src/stdio/tempnam.c

   1 #include <stdio.h>
   2 #include <fcntl.h>
   3 #include <errno.h>
   4 #include <sys/stat.h>
   5 #include <limits.h>
   6 #include <string.h>
   7 #include <stdlib.h>
   8 #include "syscall.h"
   9
  10 #define MAXTRIES 100
  11
  12 char *tempnam(const char *dir, const char *pfx)
  13 {
  14         char s[PATH_MAX];
  15         size_t l, dl, pl;
  16         int try;
  17         int r;
  18
  19         if (!dir) dir = P_tmpdir;
  20         if (!pfx) pfx = "temp";
  21
  22         dl = strlen(dir);
  23         pl = strlen(pfx);
  24         l = dl + 1 + pl + 1 + 6;
  25
  26         if (l >= PATH_MAX) {
  27                 errno = ENAMETOOLONG;
  28                 return 0;
  29         }
  30
  31         memcpy(s, dir, dl);
  32         s[dl] = '/';
  33         memcpy(s+dl+1, pfx, pl);
  34         s[dl+1+pl] = '_';
  35         s[l] = 0;
  36
  37         for (try=0; try<MAXTRIES; try++) {
  38                 __randname(s+l-6);
  39 #ifdef SYS_readlink
  40                 r = __syscall(SYS_readlink, s, (char[1]){0}, 1);
  41 #else
  42                 r = __syscall(SYS_readlinkat, AT_FDCWD, s, (char[1]){0}, 1);
  43 #endif
  44                 if (r == -ENOENT) return strdup(s);
  45         }
  46         return 0;
  47 }