1 files changed, 163 insertions, 0 deletions
diff --git a/src/cache.c b/src/cache.c
new file mode 100644
index 0000000..c2db00d
--- /dev/null
+++ b/src/cache.c
@@ -0,0 +1,163 @@
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+
+#include "cache.h"
+
+struct cache
+{
+	uint32_t begin;
+	uint32_t used;
+	uint32_t count;
+	char content[1];
+};
+
+static
+uint32_t
+lenat(
+	cache_t *cache,
+	uint32_t pos
+) {
+	uint32_t p, n;
+	char c;
+
+	p = pos + 1;
+	if (p >= cache->count)
+		p -= cache->count;
+	n = 4;
+	while (n--) {
+		do {
+			c = cache->content[p++];
+			if (p >= cache->count)
+				p -= cache->count;
+		} while(c);
+	}
+	return (p > pos ? p : (p + cache->count)) - pos;
+}
+
+static
+void
+drop_one(
+	cache_t *cache
+) {
+	uint32_t l = lenat(cache, cache->begin);
+	cache->used -= l;
+	cache->begin += l;
+	if (cache->begin > cache->count)
+		cache->begin -= cache->count;
+}
+
+static
+void
+addc(
+	cache_t *cache,
+	char c
+) {
+	uint32_t pos;
+	if (cache->used == cache->count)
+		drop_one(cache);
+	pos = cache->begin + cache->used++;
+	if (pos > cache->count)
+		pos -= cache->count;
+	cache->content[pos < cache->count ? pos : pos - cache->count] = c;
+}
+
+static
+void
+adds(
+	cache_t *cache,
+	const char *s
+) {
+	do { addc(cache, *s); } while(*s++);
+}
+
+int
+cache_put(
+	cache_t *cache,
+	const char *client,
+	const char *session,
+	const char *user,
+	const char *permission,
+	int value
+) {
+	if (cache == NULL
+	 || strlen(client) + strlen(session)
+		 + strlen(user) + strlen(permission)
+		 + 5 > cache->count)
+		return -EINVAL;
+
+	addc(cache, (char)value);
+	adds(cache, client);
+	adds(cache, session);
+	adds(cache, user);
+	adds(cache, permission);
+	return 0;
+}
+
+int
+cache_search(
+	cache_t *cache,
+	const char *client,
+	const char *session,
+	const char *user,
+	const char *permission
+) {
+	return -ENOENT;
+}
+
+void
+cache_clear(
+	cache_t *cache
+) {
+	if (cache) {
+		cache->used = 0;
+		cache->begin = 0;
+	}
+}
+
+int
+cache_resize(
+	cache_t **cache,
+	uint32_t newsize
+) {
+	cache_t *c = *cache, *nc;
+
+	while (c && c->used > newsize)
+		drop_one(c);
+
+	nc = malloc(newsize - 1 + sizeof *c);
+	if (nc == NULL)
+		return -ENOMEM;
+
+	nc->begin = 0;
+	nc->count = newsize;
+	if (!c || c->used == 0)
+		nc->used = 0;
+	else {
+		if (c->begin + c->used <= c->count)
+			memcpy(&nc->content[0], &c->content[c->begin], c->used);
+		else {
+			memcpy(&nc->content[0], &c->content[c->begin], c->count - c->begin);
+			memcpy(&nc->content[c->count - c->begin], &c->content[0], c->used + c->begin - c->count);
+		}
+
+		nc->used = c->used;
+	}
+	*cache = nc;
+	free(c);
+	return 0;
+}
+
+int
+cache_create(
+	cache_t **cache,
+	uint32_t size
+) {
+	*cache = NULL;
+	return cache_resize(cache, size);
+}
+
+
+