Add a basic logger

Only syslog is supported at this time.
Signed-off-by: Shawn Webb <shawn.webb@hardenedbsd.org>

Makefile

 SHLIB=		lattutil
 SHLIB_MAJOR=	0
-SRCS=		config.c
 INCS=		liblattutil.h
 
+SRCS+=		config.c
+SRCS+=		log-main.c
+SRCS+=		log-syslog.c
+
 .PATH: ${.CURDIR}/src
 .PATH: ${.CURDIR}/include
 
+CFLAGS+=	-D_lattutil_internal
 CFLAGS+=	-I${.CURDIR}/include
 CFLAGS+=	-I/usr/local/include
 LDFLAGS+=	-L/usr/local/lib

include/liblattutil.h

@@ -28,11 +28,20 @@
 #include <stdbool.h>
 #include <sys/queue.h>
 #include <sys/stat.h>
+#include <stdarg.h>
 
 #include <ucl.h>
 
+struct _lllog;
+
 #define	EXPORTED_SYM	__attribute__((visibility("default")))
 
+#define LATTUTIL_LOG_VERBOSITY_DEFAULT	1000
+#define LATTUTIL_LOG_DEFAULT_NAME	"lattutil"
+
+typedef ssize_t (*log_cb)(struct _lllog *, int, const char *, ...);
+typedef void (*log_close)(struct _lllog *);
+
 /*
  * Though we export the underlying data structure, using the API is
  * preferred over directly accessing the ABI.
@@ -45,6 +54,13 @@ typedef struct _llconfig {
 	const ucl_object_t	*l_rootobj;
 } lattutil_config_path_t;
 
+typedef struct _lllog {
+	int		 ll_verbosity;
+	char		*ll_path;
+	log_cb		 ll_log_info;
+	log_close	 ll_log_close;
+} lattutil_log_t;
+
 /**
  * Find a configuration file in a set of given paths
  *
@@ -111,4 +127,38 @@ char *lattutil_find_config_string(const ucl_object_t *, const char *,
  */
 int64_t find_config_int(const ucl_object_t *, const char *, int64_t);
 
+/**
+ * Initialize logger
+ *
+ * @param Path
+ * @param Verbosity
+ * @return Pointer to the logging object
+ */
+lattutil_log_t *lattutil_log_init(char *, int);
+
+/**
+ * Free logger
+ *
+ * The underlying variable is set to NULL.
+ *
+ * @param Double pointer to the logging object
+ */
+void lattutil_log_free(lattutil_log_t **);
+
+/**
+ * Initialize syslog-based logging
+ *
+ * @param Logging object
+ * @param syslog(3) logopt
+ * @param syslog(3) facility
+ * @return True on success, False otherwise
+ */
+bool lattutil_log_syslog_init(lattutil_log_t *, int, int);
+
+#ifdef _lattutil_internal
+ssize_t lattutil_log_syslog_info(lattutil_log_t *, int,
+    const char *, ...);
+void lattutil_log_syslog_close(lattutil_log_t *);
+#endif /* _lattutil_internal */
+
 #endif /* !_LIBLATTUTIL_H */

src/log-main.c

+/*-
+ * Copyright (c) 2021 Shawn Webb <shawn.webb@hardenedbsd.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <syslog.h>
+
+#include "liblattutil.h"
+
+EXPORTED_SYM
+lattutil_log_t *
+lattutil_log_init(char *path, int verbosity)
+{
+	lattutil_log_t *res;
+
+	res = calloc(1, sizeof(*res));
+	if (res == NULL) {
+		return (NULL);
+	}
+
+	res->ll_verbosity = (verbosity == -1) ? LATTUTIL_LOG_VERBOSITY_DEFAULT :
+	    verbosity;
+	if (path != NULL) {
+		res->ll_path = strdup(path);
+		if (res->ll_path == NULL) {
+			free(res);
+			return (NULL);
+		}
+	}
+
+	return (res);
+}
+
+EXPORTED_SYM
+void
+lattutil_log_free(lattutil_log_t **logp)
+{
+	lattutil_log_t *logp2;
+
+	if (logp == NULL || *logp == NULL) {
+		return;
+	}
+
+	logp2 = *logp;
+
+	if (logp2->ll_log_close != NULL) {
+		logp2->ll_log_close(logp2);
+	}
+
+	free(logp2->ll_path);
+	memset(logp2, 0, sizeof(*logp2));
+	*logp = NULL;
+}
+
+EXPORTED_SYM
+bool
+lattutil_log_syslog_init(lattutil_log_t *logp, int logopt, int facility)
+{
+	const char *name;
+
+	logp->ll_log_info = lattutil_log_syslog_info;
+	logp->ll_log_close = lattutil_log_syslog_close;
+
+	name = logp->ll_path;
+	if (name == NULL) {
+		name = getprogname();
+		if (name == NULL) {
+			name = LATTUTIL_LOG_DEFAULT_NAME;
+		}
+	}
+
+	printf("Opening log %s\n", name);
+	openlog(name, logopt, facility);
+
+	return (true);
+}

src/log-syslog.c

+/*-
+ * Copyright (c) 2021 Shawn Webb <shawn.webb@hardenedbsd.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <syslog.h>
+
+#include "liblattutil.h"
+
+ssize_t
+lattutil_log_syslog_info(lattutil_log_t *logp, int verbose,
+    const char *fmt, ...)
+{
+	va_list args;
+	size_t len;
+	char *msg;
+
+	va_start(args, fmt);
+	printf("Hey there!\n");
+	if (verbose == -1  || verbose >= logp->ll_verbosity) {
+		msg = NULL;
+		vasprintf(&msg, fmt, args);
+		printf("Attempting to log: %s\n", msg);
+		if (msg == NULL) {
+			len = -1;
+			goto end;
+		}
+		len = strlen(msg);
+		syslog(LOG_INFO, "%s", msg);
+	}
+	va_end(args);
+
+end:
+	return (len);
+}
+
+void
+lattutil_log_syslog_close(lattutil_log_t *logp)
+{
+
+	closelog();
+}