#include <stdarg.h>
#include <sys/socket.h>
#include <stdio.h>
#include <unistd.h>
#include <syslog.h>
#include <time.h>
#include <signal.h>
#include <string.h>
#include <pthread.h>
#include <errno.h>
#include <fcntl.h>
#include "libc.h"

static volatile int lock[2];
static char log_ident[32];
static int log_opt;
static int log_facility = LOG_USER;
static int log_mask = 0xff;
static int log_fd = -1;

int setlogmask(int maskpri) {
  LOCK(lock);
  int ret = log_mask;
  if (maskpri)
    log_mask = maskpri;
  UNLOCK(lock);
  return ret;
}

static const struct {
  short sun_family;
  char sun_path[9];
} log_addr = {AF_UNIX, "/dev/log"};

void closelog(void) {
  int cs;
  pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
  LOCK(lock);
  close(log_fd);
  log_fd = -1;
  UNLOCK(lock);
  pthread_setcancelstate(cs, 0);
}

static void __openlog() {
  log_fd = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
  if (log_fd >= 0)
    connect(log_fd, (void*)&log_addr, sizeof log_addr);
}

void openlog(const char* ident, int opt, int facility) {
  int cs;
  pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
  LOCK(lock);

  if (ident) {
    size_t n = strnlen(ident, sizeof log_ident - 1);
    memcpy(log_ident, ident, n);
    log_ident[n] = 0;
  } else {
    log_ident[0] = 0;
  }
  log_opt = opt;
  log_facility = facility;

  if ((opt & LOG_NDELAY) && log_fd < 0)
    __openlog();

  UNLOCK(lock);
  pthread_setcancelstate(cs, 0);
}

static int is_lost_conn(int e) {
  return e == ECONNREFUSED || e == ECONNRESET || e == ENOTCONN || e == EPIPE;
}

static void _vsyslog(int priority, const char* message, va_list ap) {
  char timebuf[16];
  time_t now;
  struct tm tm;
  char buf[1024];
  int errno_save = errno;
  int pid;
  int l, l2;
  int hlen;
  int fd;

  if (log_fd < 0)
    __openlog();

  if (!(priority & LOG_FACMASK))
    priority |= log_facility;

  now = time(NULL);
  gmtime_r(&now, &tm);
  strftime(timebuf, sizeof timebuf, "%b %e %T", &tm);

  pid = (log_opt & LOG_PID) ? getpid() : 0;
  l = snprintf(buf, sizeof buf, "<%d>%s %n%s%s%.0d%s: ", priority, timebuf,
               &hlen, log_ident, pid ? "[" : "", pid, pid ? "]" : "");
  errno = errno_save;
  l2 = vsnprintf(buf + l, sizeof buf - l, message, ap);
  if (l2 >= 0) {
    if (l2 >= sizeof buf - l)
      l = sizeof buf - 1;
    else
      l += l2;
    if (buf[l - 1] != '\n')
      buf[l++] = '\n';
    if (send(log_fd, buf, l, 0) < 0 &&
        (!is_lost_conn(errno) ||
         connect(log_fd, (void*)&log_addr, sizeof log_addr) < 0 ||
         send(log_fd, buf, l, 0) < 0) &&
        (log_opt & LOG_CONS)) {
      fd = open("/dev/console", O_WRONLY | O_NOCTTY | O_CLOEXEC);
      if (fd >= 0) {
        dprintf(fd, "%.*s", l - hlen, buf + hlen);
        close(fd);
      }
    }
    if (log_opt & LOG_PERROR)
      dprintf(2, "%.*s", l - hlen, buf + hlen);
  }
}

void __vsyslog(int priority, const char* message, va_list ap) {
  int cs;
  if (!(log_mask & LOG_MASK(priority & 7)) || (priority & ~0x3ff))
    return;
  pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
  LOCK(lock);
  _vsyslog(priority, message, ap);
  UNLOCK(lock);
  pthread_setcancelstate(cs, 0);
}

void syslog(int priority, const char* message, ...) {
  va_list ap;
  va_start(ap, message);
  __vsyslog(priority, message, ap);
  va_end(ap);
}

weak_alias(__vsyslog, vsyslog);