Use getopt_config to load options

I'm really getting a lot of use out of this config.c huh.

1 files changed, 178 insertions, 0 deletions

diff --git a/config.c b/config.c
new file mode 100644
index 0000000..b3e42f9
--- /dev/null
+++ b/config.c
@@ -0,0 +1,178 @@
+/* Copyright (C) 2019  C. McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <getopt.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "chat.h"
+
+#define CONFIG_DIR "catgirl"
+
+FILE *configOpen(const char *path, const char *mode) {
+	if (path[0] == '/' || path[0] == '.') goto local;
+
+	const char *home = getenv("HOME");
+	const char *configHome = getenv("XDG_CONFIG_HOME");
+	const char *configDirs = getenv("XDG_CONFIG_DIRS");
+
+	char buf[PATH_MAX];
+	if (configHome) {
+		snprintf(buf, sizeof(buf), "%s/" CONFIG_DIR "/%s", configHome, path);
+	} else {
+		if (!home) goto local;
+		snprintf(buf, sizeof(buf), "%s/.config/" CONFIG_DIR "/%s", home, path);
+	}
+	FILE *file = fopen(buf, mode);
+	if (file) return file;
+	if (errno != ENOENT) return NULL;
+
+	if (!configDirs) configDirs = "/etc/xdg";
+	while (*configDirs) {
+		size_t len = strcspn(configDirs, ":");
+		snprintf(
+			buf, sizeof(buf), "%.*s/" CONFIG_DIR "/%s",
+			(int)len, configDirs, path
+		);
+		file = fopen(buf, mode);
+		if (file) return file;
+		if (errno != ENOENT) return NULL;
+		configDirs += len;
+		if (*configDirs) configDirs++;
+	}
+
+local:
+	return fopen(path, mode);
+}
+
+#define WS "\t "
+
+static const char *path;
+static FILE *file;
+static size_t num;
+static char *line;
+static size_t cap;
+
+static int clean(int opt) {
+	if (file) fclose(file);
+	free(line);
+	line = NULL;
+	cap = 0;
+	return opt;
+}
+
+int getopt_config(
+	int argc, char *const *argv,
+	const char *optstring, const struct option *longopts, int *longindex
+) {
+	static int opt;
+	if (opt >= 0) {
+		opt = getopt_long(argc, argv, optstring, longopts, longindex);
+	}
+	if (opt >= 0) return opt;
+
+	for (;;) {
+		if (!file) {
+			if (optind < argc) {
+				num = 0;
+				path = argv[optind++];
+				file = configOpen(path, "r");
+				if (!file) {
+					warn("%s", path);
+					return clean('?');
+				}
+			} else {
+				return clean(-1);
+			}
+		}
+
+		for (;;) {
+			ssize_t llen = getline(&line, &cap, file);
+			if (ferror(file)) {
+				warn("%s", path);
+				return clean('?');
+			}
+			if (llen <= 0) break;
+			if (line[llen - 1] == '\n') line[llen - 1] = '\0';
+			num++;
+
+			char *name = line + strspn(line, WS);
+			size_t len = strcspn(name, WS "=");
+			if (!name[0] || name[0] == '#') continue;
+
+			const struct option *option;
+			for (option = longopts; option->name; ++option) {
+				if (strlen(option->name) != len) continue;
+				if (!strncmp(option->name, name, len)) break;
+			}
+			if (!option->name) {
+				warnx(
+					"%s:%zu: unrecognized option `%.*s'",
+					path, num, (int)len, name
+				);
+				return clean('?');
+			}
+
+			char *equal = &name[len] + strspn(&name[len], WS);
+			if (*equal && *equal != '=') {
+				warnx(
+					"%s:%zu: option `%s' missing equals sign",
+					path, num, option->name
+				);
+				return clean('?');
+			}
+			if (option->has_arg == no_argument && *equal) {
+				warnx(
+					"%s:%zu: option `%s' doesn't allow an argument",
+					path, num, option->name
+				);
+				return clean('?');
+			}
+			if (option->has_arg == required_argument && !*equal) {
+				warnx(
+					"%s:%zu: option `%s' requires an argument",
+					path, num, option->name
+				);
+				return clean(':');
+			}
+
+			optarg = NULL;
+			if (*equal) {
+				char *arg = &equal[1] + strspn(&equal[1], WS);
+				optarg = strdup(arg);
+				if (!optarg) {
+					warn("getopt_config");
+					return clean('?');
+				}
+			}
+
+			if (longindex) *longindex = option - longopts;
+			if (option->flag) {
+				*option->flag = option->val;
+				return 0;
+			} else {
+				return option->val;
+			}
+		}
+
+		fclose(file);
+		file = NULL;
+	}
+}