From 9cf4eed4faf08160ea86a41baec026d1c38ca844 Mon Sep 17 00:00:00 2001
From: jhb <jhb@FreeBSD.org>
Date: Mon, 28 Jul 2008 21:18:59 +0000
Subject: 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(-)

(limited to 'lib/libc/stdio/mktemp.c')

diff --git a/lib/libc/stdio/mktemp.c b/lib/libc/stdio/mktemp.c
index e8f51d4..3f1e699 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;
 			}
 		}
-- 
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