// ssystem.cxx

#include "dataset_util/ssystem.h"
#include "dataset_util/Environment.h"
#include "dataset_util/FileStatus.h"
#include "dataset_util/WorkingDirectory.h"
#include "dataset_util/Text.h"
#include "dataset_util/TempDir.h"
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/wait.h>
#include <errno.h>
#include <iostream>

using std::string;
using std::cerr;
using std::endl;

//**********************************************************************
// Local definitions.
//**********************************************************************

namespace {

int block_sigchld() {
  // Mask SIGCHLD now and forever.
  sigset_t blkset;
  sigemptyset(&blkset);
  sigaddset(&blkset, SIGCHLD);
  pthread_sigmask(SIG_BLOCK, &blkset, 0);
  return 0;
}

// Block sigchld early in C_++ startup so nono-main threads
// won't intercept signals.
int sigchld_blocked = block_sigchld();

}  // end unnamed namespace

//**********************************************************************
// Functions.
//**********************************************************************

/*
int ssystem(string com) {
  sigset_t blkset;
  sigemptyset(&blkset);
  sigaddset(&blkset, SIGCHLD);
  pthread_sigmask(SIG_UNBLOCK, &blkset, 0);
  return system(com.c_str());
}
*/

//**********************************************************************

// Function.
// Much of implementation copied from www.opengroup.org.

int ssystem(string scmd, bool passenv) { 
  if ( scmd.size() == 0 ) {
    return -3;
  }
  // Lock the working directory so no other thread can change it.
  WorkingDirectory wd;
  bool dbg = false;
  if ( FileStatus("DEBUG_ssystem").exists() ) {
    dbg = true;
  }
  const char* cmd = scmd.c_str();
  int rstat;
  pid_t pid;
  struct sigaction sa, savintr, savequit;
  sigset_t saveblock;
  sa.sa_handler = SIG_IGN;
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = 0;
  sigemptyset(&savintr.sa_mask);
  sigemptyset(&savequit.sa_mask);
  sigaction(SIGINT, &sa, &savintr);
  sigaction(SIGQUIT, &sa, &savequit);
  // Fix action for SIGCHLD
  // April 2005 -- DIAL needs this in a few places.
  struct sigaction sa_chld, savechld;
  sigemptyset(&sa_chld.sa_mask);
  sa_chld.sa_flags = 0;
  sa_chld.sa_handler = SIG_DFL;
  sigemptyset(&savechld.sa_mask);
  sigaction(SIGCHLD, &sa_chld, &savechld);
  // End of fix
  sigaddset(&sa.sa_mask, SIGCHLD);
  sigprocmask(SIG_BLOCK, &sa.sa_mask, &saveblock);
  if ((pid = fork()) == 0) {
    if ( dbg ) sleep(30);
    sigaction(SIGINT, &savintr, (struct sigaction *)0);
    sigaction(SIGQUIT, &savequit, (struct sigaction *)0);
    sigprocmask(SIG_SETMASK, &saveblock, (sigset_t *)0);
    string newcmd;
    if ( passenv ) {
      newcmd = cmd;
      execl("/bin/sh", "sh", "-c", cmd, (char *)0);
    } else {
      const Environment& env = Environment::posix();
      execle("/bin/sh", "sh", "-c", cmd, (char *)0, env.unsafe_env());
    }
    cerr << "ssystem: exec call failed with error " << errno << endl;
    cerr << "  " << strerror(14) << endl;
    cerr << "  " << newcmd << endl;
    _exit(127);
  }
  if (pid == -1) {
    rstat = -1; /* errno comes from fork() */
  } else { 
    while (waitpid(pid, &rstat, 0) == -1) {
      int syserr = errno;
      if ( syserr == 0 ) {
        break;
      }
      if (syserr != EINTR){
        rstat = -1;
        break;
      }
    }
  }
  sigaction(SIGINT, &savintr, (struct sigaction *)0);
  sigaction(SIGQUIT, &savequit, (struct sigaction *)0);
  // Restore SIGCHLD action.
  sigaction(SIGCHLD, &savechld, (struct sigaction *)0);
  sigprocmask(SIG_SETMASK, &saveblock, (sigset_t *)0);
  if ( rstat != -1 ) {
    if ( WIFEXITED(rstat) ) {
      rstat = WEXITSTATUS(rstat);
    } else {
      rstat = -2;
    }
  }
  return rstat;
}

//**********************************************************************

// Mutex.

PThreadMutex& ssystem_mutex() {
  static PThreadMutex mtx;
  return mtx;
}

//**********************************************************************