Fork of the Android NDK crazy linker.

third_party/android_crazy_linker/src/src/crazy_linker_elf_relro.h

Index: third_party/android_crazy_linker/src/src/crazy_linker_elf_relro.h
diff --git a/third_party/android_crazy_linker/src/src/crazy_linker_elf_relro.h b/third_party/android_crazy_linker/src/src/crazy_linker_elf_relro.h
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+// 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.
+
+#ifndef CRAZY_LINKER_ELF_RELRO_H
+#define CRAZY_LINKER_ELF_RELRO_H
+
+#include "crazy_linker_ashmem.h"
+#include "crazy_linker_memory_mapping.h"
+#include "crazy_linker_system.h"
+#include "elf_traits.h"
+
+namespace crazy {
+
+class ElfView;
+
+// A class used to model a shared RELRO section backed by an Ashmem region.
+// The region is always owned by the SharedRelro, unless DetachFd() is called.
+// The SharedRelro may or may not be mapped into the process.
+class SharedRelro {
+ public:
+  // Create a new SharedRelro. Note that the object becomes the owner of
+  // |ashmem_fd|, unless DetachFd() is called after this.
+  SharedRelro() : start_(0), size_(0), ashmem_() {}
+
+  ~SharedRelro() {}
+
+  size_t start() const { return start_; }
+  size_t end() const { return start_ + size_; }
+  size_t size() const { return size_; }
+  int fd() const { return ashmem_.fd(); }
+
+  // Return the ashmem region's file descriptor, and detach it from the object.
+  // After this call, fd() will always return -1.
+  int DetachFd() { return ashmem_.Release(); }
+
+  // Allocate a new ashmem region of |relro_size| bytes for |library_name|.
+  // This operation doesn't change the process' mappings. On error, return
+  // false and set |error| message.
+  bool Allocate(size_t relro_size, const char* library_name, Error* error);
+
+  // Copy the content of the current process' RELRO into the ashmem region.
+  // |relro_start| is the RELRO address (page-aligned).
+  // |relro_size| is the RELRO size in bytes (page-aligned), and must match
+  // the allocation size passed to Allocate().
+  // On failure, return false and set |error| message.
+  bool CopyFrom(size_t relro_start, size_t relro_size, Error* error);
+
+  // Copy the contents of the current process' RELRO into the ashmem region
+  // but adjust any relocation targets within it to correspond to a new
+  // |load_address|. |view| must point to a mapped ELF binary for the current
+  // library. |relro_start| corresponds to the address of the current
+  // process' RELRO, i.e. is not relocated.
+  bool CopyFromRelocated(const ElfView* view,
+                         size_t load_address,
+                         size_t relro_start,
+                         size_t relro_size,
+                         Error* error);
+
+  // Force the section to be read-only.
+  bool ForceReadOnly(Error* error);
+
+  // Map the ashmem region's pages into the current process, doing a comparison
+  // to avoid corrupting parts of the RELRO section that are different in this
+  // one (e.g. due to symbolic relocations to randomized system libraries).
+  // This operation is _not_ atomic, i.e. no other thread should try to execute
+  // code that reads from the RELRO region during this call.
+  // On failure, return false and set |error| message.
+  // This operation does not transfer ownership of |ashmem_fd| to the object.
+  bool InitFrom(size_t relro_start,
+                size_t relro_size,
+                int ashmem_fd,
+                Error* error);
+
+ private:
+  size_t start_;
+  size_t size_;
+  AshmemRegion ashmem_;
+};
+
+}  // namespace crazy
+
+#endif  // CRAZY_LINKER_ELF_RELRO_H