fusl/src/stdio/tempnam.c

#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/stat.h>
#include <limits.h>
#include <string.h>

#define MAXTRIES 100

char* __randname(char*);

char* tempnam(const char* dir, const char* pfx) {
  char s[PATH_MAX];
  size_t l, dl, pl;
  int try
    ;
  int r;

  if (!dir)
    dir = P_tmpdir;
  if (!pfx)
    pfx = "temp";

  dl = strlen(dir);
  pl = strlen(pfx);
  l = dl + 1 + pl + 1 + 6;

  if (l >= PATH_MAX) {
    errno = ENAMETOOLONG;
    return 0;
  }

  memcpy(s, dir, dl);
  s[dl] = '/';
  memcpy(s + dl + 1, pfx, pl);
  s[dl + 1 + pl] = '_';
  s[l] = 0;

  for (try = 0; try < MAXTRIES; try ++) {
    __randname(s + l - 6);
    r = lstat(s, &(struct stat){0});
    if (r == -ENOENT)
      return strdup(s);
  }
  return 0;
}