libifupdown: add abstract config parser implementation

Makefile

@@ -34,7 +34,8 @@ LIBIFUPDOWN_SRC = \
 	libifupdown/state.c \
 	libifupdown/environment.c \
 	libifupdown/execute.c \
-	libifupdown/lifecycle.c
+	libifupdown/lifecycle.c \
+	libifupdown/config-parser.c
 
 LIBIFUPDOWN_OBJ = ${LIBIFUPDOWN_SRC:.c=.o}
 LIBIFUPDOWN_LIB = libifupdown.a

libifupdown/config-parser.c

@@ -0,0 +1,84 @@
+/*
+ * libifupdown/config-parser.c
+ * Purpose: config parsing
+ *
+ * Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * This software is provided 'as is' and without any warranty, express or
+ * implied.  In no event shall the authors be liable for any damages arising
+ * from the use of this software.
+ */
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "libifupdown/config-parser.h"
+#include "libifupdown/fgetline.h"
+#include "libifupdown/tokenize.h"
+
+static int
+handler_cmp(const void *a, const void *b)
+{
+	const char *key = a;
+	const struct lif_config_handler *hdl = b;
+
+	return strcmp(key, hdl->key);
+}
+
+bool
+lif_config_parse_file(FILE *fd, const char *filename, struct lif_config_handler *handlers, size_t handler_count)
+{
+	char linebuf[4096];
+	size_t lineno = 0;
+
+	while (lif_fgetline(linebuf, sizeof linebuf, fd))
+	{
+		char *bufp = linebuf;
+		char *key = lif_next_token(&bufp);
+		char *value = lif_next_token(&bufp);
+
+		lineno++;
+
+		if (!*key || !*value)
+			continue;
+
+		struct lif_config_handler *hdl = bsearch(key, handlers, handler_count, sizeof(*handlers),
+			handler_cmp);
+
+		if (hdl == NULL)
+		{
+			fprintf(stderr, "ifupdown-ng: %s:%zu: warning: unknown config setting %s\n",
+				filename, lineno, key);
+			continue;
+		}
+
+		if (!hdl->handle(key, value, hdl->opaque))
+		{
+			fclose(fd);
+			return false;
+		}
+	}
+
+	fclose(fd);
+	return true;
+}
+
+bool
+lif_config_parse(const char *filename, struct lif_config_handler *handlers, size_t handler_count)
+{
+	FILE *f = fopen(filename, "r");
+
+	if (f == NULL)
+	{
+		fprintf(stderr, "ifupdown-ng: unable to parse %s: %s\n", filename, strerror(errno));
+		return false;
+	}
+
+	return lif_config_parse_file(f, filename, handlers, handler_count);
+}

libifupdown/config-parser.h

@@ -0,0 +1,32 @@
+/*
+ * libifupdown/config-parser.h
+ * Purpose: config parsing
+ *
+ * Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * This software is provided 'as is' and without any warranty, express or
+ * implied.  In no event shall the authors be liable for any damages arising
+ * from the use of this software.
+ */
+
+#ifndef LIBIFUPDOWN__CONFIG_PARSER_H
+#define LIBIFUPDOWN__CONFIG_PARSER_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+
+struct lif_config_handler {
+	const char *key;
+	bool (*handle)(const char *key, const char *value, void *opaque);
+	void *opaque;
+};
+
+extern bool lif_config_parse_file(FILE *f, const char *filename, struct lif_config_handler *handlers, size_t handler_count);
+extern bool lif_config_parse(const char *filename, struct lif_config_handler *handlers, size_t handler_count);
+
+#endif