Initial libdcache implementation

1 files changed, 73 insertions, 0 deletions

diff --git a/src/caches/dcache_save.c b/src/caches/dcache_save.c
new file mode 100644
index 0000000..1ef35f0
--- /dev/null
+++ b/src/caches/dcache_save.c
@@ -0,0 +1,73 @@
+/* ISC license. */
+
+#include <stdint.h>
+#include <stdio.h>
+
+#include <skalibs/posixplz.h>
+#include <skalibs/uint16.h>
+#include <skalibs/uint64.h>
+#include <skalibs/buffer.h>
+#include <skalibs/stralloc.h>
+#include <skalibs/tai.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/skamisc.h>
+#include <skalibs/gensetdyn.h>
+
+#include <s6-dns/dcache.h>
+
+static int write_node_iter (char *data, void *aux)
+{
+  dcache_node_t *y = (dcache_node_t *)data ;
+  buffer *b = aux ;
+  char pack[TAI_PACK * 2 + 4] ;
+  tai_pack(pack, tain_secp(&y->entry)) ;
+  tai_pack(pack + TAI_PACK, tain_secp(&y->expire)) ;
+  uint16_pack(pack + TAI_PACK * 2, y->key.len) ;
+  uint16_pack(pack + TAI_PACK * 2 + 2, y->datalen) ;
+  if (buffer_put(b, pack, TAI_PACK * 2 + 4) == -1) return 0 ;
+  if (buffer_put(b, y->key.s, y->key.len + y->datalen) == -1) return 0 ;
+  if (buffer_put(b, "", 1) == -1) return 0 ;
+  return 1 ;
+}
+
+static inline int dcache_save_to_buffer (dcache_t const *z, buffer *b)
+{
+  char pack[16] ;
+  if (buffer_puts(b, DCACHE_MAGIC) == -1) return 0 ;
+  uint64_pack_big(pack, z->size) ;
+  uint64_pack_big(pack + 8, z->motion) ;
+  if (buffer_put(b, pack, 16) < 16) return 0 ;
+
+ /* XXX: can gensetdyn_iter blow up the stack if z->storage is huge? */
+  if (gensetdyn_iter_nocancel((gensetdyn *)&z->storage, gensetdyn_n(&z->storage), &write_node_iter, b) < gensetdyn_n(&z->storage)) return 0 ;
+
+  return buffer_flush(b) ;
+}
+
+#define N 8192
+
+int dcache_save (dcache_t const *z, char const *file)
+{
+  stralloc sa = STRALLOC_ZERO ;
+  int fd ;
+  buffer b ;
+  char buf[N] ;
+  if (!stralloc_cats(&sa, file)) return 0 ;
+  if (!sauniquename(&sa) || !stralloc_0(&sa)) goto err0 ;
+  fd = open_excl(sa.s) ;
+  if (fd == -1) goto err0 ;
+  buffer_init(&b, &buffer_write, fd, buf, N) ;
+  if (!dcache_save_to_buffer(z, &b)) goto err2 ;
+  fd_close(fd) ;
+  if (rename(sa.s, file) == -1) goto err1 ;
+  stralloc_free(&sa) ;
+  return 1 ;
+
+ err2:
+  fd_close(fd) ;
+ err1:
+  unlink_void(sa.s) ;
+ err0:
+  stralloc_free(&sa) ;
+  return 0 ;
+}