libsystemd: new library, refactor sd-daemon.[ch] test code

This commit introduces a bare-bones replacement for libsystemd:

 - Build .so file and add --with-libsystemd to configure
 - Add capabilities support to test/src/serv.c
 - Update tests to account for a Finit built w/o libsystemd support

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

test/src/.gitignore

@@ -1,5 +1,5 @@
 /Makefile
 /Makefile.in
-
+/.libs/
 /.deps/
 /serv

test/src/Makefile.am

@@ -1,4 +1,8 @@
 noinst_PROGRAMS = serv
 
-serv_SOURCES    = serv.c sd-daemon.c sd-daemon.h
-serv_CPPFLAGS   = -D_XOPEN_SOURCE=600 -D_BSD_SOURCE -D_GNU_SOURCE -D_DEFAULT_SOURCE
+serv_SOURCES    = serv.c
+serv_CPPFLAGS   = -D_XOPEN_SOURCE=600 -D_BSD_SOURCE -D_GNU_SOURCE -D_DEFAULT_SOURCE -I$(top_builddir)
+if LIBSYSTEMD
+serv_CPPFLAGS  += -I$(top_srcdir)/libsystemd
+serv_SOURCES   += $(top_srcdir)/libsystemd/sd-daemon.c
+endif

test/src/sd-daemon.c

@@ -1,84 +0,0 @@
-/* SPDX-License-Identifier: MIT-0 */
-
-/*
- * systemd notify protocol, supporting readiness notification on startup
- * and reloading, according to the protocol defined at:
- * https://www.freedesktop.org/software/systemd/man/latest/sd_notify.html
- *
- * This protocol is guaranteed to be stable as per:
- * https://systemd.io/PORTABILITY_AND_STABILITY/
- */
-
-#define _GNU_SOURCE 1
-#include <errno.h>
-#include <inttypes.h>
-#include <signal.h>
-#include <stdbool.h>
-#include <stddef.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-#include <sys/socket.h>
-#include <sys/un.h>
-#include <time.h>
-#include <unistd.h>
-
-/*
- * NOTE: As per spec., this function does not return POSIX OK(0) but
- *       rather "a positive value", i.e., 1.
- */
-int sd_notify(int unset_environment, const char *state)
-{
-	struct sockaddr_un sun = {
-		.sun_family = AF_UNIX,
-	};
-	size_t len, sun_len;
-	const char *path;
-	ssize_t written;
-	int sd;
-
-	if (!state)
-		return -EINVAL;
-
-	len = strlen(state);
-	if (len == 0)
-		return -EINVAL;
-
-	/* If the variable is not set, the protocol is a noop */
-	path = getenv("NOTIFY_SOCKET");
-	if (!path)
-		return 0;	/* Not set? Nothing to do */
-
-	/* Only AF_UNIX is supported, with path or abstract sockets */
-	if (path[0] != '/' && path[0] != '@')
-		return -EAFNOSUPPORT;
-
-	/* Ensure there is room for NUL byte */
-	sun_len = strlen(path);
-	if (sun_len >= sizeof(sun.sun_path))
-		return -E2BIG;
-
-	strlcpy(sun.sun_path, path, sizeof(sun.sun_path));
-	if (sun.sun_path[0] == '@')
-		sun.sun_path[0] = 0;
-
-	sd = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
-	if (sd == -1)
-		return -errno;
-
-	if (connect(sd, (struct sockaddr *)&sun, offsetof(struct sockaddr_un, sun_path) + sun_len) == -1) {
-		close(sd);
-		return -errno;
-	}
-
-	if (unset_environment)
-		unsetenv("NOTIFY_SOCKET");
-
-	written = write(sd, state, len);
-	if (written != (ssize_t) len) {
-		close(sd);
-		return written < 0 ? -errno : -EPROTO;
-	}
-
-	return 1;
-}

test/src/sd-daemon.h

@@ -1,6 +0,0 @@
-#ifndef SD_DAEMON_H_
-#define SD_DAEMON_H_
-
-int sd_notify(int unset_environment, const char *state);
-
-#endif	/* SD_DAEMON_H_ */

test/src/serv.c

@@ -5,6 +5,10 @@
  * in foregrund it does not create a PID file by default.
  */
 
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
 #include <errno.h>
 #include <fcntl.h>
 #include <paths.h>
@@ -16,7 +20,9 @@
 #include <sysexits.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
+#ifdef HAVE_LIBSYSTEMD
 #include "sd-daemon.h"
+#endif
 
 #define PROGNM "serv"
 
@@ -146,6 +152,16 @@ static void pidfile(char *pidfn)
 	}
 }
 
+static int capabilities(void)
+{
+#ifdef HAVE_LIBSYSTEMD
+	puts("libsystemd");
+#endif
+	puts("s6");
+
+	return 0;
+}
+
 static int usage(int rc)
 {
 	FILE *fp = rc ? stderr : stdout;
@@ -153,6 +169,7 @@ static int usage(int rc)
 	fprintf(fp,
 		"%s [-nhp] [-P FILE]\n"
 		"\n"
+		" -C       Show capabilities and exit\n"
 		" -c       Crash (exit) immediately\n"
 		" -e K:V   Verify K environment variable is V value\n"
 		" -E K     Verify K is not set in the environment\n"
@@ -195,11 +212,13 @@ int main(int argc, char *argv[])
 	char cmd[80];
 	int c;
 
-	while ((c = getopt(argc, argv, "ce:E:f:F:hi:nN:pP:r:")) != EOF) {
+	while ((c = getopt(argc, argv, "cCe:E:f:F:hi:nN:pP:r:")) != EOF) {
 		switch (c) {
 		case 'c':
 			do_crash = 1;
 			break;
+		case 'C':
+			return capabilities();
 		case 'e':
 			verify_env(optarg);
 			break;
@@ -295,11 +314,15 @@ int main(int argc, char *argv[])
 						err(1, "Failed closing notify socket");
 					do_notify = 0;
 				} else {
+#ifdef HAVE_LIBSYSTEMD
 					int rc;
 
 					inf("Notifying Finit on NOTIFY_SOCKET");
 					rc = sd_notify(0, "READY=1");
 					inf("sd_notify () => %d", rc);
+#else
+					inf("Skipping systemd notify - built without libsystemd support");
+#endif
 				}
 			}
 			if (do_pidfile > 0)