = ::dlsym(wrap->GetSystem(), symbol_name);
+#ifdef __arm__
+        // Android libm.so defines isnanf as weak. This means that its
+        // address cannot be found by dlsym(), which always returns NULL
+        // for weak symbols. However, libm.so contains the real isnanf
+        // as __isnanf. If we encounter isnanf and fail to resolve it in
+        // libm.so, retry with __isnanf.
+        //
+        // This occurs only in clang, which lacks __builtin_isnanf. The
+        // gcc compiler implements isnanf as a builtin, so the symbol
+        // isnanf never need be resolved in gcc builds.
+        //
+        // http://code.google.com/p/chromium/issues/detail?id=376828
+        if (!address &&
+            !strcmp(symbol_name, "isnanf") &&
+            !strcmp(wrap->GetName(), "libm.so"))
+          address = ::dlsym(wrap->GetSystem(), "__isnanf");
+#endif
+        if (address)
+          return address;
+      }
+      if (wrap->IsCrazy()) {
+        SharedLibrary* dep = wrap->GetCrazy();
+        entry = dep->LookupSymbolEntry(symbol_name);
+        if (entry)
+          return reinterpret_cast<void*>(dep->load_bias() + entry->st_value);
+      }
+    }
+
+    // Nothing found here.
+    return NULL;
+  }
+
+ private:
+  SharedLibrary* lib_;
+  Vector<LibraryView*>* dependencies_;
+};
+
+}  // namespace
+
+SharedLibrary::SharedLibrary() { ::memset(this, 0, sizeof(*this)); }
+
+SharedLibrary::~SharedLibrary() {
+  // Ensure the library is unmapped on destruction.
+  if (view_.load_address())
+    munmap(reinterpret_cast<void*>(view_.load_address()), view_.load_size());
+}
+
+bool SharedLibrary::Load(const char* full_path,
+                         size_t load_address,
+                         size_t file_offset,
+                         Error* error) {
+  // First, record the path.
+  LOG("%s: full path '%s'\n", __FUNCTION__, full_path);
+
+  size_t full_path_len = strlen(full_path);
+  if (full_path_len >= sizeof(full_path_)) {
+    error->Format("Path too long: %s", full_path);
+    return false;
+  }
+
+  strlcpy(full_path_, full_path, sizeof(full_path_));
+  base_name_ = GetBaseNamePtr(full_path_);
+
+  // Load the ELF binary in memory.
+  LOG("%s: Loading ELF segments for %s\n", __FUNCTION__, base_name_);
+
+  {
+    ElfLoader loader;
+    if (!loader.LoadAt(full_path_, file_offset, load_address, error)) {
+      return false;
+    }
+
+    if (!view_.InitUnmapped(loader.load_start(),
+                            loader.loaded_phdr(),
+                            loader.phdr_count(),
+                            error)) {
+      return false;
+    }
+
+    if (!symbols_.Init(&view_)) {
+      *error = "Missing or malformed symbol table";
+      return false;
+    }
+  }
+
+  if (phdr_table_get_relro_info(view_.phdr(),
+                                view_.phdr_count(),
+                                view_.load_bias(),
+                                &relro_start_,
+                                &relro_size_) < 0) {
+    relro_start_ = 0;
+    relro_size_ = 0;
+  }
+
+#ifdef __arm__
+  LOG("%s: Extracting ARM.exidx table for %s\n", __FUNCTION__, base_name_);
+  (void)phdr_table_get_arm_exidx(
+      phdr(), phdr_count(), load_bias(), &arm_exidx_, &arm_exidx_count_);
+#endif
+
+  LOG("%s: Parsing dynamic table for %s\n", __FUNCTION__, base_name_);
+  ElfView::DynamicIterator dyn(&view_);
+  for (; dyn.HasNext(); dyn.GetNext()) {
+    ELF::Addr dyn_value = dyn.GetValue();
+    uintptr_t dyn_addr = dyn.GetAddress(load_bias());
+    switch (dyn.GetTag()) {
+      case DT_DEBUG:
+        if (view_.dynamic_flags() & PF_W) {
+          *dyn.GetValuePointer() =
+              reinterpret_cast<uintptr_t>(Globals::GetRDebug()->GetAddress());
+        }
+        break;
+      case DT_INIT:
+        LOG("  DT_INIT addr=%p\n", dyn_addr);
+        init_func_ = reinterpret_cast<linker_function_t>(dyn_addr);
+        break;
+      case DT_FINI:
+        LOG("  DT_FINI addr=%p\n", dyn_addr);
+        fini_func_ = reinterpret_cast<linker_function_t>(dyn_addr);
+        break;
+      case DT_INIT_ARRAY:
+        LOG("  DT_INIT_ARRAY addr=%p\n", dyn_addr);
+        init_array_ = reinterpret_cast<linker_function_t*>(dyn_addr);
+        break;
+      case DT_INIT_ARRAYSZ:
+        init_array_count_ = dyn_value / sizeof(ELF::Addr);
+        LOG("  DT_INIT_ARRAYSZ value=%p count=%p\n",
+            dyn_value,
+            init_array_count_);
+        break;
+      case DT_FINI_ARRAY:
+        LOG("  DT_FINI_ARRAY addr=%p\n", dyn_addr);
+        fini_array_ = reinterpret_cast<linker_function_t*>(dyn_addr);
+        break;
+      case DT_FINI_ARRAYSZ:
+        fini_array_count_ = dyn_value / sizeof(ELF::Addr);
+        LOG("  DT_FINI_ARRAYSZ value=%p count=%p\n",
+            dyn_value,
+            fini_array_count_);
+        break;
+      case DT_PREINIT_ARRAY:
+        LOG("  DT_PREINIT_ARRAY addr=%p\n", dyn_addr);
+        preinit_array_ = reinterpret_cast<linker_function_t*>(dyn_addr);
+        break;
+      case DT_PREINIT_ARRAYSZ:
+        preinit_array_count_ = dyn_value / sizeof(ELF::Addr);
+        LOG("  DT_PREINIT_ARRAYSZ value=%p count=%p\n",
+            dyn_value,
+            preinit_array_count_);
+        break;
+      case DT_SYMBOLIC:
+        LOG("  DT_SYMBOLIC\n");
+        has_DT_SYMBOLIC_ = true;
+        break;
+      case DT_FLAGS:
+        if (dyn_value & DF_SYMBOLIC)
+          has_DT_SYMBOLIC_ = true;
+        break;
+#if defined(__mips__)
+      case DT_MIPS_RLD_MAP:
+        *dyn.GetValuePointer() =
+            reinterpret_cast<ELF::Addr>(Globals::GetRDebug()->GetAddress());
+        break;
+#endif
+      default:
+        ;
+    }
+  }
+
+  LOG("%s: Load complete for %s\n", __FUNCTION__, base_name_);
+  return true;
+}
+
+bool SharedLibrary::Relocate(LibraryList* lib_list,
+                             Vector<LibraryView*>* dependencies,
+                             Error* error) {
+  // Apply relocations.
+  LOG("%s: Applying relocations to %s\n", __FUNCTION__, base_name_);
+
+  ElfRelocations relocations;
+
+  if (!relocations.Init(&view_, error))
+    return false;
+
+  SharedLibraryResolver resolver(this, lib_list, dependencies);
+  if (!relocations.ApplyAll(&symbols_, &resolver, error))
+    return false;
+
+  LOG("%s: Relocations applied for %s\n", __FUNCTION__, base_name_);
+  return true;
+}
+
+const ELF::Sym* SharedLibrary::LookupSymbolEntry(const char* symbol_name) {
+  return symbols_.LookupByName(symbol_name);
+}
+
+void* SharedLibrary::FindAddressForSymbol(const char* symbol_name) {
+  return symbols_.LookupAddressByName(symbol_name, view_.load_bias());
+}
+
+bool SharedLibrary::CreateSharedRelro(size_t load_address,
+                                      size_t* relro_start,
+                                      size_t* relro_size,
+                                      int* relro_fd,
+                                      Error* error) {
+  SharedRelro relro;
+
+  if (!relro.Allocate(relro_size_, base_name_, error))
+    return false;
+
+  if (load_address != 0 && load_address != this->load_address()) {
+    // Need to relocate the content of the ashmem region first to accomodate
+    // for the new load address.
+    if (!relro.CopyFromRelocated(
+             &view_, load_address, relro_start_, relro_size_, error))
+      return false;
+  } else {
+    // Simply copy, no relocations.
+    if (!relro.CopyFrom(relro_start_, relro_size_, error))
+      return false;
+  }
+
+  // Enforce read-only mode for the region's content.
+  if (!relro.ForceReadOnly(error))
+    return false;
+
+  // All good.
+  *relro_start = relro.start();
+  *relro_size = relro.size();
+  *relro_fd = relro.DetachFd();
+  return true;
+}
+
+bool SharedLibrary::UseSharedRelro(size_t relro_start,
+                                   size_t relro_size,
+                                   int relro_fd,
+                                   Error* error) {
+  LOG("%s: relro_start=%p relro_size=%p relro_fd=%d\n",
+      __FUNCTION__,
+      (void*)relro_start,
+      (void*)relro_size,
+      relro_fd);
+
+  if (relro_fd < 0 || relro_size == 0) {
+    // Nothing to do here.
+    return true;
+  }
+
+  // Sanity check: A shared RELRO is not already used.
+  if (relro_used_) {
+    *error = "Library already using shared RELRO section";
+    return false;
+  }
+
+  // Sanity check: RELRO addresses must match.
+  if (relro_start_ != relro_start || relro_size_ != relro_size) {
+    error->Format("RELRO mismatch addr=%p size=%p (wanted addr=%p size=%p)",
+                  relro_start_,
+                  relro_size_,
+                  relro_start,
+                  relro_size);
+    return false;
+  }
+
+  // Everything's good, swap pages in this process's address space.
+  SharedRelro relro;
+  if (!relro.InitFrom(relro_start, relro_size, relro_fd, error))
+    return false;
+
+  relro_used_ = true;
+  return true;
+}
+
+void SharedLibrary::CallConstructors() {
+  CallFunction(init_func_, "DT_INIT");
+  for (size_t n = 0; n < init_array_count_; ++n)
+    CallFunction(init_array_[n], "DT_INIT_ARRAY");
+}
+
+void SharedLibrary::CallDestructors() {
+  for (size_t n = fini_array_count_; n > 0; --n) {
+    CallFunction(fini_array_[n - 1], "DT_FINI_ARRAY");
+  }
+  CallFunction(fini_func_, "DT_FINI");
+}
+
+bool SharedLibrary::SetJavaVM(void* java_vm,
+                              int minimum_jni_version,
+                              Error* error) {
+  if (java_vm == NULL)
+    return true;
+
+  // Lookup for JNI_OnLoad, exit if it doesn't exist.
+  JNI_OnLoadFunctionPtr jni_onload = reinterpret_cast<JNI_OnLoadFunctionPtr>(
+      FindAddressForSymbol("JNI_OnLoad"));
+  if (!jni_onload)
+    return true;
+
+  int jni_version = (*jni_onload)(java_vm, NULL);
+  if (jni_version < minimum_jni_version) {
+    error->Format("JNI_OnLoad() in %s returned %d, expected at least %d",
+                  full_path_,
+                  jni_version,
+                  minimum_jni_version);
+    return false;
+  }
+
+  // Save the JavaVM handle for unload time.
+  java_vm_ = java_vm;
+  return true;
+}
+
+void SharedLibrary::CallJniOnUnload() {
+  if (!java_vm_)
+    return;
+
+  JNI_OnUnloadFunctionPtr jni_on_unload =
+      reinterpret_cast<JNI_OnUnloadFunctionPtr>(
+          this->FindAddressForSymbol("JNI_OnUnload"));
+
+  if (jni_on_unload)
+    (*jni_on_unload)(java_vm_, NULL);
+}
+
+bool SharedLibrary::DependencyIterator::GetNext() {
+  dep_name_ = NULL;
+  for (; iter_.HasNext(); iter_.GetNext()) {
+    if (iter_.GetTag() == DT_NEEDED) {
+      dep_name_ = symbols_->GetStringById(iter_.GetValue());
+      iter_.GetNext();
+      return true;
+    }
+  }
+  return false;
+}
+
+}  // namespace crazy