1 files changed, 121 insertions, 0 deletions
diff --git a/src/libstddjb/cdbmake.c b/src/libstddjb/cdbmake.c
new file mode 100644
index 0000000..4cc4fc8
--- /dev/null
+++ b/src/libstddjb/cdbmake.c
@@ -0,0 +1,121 @@
+/* ISC license. */
+
+#include <unistd.h>
+#include <stdint.h>
+#include <errno.h>
+
+#include <skalibs/uint32.h>
+#include <skalibs/diuint32.h>
+#include <skalibs/buffer.h>
+#include <skalibs/genalloc.h>
+#include <skalibs/cdbmake.h>
+#include "cdb-internal.h"
+
+int cdbmake_start (cdbmaker *c, int fd)
+{
+  c->hplist = genalloc_zero ;
+  c->pos = 2048 ;
+  buffer_init(&c->b, &buffer_write, fd, c->buf, BUFFER_OUTSIZE) ;
+  return lseek(fd, c->pos, SEEK_SET) >= 0 ;
+}
+
+static int posplus (cdbmaker *c, uint32_t len)
+{
+  uint32_t newpos = c->pos + len ;
+  if (newpos < len) return (errno = ENOMEM, 0) ;
+  c->pos = newpos ;
+  return 1 ;
+}
+
+static inline int cdbmake_addend (cdbmaker *c, uint32_t keylen, uint32_t datalen, uint32_t h)
+{
+  diuint32 blah = { .left = h, .right = c->pos } ;
+  return genalloc_append(diuint32, &c->hplist, &blah) && posplus(c, 8) && posplus(c, keylen) && posplus(c, datalen) ;
+}
+
+static inline ssize_t cdbmake_addbegin (cdbmaker *c, uint32_t keylen, uint32_t datalen)
+{
+  char buf[8] ;
+  uint32_pack(buf, keylen) ;
+  uint32_pack(buf + 4, datalen) ;
+  return buffer_put(&c->b, buf, 8) == 8 ;
+}
+
+int cdbmake_add (cdbmaker *c, char const *key, uint32_t keylen, char const *data, uint32_t datalen)
+{
+  if (!cdbmake_addbegin(c, keylen, datalen)
+   || buffer_put(&c->b, key, keylen) < 0
+   || buffer_put(&c->b, data, datalen) < 0
+   || !cdbmake_addend(c, keylen, datalen, cdb_hash(key, keylen)))
+  {
+    genalloc_free(diuint32, &c->hplist) ;
+    return 0 ;
+  }
+  return 1 ;
+}
+
+int cdbmake_finish (cdbmaker *c)
+{
+  uint32_t count[256] ;
+  uint32_t start[256] ;
+  char final[2048] ;
+  unsigned int size = 1 ;
+  unsigned int n = genalloc_len(diuint32, &c->hplist) ;
+  unsigned int i = 0 ;
+  diuint32 *hp = genalloc_s(diuint32, &c->hplist) ;
+
+  for (; i < 256 ; i++) count[i] = 0 ;
+  for (i = 0 ; i < n ; i++) ++count[hp[i].left & 255] ;
+
+  {
+    uint32_t u = 0 ;
+    for (i = 0 ; i < 256 ; i++) start[i] = u += count[i] ; /* bounded by n */
+    for (i = 0 ; i < 256 ; i++)
+    {
+      u = count[i] << 1 ;
+      if (u > size) size = u ;
+    }
+    size += n ; /* no overflow possible up to now */
+    u = 0xffffffffUL ; u /= sizeof(diuint32) ;
+    if (size > u) return (errno = ENOMEM, 0) ;
+  }
+  i = n ;
+  {
+    diuint32 split[size] ;
+    while (i--) split[--start[hp[i].left & 255]] = hp[i] ;
+    genalloc_free(diuint32, &c->hplist) ;
+    hp = split + n ;
+
+    for (i = 0 ; i < 256 ; ++i)
+    {
+      char buf[8] ;
+      uint32_t k = count[i] ;
+      uint32_t len = k << 1 ;  /* no overflow possible */
+      diuint32 *p = split + start[i] ;
+
+      uint32_pack(final + (i << 3), c->pos) ;
+      uint32_pack(final + (i << 3) + 4, len) ;
+
+      for (uint32_t j = 0 ; j < len ; j++) hp[j].left = hp[j].right = 0 ;
+      for (uint32_t j = 0 ; j < k ; j++)
+      {
+        uint32_t where = (p->left >> 8) % len ;
+        while (hp[where].right) if (++where == len) where = 0 ;
+        hp[where] = *p++ ;
+      }
+
+      for (uint32_t j = 0 ; j < len ; j++)
+      {
+        uint32_pack(buf, hp[j].left) ;
+        uint32_pack(buf + 4, hp[j].right) ;
+        if (buffer_put(&c->b, buf, 8) < 0) return 0 ;
+        if (!posplus(c, 8)) return 0 ;
+      }
+    }
+  }
+
+  if (!buffer_flush(&c->b)
+   || lseek(buffer_fd(&c->b), 0, SEEK_SET) < 0
+   || buffer_putflush(&c->b, final, 2048) < 0) return 0 ;
+  return 1 ;
+}