Test availability of mkstemps(3) and provide a fallback implementation

in case it is missing; needed for SUN Solaris 10.

1 files changed, 63 insertions, 0 deletions

diff --git a/compat_mkstemps.c b/compat_mkstemps.c
new file mode 100644
index 00000000..8dc4dd2b
--- /dev/null
+++ b/compat_mkstemps.c
@@ -0,0 +1,63 @@
+/* $Id$ */
+/*
+ * Copyright (c) 2015, 2021 Ingo Schwarze <schwarze@openbsd.org>
+ *
+ * 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.
+ *
+ * Parts of the algorithm of this function are inspired by OpenBSD
+ * mkdtemp(3) by Theo de Raadt and Todd Miller, but the code differs.
+ */
+#include "config.h"
+
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+int
+mkstemps(char *path, int suffixlen)
+{
+	char	*start, *end, *cp;
+	int	 fd, tries;
+	char	 backup;
+
+	end = strchr(path, '\0');
+	if (suffixlen < 0 || suffixlen > end - path - 6) {
+		errno = EINVAL;
+		return -1;
+	}
+	end -= suffixlen;
+	for (start = end; start > path; start--)
+		if (start[-1] != 'X')
+			break;
+
+	backup = *end;
+	for (tries = INT_MAX; tries; tries--) {
+		*end = '\0';
+		cp = mktemp(path);
+		*end = backup;
+		if (cp == NULL)
+			return -1;
+		fd = open(path, O_CREAT | O_EXCL | O_RDWR, S_IRUSR | S_IWUSR);
+		if (fd != -1)
+			return fd;
+		for (cp = start; cp < end; cp++)
+			*cp = 'X';
+		if (errno != EEXIST)
+			return -1;
+	}
+	errno = EEXIST;
+	return -1;
+}