overlay: Rudiments of config files and option parsing

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 282 insertions, 0 deletions

diff --git a/overlay/config.c b/overlay/config.c
new file mode 100644
index 00000000..f0f7ce8b
--- /dev/null
+++ b/overlay/config.c
@@ -0,0 +1,282 @@
+/*
+ * Copyright © 2013 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "overlay.h"
+
+#define DEFAULT_SECTION "window"
+
+static const char *skip_whitespace(const char *s, const char *end)
+{
+	while (s < end && isspace(*s))
+		s++;
+	return s;
+}
+
+static const char *trim_whitespace(const char *s, const char *end)
+{
+	if (end == NULL)
+		return end;
+
+	while (end > s && isspace(*--end))
+		;
+
+	return end + 1;
+}
+
+static const char *skip_past_newline(const char *s, const char *end)
+{
+	while (s < end && *s++ != '\n')
+		;
+
+	return s;
+}
+
+static const char *find(const char *s, const char *end, int c)
+{
+	while (s < end && *s != c) {
+		if (*s == '#')
+			break;
+
+		if (*s == '\n')
+			return NULL;
+		s++;
+	}
+
+	return s;
+}
+
+static int parse(const char *buf, int len,
+		 int (*func)(const char *section,
+			     const char *name,
+			     const char *value,
+			     void *data),
+		 void *data)
+{
+	char section[128] = DEFAULT_SECTION, name[128], value[128];
+	const char *buf_end = buf + len;
+	const char *end;
+	int line = 0;
+
+	for (line = 0 ; ++line; buf = skip_past_newline(buf, buf_end)) {
+		++line;
+		buf = skip_whitespace(buf, buf_end);
+		if (buf >= buf_end)
+			break;
+
+		if (*buf == ';' || *buf == '#') {
+			/* comment */
+		} else if (*buf == '[') { /* new section */
+			end = find(++buf, buf_end, ']');
+			end = trim_whitespace(buf, end);
+			if (end <= buf)
+				continue;
+
+			len = end - buf;
+			if (len == 0 || len >= sizeof(section))
+				return line;
+
+			memcpy(section, buf, len);
+			section[len] = '\0';
+		} else { /* name = value */
+			const char *sep;
+			int has_value = 1;
+
+			sep = find(buf, buf_end, '=');
+			if (sep == NULL)
+				sep = find(buf, buf_end, ':');
+			if (sep == NULL) {
+				sep = find(buf, buf_end, '\n');
+				has_value = 0;
+			}
+			end = trim_whitespace(buf, sep);
+			if (end <= buf)
+				continue;
+
+			len = end - buf;
+			if (len == 0 || len >= sizeof(name))
+				return line;
+
+			memcpy(name, buf, len);
+			name[len] = '\0';
+
+			if (has_value) {
+				buf = skip_whitespace(sep + 1, buf_end);
+				end = find(buf, buf_end, '\n');
+				end = trim_whitespace(buf, end);
+
+				len = end - buf;
+				if (len >= sizeof(name))
+					return line;
+
+				memcpy(value, buf, len);
+				value[len] = '\0';
+			} else
+				value[0] = '\0';
+
+			if (!func(section, name, value, data))
+				return line;
+		}
+	}
+
+	return 0;
+}
+
+static int add_value(const char *section,
+		     const char *name,
+		     const char *value,
+		     void *data)
+{
+	struct config *c = data;
+	struct config_section *s;
+	struct config_value *v, **prev;
+
+	for (s = c->sections; s != NULL; s = s->next)
+		if (strcmp(s->name, section) == 0)
+			break;
+	if (s == NULL) {
+		int len = strlen(section) + 1;
+
+		s = malloc(sizeof(*s)+len);
+		if (s == NULL)
+			return 0;
+
+		memcpy(s->name, section, len);
+		s->next = c->sections;
+		c->sections = s;
+	}
+
+	for (prev = &s->values; (v = *prev) != NULL; prev = &v->next) {
+		if (strcmp(v->name, name) == 0) {
+			*prev = v->next;
+			free(v);
+			break;
+		}
+	}
+	{
+		int name_len = strlen(name) + 1;
+		int value_len = *value ? strlen(value) + 1 : 0;
+
+		v = malloc(sizeof(*v) + name_len + value_len);
+		if (v == NULL)
+			return 0;
+
+		v->name = memcpy(v+1, name, name_len);
+
+		if (*value)
+			v->value = memcpy(v->name + name_len, value, value_len);
+		else
+			v->value = NULL;
+
+		v->next = s->values;
+		s->values = v;
+	}
+
+	return 1;
+}
+
+static int config_init_from_file(struct config *config, const char *filename)
+{
+	struct stat st;
+	int fd, err = -1;
+	char *str;
+
+	fd = open(filename, 0);
+	if (fd < 0)
+		return -1;
+
+	if (fstat(fd, &st) < 0)
+		goto err_fd;
+
+	if ((str = mmap(0, st.st_size, PROT_READ, MAP_SHARED, fd, 0)) == (void *)-1)
+		goto err_fd;
+
+	err = parse(str, st.st_size, add_value, config);
+	munmap(str, st.st_size);
+
+err_fd:
+	close(fd);
+	return err;
+}
+
+void config_init(struct config *config)
+{
+	memset(config, 0, sizeof(*config));
+}
+
+void config_parse_string(struct config *config, const char *str)
+{
+	int err;
+
+	if (str == NULL)
+		return;
+
+	err = config_init_from_file(config, str);
+	if (err == -1)
+		err = parse(str, strlen(str), add_value, config);
+	if (err) {
+		fprintf(stderr, "Failed to parse config string at line %d\n", err);
+		exit(1);
+	}
+}
+
+void config_set_value(struct config *c,
+		      const char *section,
+		      const char *name,
+		      const char *value)
+{
+	add_value(section, name, value, c);
+}
+
+const char *config_get_value(struct config *c,
+			     const char *section,
+			     const char *name)
+{
+	struct config_section *s;
+	struct config_value *v;
+
+	for (s = c->sections; s != NULL; s = s->next) {
+		if (strcmp(s->name, section))
+			continue;
+
+		for (v = s->values; v != NULL; v = v->next) {
+			if (strcmp(v->name, name))
+				continue;
+
+			return v->value;
+		}
+	}
+
+	return NULL;
+}