1 files changed, 83 insertions, 0 deletions

diff --git a/src/lib/libc/stdlib/__mktemp4.c b/src/lib/libc/stdlib/__mktemp4.c
new file mode 100644
index 0000000000..4b4500018b
--- /dev/null
+++ b/src/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;
+}