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-rw-r--r--cdb.c136
1 files changed, 136 insertions, 0 deletions
diff --git a/cdb.c b/cdb.c
new file mode 100644
index 0000000..b09d3a5
--- /dev/null
+++ b/cdb.c
@@ -0,0 +1,136 @@
+/* Public domain. */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include "readwrite.h"
+#include "error.h"
+#include "seek.h"
+#include "byte.h"
+#include "cdb.h"
+
+void cdb_free(struct cdb *c)
+{
+ if (c->map) {
+ munmap(c->map,c->size);
+ c->map = 0;
+ }
+}
+
+void cdb_findstart(struct cdb *c)
+{
+ c->loop = 0;
+}
+
+void cdb_init(struct cdb *c,int fd)
+{
+ struct stat st;
+ char *x;
+
+ cdb_free(c);
+ cdb_findstart(c);
+ c->fd = fd;
+
+ if (fstat(fd,&st) == 0)
+ if (st.st_size <= 0xffffffff) {
+ x = mmap(0,st.st_size,PROT_READ,MAP_SHARED,fd,0);
+ if (x + 1) {
+ c->size = st.st_size;
+ c->map = x;
+ }
+ }
+}
+
+int cdb_read(struct cdb *c,char *buf,unsigned int len,uint32 pos)
+{
+ if (c->map) {
+ if ((pos > c->size) || (c->size - pos < len)) goto FORMAT;
+ byte_copy(buf,len,c->map + pos);
+ }
+ else {
+ if (seek_set(c->fd,pos) == -1) return -1;
+ while (len > 0) {
+ int r;
+ do
+ r = read(c->fd,buf,len);
+ while ((r == -1) && (errno == error_intr));
+ if (r == -1) return -1;
+ if (r == 0) goto FORMAT;
+ buf += r;
+ len -= r;
+ }
+ }
+ return 0;
+
+ FORMAT:
+ errno = error_proto;
+ return -1;
+}
+
+static int match(struct cdb *c,char *key,unsigned int len,uint32 pos)
+{
+ char buf[32];
+ int n;
+
+ while (len > 0) {
+ n = sizeof buf;
+ if (n > len) n = len;
+ if (cdb_read(c,buf,n,pos) == -1) return -1;
+ if (byte_diff(buf,n,key)) return 0;
+ pos += n;
+ key += n;
+ len -= n;
+ }
+ return 1;
+}
+
+int cdb_findnext(struct cdb *c,char *key,unsigned int len)
+{
+ char buf[8];
+ uint32 pos;
+ uint32 u;
+
+ if (!c->loop) {
+ u = cdb_hash(key,len);
+ if (cdb_read(c,buf,8,(u << 3) & 2047) == -1) return -1;
+ uint32_unpack(buf + 4,&c->hslots);
+ if (!c->hslots) return 0;
+ uint32_unpack(buf,&c->hpos);
+ c->khash = u;
+ u >>= 8;
+ u %= c->hslots;
+ u <<= 3;
+ c->kpos = c->hpos + u;
+ }
+
+ while (c->loop < c->hslots) {
+ if (cdb_read(c,buf,8,c->kpos) == -1) return -1;
+ uint32_unpack(buf + 4,&pos);
+ if (!pos) return 0;
+ c->loop += 1;
+ c->kpos += 8;
+ if (c->kpos == c->hpos + (c->hslots << 3)) c->kpos = c->hpos;
+ uint32_unpack(buf,&u);
+ if (u == c->khash) {
+ if (cdb_read(c,buf,8,pos) == -1) return -1;
+ uint32_unpack(buf,&u);
+ if (u == len)
+ switch(match(c,key,len,pos + 8)) {
+ case -1:
+ return -1;
+ case 1:
+ uint32_unpack(buf + 4,&c->dlen);
+ c->dpos = pos + 8 + len;
+ return 1;
+ }
+ }
+ }
+
+ return 0;
+}
+
+int cdb_find(struct cdb *c,char *key,unsigned int len)
+{
+ cdb_findstart(c);
+ return cdb_findnext(c,key,len);
+}