path: root/src/faketime.c

/*
 *  libfaketime wrapper command
 *
 *  This file is part of libfaketime, version 0.9.9
 *
 *  libfaketime is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License v2 as published by the
 *  Free Software Foundation.
 *
 *  libfaketime is distributed in the hope that it will be useful, but WITHOUT
 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 *  more details.
 *
 *  You should have received a copy of the GNU General Public License v2 along
 *  with the libfaketime; if not, write to the Free Software Foundation,
 *  Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Converted from shell script by Balint Reczey with the following credits
 * and comments:
 *
 * Thanks to Daniel Kahn Gillmor for improvement suggestions.

 * This wrapper exposes only a small subset of the libfaketime functionality.
 * Please see libfaketime's README file and man page for more details.

 * Acknowledgment: Parts of the functionality of this wrapper have been
 * inspired by Matthias Urlichs' datefudge 1.14.

 * Compile time configuration: Path where the libfaketime libraries can be found
 * on Linux/UNIX
 *
 */

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include <time.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <semaphore.h>

#include "faketime_common.h"

const char version[] = "0.9.9";

#if (defined __APPLE__) || (defined __sun)
static const char *date_cmd = "gdate";
#else
static const char *date_cmd = "date";
#endif

#define PATH_BUFSIZE 4096

/* semaphore and shared memory names */
char sem_name[PATH_BUFSIZE] = {0}, shm_name[PATH_BUFSIZE] = {0};

void usage(const char *name)
{
  printf("\n"
  "Usage: %s [switches] <timestamp> <program with arguments>\n"
  "\n"
  "This will run the specified 'program' with the given 'arguments'.\n"
  "The program will be tricked into seeing the given 'timestamp' as its starting date and time.\n"
  "The clock will continue to run from this timestamp. Please see the manpage (man faketime)\n"
  "for advanced options, such as stopping the wall clock and make it run faster or slower.\n"
  "\n"
  "The optional switches are:\n"
  "  -m                  : Use the multi-threaded version of libfaketime\n"
  "  -f                  : Use the advanced timestamp specification format (see manpage)\n"
  "  --exclude-monotonic : Prevent monotonic clock from drifting (not the raw monotonic one)\n"
#ifdef FAKE_PID
  "  -p PID              : Pretend that the program's process ID is PID\n"
#endif
  "  --date-prog PROG    : Use specified GNU-compatible implementation of 'date' program\n"
  "\n"
  "Examples:\n"
  "%s 'last friday 5 pm' /bin/date\n"
  "%s '2008-12-24 08:15:42' /bin/date\n"
  "%s -f '+2,5y x10,0' /bin/bash -c 'date; while true; do echo $SECONDS ; sleep 1 ; done'\n"
  "%s -f '+2,5y x0,50' /bin/bash -c 'date; while true; do echo $SECONDS ; sleep 1 ; done'\n"
  "%s -f '+2,5y i2,0' /bin/bash -c 'date; while true; do date; sleep 1 ; done'\n"
  "In this single case all spawned processes will use the same global clock\n"
  "without restarting it at the start of each process.\n\n"
  "(Please note that it depends on your locale settings whether . or , has to be used for fractions)\n"
  "\n", name, name, name, name, name, name);
}

/** Clean up shared objects */
static void cleanup_shobjs()
{
  if (-1 == sem_unlink(sem_name))
  {
    perror("faketime: sem_unlink");
  }
  if (-1 == shm_unlink(shm_name))
  {
    perror("faketime: shm_unlink");
  }
}

int main (int argc, char **argv)
{
  pid_t child_pid;
  int curr_opt = 1;
  bool use_mt = false, use_direct = false;
  long offset;
  bool fake_pid = false;
  const char *pid_val;

  while (curr_opt < argc)
  {
    if (0 == strcmp(argv[curr_opt], "-m"))
    {
      use_mt = true;
      curr_opt++;
      continue;
    }
    if (0 == strcmp(argv[curr_opt], "-p"))
    {
      fake_pid = true;
      pid_val = argv[curr_opt + 1];
      curr_opt += 2;
#ifndef FAKE_PID
      fprintf(stderr, "faketime: -p argument probably won't work (try rebuilding with -DFAKE_PID)\n");
#endif
      continue;
    }
    else if (0 == strcmp(argv[curr_opt], "-f"))
    {
      use_direct = true;
      curr_opt++;
      continue;
    }
    else if (0 == strcmp(argv[curr_opt], "--exclude-monotonic"))
    {
      setenv("FAKETIME_DONT_FAKE_MONOTONIC", "1", true);
      curr_opt++;
      continue;
    }
    else if (0 == strcmp(argv[curr_opt], "--date-prog"))
    {
      curr_opt++;
      if (curr_opt > argc) {
        // At best this avoids a segfault reading beyond the argv[]
        // Realistically there would be other args (e.g. program to call)
        fprintf(stderr, "faketime: --date-prog requires a further argument\n");
      } else {
        date_cmd = argv[curr_opt];
        curr_opt++;
        //fprintf(stderr, "faketime: --date-prog assigned: %s\n", date_cmd);
      }
      continue;
    }
    else if ((0 == strcmp(argv[curr_opt], "-v")) ||
             (0 == strcmp(argv[curr_opt], "--version")))
    {
      printf("\n%s: Version %s\n"
         "For usage information please use '%s --help'.\n",
         argv[0], version, argv[0]);
      exit(EXIT_SUCCESS);
    }
    else if ((0 == strcmp(argv[curr_opt], "-h")) ||
             (0 == strcmp(argv[curr_opt], "-?")) ||
             (0 == strcmp(argv[curr_opt], "--help")))
    {
      usage(argv[0]);
      exit(EXIT_SUCCESS);
    }
    else
    {
      /* we parsed all options */
      break;
    }
  }

  /* we need at least a timestamp string and a command to run */
  if (argc - curr_opt < 2)
  {
    usage(argv[0]);
    exit(EXIT_FAILURE);
  }

  if (!use_direct)
  {
    // TODO get seconds
    int pfds[2];
    (void) (pipe(pfds) + 1);
    int ret = EXIT_SUCCESS;

    if (0 == (child_pid = fork()))
    {
      close(1);       /* close normal stdout */
      (void) (dup(pfds[1]) + 1);   /* make stdout same as pfds[1] */
      close(pfds[0]); /* we don't need this */
      // fprintf(stderr, "faketime: using --date-prog: %s\n", date_cmd);
      if (EXIT_SUCCESS != execlp(date_cmd, date_cmd, "-d", argv[curr_opt], "+%s",(char *) NULL))
      {
        perror("faketime: Running (g)date failed");
        exit(EXIT_FAILURE);
      }
    }
    else
    {
      char buf[256] = {0}; /* e will have way less than 256 digits */
      close(pfds[1]);   /* we won't write to this */
      (void) (read(pfds[0], buf, 256) + 1);
      waitpid(child_pid, &ret, 0);
      if (ret != EXIT_SUCCESS)
      {
        printf("Error: Timestamp to fake not recognized, please re-try with a "
               "different timestamp.\n");
        exit(EXIT_FAILURE);
      }
      offset = atol(buf) - time(NULL);
      ret = snprintf(buf, sizeof(buf), "%s%ld", (offset >= 0)?"+":"", offset);
      setenv("FAKETIME", buf, true);
      close(pfds[0]); /* finished reading */
    }
  }
  else
  {
    /* simply pass format string along */
    setenv("FAKETIME", argv[curr_opt], true);
  }
  if (fake_pid)
    setenv("FAKETIME_FAKEPID", pid_val, true);
  int keepalive_fds[2];
  (void) (pipe(keepalive_fds) + 1);

  /* we just consumed the timestamp option */
  curr_opt++;

  {
    /* create semaphores and shared memory */
    int shm_fd;
    sem_t *sem;
    struct ft_shared_s *ft_shared;
    char shared_objs[PATH_BUFSIZE * 2 + 1];

    /*
     * Casting of getpid() return value to long needed to make GCC on SmartOS
     * happy, since getpid's return value's type on SmartOS is long. Since
     * getpid's return value's type is int on most other systems, and that
     * sizeof(long) always >= sizeof(int), this works on all platforms without
     * the need for crazy #ifdefs.
     */
    snprintf(sem_name, PATH_BUFSIZE -1 ,"/faketime_sem_%ld", (long)getpid());
    snprintf(shm_name, PATH_BUFSIZE -1 ,"/faketime_shm_%ld", (long)getpid());

    if (SEM_FAILED == (sem = sem_open(sem_name, O_CREAT|O_EXCL, S_IWUSR|S_IRUSR, 1)))
    {
      perror("faketime: sem_open");
      fprintf(stderr, "The faketime wrapper only works on platforms that support the sem_open()\nsystem call. However, you may LD_PRELOAD libfaketime without using this wrapper.\n");
      exit(EXIT_FAILURE);
    }

    /* create shm */
    if (-1 == (shm_fd = shm_open(shm_name, O_CREAT|O_EXCL|O_RDWR, S_IWUSR|S_IRUSR)))
    {
      perror("faketime: shm_open");
      if (-1 == sem_unlink(argv[2]))
      {
        perror("faketime: sem_unlink");
      }
      exit(EXIT_FAILURE);
    }

    /* set shm size */
    if (-1 == ftruncate(shm_fd, sizeof(uint64_t)))
    {
      perror("faketime: ftruncate");
      cleanup_shobjs();
      exit(EXIT_FAILURE);
    }

    /* map shm */
    if (MAP_FAILED == (ft_shared = mmap(NULL, sizeof(struct ft_shared_s), PROT_READ|PROT_WRITE,
                        MAP_SHARED, shm_fd, 0)))
    {
      perror("faketime: mmap");
      cleanup_shobjs();
      exit(EXIT_FAILURE);
    }

    if (sem_wait(sem) == -1)
    {
      perror("faketime: sem_wait");
      cleanup_shobjs();
      exit(EXIT_FAILURE);
    }

    /* init elapsed time ticks to zero */
    ft_shared->ticks = 0;
    ft_shared->file_idx = 0;
    ft_shared->start_time.real.tv_sec = 0;
    ft_shared->start_time.real.tv_nsec = -1;
    ft_shared->start_time.mon.tv_sec = 0;
    ft_shared->start_time.mon.tv_nsec = -1;
    ft_shared->start_time.mon_raw.tv_sec = 0;
    ft_shared->start_time.mon_raw.tv_nsec = -1;

    if (-1 == munmap(ft_shared, (sizeof(struct ft_shared_s))))
    {
      perror("faketime: munmap");
      cleanup_shobjs();
      exit(EXIT_FAILURE);
    }

    if (sem_post(sem) == -1)
    {
      perror("faketime: semop");
      cleanup_shobjs();
      exit(EXIT_FAILURE);
    }

    snprintf(shared_objs, sizeof(shared_objs), "%s %s", sem_name, shm_name);
    setenv("FAKETIME_SHARED", shared_objs, true);
    sem_close(sem);
  }

  {
    char *ftpl_path;
#ifdef __APPLE__
    ftpl_path = PREFIX "/libfaketime.1.dylib";
    FILE *check;
    check = fopen(ftpl_path, "ro");
    if (check == NULL)
    {
      ftpl_path = PREFIX "/lib/faketime/libfaketime.1.dylib";
    }
    else
    {
      fclose(check);
    }
    setenv("DYLD_INSERT_LIBRARIES", ftpl_path, true);
    setenv("DYLD_FORCE_FLAT_NAMESPACE", "1", true);
#else
    {
      char *ld_preload_new, *ld_preload = getenv("LD_PRELOAD");
      size_t len;
      if (use_mt)
      {
        /*
         * on MultiArch platforms, such as Debian, we put a literal $LIB into LD_PRELOAD.
         */
#ifndef MULTI_ARCH
        ftpl_path = PREFIX LIBDIRNAME "/libfaketimeMT.so.1";
#else
        ftpl_path = PREFIX "/$LIB/faketime/libfaketimeMT.so.1";
#endif
      }
      else
      {
#ifndef MULTI_ARCH
        ftpl_path = PREFIX LIBDIRNAME "/libfaketime.so.1";
#else
        ftpl_path = PREFIX "/$LIB/faketime/libfaketime.so.1";
#endif
      }
      len = ((ld_preload)?strlen(ld_preload) + 1: 0) + 1 + strlen(ftpl_path);
      ld_preload_new = malloc(len);
      snprintf(ld_preload_new, len ,"%s%s%s", (ld_preload)?ld_preload:"",
              (ld_preload)?":":"", ftpl_path);
      setenv("LD_PRELOAD", ld_preload_new, true);
      free(ld_preload_new);
    }
#endif
  }

  /* run command and clean up shared objects */
  if (0 == (child_pid = fork()))
  {
    close(keepalive_fds[0]); /* only parent needs to read this */
    // fprintf(stderr, "faketime: Executing: %s\n", argv[curr_opt]);
    if (EXIT_SUCCESS != execvp(argv[curr_opt], &argv[curr_opt]))
    {
      perror("faketime: Running specified command failed");
      exit(EXIT_FAILURE);
    }
  }
  else
  {
    int ret;
    char buf;
    close(keepalive_fds[1]); /* only children need keep this open */
    waitpid(child_pid, &ret, 0);
    (void) (read(keepalive_fds[0], &buf, 1) + 1); /* reads 0B when all children exit */
    cleanup_shobjs();
    if (WIFSIGNALED(ret))
    {
      fprintf(stderr, "Caught %s\n", strsignal(WTERMSIG(ret)));
      exit(EXIT_FAILURE);
    }
    exit(WEXITSTATUS(ret));
  }

  return EXIT_SUCCESS;
}

/*
 * Editor modelines
 *
 * Local variables:
 * c-basic-offset: 2
 * tab-width: 2
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=2 tabstop=2 expandtab:
 * :indentSize=2:tabSize=2:noTabs=true:
 */

/* eof */