From e68d07ff16b5a25a38fd7f0a2ddf75a9415b9209 Mon Sep 17 00:00:00 2001
From: John Baldwin <jhb@FreeBSD.org>
Date: Mon, 28 Jul 2008 21:18:59 +0000
Subject: [PATCH] Fix a few bugs with the _gettemp() routine which implements
 mkstemp(), mkstemps(), and mkdtemp(). - Add proper range checking for the
 'slen' parameter passed to mkstemps(). - Try all possible permutations of a
 template if a collision is encountered.   Previously, once a single template
 character reached 'z', it would not wrap   around to '0' and keep going until
 it encountered the original starting   letter.  In the edge case that the
 randomly generated starting name used   all 'z' characters, only that single
 name would be tried before giving up.

PR:		standards/66531
Submitted by:	Jim Luther
Obtained from:	Apple
MFC after:	1 week
---
 lib/libc/stdio/mktemp.c | 37 ++++++++++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/lib/libc/stdio/mktemp.c b/lib/libc/stdio/mktemp.c
index e8f51d40e30b..3f1e699f213e 100644
--- a/lib/libc/stdio/mktemp.c
+++ b/lib/libc/stdio/mktemp.c
@@ -34,7 +34,7 @@ static char sccsid[] = "@(#)mktemp.c	8.1 (Berkeley) 6/4/93";
 __FBSDID("$FreeBSD$");
 
 #include "namespace.h"
-#include <sys/types.h>
+#include <sys/param.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <errno.h>
@@ -102,13 +102,14 @@ _gettemp(path, doopen, domkdir, slen)
 	int domkdir;
 	int slen;
 {
-	char *start, *trv, *suffp;
+	char *start, *trv, *suffp, *carryp;
 	char *pad;
 	struct stat sbuf;
 	int rval;
 	uint32_t rand;
+	char carrybuf[MAXPATHLEN];
 
-	if (doopen != NULL && domkdir) {
+	if ((doopen != NULL && domkdir) || slen < 0) {
 		errno = EINVAL;
 		return (0);
 	}
@@ -118,7 +119,7 @@ _gettemp(path, doopen, domkdir, slen)
 	trv -= slen;
 	suffp = trv;
 	--trv;
-	if (trv < path) {
+	if (trv < path || NULL != strchr(suffp, '/')) {
 		errno = EINVAL;
 		return (0);
 	}
@@ -130,6 +131,9 @@ _gettemp(path, doopen, domkdir, slen)
 	}
 	start = trv + 1;
 
+	/* save first combination of random characters */
+	memcpy(carrybuf, start, suffp - start);
+
 	/*
 	 * check the target directory.
 	 */
@@ -166,14 +170,25 @@ _gettemp(path, doopen, domkdir, slen)
 			return (errno == ENOENT);
 
 		/* If we have a collision, cycle through the space of filenames */
-		for (trv = start;;) {
-			if (*trv == '\0' || trv == suffp)
-				return (0);
+		for (trv = start, carryp = carrybuf;;) {
+			/* have we tried all possible permutations? */
+			if (trv == suffp)
+				return (0); /* yes - exit with EEXIST */
 			pad = strchr(padchar, *trv);
-			if (pad == NULL || *++pad == '\0')
-				*trv++ = padchar[0];
-			else {
-				*trv++ = *pad;
+			if (pad == NULL) {
+				/* this should never happen */
+				errno = EIO;
+				return (0);
+			}
+			/* increment character */
+			*trv = (*++pad == '\0') ? padchar[0] : *pad;
+			/* carry to next position? */
+			if (*trv == *carryp) {
+				/* increment position and loop */
+				++trv;
+				++carryp;
+			} else {
+				/* try with new name */
 				break;
 			}
 		}