support compilation & use without libsystemd

Allows us to run on travis more easily, but also potentially allows
slightly greater portability.

Default is to require libsystemd unless the --without-libsystemd flag
is passed to configure (ie: default behaivor stays the same without
extra flag).

Could be relaxed to auto-select in the future if desired.

Author: codyps

configure.ac

@@ -62,8 +62,16 @@ AC_CHECK_DECLS([gettid, getrandom], [], [], [[
 #include <linux/random.h>
 ]])
 
-PKG_CHECK_MODULES(LIBSYSTEMD, [libsystemd >= 221],
-	[], [AC_MSG_ERROR([*** libsystemd library not found])])
+AC_ARG_WITH(libsystemd,
+        AS_HELP_STRING([--without-libsystemd], [Disable use of libsystemd for journal output]),
+        [], [with_libsystemd=yes])
+
+AS_IF([test "x$with_libsystemd" != xno],
+        [PKG_CHECK_MODULES(LIBSYSTEMD, [libsystemd >= 221],
+                [AC_DEFINE([HAVE_LIBSYSTEMD],[1],[Define if you have libsystemd])],
+                [AC_MSG_ERROR([*** libsystemd library not found])]
+        )]
+)
 
 CC_CHECK_FLAGS_APPEND([with_cflags], [CFLAGS], [\
         -pipe \

src/bootchart.c

@@ -45,7 +45,9 @@
 #include <time.h>
 #include <unistd.h>
 
+#ifdef HAVE_LIBSYSTEMD
 #include <systemd/sd-journal.h>
+#endif
 
 #include "alloc-util.h"
 #include "bootchart.h"
@@ -258,6 +260,7 @@ static int parse_argv(int argc, char *argv[]) {
 }
 
 static int do_journal_append(char *file) {
+#ifdef HAVE_LIBSYSTEMD
         _cleanup_free_ char *bootchart_message = NULL;
         _cleanup_free_ char *bootchart_file = NULL;
         _cleanup_free_ char *p = NULL;
@@ -301,6 +304,9 @@ static int do_journal_append(char *file) {
         if (r < 0)
                 log_error_errno(r, "Failed to send bootchart: %m");
 
+#else
+        (void)file;
+#endif
         return 0;
 }
 

src/log.c

@@ -323,7 +323,9 @@ int log_syntax_internal(
         r = log_struct_internal(
                         level, error,
                         file, line, func,
+#ifdef HAVE_LIBSYSTEMD
                         LOG_MESSAGE_ID(SD_MESSAGE_INVALID_CONFIGURATION),
+#endif
                         "CONFIG_FILE=%s", config_file,
                         "CONFIG_LINE=%u", config_line,
                         LOG_MESSAGE("[%s:%u] %s", config_file, config_line, buffer),

src/log.h

@@ -24,8 +24,6 @@
 #include <stdlib.h>
 #include <syslog.h>
 
-#include <systemd/sd-id128.h>
-
 #include "alloc-util.h"
 #include "attributes.h"
 

src/sd-messages.h

@@ -20,6 +20,7 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
+#ifdef HAVE_LIBSYSTEMD
 #include <systemd/sd-id128.h>
 
 #include "_sd-common.h"
@@ -30,5 +31,6 @@ _SD_BEGIN_DECLARATIONS;
 #define SD_MESSAGE_BOOTCHART             SD_ID128_MAKE(9f,26,aa,56,2c,f4,40,c2,b1,6c,77,3d,04,79,b5,18)
 
 _SD_END_DECLARATIONS;
+#endif
 
 #endif