operating system - Random access alternative to named pipes -

is there way create "file" (i.e. point in file system) can opened program regular file, reading/writing go program instead of disk? named pipe seems meet requirements, except allows serial file access.

i interested in *nix type systems, curious hear of such system on os/file system.

here implementation:

demon.c:

#include <stdio.h> #include <stdlib.h> #include <sys/mman.h> #include <unistd.h> #include <fcntl.h> #include <assert.h> #include <string.h> #include <errno.h>  void map_file(const char *f) {     int fd = open(f, o_creat|o_rdwr, 0666);     if (fd < 0) {         perror("fd open error\n");         exit(-1);     }     char *addr = (char *)mmap(null, 10, prot_read | prot_write, map_shared, fd, 0);     if (addr == map_failed) {         exit(-1);     }     int i;     (i = 0; != 10; ++i) {         addr[i] = '0' + i;     }     while (1) {         (i = 0; != 10; ++i) {             if (addr[i] != '0' + i) {                 printf("addr[%d]: %c\n", i, addr[i]);             }         }         sleep(1);     } }  int main() {     map_file("/dev/mem");     return 0;  } 

cli.c:

#include <sys/mman.h> #include <assert.h> #include <stdlib.h> #include <fcntl.h> #include <unistd.h>  int main() {     const char *f = "/dev/mem";     int fd = open(f, o_rdwr, 0666);     assert(fd >= 0);      lseek(fd, rand() % 10, seek_set);     write(fd, "x", 1);      close(fd);     return 0; }    

we map 10 bytes memory "/dev/mem" our demon program. cli open file regular file, , write byte in random address. of course, can map other file instead of /dev/mem, need 'alloc' byte regular file before mmap. eg:

fd = open("/path/to/myfile", o_creat|o_rdwr, 0666); write(fd, "0123456789", 10);   // 'allocate' 10 bytes regular file addr = (char *)mmap(null, 10, prot_read|prot_write, map_shared, fd, 0);