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 *
tmpnam(char * s)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 }
53