protobuf/conformance/conformance_test_runner.cc

// Protocol Buffers - Google's data interchange format
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// https://developers.google.com/protocol-buffers/
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// This file contains a program for running the test suite in a separate
// process.  The other alternative is to run the suite in-process.  See
// conformance.proto for pros/cons of these two options.
//
// This program will fork the process under test and communicate with it over
// its stdin/stdout:
//
//     +--------+   pipe   +----------+
//     | tester | <------> | testee   |
//     |        |          |          |
//     |  C++   |          | any lang |
//     +--------+          +----------+
//
// The tester contains all of the test cases and their expected output.
// The testee is a simple program written in the target language that reads
// each test case and attempts to produce acceptable output for it.
//
// Every test consists of a ConformanceRequest/ConformanceResponse
// request/reply pair.  The protocol on the pipe is simply:
//
//   1. tester sends 4-byte length N (little endian)
//   2. tester sends N bytes representing a ConformanceRequest proto
//   3. testee sends 4-byte length M (little endian)
//   4. testee sends M bytes representing a ConformanceResponse proto

#include <errno.h>
#include <unistd.h>

#include "conformance.pb.h"
#include "conformance_test.h"

using conformance::ConformanceRequest;
using conformance::ConformanceResponse;
using google::protobuf::internal::scoped_array;

#define STRINGIFY(x) #x
#define TOSTRING(x) STRINGIFY(x)
#define CHECK_SYSCALL(call) \
  if (call < 0) { \
    perror(#call " " __FILE__ ":" TOSTRING(__LINE__)); \
    exit(1); \
  }

// Test runner that spawns the process being tested and communicates with it
// over a pipe.
class ForkPipeRunner : public google::protobuf::ConformanceTestRunner {
 public:
  ForkPipeRunner(const std::string &executable)
      : executable_(executable), running_(false) {}

  void RunTest(const std::string& request, std::string* response) {
    if (!running_) {
      SpawnTestProgram();
    }

    uint32_t len = request.size();
    CheckedWrite(write_fd_, &len, sizeof(uint32_t));
    CheckedWrite(write_fd_, request.c_str(), request.size());
    CheckedRead(read_fd_, &len, sizeof(uint32_t));
    response->resize(len);
    CheckedRead(read_fd_, (void*)response->c_str(), len);
  }

 private:
  // TODO(haberman): make this work on Windows, instead of using these
  // UNIX-specific APIs.
  //
  // There is a platform-agnostic API in
  //    src/google/protobuf/compiler/subprocess.h
  //
  // However that API only supports sending a single message to the subprocess.
  // We really want to be able to send messages and receive responses one at a
  // time:
  //
  // 1. Spawning a new process for each test would take way too long for thousands
  //    of tests and subprocesses like java that can take 100ms or more to start
  //    up.
  //
  // 2. Sending all the tests in one big message and receiving all results in one
  //    big message would take away our visibility about which test(s) caused a
  //    crash or other fatal error.  It would also give us only a single failure
  //    instead of all of them.
  void SpawnTestProgram() {
    int toproc_pipe_fd[2];
    int fromproc_pipe_fd[2];
    if (pipe(toproc_pipe_fd) < 0 || pipe(fromproc_pipe_fd) < 0) {
      perror("pipe");
      exit(1);
    }

    pid_t pid = fork();
    if (pid < 0) {
      perror("fork");
      exit(1);
    }

    if (pid) {
      // Parent.
      CHECK_SYSCALL(close(toproc_pipe_fd[0]));
      CHECK_SYSCALL(close(fromproc_pipe_fd[1]));
      write_fd_ = toproc_pipe_fd[1];
      read_fd_ = fromproc_pipe_fd[0];
      running_ = true;
    } else {
      // Child.
      CHECK_SYSCALL(close(STDIN_FILENO));
      CHECK_SYSCALL(close(STDOUT_FILENO));
      CHECK_SYSCALL(dup2(toproc_pipe_fd[0], STDIN_FILENO));
      CHECK_SYSCALL(dup2(fromproc_pipe_fd[1], STDOUT_FILENO));

      CHECK_SYSCALL(close(toproc_pipe_fd[0]));
      CHECK_SYSCALL(close(fromproc_pipe_fd[1]));
      CHECK_SYSCALL(close(toproc_pipe_fd[1]));
      CHECK_SYSCALL(close(fromproc_pipe_fd[0]));

      scoped_array<char> executable(new char[executable_.size()]);
      memcpy(executable.get(), executable_.c_str(), executable_.size());

      char *const argv[] = {executable.get(), NULL};
      CHECK_SYSCALL(execv(executable.get(), argv));  // Never returns.
    }
  }

  void CheckedWrite(int fd, const void *buf, size_t len) {
    if (write(fd, buf, len) != len) {
      GOOGLE_LOG(FATAL) << "Error writing to test program: " << strerror(errno);
    }
  }

  void CheckedRead(int fd, void *buf, size_t len) {
    size_t ofs = 0;
    while (len > 0) {
      ssize_t bytes_read = read(fd, (char*)buf + ofs, len);

      if (bytes_read == 0) {
        GOOGLE_LOG(FATAL) << "Unexpected EOF from test program";
      } else if (bytes_read < 0) {
        GOOGLE_LOG(FATAL) << "Error reading from test program: " << strerror(errno);
      }

      len -= bytes_read;
      ofs += bytes_read;
    }
  }

  int write_fd_;
  int read_fd_;
  bool running_;
  std::string executable_;
};


int main(int argc, char *argv[]) {
  if (argc < 2) {
    fprintf(stderr, "Usage: conformance-test-runner <test-program>\n");
    exit(1);
  }

  ForkPipeRunner runner(argv[1]);
  google::protobuf::ConformanceTestSuite suite;

  std::string output;
  suite.RunSuite(&runner, &output);

  fwrite(output.c_str(), 1, output.size(), stderr);
}