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| -rw-r--r-- | plugins/zip.lua | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/plugins/zip.lua b/plugins/zip.lua new file mode 100644 index 0000000..a1b61de --- /dev/null +++ b/plugins/zip.lua @@ -0,0 +1,81 @@ +-- +-- zip.lua: ZIP archives +-- +-- Copyright (c) 2017, Přemysl Janouch <p.janouch@gmail.com> +-- +-- Permission to use, copy, modify, and/or distribute this software for any +-- purpose with or without fee is hereby granted, provided that the above +-- copyright notice and this permission notice appear in all copies. +-- +-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES +-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY +-- SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION +-- OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN +-- CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +-- + +-- Heuristics required, see https://en.wikipedia.org/wiki/Zip_(file_format) +local detect = function (c) + c.endianity = "le" + for o = #c - 22 + 1, #c - 65535 - 22 + 1, -1 do + if o < 1 then break end + c.position = o + if c:u32 () == 0x06054b50 then return o end + end +end + +local decode = function (c) + local eocd = detect (c ()) + if not eocd then error ("not a ZIP file") end + c.endianity = "le" + + c.position = eocd + c:u32 ("end of CD magic: %#x") + c:u16 ("# of this disk: %d") + c:u16 ("disk # where CD starts: %d") + local cd_len = c:u16 ("# of CD records on this disk: %d") + c:u16 ("total # of CD records: %d") + c:u32 ("size of CD: %d") + local cd_offset = c:u32 ("offset of (start of CD - start of archive): %d") + local comment_len = c:u16 ("comment length: %d") + c (c.position, c.position + comment_len - 1):mark ("comment") + + -- TODO: decode the fields better + -- TODO: also mark actual file data if someone wants to put in the effort + c.position = cd_offset + 1 + for i = 1, cd_len do + local p, magic = c.position, c:u32 () + if magic ~= 0x02014b50 then break end + c (p, c.position - 1):mark ("CD file header magic: %#x", magic) + c:u16 ("version made by: %d") + c:u16 ("version needed to extract: %d") + c:u16 ("general purpose bit flag: %#x") + c:u16 ("compression method: %d") + c:u16 ("file last modification time: %d") + c:u16 ("file last modification date: %d") + c:u32 ("CRC-32: %#x") + c:u32 ("compressed size: %d") + c:u32 ("uncompressed size: %d") + local filename_len = c:u16 ("file name length: %d") + local extra_len = c:u16 ("extra field length: %d") + local comment_len = c:u16 ("file comment length: %d") + c:u16 ("disk # where file starts: %d") + c:u16 ("internal file attributes: %#x") + c:u32 ("external file attributes: %#x") + c:u32 ("offset of (start of local file header - start of archive): %d") + + c (c.position, c.position + filename_len - 1):mark ("filename") + c.position = c.position + filename_len + + c (c.position, c.position + extra_len - 1):mark ("extra field") + c.position = c.position + extra_len + + c (c.position, c.position + comment_len - 1):mark ("file comment") + c.position = c.position + comment_len + end +end + +hex.register { type="zip", detect=detect, decode=decode } + |