1 files changed, 141 insertions, 0 deletions
diff --git a/cmd/zgenhostid.c b/cmd/zgenhostid.c
new file mode 100644
index 000000000..853931c6a
--- /dev/null
+++ b/cmd/zgenhostid.c
@@ -0,0 +1,141 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2020, Georgy Yakovlev.  All rights reserved.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <time.h>
+#include <unistd.h>
+
+static __attribute__((noreturn)) void
+usage(void)
+{
+	(void) fprintf(stderr,
+	    "usage: zgenhostid [-fh] [-o path] [value]\n\n"
+	    "  -f\t\t force hostid file write\n"
+	    "  -h\t\t print this usage and exit\n"
+	    "  -o <filename>\t write hostid to this file\n\n"
+	    "If hostid file is not present, store a hostid in it.\n"
+	    "The optional value should be an 8-digit hex number between"
+	    " 1 and 2^32-1.\n"
+	    "If the value is 0 or no value is provided, a random one"
+	    " will be generated.\n"
+	    "The value must be unique among your systems.\n");
+	exit(EXIT_FAILURE);
+}
+
+int
+main(int argc, char **argv)
+{
+	/* default file path, can be optionally set by user */
+	const char *path = "/etc/hostid";
+	/* holds converted user input or lrand48() generated value */
+	unsigned long input_i = 0;
+
+	int opt;
+	int force_fwrite = 0;
+	while ((opt = getopt_long(argc, argv, "fo:h?", 0, 0)) != -1) {
+		switch (opt) {
+		case 'f':
+			force_fwrite = 1;
+			break;
+		case 'o':
+			path = optarg;
+			break;
+		case 'h':
+		case '?':
+			usage();
+		}
+	}
+
+	char *in_s = argv[optind];
+	if (in_s != NULL) {
+		/* increment pointer by 2 if string is 0x prefixed */
+		if (strncasecmp("0x", in_s, 2) == 0) {
+			in_s += 2;
+		}
+
+		/* need to be exactly 8 characters */
+		const char *hex = "0123456789abcdefABCDEF";
+		if (strlen(in_s) != 8 || strspn(in_s, hex) != 8) {
+			fprintf(stderr, "%s\n", strerror(ERANGE));
+			usage();
+		}
+
+		input_i = strtoul(in_s, NULL, 16);
+		if (errno != 0) {
+			perror("strtoul");
+			exit(EXIT_FAILURE);
+		}
+
+		if (input_i > UINT32_MAX) {
+			fprintf(stderr, "%s\n", strerror(ERANGE));
+			usage();
+		}
+	}
+
+	struct stat fstat;
+	if (force_fwrite == 0 && stat(path, &fstat) == 0 &&
+	    S_ISREG(fstat.st_mode)) {
+		fprintf(stderr, "%s: %s\n", path, strerror(EEXIST));
+		exit(EXIT_FAILURE);
+	}
+
+	/*
+	 * generate if not provided by user
+	 * also handle unlikely zero return from lrand48()
+	 */
+	while (input_i == 0) {
+		srand48(getpid() ^ time(NULL));
+		input_i = lrand48();
+	}
+
+	FILE *fp = fopen(path, "wb");
+	if (!fp) {
+		perror("fopen");
+		exit(EXIT_FAILURE);
+	}
+
+	/*
+	 * we need just 4 bytes in native endianness
+	 * not using sethostid() because it may be missing or just a stub
+	 */
+	uint32_t hostid = input_i;
+	int written = fwrite(&hostid, 1, 4, fp);
+	if (written != 4) {
+		perror("fwrite");
+		exit(EXIT_FAILURE);
+	}
+
+	fclose(fp);
+	exit(EXIT_SUCCESS);
+}