1 files changed, 464 insertions, 0 deletions
diff --git a/src/cfg.c b/src/cfg.c
new file mode 100644
index 0000000..b8925f9
--- /dev/null
+++ b/src/cfg.c
@@ -0,0 +1,464 @@
+/*
+ * Copyright (C) 2021 Daiki Ueno
+ *
+ * This file is part of GnuTLS.
+ *
+ * GnuTLS 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.
+ *
+ * GnuTLS 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 "config.h"
+
+#include "cfg.h"
+
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "xsize.h"
+
+#define SIZEOF(x) (sizeof(x) / sizeof((x)[0]))
+
+struct options_st {
+	struct cfg_option_st *data;
+	size_t length;
+	size_t capacity;
+};
+
+struct parser_st
+{
+	FILE *fp;
+	char pushback[2];
+	size_t pushback_length;
+};
+
+static inline void
+clear_option(struct cfg_option_st *option)
+{
+	free(option->name);
+	free(option->value);
+	memset(option, 0, sizeof(*option));
+}
+
+void
+cfg_free(cfg_option_t options)
+{
+	for (size_t i = 0; options[i].name; i++) {
+		clear_option(&options[i]);
+	}
+	free(options);
+}
+
+#define HORIZONTAL_WHITESPACE "\t "
+#define WHITESPACE HORIZONTAL_WHITESPACE "\n\v\f\r\b"
+#define ALPHABETIC "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+#define DECIMAL "0123456789"
+#define NAME_FIRST_CHARS "_" ALPHABETIC
+#define VALUE_NAME_CHARS ":^-" NAME_FIRST_CHARS DECIMAL
+
+struct buffer_st {
+	char *data;
+	size_t length;
+	size_t capacity;
+};
+
+static int
+buffer_append(struct buffer_st *buffer, int c)
+{
+	size_t new_length = xsum(buffer->length, 1);
+	if (size_overflow_p(new_length)) {
+		return -EINVAL;
+	}
+	if (buffer->capacity < new_length) {
+		size_t new_capacity;
+		char *new_array;
+
+		new_capacity = xtimes(xsum(buffer->capacity, 1), 2);
+		if (size_overflow_p(new_capacity)) {
+			return -EINVAL;
+		}
+		new_array = realloc(buffer->data, new_capacity);
+		if (!new_array) {
+			return -errno;
+		}
+		buffer->capacity = new_capacity;
+		buffer->data = new_array;
+	}
+	assert(buffer->data);
+	buffer->data[buffer->length++] = c;
+	return 0;
+}
+
+static int
+parser_getc(struct parser_st *parser)
+{
+	if (parser->pushback_length > 0) {
+		return parser->pushback[--parser->pushback_length];
+	}
+	int c = getc(parser->fp);
+	return c;
+}
+
+static void
+parser_ungetc(struct parser_st *parser, int c)
+{
+	assert(parser->pushback_length < SIZEOF(parser->pushback));
+	parser->pushback[parser->pushback_length++] = c;
+}
+
+static void
+skip_comment(struct parser_st *parser)
+{
+	int c;
+
+	c = parser_getc(parser);
+	if (c == EOF) {
+		return;
+	}
+
+	if (c == '#') {
+		for (;;) {
+			c = parser_getc(parser);
+			if (c == EOF) {
+				return;
+			}
+			if (c == '\n') {
+				break;
+			}
+		}
+	}
+	parser_ungetc(parser, c);
+}
+
+static void
+skip_chars(struct parser_st *parser, const char *chars)
+{
+	int c;
+
+	for (;;) {
+		c = parser_getc(parser);
+		if (c == EOF) {
+			return;
+		}
+		if (!strchr(chars, c)) {
+			break;
+		}
+	}
+	parser_ungetc(parser, c);
+}
+
+static void
+skip_comments_and_whitespaces(struct parser_st *parser)
+{
+	int c;
+
+	for (;;) {
+		c = parser_getc(parser);
+		if (c == EOF) {
+			return;
+		}
+		parser_ungetc(parser, c);
+		if (c == '#') {
+			skip_comment(parser);
+		} else if (strchr(WHITESPACE, c)) {
+			skip_chars(parser, WHITESPACE);
+		} else {
+			break;
+		}
+	}
+}
+
+/* Read the name part of an option.  Returns NULL if it fails.  */
+static char *
+read_name(struct parser_st *parser)
+{
+	struct buffer_st buffer;
+	int c;
+
+	memset(&buffer, 0, sizeof(buffer));
+
+	skip_comments_and_whitespaces(parser);
+
+	c = parser_getc(parser);
+	if (c == EOF) {
+		return NULL;
+	}
+
+	if (!strchr(NAME_FIRST_CHARS, c)) {
+		parser_ungetc(parser, c);
+		return NULL;
+	}
+
+	buffer_append(&buffer, c);
+	for (;;) {
+		c = parser_getc(parser);
+		if (c == EOF) {
+			break;
+		}
+		if (!strchr(VALUE_NAME_CHARS, c)) {
+			parser_ungetc(parser, c);
+			break;
+		}
+		buffer_append(&buffer, c);
+	}
+	assert(buffer.data);
+	if (buffer.data[buffer.length - 1] == ':') {
+		buffer.data[buffer.length - 1] = '\0';
+		buffer.length--;
+		parser_ungetc(parser, ':');
+	}
+
+	/* NUL terminate */
+	buffer_append(&buffer, '\0');
+	return buffer.data;
+}
+
+static char *
+read_quoted_value(struct parser_st *parser)
+{
+	struct buffer_st buffer;
+	int c, quote_char;
+
+	memset(&buffer, 0, sizeof(buffer));
+
+	c = parser_getc(parser);
+	if (c == EOF) {
+		assert(false);
+		return NULL;
+	}
+
+	if (c == '"' || c == '\'') {
+		quote_char = c;
+	} else {
+		assert(false);
+		return NULL;
+	}
+
+	for (;;) {
+		c = parser_getc(parser);
+		if (c == EOF) {
+			break;
+		}
+		if (c == '\\') {
+			c = parser_getc(parser);
+			if (c == EOF) {
+				/* unmatched quote */
+				free(buffer.data);
+				return NULL;
+			}
+			if (c == '\n') {
+				buffer_append(&buffer, ' ');
+			} else if (c == quote_char) {
+				buffer_append(&buffer, c);
+			}
+		} else if (c == quote_char) {
+			break;
+		} else {
+			buffer_append(&buffer, c);
+		}
+	}
+
+	/* NUL terminate */
+	buffer_append(&buffer, '\0');
+	return buffer.data;
+}
+
+/* Read the value part of an option.  Returns NULL if it fails.  */
+static char *
+read_value(struct parser_st *parser)
+{
+	struct buffer_st buffer;
+	int c;
+
+	memset(&buffer, 0, sizeof(buffer));
+
+	skip_chars(parser, HORIZONTAL_WHITESPACE);
+
+	c = parser_getc(parser);
+	if (c == EOF) {
+		goto out;
+	}
+
+	/* skip delimiter if any, followed by horizontal whitespaces */
+	if (c == ':' || c == '=') {
+		c = parser_getc(parser);
+		if (c == EOF) {
+			goto out;
+		}
+		parser_ungetc(parser, c);
+		skip_chars(parser, HORIZONTAL_WHITESPACE);
+		c = parser_getc(parser);
+		if (c == EOF) {
+			goto out;
+		}
+	}
+
+	if (c == '\n') {
+		return strdup(""); /* empty value */
+	} else if (c == '"' || c == '\'') {
+		parser_ungetc(parser, c);
+		return read_quoted_value(parser);
+	}
+
+	buffer_append(&buffer, c);
+	for (;;) {
+		c = parser_getc(parser);
+		if (c == EOF) {
+			break;
+		}
+		if (c == '\\') {
+			c = parser_getc(parser);
+			if (c == EOF) {
+				break;
+			}
+			if (c == '\n') {
+				buffer_append(&buffer, c);
+			}
+		} else if (c == '\n') {
+			break;
+		} else {
+			buffer_append(&buffer, c);
+		}
+	}
+
+ out:
+	/* NUL terminate */
+	buffer_append(&buffer, '\0');
+	return buffer.data;
+}
+
+/* Append OPTION to OPTIONS.  Take ownership of the fields of OPTION.  */
+static int
+take_option(struct options_st *options, struct cfg_option_st *option)
+{
+	size_t new_length = xsum(options->length, 1);
+	if (size_overflow_p(new_length)) {
+		return -EINVAL;
+	}
+	if (options->capacity < new_length) {
+		size_t new_capacity;
+		struct cfg_option_st *new_array;
+
+		new_capacity = xtimes(xsum(options->capacity, 1), 2);
+		if (size_overflow_p(new_capacity)) {
+			return -EINVAL;
+		}
+		new_array = reallocarray(options->data, new_capacity,
+					 sizeof(*option));
+		if (!new_array) {
+			return -errno;
+		}
+		options->capacity = new_capacity;
+		options->data = new_array;
+	}
+
+	assert(options->data);
+
+	options->data[options->length].name = option->name;
+	options->data[options->length].value = option->value;
+
+	options->length++;
+
+	option->name = NULL;
+	option->value = NULL;
+
+	return 0;
+}
+
+static void
+clear_options(struct options_st *options)
+{
+	for (size_t i = 0; options->length; i++) {
+		clear_option(&options->data[i]);
+	}
+}
+
+cfg_option_t
+cfg_load(const char *filename)
+{
+	struct parser_st parser;
+	struct options_st options;
+	struct cfg_option_st null_option = { NULL, NULL };
+
+	memset(&parser, 0, sizeof(parser));
+	memset(&options, 0, sizeof(options));
+
+	parser.fp = fopen(filename, "r");
+	if (!parser.fp) {
+		return NULL;
+	}
+
+	for (;;) {
+		struct cfg_option_st option;
+
+		option.name = read_name(&parser);
+		if (!option.name) {
+			break;
+		}
+
+		option.value = read_value(&parser);
+		if (!option.value) {
+			clear_option(&option);
+			goto error;
+		}
+
+		if (take_option(&options, &option) < 0) {
+			clear_option(&option);
+			goto error;
+		}
+		assert(!option.name && !option.value);
+	}
+
+	fclose(parser.fp);
+	/* NUL terminate */
+	take_option(&options, &null_option);
+	return options.data;
+
+error:
+	clear_options(&options);
+	fclose(parser.fp);
+	return NULL;
+}
+
+cfg_option_t
+cfg_next(const cfg_option_t options, const char *name)
+{
+	for (size_t i = 0; options[i].name; i++) {
+		if (strcmp(options[i].name, name) == 0) {
+			return &options[i];
+		}
+	}
+	return NULL;
+}
+
+#ifdef TEST
+int
+main(int argc, char **argv)
+{
+	cfg_option_t opts;
+
+	assert(argc == 2);
+
+	opts = cfg_load(argv[1]);
+	for (size_t i = 0; opts[i].name; i++) {
+		printf("%s: %s\n", opts[i].name, opts[i].value);
+	}
+	cfg_free(opts);
+
+	return 0;
+}
+#endif