| // 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. |
| // |
| // 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 "elf_traits.h" |
| #include "libelf.h" |
| |
| #include "nativehelper/ScopedFd.h" |
| |
| static 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); |
| |
| printf( |
| "Debug sections are not handled, so packing should not be used on\n" |
| "shared libraries compiled for debugging or otherwise unstripped.\n"); |
| } |
| |
| 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!"; |
| } |
| |
| const char* file = argv[argc - 1]; |
| ScopedFd fd(open(file, O_RDWR)); |
| if (fd.get() == -1) { |
| LOG(ERROR) << file << ": " << strerror(errno); |
| return 1; |
| } |
| |
| if (is_verbose) |
| relocation_packer::Logger::SetVerbose(1); |
| |
| // We need to detect elf class in order to create |
| // correct implementation |
| uint8_t e_ident[EI_NIDENT]; |
| if (TEMP_FAILURE_RETRY(read(fd.get(), e_ident, EI_NIDENT) != EI_NIDENT)) { |
| LOG(ERROR) << file << ": failed to read elf header:" << strerror(errno); |
| return 1; |
| } |
| |
| if (TEMP_FAILURE_RETRY(lseek(fd.get(), 0, SEEK_SET)) != 0) { |
| LOG(ERROR) << file << ": lseek to 0 failed:" << strerror(errno); |
| return 1; |
| } |
| |
| bool status = false; |
| |
| if (e_ident[EI_CLASS] == ELFCLASS32) { |
| relocation_packer::ElfFile<ELF32_traits> elf_file(fd.get()); |
| elf_file.SetPadding(is_padding); |
| |
| if (is_unpacking) { |
| status = elf_file.UnpackRelocations(); |
| } else { |
| status = elf_file.PackRelocations(); |
| } |
| } else if (e_ident[EI_CLASS] == ELFCLASS64) { |
| relocation_packer::ElfFile<ELF64_traits> elf_file(fd.get()); |
| elf_file.SetPadding(is_padding); |
| |
| if (is_unpacking) { |
| status = elf_file.UnpackRelocations(); |
| } else { |
| status = elf_file.PackRelocations(); |
| } |
| } else { |
| LOG(ERROR) << file << ": unknown ELFCLASS: " << e_ident[EI_CLASS]; |
| return 1; |
| } |
| |
| if (!status) { |
| LOG(ERROR) << file << ": failed to pack/unpack file"; |
| return 1; |
| } |
| |
| return 0; |
| } |