Tooltron

#include "util.h"

#include "log.h"

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#define BUF_SIZE 1024

/*

 * read_file

 *

 * Reads the first line of a file. Returns NULL on error, or a pointer to a

 * malloc'd string which should later be freed.

 */

char *read_file(const char *filename) {

  char buf[BUF_SIZE];

  int len;

  FILE *file;

  file = fopen(filename, "r");

  if (file == NULL) {

    log_perror(filename);

    return NULL;

  }

  fgets(buf, BUF_SIZE, file);

  if (ferror(file)) {

    log_perror(filename);

    fclose(file);

    return NULL;

  }

  len = strlen(buf);

  if (len > 0 && buf[len-1] == '\n')

    buf[len-1] = '\0';

  fclose(file);

  return strdup(buf);

}

/*

 * create_pid_file

 *

 * Creates PIDFILE containing the PID of the current process.  Returns 0 if

 * successful, or nonzero if there is an error or it already exists.

 */

int create_pid_file() {

  int fd;

  FILE *file;

  fd = open(PIDFILE, O_CREAT | O_EXCL | O_WRONLY, 0644);

  if (fd < 0) {

    if (errno == EEXIST)

      fprintf(stderr, "ERROR: tooltron is already running, or the pidfile "

          PIDFILE " is stale");

    else

      log_perror(PIDFILE);

    return 1;

  }

  file = fdopen(fd, "w");

  if (!file) {

    log_perror("fdopen");

    return 1;

  }

  fprintf(file, "%d", getpid());

  fclose(file);

  return 0;

}

/*

 * remove_pid_file

 *

 * Removes PIDFILE.

 */

void remove_pid_file() {

  if (unlink(PIDFILE))

    log_perror(PIDFILE);

}

/*

 * read_pid_file

 *

 * Returns the integer found in PIDFILE, or 0 if there was an

 * error.

 */

pid_t read_pid_file() {

  FILE *file;

  int pid;

  file = fopen(PIDFILE, "r");

  if (!file) {

    if (errno == ENOENT)

      fprintf(stderr, "ERROR: tooltron does not appear to be running\n");

    else

      perror(PIDFILE);

    return 0;

  }

  if (fscanf(file, "%d", &pid) != 1) {

    perror("fscanf");

    fclose(file);

    return 0;

  }

  fclose(file);

  return pid;

}