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author | Dirk Engling <erdgeist@erdgeist.org> | 2014-02-08 23:39:56 +0100 |
---|---|---|
committer | Dirk Engling <erdgeist@erdgeist.org> | 2014-02-08 23:39:56 +0100 |
commit | 4affb3811c4a57cb4e033ddd40f5e99236b59250 (patch) | |
tree | 87474b22efd29e638d79169f3ea9dd95b52591fe /src/decompress.c | |
parent | a9d5ab4dbf4a7c3e2caf54c96daecc8468eacf0c (diff) |
Speed up decompress script by avoiding to wastefully copying a megabyte of data each time we scan for a new decompression offset
Diffstat (limited to 'src/decompress.c')
-rw-r--r-- | src/decompress.c | 55 |
1 files changed, 29 insertions, 26 deletions
diff --git a/src/decompress.c b/src/decompress.c index 6074db6..fbf33ec 100644 --- a/src/decompress.c +++ b/src/decompress.c | |||
@@ -1,52 +1,55 @@ | |||
1 | #include <zlib.h> | 1 | #include <stdlib.h> |
2 | #include <stdio.h> | 2 | #include <stdio.h> |
3 | #include <unistd.h> | 3 | #include <unistd.h> |
4 | #include <fcntl.h> | 4 | #include <fcntl.h> |
5 | #include <string.h> | 5 | #include <string.h> |
6 | #include <zlib.h> | ||
7 | #include "mystdlib.h" | ||
6 | 8 | ||
7 | #define XORLEN (29) | 9 | #define XORLEN (29) |
8 | #define HUGEBLOCK (1024*1024) | 10 | #define HUGEBLOCK (1024*1024) |
9 | 11 | ||
10 | int main(int argc, char **argv) { | 12 | int main(int argc, char **argv) { |
11 | // int infile = open("/Volumes/DasTelefonbuch/atb/phonebook.db", O_RDONLY); | 13 | MAP in = map_file( argv[1], 1 ); |
12 | |||
13 | int infile = open( argv[1], O_RDONLY); | ||
14 | 14 | ||
15 | unsigned const char xorkey [XORLEN] = "Just for Fun. Linus Torvalds."; | 15 | unsigned const char xorkey [XORLEN] = "Just for Fun. Linus Torvalds."; |
16 | unsigned char input [HUGEBLOCK]; | 16 | unsigned char input [XORLEN]; |
17 | unsigned char output [HUGEBLOCK]; | 17 | unsigned char output [HUGEBLOCK]; |
18 | char respath[32]; /* file_XXXXX\0 */ | 18 | char respath[32]; /* file_XXXXX\0 */ |
19 | int i, offs = 0, zres = 0, filenum = 0, resfile, avail=1; | 19 | int i, zres = 0, filenum = 0, resfile; |
20 | z_stream z; memset( &z, 0, sizeof(z)); | 20 | size_t offs = 0; |
21 | 21 | ||
22 | while( avail ) { | 22 | z_stream z; memset( &z, 0, sizeof(z)); |
23 | do { | ||
24 | lseek( infile, offs, SEEK_SET ); | ||
25 | avail = read( infile, input, HUGEBLOCK ); | ||
26 | if( !avail) break; | ||
27 | for( i=0; i<XORLEN; ++i ) input[i] ^= xorkey[i]; | ||
28 | 23 | ||
29 | z.next_in = input; z.avail_in = avail; | 24 | while( offs < in->size - XORLEN ) { |
30 | z.next_out = output; z.avail_out = HUGEBLOCK; | 25 | for( i=0; i<XORLEN; ++i ) input[i] = in->addr[offs+i] ^ xorkey[i]; |
31 | inflateInit( &z ); zres = inflate( &z, Z_NO_FLUSH ); | 26 | z.next_in = input; z.avail_in = XORLEN; |
27 | z.next_out = output; z.avail_out = HUGEBLOCK; | ||
28 | inflateInit( &z ); zres = inflate( &z, Z_NO_FLUSH ); | ||
29 | if( (zres != Z_OK) && (zres != Z_STREAM_END) ) | ||
30 | goto error_continue; | ||
32 | 31 | ||
33 | if( (zres != Z_OK) && (zres != Z_STREAM_END) ) { | 32 | z.next_in = in->addr + offs + XORLEN; z.avail_in = in->size - offs - XORLEN; |
34 | inflateEnd(&z); memset( &z, 0, sizeof(z)); | 33 | while( zres == Z_OK ) zres = inflate( &z, Z_NO_FLUSH ); |
35 | offs++; | ||
36 | } | ||
37 | } while((zres != Z_OK) && (zres != Z_STREAM_END)); | ||
38 | 34 | ||
39 | if( !avail ) break; | 35 | if( zres != Z_STREAM_END ) { |
40 | if( zres == Z_OK) while( inflate( &z, Z_NO_FLUSH ) == Z_OK ); | 36 | error_continue: |
37 | inflateEnd(&z); memset( &z, 0, sizeof(z)); | ||
38 | offs++; | ||
39 | continue; | ||
40 | } | ||
41 | 41 | ||
42 | sprintf( respath, "file_%05X", filenum++ ); | 42 | sprintf( respath, "file_%05X", filenum++ ); |
43 | resfile = open( respath, O_RDWR | O_CREAT, 0644 ); | 43 | resfile = open( respath, O_RDWR | O_CREAT, 0644 ); |
44 | /* I know, I know, error checking */ | 44 | if( resfile < 0 ) { |
45 | fprintf( stderr, "Could not open output file %s\n", respath ); | ||
46 | exit(1); | ||
47 | } | ||
45 | write( resfile, output, z.total_out ); | 48 | write( resfile, output, z.total_out ); |
46 | close( resfile ); | 49 | close( resfile ); |
47 | offs += z.total_in; | 50 | offs += z.total_in; |
48 | 51 | ||
49 | inflateEnd(&z); memset( &z, 0, sizeof(z)); | 52 | inflateEnd(&z); memset( &z, 0, sizeof(z)); |
50 | } | 53 | } |
51 | close( infile ); | 54 | unmap_file(&in); |
52 | } | 55 | } |