diff options
| -rw-r--r-- | src/couchdb/couch_file.erl | 69 |
1 files changed, 41 insertions, 28 deletions
diff --git a/src/couchdb/couch_file.erl b/src/couchdb/couch_file.erl index 64a9ed7b..7a4c32a3 100644 --- a/src/couchdb/couch_file.erl +++ b/src/couchdb/couch_file.erl @@ -118,34 +118,7 @@ pread_binary(Fd, Pos) -> pread_iolist(Fd, Pos) -> - {ok, LenIolist, NextPos} = read_raw_iolist(Fd, Pos, 4), - case iolist_to_binary(LenIolist) of - <<1:1/integer,Len:31/integer>> -> - {ok, Md5List, ValPos} = read_raw_iolist(Fd, NextPos, 16), - Md5 = iolist_to_binary(Md5List), - {ok, IoList, _} = read_raw_iolist(Fd,ValPos,Len), - case couch_util:md5(IoList) of - Md5 -> ok; - _ -> throw(file_corruption) - end, - {ok, IoList}; - <<0:1/integer,Len:31/integer>> -> - {ok, Iolist, _} = read_raw_iolist(Fd, NextPos, Len), - {ok, Iolist} - end. - - -read_raw_iolist(Fd, Pos, Len) -> - BlockOffset = Pos rem ?SIZE_BLOCK, - TotalBytes = calculate_total_read_len(BlockOffset, Len), - {ok, <<RawBin:TotalBytes/binary>>, HasPrefixes} = gen_server:call(Fd, {pread, Pos, TotalBytes}, infinity), - if HasPrefixes -> - {ok, remove_block_prefixes(BlockOffset, RawBin), Pos + TotalBytes}; - true -> - % 09 UPGRADE CODE - <<ReturnBin:Len/binary, _/binary>> = RawBin, - {ok, [ReturnBin], Pos + Len} - end. + gen_server:call(Fd, {pread_iolist, Pos}, infinity). %%---------------------------------------------------------------------- %% Purpose: The length of a file, in bytes. @@ -277,6 +250,22 @@ terminate(_Reason, _Fd) -> ok. +handle_call({pread_iolist, Pos}, _From, File) -> + {LenIolist, NextPos} = read_raw_iolist_int(File, Pos, 4), + case iolist_to_binary(LenIolist) of + <<1:1/integer,Len:31/integer>> -> % an MD5-prefixed term + {Md5AndIoList, _} = read_raw_iolist_int(File, NextPos, Len+16), + {Md5, IoList} = extract_md5(Md5AndIoList), + case couch_util:md5(IoList) of + Md5 -> + {reply, {ok, IoList}, File}; + _ -> + {stop, file_corruption, {error,file_corruption}, File} + end; + <<0:1/integer,Len:31/integer>> -> + {Iolist, _} = read_raw_iolist_int(File, NextPos, Len), + {reply, {ok, Iolist}, File} + end; handle_call({pread, Pos, Bytes}, _From, #file{fd=Fd,tail_append_begin=TailAppendBegin}=File) -> {ok, Bin} = file:pread(Fd, Pos, Bytes), {reply, {ok, Bin, Pos >= TailAppendBegin}, File}; @@ -468,6 +457,25 @@ load_header(Fd, Block) -> Md5Sig = couch_util:md5(HeaderBin), {ok, HeaderBin}. +-spec read_raw_iolist_int(#file{}, Pos::non_neg_integer(), Len::non_neg_integer()) -> + {Data::iolist(), CurPos::non_neg_integer()}. +read_raw_iolist_int(#file{fd=Fd, tail_append_begin=TAB}, Pos, Len) -> + BlockOffset = Pos rem ?SIZE_BLOCK, + TotalBytes = calculate_total_read_len(BlockOffset, Len), + {ok, <<RawBin:TotalBytes/binary>>} = file:pread(Fd, Pos, TotalBytes), + if Pos >= TAB -> + {remove_block_prefixes(BlockOffset, RawBin), Pos + TotalBytes}; + true -> + % 09 UPGRADE CODE + <<ReturnBin:Len/binary, _/binary>> = RawBin, + {[ReturnBin], Pos + Len} + end. + +-spec extract_md5(iolist()) -> {binary(), iolist()}. +extract_md5(FullIoList) -> + {Md5List, IoList} = split_iolist(FullIoList, 16, []), + {iolist_to_binary(Md5List), IoList}. + calculate_total_read_len(0, FinalLen) -> calculate_total_read_len(1, FinalLen) + 1; calculate_total_read_len(BlockOffset, FinalLen) -> @@ -506,6 +514,11 @@ make_blocks(BlockOffset, IoList) -> IoList end. +%% @doc Returns a tuple where the first element contains the leading SplitAt +%% bytes of the original iolist, and the 2nd element is the tail. If SplitAt +%% is larger than byte_size(IoList), return the difference. +-spec split_iolist(IoList::iolist(), SplitAt::non_neg_integer(), Acc::list()) -> + {iolist(), iolist()} | non_neg_integer(). split_iolist(List, 0, BeginAcc) -> {lists:reverse(BeginAcc), List}; split_iolist([], SplitAt, _BeginAcc) -> |