/usr.bin/tail/misc.c

https://bitbucket.org/freebsd/freebsd-head/ · C · 115 lines · 61 code · 14 blank · 40 comment · 14 complexity · bc249ac6ab19d81539003fddc9e52561 MD5 · raw file

  1. /*-
  2. * Copyright (c) 1991, 1993
  3. * The Regents of the University of California. All rights reserved.
  4. *
  5. * This code is derived from software contributed to Berkeley by
  6. * Edward Sze-Tyan Wang.
  7. *
  8. * Redistribution and use in source and binary forms, with or without
  9. * modification, are permitted provided that the following conditions
  10. * are met:
  11. * 1. Redistributions of source code must retain the above copyright
  12. * notice, this list of conditions and the following disclaimer.
  13. * 2. Redistributions in binary form must reproduce the above copyright
  14. * notice, this list of conditions and the following disclaimer in the
  15. * documentation and/or other materials provided with the distribution.
  16. * 4. Neither the name of the University nor the names of its contributors
  17. * may be used to endorse or promote products derived from this software
  18. * without specific prior written permission.
  19. *
  20. * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21. * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23. * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24. * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25. * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26. * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29. * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30. * SUCH DAMAGE.
  31. */
  32. #include <sys/cdefs.h>
  33. __FBSDID("$FreeBSD$");
  34. #ifndef lint
  35. static const char sccsid[] = "@(#)misc.c 8.1 (Berkeley) 6/6/93";
  36. #endif
  37. #include <sys/types.h>
  38. #include <sys/stat.h>
  39. #include <sys/mman.h>
  40. #include <err.h>
  41. #include <errno.h>
  42. #include <stdio.h>
  43. #include <stdlib.h>
  44. #include <string.h>
  45. #include <unistd.h>
  46. #include "extern.h"
  47. void
  48. ierr(const char *fname)
  49. {
  50. warn("%s", fname);
  51. rval = 1;
  52. }
  53. void
  54. oerr(void)
  55. {
  56. err(1, "stdout");
  57. }
  58. /*
  59. * Print `len' bytes from the file associated with `mip', starting at
  60. * absolute file offset `startoff'. May move map window.
  61. */
  62. int
  63. mapprint(struct mapinfo *mip, off_t startoff, off_t len)
  64. {
  65. int n;
  66. while (len > 0) {
  67. if (startoff < mip->mapoff || startoff >= mip->mapoff +
  68. (off_t)mip->maplen) {
  69. if (maparound(mip, startoff) != 0)
  70. return (1);
  71. }
  72. n = (mip->mapoff + mip->maplen) - startoff;
  73. if (n > len)
  74. n = len;
  75. WR(mip->start + (startoff - mip->mapoff), n);
  76. startoff += n;
  77. len -= n;
  78. }
  79. return (0);
  80. }
  81. /*
  82. * Move the map window so that it contains the byte at absolute file
  83. * offset `offset'. The start of the map window will be TAILMAPLEN
  84. * aligned.
  85. */
  86. int
  87. maparound(struct mapinfo *mip, off_t offset)
  88. {
  89. if (mip->start != NULL && munmap(mip->start, mip->maplen) != 0)
  90. return (1);
  91. mip->mapoff = offset & ~((off_t)TAILMAPLEN - 1);
  92. mip->maplen = TAILMAPLEN;
  93. if ((off_t)mip->maplen > mip->maxoff - mip->mapoff)
  94. mip->maplen = mip->maxoff - mip->mapoff;
  95. if (mip->maplen <= 0)
  96. abort();
  97. if ((mip->start = mmap(NULL, mip->maplen, PROT_READ, MAP_SHARED,
  98. mip->fd, mip->mapoff)) == MAP_FAILED)
  99. return (1);
  100. return (0);
  101. }