diff options
Diffstat (limited to 'src/processor/disassembler_objdump.cc')
| -rw-r--r-- | src/processor/disassembler_objdump.cc | 197 |
1 files changed, 82 insertions, 115 deletions
diff --git a/src/processor/disassembler_objdump.cc b/src/processor/disassembler_objdump.cc index dfe10d58..9f9569a5 100644 --- a/src/processor/disassembler_objdump.cc +++ b/src/processor/disassembler_objdump.cc @@ -30,10 +30,16 @@ // // Author: Mark Brand +#ifdef HAVE_CONFIG_H +#include <config.h> // Must come first +#endif + #include "processor/disassembler_objdump.h" -#ifdef __linux__ #include <unistd.h> +#include <sys/wait.h> + +#include <array> #include <fstream> #include <iostream> #include <iterator> @@ -41,76 +47,15 @@ #include <sstream> #include <vector> +#include "common/linux/eintr_wrapper.h" +#include "common/linux/scoped_pipe.h" +#include "common/linux/scoped_tmpfile.h" #include "processor/logging.h" namespace google_breakpad { namespace { -const size_t kMaxX86InstructionLength = 15; - -// Small RAII wrapper for temporary files. -// -// Example: -// ScopedTmpFile tmp("/tmp/tmpfile-XXXX"); -// if (tmp.Create()) { -// std::cerr << tmp.path() << std::endl; -// } -class ScopedTmpFile { - public: - // Initialize the ScopedTmpFile object - this does not create the temporary - // file yet. - ScopedTmpFile(const char* path_format); - ~ScopedTmpFile(); - - // Creates the temporary file, returns true on success. - bool Create(); - - // Writes bytes to the temporary file, returns true on success. - bool Write(const uint8_t* bytes, unsigned int bytes_len); - - // Returns the path of the temporary file. - string path() const { return path_; } - - private: - int fd_; - string path_; -}; - -ScopedTmpFile::ScopedTmpFile(const char* path_format) : path_(path_format) {} - -ScopedTmpFile::~ScopedTmpFile() { - if (fd_) { - close(fd_); - unlink(path_.c_str()); - } -} - -bool ScopedTmpFile::Create() { - fd_ = mkstemp(path_.data()); - if (fd_ < 0) { - unlink(path_.c_str()); - fd_ = 0; - path_ = ""; - return false; - } - - return true; -} -bool ScopedTmpFile::Write(const uint8_t* bytes, unsigned int bytes_len) { - if (fd_) { - do { - ssize_t result = write(fd_, bytes, bytes_len); - if (result < 0) { - break; - } - - bytes += result; - bytes_len -= result; - } while (bytes_len); - } - - return bytes_len == 0; -} +const size_t kMaxX86InstructionLength = 15; bool IsInstructionPrefix(const string& token) { if (token == "lock" || token == "rep" || token == "repz" || @@ -285,47 +230,87 @@ bool DisassemblerObjdump::DisassembleInstruction(uint32_t cpu, return false; } - // Create two temporary files, one for the raw instruction bytes to pass to - // objdump, and one for the output, and write the bytes to the input file. - ScopedTmpFile raw_bytes_file("/tmp/breakpad_mem_region-raw_bytes-XXXXXX"); - ScopedTmpFile disassembly_file("/tmp/breakpad_mem_region-disassembly-XXXXXX"); - if (!raw_bytes_file.Create() || !disassembly_file.Create() || - !raw_bytes_file.Write(raw_bytes, raw_bytes_len)) { - BPLOG(ERROR) << "Failed creating temporary files."; + // Create a temporary file for the raw instruction bytes to pass to + // objdump, and write the bytes to the input file. + ScopedTmpFile raw_bytes_file; + if (!raw_bytes_file.InitData(raw_bytes, raw_bytes_len)) { + BPLOG(ERROR) << "Failed creating temporary file."; + return false; + } + + // Create a pipe to use to read the disassembly back from objdump. + ScopedPipe disassembly_pipe; + if (!disassembly_pipe.Init()) { + BPLOG(ERROR) << "Failed creating pipe for output."; return false; } - char cmd[1024] = {0}; - snprintf(cmd, 1024, - "objdump -D --no-show-raw-insn -b binary -M intel -m %s %s > %s", - architecture.c_str(), raw_bytes_file.path().c_str(), - disassembly_file.path().c_str()); - if (system(cmd)) { - BPLOG(ERROR) << "Failed to call objdump."; + pid_t child_pid = fork(); + if (child_pid < 0) { + BPLOG(ERROR) << "Fork failed."; return false; } - // Pipe each output line into the string until the string contains the first - // instruction from objdump. - std::ifstream objdump_stream(disassembly_file.path()); + if (child_pid == 0) { + // In the child process, set up the input and output file descriptors. + if (dup2(raw_bytes_file.GetFd(), STDIN_FILENO) < 0 || + disassembly_pipe.Dup2WriteFd(STDOUT_FILENO) < 0 || + disassembly_pipe.Dup2WriteFd(STDERR_FILENO) < 0) { + BPLOG(ERROR) << "Failed dup'ing file descriptors."; + exit(-1); + } - // Match the instruction line, from: - // 0: lock cmpxchg DWORD PTR [esi+0x10],eax - // extract the string "lock cmpxchg DWORD PTR [esi+0x10],eax" - std::regex instruction_regex( - "^\\s+[0-9a-f]+:\\s+" // " 0:" - "((?:\\s*\\S*)+)$"); // "lock cmpxchg..." + // We need to close the read end of the pipe in the child process so that + // when the parent closes it, the pipe is disconnected. + disassembly_pipe.CloseReadFd(); - std::string line; - std::smatch match; - do { - if (!getline(objdump_stream, line)) { - BPLOG(INFO) << "Failed to find instruction in objdump output."; + // We use "/proc/self/fd/0" here to allow objdump to parse an unnamed file, + // since objdump does not have a mode to read from stdin. This cannot be + // used with a pipe, since objdump requires that the input is a standard + // file. + execlp("objdump", "objdump", "-D", "--no-show-raw-insn", "-b", "binary", + "-M", "intel", "-m", architecture.c_str(), "/proc/self/fd/0", + nullptr); + + BPLOG(ERROR) << "Failed to exec objdump."; + exit(-1); + } else { + // In the parent process, parse the objdump output. + + // Match the instruction line, from: + // 0: lock cmpxchg DWORD PTR [esi+0x10],eax + // extract the string "lock cmpxchg DWORD PTR [esi+0x10],eax" + std::regex instruction_regex( + "^\\s+[0-9a-f]+:\\s+" // " 0:" + "((?:\\s*\\S*)+)$"); // "lock cmpxchg..." + + std::string line; + std::smatch match; + while (disassembly_pipe.ReadLine(line)) { + if (std::regex_match(line, match, instruction_regex)) { + instruction = match[1].str(); + break; + } + } + + // Close the read pipe so that objdump will exit (in case we broke out of + // the loop above before reading all of the output). + disassembly_pipe.CloseReadFd(); + + // Now wait for objdump to exit. + int status = 0; + HANDLE_EINTR(waitpid(child_pid, &status, 0)); + + if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { + BPLOG(ERROR) << "objdump didn't run successfully."; return false; } - } while (!std::regex_match(line, match, instruction_regex)); - instruction = match[1].str(); + if (instruction == "") { + BPLOG(ERROR) << "Failed to find instruction in objdump output."; + return false; + } + } return true; } @@ -498,23 +483,5 @@ bool DisassemblerObjdump::CalculateDestAddress(const DumpContext& context, uint64_t& address) { return CalculateAddress(context, dest_, address); } -} // namespace google_breakpad - -#else // __linux__ -namespace google_breakpad { -DisassemblerObjdump::DisassemblerObjdump(const uint32_t cpu, - const MemoryRegion* memory_region, - uint64_t address) {} - -bool DisassemblerObjdump::CalculateSrcAddress(const DumpContext& context, - uint64_t& address) { - return false; -} - -bool DisassemblerObjdump::CalculateDestAddress(const DumpContext& context, - uint64_t& address) { - return false; -} -} // namespace google_breakpad -#endif // __linux__ +} // namespace google_breakpad
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