1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
|
/* $XConsortium: gunzip.c /main/1 1996/11/03 19:33:23 kaleb $ */
/* lib/font/fontfile/gunzip.c
written by Mark Eichin <eichin@kitten.gen.ma.us> September 1996.
intended for inclusion in X11 public releases. */
/* $XFree86: xc/lib/font/fontfile/gunzip.c,v 1.4 2000/09/19 12:46:08 eich Exp $ */
#include "fontmisc.h"
#include <bufio.h>
#include <zlib.h>
typedef struct _xzip_buf {
z_stream z;
int zstat;
BufChar b[BUFFILESIZE];
BufChar b_in[BUFFILESIZE];
BufFilePtr f;
} xzip_buf;
static int BufZipFileClose ( BufFilePtr f, int flag );
static int BufZipFileFill ( BufFilePtr f );
static int BufZipFileSkip ( BufFilePtr f, int c );
static int BufCheckZipHeader ( BufFilePtr f );
BufFilePtr
BufFilePushZIP (BufFilePtr f)
{
xzip_buf *x;
x = (xzip_buf *) xalloc (sizeof (xzip_buf));
if (!x) return 0;
/* these are just for raw calloc/free */
x->z.zalloc = Z_NULL;
x->z.zfree = Z_NULL;
x->z.opaque = Z_NULL;
x->f = f;
/* force inflateInit to allocate it's own history buffer */
x->z.next_in = Z_NULL;
x->z.next_out = Z_NULL;
x->z.avail_in = x->z.avail_out = 0;
/* using negative windowBits sets "nowrap" mode, which turns off
zlib header checking [undocumented, for gzip compatibility only?] */
x->zstat = inflateInit2(&(x->z), -MAX_WBITS);
if (x->zstat != Z_OK) {
xfree(x);
return 0;
}
/* now that the history buffer is allocated, we provide the data buffer */
x->z.next_out = x->b;
x->z.avail_out = BUFFILESIZE;
x->z.next_out = x->b_in;
x->z.avail_in = 0;
if (BufCheckZipHeader(x->f)) {
xfree(x);
return 0;
}
return BufFileCreate((char *)x,
BufZipFileFill,
0,
BufZipFileSkip,
BufZipFileClose);
}
static int
BufZipFileClose(BufFilePtr f, int flag)
{
xzip_buf *x = (xzip_buf *)f->private;
inflateEnd (&(x->z));
BufFileClose (x->f, flag);
xfree (x);
return 1;
}
/* here's the real work.
-- we need to put stuff in f.buffer, update f.left and f.bufp,
then return the first byte (or BUFFILEEOF).
-- to do this, we need to get stuff into avail_in, and next_in,
and call inflate appropriately.
-- we may also need to add CRC maintenance - if inflate tells us
Z_STREAM_END, we then have 4bytes CRC and 4bytes length...
gzio.c:gzread shows most of the mechanism.
*/
static int
BufZipFileFill (BufFilePtr f)
{
xzip_buf *x = (xzip_buf *)f->private;
/* we only get called when left == 0... */
/* but just in case, deal */
if (f->left >= 0) {
f->left--;
return *(f->bufp++);
}
/* did we run out last time? */
switch (x->zstat) {
case Z_OK:
break;
case Z_STREAM_END:
case Z_DATA_ERROR:
case Z_ERRNO:
f->left = 0;
return BUFFILEEOF;
default:
return BUFFILEEOF;
}
/* now we work to consume what we can */
/* let zlib know what we can handle */
x->z.next_out = x->b;
x->z.avail_out = BUFFILESIZE;
/* and try to consume all of it */
while (x->z.avail_out > 0) {
/* if we don't have anything to work from... */
if (x->z.avail_in == 0) {
/* ... fill the z buf from underlying file */
int i, c;
for (i = 0; i < sizeof(x->b_in); i++) {
c = BufFileGet(x->f);
if (c == BUFFILEEOF) break;
x->b_in[i] = c;
}
x->z.avail_in += i;
x->z.next_in = x->b_in;
}
/* so now we have some output space and some input data */
x->zstat = inflate(&(x->z), Z_NO_FLUSH);
/* the inflation output happens in the f buffer directly... */
if (x->zstat == Z_STREAM_END) {
/* deal with EOF, crc */
break;
}
if (x->zstat != Z_OK) {
break;
}
}
f->bufp = x->b;
f->left = BUFFILESIZE - x->z.avail_out;
if (f->left >= 0) {
f->left--;
return *(f->bufp++);
} else {
return BUFFILEEOF;
}
}
/* there should be a BufCommonSkip... */
static int
BufZipFileSkip (BufFilePtr f, int c)
{
/* BufFileRawSkip returns the count unchanged.
BufCompressedSkip returns 0.
That means it probably never gets called... */
int retval = c;
while(c--) {
int get = BufFileGet(f);
if (get == BUFFILEEOF) return get;
}
return retval;
}
/* now we need to duplicate check_header */
/* contents:
0x1f, 0x8b -- magic number
1 byte -- method (Z_DEFLATED)
1 byte -- flags (mask with RESERVED -> fail)
4 byte -- time (discard)
1 byte -- xflags (discard)
1 byte -- "os" code (discard)
[if flags & EXTRA_FIELD:
2 bytes -- LSBfirst length n
n bytes -- extra data (discard)]
[if flags & ORIG_NAME:
n bytes -- null terminated name (discard)]
[if flags & COMMENT:
n bytes -- null terminated comment (discard)]
[if flags & HEAD_CRC:
2 bytes -- crc of headers? (discard)]
*/
/* gzip flag byte -- from gzio.c */
#define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
#define HEAD_CRC 0x02 /* bit 1 set: header CRC present */
#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
#define ORIG_NAME 0x08 /* bit 3 set: original file name present */
#define COMMENT 0x10 /* bit 4 set: file comment present */
#define RESERVED 0xE0 /* bits 5..7: reserved */
#define GET(f) do {c = BufFileGet(f); if (c == BUFFILEEOF) return c;} while(0)
static int
BufCheckZipHeader(BufFilePtr f)
{
int c, flags;
GET(f); if (c != 0x1f) return 1; /* magic 1 */
GET(f); if (c != 0x8b) return 2; /* magic 2 */
GET(f); if (c != Z_DEFLATED) return 3; /* method */
GET(f); if (c & RESERVED) return 4; /* reserved flags */
flags = c;
GET(f); GET(f); GET(f); GET(f); /* time */
GET(f); /* xflags */
GET(f); /* os code */
if (flags & EXTRA_FIELD) {
int len;
GET(f); len = c;
GET(f); len += (c<<8);
while (len-- >= 0) {
GET(f);
}
}
if (flags & ORIG_NAME) {
do { GET(f); } while (c != 0);
}
if (flags & COMMENT) {
do { GET(f); } while (c != 0);
}
if (flags & HEAD_CRC) {
GET(f); GET(f); /* header crc */
}
return 0;
}
|
