libiberty/tmpnam.c

   1 /*
   2
   3 @deftypefn Supplemental char* tmpnam (char *@var{s})
   4
   5 This function attempts to create a name for a temporary file, which
   6 will be a valid file name yet not exist when @code{tmpnam} checks for
   7 it.  @var{s} must point to a buffer of at least @code{L_tmpnam} bytes,
   8 or be @code{NULL}.  Use of this function creates a security risk, and it must
   9 not be used in new projects.  Use @code{mkstemp} instead.
  10
  11 @end deftypefn
  12
  13 */
  14
  15 #include <stdio.h>
  16
  17 #ifndef L_tmpnam
  18 #define L_tmpnam 100
  19 #endif
  20 #ifndef P_tmpdir
  21 #define P_tmpdir "/usr/tmp"
  22 #endif
  23
  24 static char tmpnam_buffer[L_tmpnam];
  25 static int tmpnam_counter;
  26
  27 extern int getpid (void);
  28
  29 char *
  30 tmpnam (char *s)
  31 {
  32   int pid = getpid ();
  33
  34   if (s == NULL)
  35     s = tmpnam_buffer;
  36
  37   /*  Generate the filename and make sure that there isn't one called
  38       it already.  */
  39
  40   while (1)
  41     {
  42       FILE *f;
  43       sprintf (s, "%s/%s%x.%x", P_tmpdir, "t", pid, tmpnam_counter);
  44       f = fopen (s, "r");
  45       if (f == NULL)
  46         break;
  47       tmpnam_counter++;
  48       fclose (f);
  49     }
  50
  51   return s;
  52 }