1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 // The GZipHeader class allows you to parse a gzip header, such as you
6 // might find at the beginning of a file compressed by gzip (ie, a .gz
7 // file), or at the beginning of an HTTP response that uses a gzip
8 // Content-Encoding. See RFC 1952 for the specification for the gzip
11 // The model is that you call ReadMore() for each chunk of bytes
12 // you've read from a file or socket.
15 #ifndef NET_BASE_GZIP_HEADER_H_
16 #define NET_BASE_GZIP_HEADER_H_
19 #include "base/basictypes.h"
26 INCOMPLETE_HEADER
, // don't have all the bits yet...
27 COMPLETE_HEADER
, // complete, valid header
28 INVALID_HEADER
, // found something invalid in the header
34 // Wipe the slate clean and start from scratch.
37 // Attempt to parse the given buffer as the next installment of
38 // bytes from a gzip header. If the bytes we've seen so far do not
39 // yet constitute a complete gzip header, return
40 // INCOMPLETE_HEADER. If these bytes do not constitute a *valid*
41 // gzip header, return INVALID_HEADER. When we've seen a complete
42 // gzip header, return COMPLETE_HEADER and set the pointer pointed
43 // to by header_end to the first byte beyond the gzip header.
44 Status
ReadMore(const char* inbuf
,
46 const char** header_end
);
48 enum { // flags (see RFC)
49 FLAG_FTEXT
= 0x01, // bit 0 set: file probably ascii text
50 FLAG_FHCRC
= 0x02, // bit 1 set: header CRC present
51 FLAG_FEXTRA
= 0x04, // bit 2 set: extra field present
52 FLAG_FNAME
= 0x08, // bit 3 set: original file name present
53 FLAG_FCOMMENT
= 0x10, // bit 4 set: file comment present
54 FLAG_RESERVED
= 0xE0, // bits 5..7: reserved
58 // The first 10 bytes are the fixed-size header:
63 IN_HEADER_MTIME_BYTE_0
,
64 IN_HEADER_MTIME_BYTE_1
,
65 IN_HEADER_MTIME_BYTE_2
,
66 IN_HEADER_MTIME_BYTE_3
,
84 static const uint8 magic
[]; // gzip magic header
86 int state_
; // our current State in the parsing FSM: an int so we can ++
87 uint8 flags_
; // the flags byte of the header ("FLG" in the RFC)
88 uint16 extra_length_
; // how much of the "extra field" we have yet to read
90 DISALLOW_COPY_AND_ASSIGN(GZipHeader
);
95 #endif // NET_BASE_GZIP_HEADER_H_