Mercurial > hg > Applications > Grep

comparison c/blocked_mmap/main.cc @ 30:edecf5b459c9

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
rename mmap to blocked_mmap
author Masataka Kohagura <kohagura@cr.ie.u-ryukyu.ac.jp>
date Sun, 11 May 2014 19:32:39 +0900
parents c/mmap/main.cc@b9d005c23aaa
children 4580f792d4c6
comparison
equal deleted inserted replaced
29:b9d005c23aaa 30:edecf5b459c9
1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <string.h>
4 #include <unistd.h>
5 #include <fcntl.h>
6 #include <sys/stat.h>
7 #include <sys/types.h>
8 #include <sys/mman.h>
9
10
11 const char *usr_help_str = "Usage : ./mmap [-file filename]";
12
13 int main(int argc, char *argv[]){
14
15 struct stat sb;
16
17 char *filename = 0;
18 for (int i = 1; argv[i]; ++i) {
19 if (strcmp(argv[i], "-file") == 0){
20 filename = argv[i+1]; i++;
21 }
22 }
23
24 if (filename == 0){
25 puts(usr_help_str);
26 exit(1);
27 }
28
29 int fd = -1;
30 if ((fd=open(filename,O_RDONLY,0666))==0){
31 fprintf(stderr,"can't open %s\n",filename);
32 }
33
34 if (fstat(fd,&sb)){
35 fprintf(stderr,"can't open %s\n",filename);
36 }
37
38 int file_size = sb.st_size;
39 int page_size = getpagesize();
40
41 int loop_num = file_size / page_size;
42 loop_num += (file_size % page_size != 0);
43
44 char * file_mmap = NULL;
45 char * file_head = NULL; // head of read file
46
47 for (int i = 0; i < loop_num; i++) {
48 // mmap 6th arg must be a multiple of the paging size.
49 file_mmap = (char *)mmap(0, page_size, PROT_READ, MAP_PRIVATE, fd, i*page_size);
50 if (i == 0) file_head = file_mmap;
51 file_mmap += page_size;
52 }
53
54 printf("%s\n",file_head);
55
56 munmap(file_mmap, file_size);
57 close(fd);
58
59 return 0;
60 }