memdump.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <fcntl.h>
   4 #include <sys/mman.h>
   5 #include <fcntl.h>
   6
   7 #define LEN 0x1000
   8 #define ADDR 0x0
   9 #define SIZE 8*1024
  10
  11 int main()
  12 {
  13         int fdpair[2];
  14         int fd, i=0;
  15         int mapfd, status;
  16         char *map;
  17         char buf[LEN];
  18         char lastbuf[LEN];
  19
  20         fd = open("mem.dat", O_WRONLY|O_CREAT|O_TRUNC, 0600);
  21         if (fd == -1) {
  22                 perror("open");
  23                 exit(1);
  24         }
  25
  26         mapfd = open("/dev/zero", O_RDWR);
  27         if (mapfd == -1) {
  28                 perror("open");
  29                 exit(1);
  30         }
  31
  32         map = mmap(0, SIZE*LEN, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_FILE,
  33                    mapfd, 0);
  34
  35         while (i < SIZE && pipe(fdpair) == 0) {
  36                 if (fork()) {
  37                         memset(buf,'Z', LEN);
  38                         if (read(fdpair[0], buf, LEN) != LEN) {
  39                                 perror("read");
  40                                 exit(1);
  41                         }
  42                         if (memcmp(lastbuf,buf,LEN)) {
  43                                 if (write(fd,buf,LEN) != LEN) {
  44                                         perror("write");
  45                                         exit(1);
  46                                 } else {
  47                                         printf(".");
  48                                         fflush(stdout);
  49                                 }
  50                         }
  51                         memcpy(lastbuf, buf, LEN);
  52                         waitpid(-1, &status, 0);
  53                 } else {
  54                         if (write(fdpair[1],ADDR,LEN) != LEN) {
  55                                 perror("write");
  56                                 exit(1);
  57                         }
  58                         _exit(0);
  59                 }
  60                 close(fdpair[0]);
  61                 close(fdpair[1]);
  62
  63                 map[i*LEN] = i++;
  64         }
  65
  66         return 0;
  67 }