1 files changed, 83 insertions, 0 deletions
diff --git a/lib/libc/stdlib/__mktemp4.c b/lib/libc/stdlib/__mktemp4.c
new file mode 100644
index 00000000000..4b4500018b8
--- /dev/null
+++ b/lib/libc/stdlib/__mktemp4.c
@@ -0,0 +1,83 @@
+/*	$OpenBSD: __mktemp4.c,v 1.1 2024/01/19 19:45:02 millert Exp $ */
+/*
+ * Copyright (c) 1996-1998, 2008 Theo de Raadt
+ * Copyright (c) 1997, 2008-2009, 2024 Todd C. Miller
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <errno.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define TEMPCHARS	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
+#define NUM_CHARS	(sizeof(TEMPCHARS) - 1)
+#define MIN_X		6
+
+#ifndef nitems
+#define nitems(_a)	(sizeof((_a)) / sizeof((_a)[0]))
+#endif
+
+/*
+ * Internal driver for the mktemp(3) family of functions.
+ * The supplied callback does the actual work of testing or
+ * creating the file/directory.
+ */
+int
+__mktemp4(char *path, int slen, int flags, int (*cb)(const char *, int))
+{
+	char *start, *cp, *ep;
+	const char tempchars[] = TEMPCHARS;
+	unsigned int tries;
+	size_t len;
+	int ret;
+
+	len = strlen(path);
+	if (len < MIN_X || slen < 0 || (size_t)slen > len - MIN_X) {
+		errno = EINVAL;
+		return -1;
+	}
+	ep = path + len - slen;
+
+	for (start = ep; start > path && start[-1] == 'X'; start--)
+		;
+	if (ep - start < MIN_X) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	tries = INT_MAX;
+	do {
+		cp = start;
+		do {
+			unsigned short rbuf[16];
+			unsigned int i;
+
+			/*
+			 * Avoid lots of arc4random() calls by using
+			 * a buffer sized for up to 16 Xs at a time.
+			 */
+			arc4random_buf(rbuf, sizeof(rbuf));
+			for (i = 0; i < nitems(rbuf) && cp != ep; i++)
+				*cp++ = tempchars[rbuf[i] % NUM_CHARS];
+		} while (cp != ep);
+
+		ret = cb(path, flags);
+		if (ret != -1 || errno != EEXIST)
+			return ret;
+	} while (--tries);
+
+	errno = EEXIST;
+	return -1;
+}