thodg/got/lib/lockfile.c

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  Commit

• Author : Stefan Sperling
  Date : 2019-05-13 12:40:57
  Hash : 638f9024
  Message : rename got_error_prefix_errno() to got_error_from_errno()

• lib/lockfile.c

• /*
   * Copyright (c) 2019 Stefan Sperling <stsp@openbsd.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include <sys/stat.h>
  #include <sys/queue.h>
  
  #include <errno.h>
  #include <fcntl.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include <string.h>
  #include <stdio.h>
  #include <time.h>
  
  #include "got_error.h"
  #include "got_path.h"
  
  #include "got_lib_lockfile.h"
  
  const struct got_error *
  got_lockfile_lock(struct got_lockfile **lf, const char *path)
  {
  	const struct got_error *err = NULL;
  	int attempts = 5;
  
  	*lf = calloc(1, sizeof(**lf));
  	if (*lf == NULL)
  		return got_error_from_errno("calloc");
  	(*lf)->fd = -1;
  
  	(*lf)->locked_path = strdup(path);
  	if ((*lf)->locked_path == NULL) {
  		err = got_error_from_errno("strdup");
  		goto done;
  	}
  
  	if (asprintf(&(*lf)->path, "%s%s", path, GOT_LOCKFILE_SUFFIX) == -1) {
  		err = got_error_from_errno("asprintf");
  		goto done;
  	}
  
  	do {
  		(*lf)->fd = open((*lf)->path,
  		    O_RDONLY | O_CREAT | O_EXCL | O_EXLOCK,
  		    GOT_DEFAULT_FILE_MODE);
  		if ((*lf)->fd != -1)
  			break;
  		if (errno != EEXIST) {
  			err = got_error_from_errno2("open", (*lf)->path);
  			goto done;
  		}
  		sleep(1);
  	} while (--attempts > 0);
  
  	if ((*lf)->fd == -1)
  		err = got_error(GOT_ERR_LOCKFILE_TIMEOUT);
  done:
  	if (err) {
  		got_lockfile_unlock(*lf);
  		*lf = NULL;
  	}
  	return err;
  }
  
  const struct got_error *
  got_lockfile_unlock(struct got_lockfile *lf)
  {
  	const struct got_error *err = NULL;
  
  	if (lf->path && lf->fd != -1 && unlink(lf->path) != 0)
  		err = got_error_from_errno("unlink");
  	if (lf->fd != -1 && close(lf->fd) != 0 && err == NULL)
  		err = got_error_from_errno("close");
  	free(lf->path);
  	free(lf->locked_path);
  	free(lf);
  	return err;
  }