Signed-off-by: Nguyễn Thái Ngọc Duy <pclo...@gmail.com>
---
 builtin/index-pack.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 100 insertions(+), 4 deletions(-)

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 210b78d..51ca64b 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -319,6 +319,21 @@ static const unsigned char *read_sha1ref(void)
        return sha1_table + index * 20;
 }
 
+static const unsigned char *read_sha1table_ref(void)
+{
+       const unsigned char *sha1 = read_sha1ref();
+       if (sha1 < sha1_table || sha1 >= sha1_table + nr_objects * 20) {
+               unsigned char *found;
+               found = bsearch(sha1, sha1_table, nr_objects, 20,
+                               (int (*)(const void *, const void *))hashcmp);
+               if (!found)
+                       bad_object(consumed_bytes,
+                                  _("SHA-1 %s not found in SHA-1 table"),
+                                  sha1_to_hex(sha1));
+       }
+       return sha1;
+}
+
 static const unsigned char *read_dictref(struct packv4_dict *dict)
 {
        unsigned int index = read_varint();
@@ -561,17 +576,93 @@ static void *unpack_commit_v4(unsigned int offset,
        return dst.buf;
 }
 
-static void *unpack_entry_data(unsigned long offset, unsigned long size,
-                              enum object_type type, unsigned char *sha1)
+/*
+ * v4 trees are actually kind of deltas and we don't do delta in the
+ * first pass. This function only walks through a tree object to find
+ * the end offset, register object dependencies and performs limited
+ * validation.
+ */
+static void *unpack_tree_v4(struct object_entry *obj,
+                           unsigned int offset, unsigned long size,
+                           unsigned char *sha1)
+{
+       unsigned int nr = read_varint();
+       const unsigned char *last_base = NULL;
+       struct strbuf sb = STRBUF_INIT;
+       while (nr) {
+               unsigned int copy_start_or_path = read_varint();
+               if (copy_start_or_path & 1) { /* copy_start */
+                       unsigned int copy_count = read_varint();
+                       if (copy_count & 1) { /* first delta */
+                               last_base = read_sha1table_ref();
+                       } else if (!last_base)
+                               bad_object(offset,
+                                          _("bad copy count index in 
unpack_tree_v4"));
+                       copy_count >>= 1;
+                       if (!copy_count)
+                               bad_object(offset,
+                                          _("bad copy count index in 
unpack_tree_v4"));
+                       nr -= copy_count;
+               } else {        /* path */
+                       unsigned int path_idx = copy_start_or_path >> 1;
+                       const unsigned char *entry_sha1;
+
+                       if (path_idx >= path_dict->nb_entries)
+                               bad_object(offset,
+                                          _("bad path index in 
unpack_tree_v4"));
+                       entry_sha1 = read_sha1ref();
+                       nr--;
+
+                       if (!last_base) {
+                               const unsigned char *path;
+                               unsigned mode;
+
+                               path = path_dict->data + 
path_dict->offsets[path_idx];
+                               mode = (path[0] << 8) | path[1];
+                               strbuf_addf(&sb, "%o %s%c", mode, path+2, '\0');
+                               strbuf_add(&sb, entry_sha1, 20);
+                               if (sb.len > size)
+                                       bad_object(offset,
+                                                  _("tree larger than 
expected"));
+                       }
+               }
+       }
+
+       if (last_base) {
+               strbuf_release(&sb);
+               return NULL;
+       } else {
+               git_SHA_CTX ctx;
+               char hdr[32];
+               int hdrlen;
+
+               if (sb.len != size)
+                       bad_object(offset, _("tree size mismatch"));
+
+               hdrlen = sprintf(hdr, "tree %lu", size) + 1;
+               git_SHA1_Init(&ctx);
+               git_SHA1_Update(&ctx, hdr, hdrlen);
+               git_SHA1_Update(&ctx, sb.buf, size);
+               git_SHA1_Final(sha1, &ctx);
+               return strbuf_detach(&sb, NULL);
+       }
+}
+
+static void *unpack_entry_data(struct object_entry *obj, unsigned char *sha1)
 {
        static char fixed_buf[8192];
        void *buf;
        git_SHA_CTX c;
        char hdr[32];
        int hdrlen;
+       unsigned long offset = obj->idx.offset;
+       unsigned long size = obj->size;
+       enum object_type type = obj->type;
 
        if (type == OBJ_PV4_COMMIT)
                return unpack_commit_v4(offset, size, sha1);
+       if (type == OBJ_PV4_TREE)
+               return unpack_tree_v4(obj, offset, size, sha1);
 
        if (!is_delta_type(type)) {
                hdrlen = sprintf(hdr, "%s %lu", typename(type), size) + 1;
@@ -640,16 +731,19 @@ static void *unpack_raw_entry(struct object_entry *obj,
        case OBJ_BLOB:
        case OBJ_TAG:
                break;
-
        case OBJ_PV4_COMMIT:
                obj->real_type = OBJ_COMMIT;
                break;
+       case OBJ_PV4_TREE:
+               obj->real_type = OBJ_TREE;
+               break;
+
        default:
                bad_object(obj->idx.offset, _("unknown object type %d"), 
obj->type);
        }
        obj->hdr_size = consumed_bytes - obj->idx.offset;
 
-       data = unpack_entry_data(obj->idx.offset, obj->size, obj->type, sha1);
+       data = unpack_entry_data(obj, sha1);
        obj->idx.crc32 = input_crc32;
        return data;
 }
@@ -1186,6 +1280,8 @@ static void parse_pack_objects(unsigned char *sha1)
                        nr_deltas++;
                        delta->obj_no = i;
                        delta++;
+               } else if (!data && obj->type == OBJ_PV4_TREE) {
+                       /* delay sha1_object() until second pass */
                } else if (!data) {
                        /* large blobs, check later */
                        obj->real_type = OBJ_BAD;
-- 
1.8.2.83.gc99314b

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