tempname.c 6.7 KB

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  1. /* Copyright (C) 1991,92,93,94,95,96,97,98,99 Free Software Foundation, Inc.
  2. This file is part of the GNU C Library.
  3. The GNU C Library is free software; you can redistribute it and/or
  4. modify it under the terms of the GNU Library General Public License as
  5. published by the Free Software Foundation; either version 2 of the
  6. License, or (at your option) any later version.
  7. The GNU C Library is distributed in the hope that it will be useful,
  8. but WITHOUT ANY WARRANTY; without even the implied warranty of
  9. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  10. Library General Public License for more details.
  11. You should have received a copy of the GNU Library General Public
  12. License along with the GNU C Library; see the file COPYING.LIB. If not,
  13. write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  14. Boston, MA 02111-1307, USA. */
  15. /* March 11, 2002 Manuel Novoa III
  16. *
  17. * Modify code to remove dependency on libgcc long long arith support funcs.
  18. */
  19. /* June 6, 2004 Erik Andersen
  20. *
  21. * Don't use brain damaged getpid() based randomness.
  22. */
  23. /* April 15, 2005 Mike Frysinger
  24. *
  25. * Use brain damaged getpid() if real random fails.
  26. */
  27. #include <stddef.h>
  28. #include <stdint.h>
  29. #include <stdio.h>
  30. #include <stdlib.h>
  31. #include <string.h>
  32. #include <errno.h>
  33. #include <fcntl.h>
  34. #include <unistd.h>
  35. #include <assert.h>
  36. #include <sys/types.h>
  37. #include <sys/stat.h>
  38. #include <sys/time.h>
  39. #include "tempname.h"
  40. /* Return nonzero if DIR is an existent directory. */
  41. static int direxists (const char *dir)
  42. {
  43. struct stat buf;
  44. return stat(dir, &buf) == 0 && S_ISDIR (buf.st_mode);
  45. }
  46. /* Path search algorithm, for tmpnam, tmpfile, etc. If DIR is
  47. non-null and exists, uses it; otherwise uses the first of $TMPDIR,
  48. P_tmpdir, /tmp that exists. Copies into TMPL a template suitable
  49. for use with mk[s]temp. Will fail (-1) if DIR is non-null and
  50. doesn't exist, none of the searched dirs exists, or there's not
  51. enough space in TMPL. */
  52. int attribute_hidden ___path_search (char *tmpl, size_t tmpl_len, const char *dir,
  53. const char *pfx /*, int try_tmpdir*/)
  54. {
  55. /*const char *d; */
  56. /* dir and pfx lengths should always fit into an int,
  57. so don't bother using size_t here. Especially since
  58. the printf func requires an int for precision (%*s). */
  59. int dlen, plen;
  60. if (!pfx || !pfx[0])
  61. {
  62. pfx = "file";
  63. plen = 4;
  64. }
  65. else
  66. {
  67. plen = strlen (pfx);
  68. if (plen > 5)
  69. plen = 5;
  70. }
  71. /* Disable support for $TMPDIR */
  72. #if 0
  73. if (try_tmpdir)
  74. {
  75. d = __secure_getenv ("TMPDIR");
  76. if (d != NULL && direxists (d))
  77. dir = d;
  78. else if (dir != NULL && direxists (dir))
  79. /* nothing */ ;
  80. else
  81. dir = NULL;
  82. }
  83. #endif
  84. if (dir == NULL)
  85. {
  86. if (direxists (P_tmpdir))
  87. dir = P_tmpdir;
  88. else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
  89. dir = "/tmp";
  90. else
  91. {
  92. __set_errno (ENOENT);
  93. return -1;
  94. }
  95. }
  96. dlen = strlen (dir);
  97. while (dlen > 1 && dir[dlen - 1] == '/')
  98. dlen--; /* remove trailing slashes */
  99. /* check we have room for "${dir}/${pfx}XXXXXX\0" */
  100. if (tmpl_len < dlen + 1 + plen + 6 + 1)
  101. {
  102. __set_errno (EINVAL);
  103. return -1;
  104. }
  105. sprintf (tmpl, "%.*s/%.*sXXXXXX", dlen, dir, plen, pfx);
  106. return 0;
  107. }
  108. /* These are the characters used in temporary filenames. */
  109. static const char letters[] =
  110. "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
  111. #define NUM_LETTERS (62)
  112. static unsigned int fillrand(unsigned char *buf, unsigned int len)
  113. {
  114. int fd;
  115. unsigned int result = -1;
  116. fd = open("/dev/urandom", O_RDONLY);
  117. if (fd < 0) {
  118. fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
  119. }
  120. if (fd >= 0) {
  121. result = read(fd, buf, len);
  122. close(fd);
  123. }
  124. return result;
  125. }
  126. static void brain_damaged_fillrand(unsigned char *buf, unsigned int len)
  127. {
  128. unsigned int i, k;
  129. struct timeval tv;
  130. uint32_t high, low, rh;
  131. static uint64_t value;
  132. gettimeofday(&tv, NULL);
  133. value += ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid();
  134. low = value & UINT32_MAX;
  135. high = value >> 32;
  136. for (i = 0; i < len; ++i) {
  137. rh = high % NUM_LETTERS;
  138. high /= NUM_LETTERS;
  139. #define L ((UINT32_MAX % NUM_LETTERS + 1) % NUM_LETTERS)
  140. k = (low % NUM_LETTERS) + (L * rh);
  141. #undef L
  142. #define H ((UINT32_MAX / NUM_LETTERS) + ((UINT32_MAX % NUM_LETTERS + 1) / NUM_LETTERS))
  143. low = (low / NUM_LETTERS) + (H * rh) + (k / NUM_LETTERS);
  144. #undef H
  145. k %= NUM_LETTERS;
  146. buf[i] = letters[k];
  147. }
  148. }
  149. /* Generate a temporary file name based on TMPL. TMPL must match the
  150. rules for mk[s]temp (i.e. end in "XXXXXX"). The name constructed
  151. does not exist at the time of the call to __gen_tempname. TMPL is
  152. overwritten with the result.
  153. KIND may be one of:
  154. __GT_NOCREATE: simply verify that the name does not exist
  155. at the time of the call. mode argument is ignored.
  156. __GT_FILE: create the file using open(O_CREAT|O_EXCL)
  157. and return a read-write fd with given mode.
  158. __GT_BIGFILE: same as __GT_FILE but use open64().
  159. __GT_DIR: create a directory with given mode.
  160. */
  161. int __gen_tempname (char *tmpl, int kind, mode_t mode)
  162. {
  163. char *XXXXXX;
  164. unsigned int i;
  165. int fd, save_errno = errno;
  166. unsigned char randomness[6];
  167. size_t len;
  168. len = strlen (tmpl);
  169. /* This is where the Xs start. */
  170. XXXXXX = tmpl + len - 6;
  171. if (len < 6 || strcmp (XXXXXX, "XXXXXX"))
  172. {
  173. __set_errno (EINVAL);
  174. return -1;
  175. }
  176. for (i = 0; i < TMP_MAX; ++i) {
  177. int j;
  178. /* Get some random data. */
  179. if (fillrand(randomness, sizeof(randomness)) != sizeof(randomness)) {
  180. /* if random device nodes failed us, lets use the braindamaged ver */
  181. brain_damaged_fillrand(randomness, sizeof(randomness));
  182. }
  183. for (j = 0; j < sizeof(randomness); ++j)
  184. XXXXXX[j] = letters[randomness[j] % NUM_LETTERS];
  185. switch (kind) {
  186. case __GT_NOCREATE:
  187. {
  188. struct stat st;
  189. if (stat (tmpl, &st) < 0) {
  190. if (errno == ENOENT) {
  191. fd = 0;
  192. goto restore_and_ret;
  193. } else
  194. /* Give up now. */
  195. return -1;
  196. } else
  197. fd = 0;
  198. }
  199. case __GT_FILE:
  200. fd = open (tmpl, O_RDWR | O_CREAT | O_EXCL, mode);
  201. break;
  202. #if defined __UCLIBC_HAS_LFS__
  203. case __GT_BIGFILE:
  204. fd = open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, mode);
  205. break;
  206. #endif
  207. case __GT_DIR:
  208. fd = mkdir (tmpl, mode);
  209. break;
  210. default:
  211. fd = -1;
  212. assert (! "invalid KIND in __gen_tempname");
  213. }
  214. if (fd >= 0) {
  215. restore_and_ret:
  216. __set_errno (save_errno);
  217. return fd;
  218. }
  219. else if (errno != EEXIST)
  220. /* Any other error will apply also to other names we might
  221. try, and there are 2^32 or so of them, so give up now. */
  222. return -1;
  223. }
  224. /* We got out of the loop because we ran out of combinations to try. */
  225. __set_errno (EEXIST);
  226. return -1;
  227. }