tempnam.c

-

/*
 * $Id: tempnam.c,v 1.10 1998/09/23 17:14:24 wessels Exp $
 */

/* A reasonably functional tmpnam. */

/* Originally by Tom Hageman, [e-mail] */

/*
 * This tmpnam() was changed by [e-mail] to serve as
 * tempnam() for squid-1.1.6. It ignores the directory parameter, every
 * temp file is written in /tmp.
 */

#include "config.h"

#if HAVE_LIBC_H
#include <libc.h>
#endif
#if HAVE_STDIO_H
#include <stdio.h>
#endif
#if HAVE_TYPES_H
#include <sys/types.h>
#endif
#if HAVE_LIMITS_H
#include <limits.h>
#endif
#if HAVE_UNISTD_H
#include <unistd.h>
#endif

#undef TMP_MAX

#define _tmp		"/tmp/"
#define lengthof_tmp	5

#ifndef LONG_BIT
#define LONG_BIT	(CHAR_BIT * 4)	/* assume sizeof(long) == 4 */
#endif

#define L_tmpmin	(lengthof_tmp + 5)	/* 5 chars for pid. */

#if (L_tmpnam > L_tmpmin)
#if (L_tmpnam > L_tmpmin + LONG_BIT / 6)	/* base 64 */
#define TMP_MAX	ULONG_MAX
#else
#define TMP_MAX	((1L << (6 * (L_tmpnam - L_tmpmin))) - 1)
#endif
#else
#ifndef L_tmpnam
#error "tmpnam: L_tmpnam undefined"
#else
#error "tmpnam: L_tmpnam too small"
#endif
#endif


static char *
_tmpnam(void)
{
    static const char digits[] =
#if (L_tmpnam >= L_tmpmin + LONG_BIT / 4)
    "0123456789abcdef";
#define TMP_BASE	16
#else
    "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-";
#define TMP_BASE	64
#endif
    static unsigned long lastcount = 0;
    static char buffer[L_tmpnam + 1];
    char *s = buffer;
    unsigned long count = lastcount;
    pid_t pid = getpid();

    if (sizeof(_tmp) - 1 != lengthof_tmp)
	abort();		/* Consistency error. */

    for (;;) {
	register int i = L_tmpnam;
	register unsigned long c;
	register unsigned int p;

	/* Build filename. (the hard way) */
	s += i;
	*s = '\0';

	c = (count == TMP_MAX) ? 0 : ++count;
	do {
	    *--s = digits[c % TMP_BASE];
	    c /= TMP_BASE;
	} while (--i > L_tmpmin);

	p = (unsigned int) pid;
	do {
	    *--s = digits[p % 10];
	    p /= 10;
	} while (--i > lengthof_tmp);

	do {
	    *--s = _tmp[--i];
	} while (i > 0);

	/* Check that the file doesn't exist. */
	if (access(s, 0) != 0)
	    break;

	/* It exists; retry unless we tried them all. */
	if (count == lastcount) {
	    s = NULL;
	    break;
	}
    }

    lastcount = count;

    return s;
}

char *
tempnam(const char *dir, const char *pfx)
{
    return _tmpnam();
}

#ifdef TEST
int
main()
{
    char *t;
    int n = 0;
    while ((t = tempnam(NULL, NULL))) {
	printf("%s\n", t);
	if (++n == 1000)
	    break;
    }
    return 1;
}
#endif