Add a --version option displaying that, and also include this
information in the log files.

Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>
---
v2:
  - Drop (C) and years from license notice in version information (David
    Gibson)
  - Rewrite commit message (David Gibson)
  - Drop short form -v, it often means --verbose (David Gibson)

 Makefile | 3 +++
 conf.c   | 8 ++++++++
 log.c    | 4 ++--
 passt.1  | 4 ++++
 util.h   | 8 ++++++++
 5 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index fafb024..f7ddb84 100644
--- a/Makefile
+++ b/Makefile
@@ -9,6 +9,8 @@
 # Copyright (c) 2021 Red Hat GmbH
 # Author: Stefano Brivio <sbrivio(a)redhat.com>
 
+VERSION ?= $(shell git describe --tags HEAD || echo "unknown\ version")
+
 RLIMIT_STACK_VAL := $(shell /bin/sh -c 'ulimit -s')
 ifeq ($(RLIMIT_STACK_VAL),unlimited)
 RLIMIT_STACK_VAL := 1024
@@ -31,6 +33,7 @@ FLAGS += -DNETNS_RUN_DIR=\"/run/netns\"
 FLAGS += -DPASST_AUDIT_ARCH=AUDIT_ARCH_$(AUDIT_ARCH)
 FLAGS += -DRLIMIT_STACK_VAL=$(RLIMIT_STACK_VAL)
 FLAGS += -DARCH=\"$(TARGET_ARCH)\"
+FLAGS += -DVERSION=\"$(VERSION)\"
 
 PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c icmp.c igmp.c \
 	isolation.c lineread.c log.c mld.c ndp.c netlink.c packet.c passt.c \
diff --git a/conf.c b/conf.c
index f22940b..7c3e346 100644
--- a/conf.c
+++ b/conf.c
@@ -626,6 +626,7 @@ static void usage(const char *name)
 	}
 	info("");
 
+
 	info(   "  -d, --debug		Be verbose, don't run in background");
 	info(   "      --trace		Be extra verbose, implies --debug");
 	info(   "  -q, --quiet		Don't print informational messages");
@@ -640,6 +641,7 @@ static void usage(const char *name)
 	info(   "    numeric, or login and group names");
 	info(   "    default: drop to user \"nobody\"");
 	info(   "  -h, --help		Display this help message and exit");
+	info(   "  --version		Show version and exit");
 
 	if (strstr(name, "pasta")) {
 		info(   "  -I, --ns-ifname NAME	namespace interface name");
@@ -1039,6 +1041,7 @@ void conf(struct ctx *c, int argc, char **argv)
 		{"trace",	no_argument,		NULL,		11 },
 		{"runas",	required_argument,	NULL,		12 },
 		{"log-size",	required_argument,	NULL,		13 },
+		{"version",	no_argument,		NULL,		14 },
 		{ 0 },
 	};
 	struct get_bound_ports_ns_arg ns_ports_arg = { .c = c };
@@ -1197,6 +1200,11 @@ void conf(struct ctx *c, int argc, char **argv)
 				usage(argv[0]);
 			}
 			break;
+		case 14:
+			fprintf(stdout,
+				c->mode == MODE_PASST ? "passt " : "pasta ");
+			fprintf(stdout, VERSION_BLOB);
+			exit(EXIT_SUCCESS);
 		case 'd':
 			if (c->debug) {
 				err("Multiple --debug options given");
diff --git a/log.c b/log.c
index 3bf0a18..47e4b4f 100644
--- a/log.c
+++ b/log.c
@@ -172,7 +172,7 @@ void passt_vsyslog(int pri, const char *format, va_list ap)
 }
 
 /**
- * logfile_init() - Open log file and write header with PID and path
+ * logfile_init() - Open log file and write header with PID, version, path
  * @name:	Identifier for header: passt or pasta
  * @path:	Path to log file
  * @size:	Maximum size of log file: log_cut_size is calculatd here
@@ -196,7 +196,7 @@ void logfile_init(const char *name, const char *path, size_t size)
 
 	log_size = size ? size : LOGFILE_SIZE_DEFAULT;
 
-	n = snprintf(log_header, sizeof(log_header), "%s: %s (%i)",
+	n = snprintf(log_header, sizeof(log_header), "%s " VERSION ": %s (%i)",
 		     name, exe, getpid());
 
 	if (write(log_file, log_header, n) <= 0 ||
diff --git a/passt.1 b/passt.1
index 64236b6..667c1bc 100644
--- a/passt.1
+++ b/passt.1
@@ -124,6 +124,10 @@ Default is to change to user \fInobody\fR if started as root.
 .BR \-h ", " \-\-help
 Display a help message and exit.
 
+.TP
+.BR \-\-version
+Show version and exit.
+
 .TP
 .BR \-p ", " \-\-pcap " " \fIfile
 Capture tap-facing (that is, guest-side or namespace-side) network packets to
diff --git a/util.h b/util.h
index 1adbf04..f9a8ec6 100644
--- a/util.h
+++ b/util.h
@@ -6,6 +6,14 @@
 #ifndef UTIL_H
 #define UTIL_H
 
+#define VERSION_BLOB							       \
+	VERSION "\n"							       \
+	"Copyright Red Hat\n"						       \
+	"GNU Affero GPL version 3 or later "				       \
+	"<https://www.gnu.org/licenses/agpl-3.0.html>\n"		       \
+	"This is free software: you are free to change and redistribute it.\n" \
+	"There is NO WARRANTY, to the extent permitted by law.\n\n"
+
 #ifndef SECCOMP_RET_KILL_PROCESS
 #define SECCOMP_RET_KILL_PROCESS	SECCOMP_RET_KILL
 #endif
-- 
2.35.1