xref: /csrg-svn/lib/libc/stdio/mktemp.c (revision 46611)

/*
 * Copyright (c) 1987 Regents of the University of California.
 * All rights reserved.
 *
 * %sccs.include.redist.c%
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)mktemp.c	5.10 (Berkeley) 02/24/91";
#endif /* LIBC_SCCS and not lint */

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

static int _gettemp();

mkstemp(path)
	char *path;
{
	int fd;

	return (_gettemp(path, &fd) ? fd : -1);
}

char *
mktemp(path)
	char *path;
{
	return(_gettemp(path, (int *)NULL) ? path : (char *)NULL);
}

static
_gettemp(path, doopen)
	char *path;
	register int *doopen;
{
	extern int errno;
	register char *start, *trv;
	struct stat sbuf;
	u_int pid;

	pid = getpid();
	for (trv = path; *trv; ++trv);		/* extra X's get set to 0's */
	while (*--trv == 'X') {
		*trv = (pid % 10) + '0';
		pid /= 10;
	}

	/*
	 * check the target directory; if you have six X's and it
	 * doesn't exist this runs for a *very* long time.
	 */
	for (start = trv + 1;; --trv) {
		if (trv <= path)
			break;
		if (*trv == '/') {
			*trv = '\0';
			if (stat(path, &sbuf))
				return(0);
			if (!S_ISDIR(sbuf.st_mode)) {
				errno = ENOTDIR;
				return(0);
			}
			*trv = '/';
			break;
		}
	}

	for (;;) {
		if (doopen) {
			if ((*doopen =
			    open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
				return(1);
			if (errno != EEXIST)
				return(0);
		}
		else if (stat(path, &sbuf))
			return(errno == ENOENT ? 1 : 0);

		/* tricky little algorithm for backward compatibility */
		for (trv = start;;) {
			if (!*trv)
				return(0);
			if (*trv == 'z')
				*trv++ = 'a';
			else {
				if (isdigit(*trv))
					*trv = 'a';
				else
					++*trv;
				break;
			}
		}
	}
	/*NOTREACHED*/
}