tests/shared_mmap.c

   1 /* this tests whether we can use a shared writeable mmap on a file -
   2    as needed for the mmap variant of FAST_SHARE_MODES */
   3
   4 #if defined(HAVE_UNISTD_H)
   5 #include <unistd.h>
   6 #endif
   7 #include <sys/mman.h>
   8 #include <sys/types.h>
   9 #include <sys/stat.h>
  10 #include <fcntl.h>
  11
  12 #define DATA "conftest.mmap"
  13
  14 #ifndef MAP_FILE
  15 #define MAP_FILE 0
  16 #endif
  17
  18 int main(void)
  19 {
  20         int *buf;
  21         int i;
  22         int fd = open(DATA,O_RDWR|O_CREAT|O_TRUNC,0666);
  23         int count=7;
  24
  25         if (fd == -1) exit(1);
  26
  27         for (i=0;i<10000;i++) {
  28                 write(fd,&i,sizeof(i));
  29         }
  30
  31         close(fd);
  32
  33         if (fork() == 0) {
  34                 fd = open(DATA,O_RDWR);
  35                 if (fd == -1) exit(1);
  36
  37                 buf = (int *)mmap(NULL, 10000*sizeof(int),
  38                                    (PROT_READ | PROT_WRITE),
  39                                    MAP_FILE | MAP_SHARED,
  40                                    fd, 0);
  41
  42                 if (buf == (int *)-1) exit(1);
  43
  44                 while (count-- && buf[9124] != 55732) sleep(1);
  45
  46                 if (count <= 0) exit(1);
  47
  48                 buf[1763] = 7268;
  49                 exit(0);
  50         }
  51
  52         fd = open(DATA,O_RDWR);
  53         if (fd == -1) exit(1);
  54
  55         buf = (int *)mmap(NULL, 10000*sizeof(int),
  56                            (PROT_READ | PROT_WRITE),
  57                            MAP_FILE | MAP_SHARED,
  58                            fd, 0);
  59
  60         if (buf == (int *)-1) exit(1);
  61
  62         buf[9124] = 55732;
  63
  64         while (count-- && buf[1763] != 7268) sleep(1);
  65
  66         unlink(DATA);
  67
  68         if (count > 0) exit(0);
  69         exit(1);
  70 }