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
|
/* fkt_extract.c
fkt_extract -- program to extract a portion of a trace, given by its page
numbers.
Copyright (C) 2003 Samuel Thibault <samuel.thibault@ens-lyon.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <config.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/sendfile.h>
#include <sys/mman.h>
ssize_t slow_copyfile(int out_fd, int in_fd, off_t *offset, size_t count)
{
void *buffer;
size_t done,donebuffer;
ssize_t res;
int page_size = getpagesize();
if( count%page_size )
{
fprintf(stderr,"size is not page-aligned\n");
exit(EXIT_FAILURE);
}
if( (buffer = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS,0,0)) == MAP_FAILED
&& !(buffer = malloc(page_size)))
{
perror("allocating page buffer\n");
exit(EXIT_FAILURE);
}
done=0;
while( done<count )
{
donebuffer=0;
while( donebuffer<page_size )
{
if( (res=read(in_fd, buffer+donebuffer, page_size-donebuffer) < 0) )
{
if( res != EINTR )
{
perror("read");
exit(EXIT_FAILURE);
}
}
else if( res==0 )
{
fprintf(stderr,"unexpected end of file\n");
exit(EXIT_FAILURE);
}
else donebuffer+=res;
}
donebuffer=0;
while( donebuffer<page_size )
{
if( (res=write(in_fd, buffer+donebuffer, page_size-donebuffer) < 0) )
{
if( res != EINTR )
{
perror("write");
exit(EXIT_FAILURE);
}
}
else donebuffer+=res;
}
done+=page_size;
}
return done;
}
ssize_t copyfile(int out_fd, int in_fd, off_t *offset, size_t count)
{
size_t done=0;
ssize_t ret;
while( done<count )
{
if( (ret=sendfile(out_fd, in_fd, offset, count-done)) < 0 )
{
if( errno == EINVAL && done==0 )
return slow_copyfile(out_fd, in_fd, offset, count);
perror("sendfile");
exit(EXIT_FAILURE);
}
else if( ret == 0 )
{
fprintf(stderr,"unexpected end of file\n");
exit(EXIT_FAILURE);
}
else done+=ret;
}
return done;
}
void usage( char *argv0 )
{
fprintf(stderr,"\
usage: %s in-file out-file begin end\n\
where begin and end are page numbers, inclusive\n\
",argv0);
exit(EXIT_FAILURE);
}
int main( int argc, char *argv[] )
{
char *c;
int fdin,fdout;
size_t begin, end;
unsigned int offset;
off_t copyoff;
int res;
int page_size = getpagesize();
if( argc < 5 )
usage(argv[0]);
if( (fdin=open(argv[1],O_RDONLY)) < 0 )
{
fprintf(stderr,"couldn't open %s\n",argv[1]);
perror("open");
exit(EXIT_FAILURE);
}
if( (fdout=open(argv[2],O_WRONLY|O_CREAT|O_TRUNC,0664)) < 0 )
{
fprintf(stderr,"couldn't open %s\n",argv[2]);
perror("open");
exit(EXIT_FAILURE);
}
begin=strtoll(argv[3],&c,0)*page_size;
if( c == argv[3] )
usage(argv[0]);
end=(strtoll(argv[4],&c,0)+1)*page_size;
if( c == argv[4] )
usage(argv[0]);
if( (res=read(fdin, &offset, sizeof(offset))) < sizeof(offset) )
{
if( res<0 )
perror("read offset");
else
fprintf(stderr,"Unexpected end of file\n");
exit(EXIT_FAILURE);
}
if( offset <= 32 || offset%page_size )
{
fprintf(stderr,"incorrect offset\n");
exit(EXIT_FAILURE);
}
lseek(fdin,0,SEEK_SET);
/* copy header */
copyoff=0;
copyfile(fdout,fdin,©off,offset);
/* copy data */
copyoff=offset+begin;
copyfile(fdout,fdin,©off,end-begin);
/* and that's it :) */
return EXIT_SUCCESS;
}
/* vim: ts=4
*/
|