bsd-flock.c 2.2 KB

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  1. /* $NetBSD: flock.c,v 1.6 2008/04/28 20:24:12 martin Exp $ */
  2. /*-
  3. * Copyright (c) 2001 The NetBSD Foundation, Inc.
  4. * All rights reserved.
  5. *
  6. * This code is derived from software contributed to The NetBSD Foundation
  7. * by Todd Vierling.
  8. *
  9. * Redistribution and use in source and binary forms, with or without
  10. * modification, are permitted provided that the following conditions
  11. * are met:
  12. * 1. Redistributions of source code must retain the above copyright
  13. * notice, this list of conditions and the following disclaimer.
  14. * 2. Redistributions in binary form must reproduce the above copyright
  15. * notice, this list of conditions and the following disclaimer in the
  16. * documentation and/or other materials provided with the distribution.
  17. *
  18. * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  19. * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  20. * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  21. * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  22. * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  23. * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  24. * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  25. * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  26. * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  27. * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  28. * POSSIBILITY OF SUCH DAMAGE.
  29. */
  30. /*
  31. * Emulate flock() with fcntl(), where available.
  32. * Otherwise, don't do locking; just pretend success.
  33. */
  34. #include "includes.h"
  35. #ifndef HAVE_FLOCK
  36. #include <errno.h>
  37. #include <fcntl.h>
  38. int
  39. flock(int fd, int op)
  40. {
  41. int rc = 0;
  42. #if defined(F_SETLK) && defined(F_SETLKW)
  43. struct flock fl = {0};
  44. switch (op & (LOCK_EX|LOCK_SH|LOCK_UN)) {
  45. case LOCK_EX:
  46. fl.l_type = F_WRLCK;
  47. break;
  48. case LOCK_SH:
  49. fl.l_type = F_RDLCK;
  50. break;
  51. case LOCK_UN:
  52. fl.l_type = F_UNLCK;
  53. break;
  54. default:
  55. errno = EINVAL;
  56. return -1;
  57. }
  58. fl.l_whence = SEEK_SET;
  59. rc = fcntl(fd, op & LOCK_NB ? F_SETLK : F_SETLKW, &fl);
  60. if (rc && (errno == EAGAIN))
  61. errno = EWOULDBLOCK;
  62. #else
  63. rc = -1;
  64. errno = ENOSYS;
  65. #endif
  66. return rc;
  67. }
  68. #endif