From 027f53e35bc57e0046bbb3c02f74e8504961b499 Mon Sep 17 00:00:00 2001
From: Magnus Ahltorp <map@kth.se>
Date: Thu, 11 Feb 2016 15:51:34 +0100
Subject: Added rudimentary support for chunks. This means that the
 implementation should be compatible with the specification.

---
 c_src/permdb.c      | 25 ++++++++++++++++++++++---
 test/listpermdb.erl |  2 +-
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/c_src/permdb.c b/c_src/permdb.c
index c6ae1c9..624e1da 100644
--- a/c_src/permdb.c
+++ b/c_src/permdb.c
@@ -1087,6 +1087,16 @@ readnet32(void *ptr)
         return ntohl(data);
 }
 
+static uint16_t
+readnet16(void *ptr)
+{
+        uint16_t data;
+
+        memcpy(&data, ptr, sizeof(data));
+
+        return ntohs(data);
+}
+
 static unsigned char *
 readdatakeyandlen(permdb_object *state, node_offset offset, size_t *datalen)
 {
@@ -1100,7 +1110,11 @@ readdatakeyandlen(permdb_object *state, node_offset offset, size_t *datalen)
                 return NULL;
         }
         unsigned char *result = memsub(data, sizeof(data_entry_cookie), keylen);
-        *datalen = readnet32(data+sizeof(data_entry_cookie)+keylen);
+        uint16_t nchunks = readnet16(data+sizeof(data_entry_cookie)+keylen);
+        *datalen = readnet16(data+sizeof(data_entry_cookie)+keylen+sizeof(uint16_t));
+        if (nchunks != 1) {
+                errx(1, "number of chunks is %d, but only one chunk is supported right now", nchunks);
+        }
         free(data);
         return result;
 }
@@ -1115,7 +1129,11 @@ readdata(permdb_object *state, node_offset offset, size_t datalen)
 static node_offset
 writedata(permdb_object *state, const unsigned char *key, const unsigned char *data, size_t datalength)
 {
-        uint32_t coded_datalength = htonl(datalength);
+        if (datalength > 65535) {
+                errx(1, "data length is %zu, but only < 64K lengths are supported right now", datalength);
+        }
+        uint16_t chunk_length = htons(datalength);
+        uint16_t nchunks = htons(1);
         node_offset offset = state->datafile.datasize;
 
 #if DEBUG_WRITE
@@ -1123,7 +1141,8 @@ writedata(permdb_object *state, const unsigned char *key, const unsigned char *d
 #endif
         writebuffer_add(&state->datafile, &data_entry_cookie, sizeof(data_entry_cookie));
         writebuffer_add(&state->datafile, key, keylen);
-        writebuffer_add(&state->datafile, &coded_datalength, 4);
+        writebuffer_add(&state->datafile, &nchunks, sizeof(uint16_t));
+        writebuffer_add(&state->datafile, &chunk_length, sizeof(uint16_t));
         writebuffer_add(&state->datafile, data, datalength);
 
         return offset;
diff --git a/test/listpermdb.erl b/test/listpermdb.erl
index 04acbfa..a12e5e4 100755
--- a/test/listpermdb.erl
+++ b/test/listpermdb.erl
@@ -101,7 +101,7 @@ printindex(<<Unknown:16/binary, _Rest/binary>>, FileOffset) ->
 
 printdata(<<>>, FileOffset) ->
     {ok, FileOffset};
-printdata(<<?DATA_ENTRY_COOKIE:64, Key:32/binary, Length:32, Rest/binary>>, FileOffset) ->
+printdata(<<?DATA_ENTRY_COOKIE:64, Key:32/binary, 1:16, Length:16, Rest/binary>>, FileOffset) ->
     FileOffset2 = FileOffset + 8 + 32 + 4,
     io:format("data ~p key ~p length ~p~n", [FileOffset, Key, Length]),
     <<Data:Length/binary, Rest2/binary>> = Rest,
-- 
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