Import relocation packer from chromium repo
Bug: 18051137
Change-Id: Ia67fa11da8247e3f86f70a8ce99e6695f2c05423
diff --git a/tools/relocation_packer/src/main.cc b/tools/relocation_packer/src/main.cc
new file mode 100644
index 0000000..28f5b04
--- /dev/null
+++ b/tools/relocation_packer/src/main.cc
@@ -0,0 +1,175 @@
+// Copyright 2014 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.
+
+// Tool to pack and unpack relative relocations in a shared library.
+//
+// Packing removes relative relocations from .rel.dyn and writes them
+// in a more compact form to .android.rel.dyn. Unpacking does the reverse.
+//
+// Invoke with -v to trace actions taken when packing or unpacking.
+// Invoke with -p to pad removed relocations with R_*_NONE. Suppresses
+// shrinking of .rel.dyn.
+// See PrintUsage() below for full usage details.
+//
+// NOTE: Breaks with libelf 0.152, which is buggy. libelf 0.158 works.
+
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <string>
+
+#include "debug.h"
+#include "elf_file.h"
+#include "libelf.h"
+
+namespace {
+
+void PrintUsage(const char* argv0) {
+ std::string temporary = argv0;
+ const size_t last_slash = temporary.find_last_of("/");
+ if (last_slash != temporary.npos) {
+ temporary.erase(0, last_slash + 1);
+ }
+ const char* basename = temporary.c_str();
+
+ printf(
+ "Usage: %s [-u] [-v] [-p] file\n\n"
+ "Pack or unpack relative relocations in a shared library.\n\n"
+ " -u, --unpack unpack previously packed relative relocations\n"
+ " -v, --verbose trace object file modifications (for debugging)\n"
+ " -p, --pad do not shrink relocations, but pad (for debugging)\n\n",
+ basename);
+
+ if (ELF::kMachine == EM_ARM) {
+ printf(
+ "Extracts relative relocations from the .rel.dyn section, packs them\n"
+ "into a more compact format, and stores the packed relocations in\n"
+ ".android.rel.dyn. Expands .android.rel.dyn to hold the packed\n"
+ "data, and shrinks .rel.dyn by the amount of unpacked data removed\n"
+ "from it.\n\n"
+ "Before being packed, a shared library needs to be prepared by adding\n"
+ "a null .android.rel.dyn section.\n\n"
+ "To pack relocations in a shared library:\n\n"
+ " echo -n 'NULL' >/tmp/small\n"
+ " arm-linux-androideabi-objcopy \\\n"
+ " --add-section .android.rel.dyn=/tmp/small \\\n"
+ " libchrome.<version>.so\n"
+ " rm /tmp/small\n"
+ " %s libchrome.<version>.so\n\n"
+ "To unpack and restore the shared library to its original state:\n\n"
+ " %s -u libchrome.<version>.so\n"
+ " arm-linux-androideabi-objcopy \\\n"
+ " --remove-section=.android.rel.dyn libchrome.<version>.so\n\n",
+ basename, basename);
+ } else if (ELF::kMachine == EM_AARCH64) {
+ printf(
+ "Extracts relative relocations from the .rela.dyn section, packs them\n"
+ "into a more compact format, and stores the packed relocations in\n"
+ ".android.rela.dyn. Expands .android.rela.dyn to hold the packed\n"
+ "data, and shrinks .rela.dyn by the amount of unpacked data removed\n"
+ "from it.\n\n"
+ "Before being packed, a shared library needs to be prepared by adding\n"
+ "a null .android.rela.dyn section.\n\n"
+ "To pack relocations in a shared library:\n\n"
+ " echo -n 'NULL' >/tmp/small\n"
+ " aarch64-linux-android-objcopy \\\n"
+ " --add-section .android.rela.dyn=/tmp/small \\\n"
+ " libchrome.<version>.so\n"
+ " rm /tmp/small\n"
+ " %s libchrome.<version>.so\n\n"
+ "To unpack and restore the shared library to its original state:\n\n"
+ " %s -u libchrome.<version>.so\n"
+ " aarch64-linux-android-objcopy \\\n"
+ " --remove-section=.android.rela.dyn libchrome.<version>.so\n\n",
+ basename, basename);
+ } else {
+ NOTREACHED();
+ }
+
+ printf(
+ "Debug sections are not handled, so packing should not be used on\n"
+ "shared libraries compiled for debugging or otherwise unstripped.\n");
+}
+
+} // namespace
+
+int main(int argc, char* argv[]) {
+ bool is_unpacking = false;
+ bool is_verbose = false;
+ bool is_padding = false;
+
+ static const option options[] = {
+ {"unpack", 0, 0, 'u'}, {"verbose", 0, 0, 'v'}, {"pad", 0, 0, 'p'},
+ {"help", 0, 0, 'h'}, {NULL, 0, 0, 0}
+ };
+ bool has_options = true;
+ while (has_options) {
+ int c = getopt_long(argc, argv, "uvph", options, NULL);
+ switch (c) {
+ case 'u':
+ is_unpacking = true;
+ break;
+ case 'v':
+ is_verbose = true;
+ break;
+ case 'p':
+ is_padding = true;
+ break;
+ case 'h':
+ PrintUsage(argv[0]);
+ return 0;
+ case '?':
+ LOG(INFO) << "Try '" << argv[0] << " --help' for more information.";
+ return 1;
+ case -1:
+ has_options = false;
+ break;
+ default:
+ NOTREACHED();
+ return 1;
+ }
+ }
+ if (optind != argc - 1) {
+ LOG(INFO) << "Try '" << argv[0] << " --help' for more information.";
+ return 1;
+ }
+
+ if (elf_version(EV_CURRENT) == EV_NONE) {
+ LOG(WARNING) << "Elf Library is out of date!";
+ }
+
+ LOG(INFO) << "Configured for " << ELF::Machine();
+
+ const char* file = argv[argc - 1];
+ const int fd = open(file, O_RDWR);
+ if (fd == -1) {
+ LOG(ERROR) << file << ": " << strerror(errno);
+ return 1;
+ }
+
+ if (is_verbose)
+ relocation_packer::Logger::SetVerbose(1);
+
+ relocation_packer::ElfFile elf_file(fd);
+ elf_file.SetPadding(is_padding);
+
+ bool status;
+ if (is_unpacking)
+ status = elf_file.UnpackRelocations();
+ else
+ status = elf_file.PackRelocations();
+
+ close(fd);
+
+ if (!status) {
+ LOG(ERROR) << file << ": failed to pack/unpack file";
+ return 1;
+ }
+
+ return 0;
+}