mmap_check.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <fcntl.h>
   4 #include <unistd.h>
   5 #include <sys/mman.h>
   6 #include <fcntl.h>
   7 #include <sys/socket.h>
   8 #include <sys/wait.h>
   9
  10 #ifndef MAP_FILE
  11 #define MAP_FILE 0
  12 #endif
  13
  14
  15 static pid_t child_pid;
  16
  17 #define LENGTH (1<<20)
  18 #define FNAME "mmap.dat"
  19
  20 static void child_main(int pfd)
  21 {
  22         int fd;
  23         char *map;
  24
  25         while ((fd = open(FNAME,O_RDWR)) == -1) sleep(1);
  26
  27         map = mmap(0, LENGTH, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FILE, fd, 0);
  28
  29         while (1) {
  30                 int ofs, len, ret;
  31                 int i;
  32                 char buf[64];
  33
  34                 read(pfd, &ofs, sizeof(ofs));
  35                 read(pfd, &len, sizeof(len));
  36
  37                 if (random() % 2) {
  38                         memcpy(buf, map+ofs, len);
  39                 } else {
  40                         pread(fd, buf, len, ofs);
  41                 }
  42
  43                 for (i=0;i<len;i++) {
  44                         if (buf[i] != (char)(ofs+len+i)) {
  45                                 printf("child failed\n");
  46                                 exit(1);
  47                         }
  48                 }
  49
  50                 ret = 0;
  51                 write(pfd, &ret, sizeof(ret));
  52         }
  53 }
  54
  55
  56 static void parent_main(int pfd)
  57 {
  58         char *map;
  59         int fd = open(FNAME,O_RDWR|O_CREAT|O_TRUNC, 0600);
  60
  61         ftruncate(fd, LENGTH);
  62
  63         map = mmap(0, LENGTH, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FILE, fd, 0);
  64
  65         while (1) {
  66                 int ofs, len, ret;
  67                 int i;
  68                 char buf[64];
  69
  70                 ofs = random() % (LENGTH-64);
  71                 len = random() % 64;
  72
  73                 for (i=0;i<len;i++) buf[i] = ofs+len+i;
  74
  75                 if (random() % 2) {
  76                         memcpy(map+ofs, buf, len);
  77                 } else {
  78                         pwrite(fd, buf, len, ofs);
  79                 }
  80
  81                 write(pfd, &ofs, sizeof(ofs));
  82                 write(pfd, &len, sizeof(len));
  83
  84                 read(pfd, &ret, sizeof(ret));
  85         }
  86 }
  87
  88
  89
  90 int main()
  91 {
  92         int pfd[2];
  93
  94         socketpair(AF_UNIX, SOCK_STREAM, 0, pfd);
  95
  96         srandom(getpid());
  97
  98         if ((child_pid=fork()) == 0) {
  99                 close(pfd[0]);
 100                 child_main(pfd[1]);
 101         } else {
 102                 close(pfd[1]);
 103                 parent_main(pfd[0]);
 104         }
 105         return 0;
 106 }