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      1 /* nbd-client.c - network block device client
      2  *
      3  * Copyright 2010 Rob Landley <rob (at) landley.net>
      4  *
      5  * Not in SUSv4.
      6 
      7 // This little dance is because a NEWTOY with - in the name tries to do
      8 // things like prototype "nbd-client_main" which isn't a valid symbol. So
      9 // we hide the underscore name and OLDTOY the name we want.
     10 USE_NBD_CLIENT(NEWTOY(nbd_client, "<3>3ns", 0))
     11 USE_NBD_CLIENT(OLDTOY(nbd-client, nbd_client, TOYFLAG_USR|TOYFLAG_BIN))
     12 
     13 config NBD_CLIENT
     14   bool "nbd-client"
     15   depends on TOYBOX_FORK
     16   default y
     17   help
     18     usage: nbd-client [-ns] HOST PORT DEVICE
     19 
     20     -n	Do not fork into background
     21     -s	nbd swap support (lock server into memory)
     22 */
     23 
     24 /*  TODO:
     25     usage: nbd-client [-sSpn] [-b BLKSZ] [-t SECS] [-N name] HOST PORT DEVICE
     26 
     27     -b	block size
     28     -t	timeout in seconds
     29     -S	sdp
     30     -p	persist
     31     -n	nofork
     32     -d	DEVICE
     33     -c	DEVICE
     34 */
     35 
     36 #define FOR_nbd_client
     37 #include "toys.h"
     38 #include <linux/nbd.h>
     39 
     40 void nbd_client_main(void)
     41 {
     42   int sock = -1, nbd, flags;
     43   unsigned long timeout = 0;
     44   char *host=toys.optargs[0], *port=toys.optargs[1], *device=toys.optargs[2];
     45   uint64_t devsize;
     46 
     47   // Repeat until spanked
     48 
     49   nbd = xopen(device, O_RDWR);
     50   for (;;) {
     51     int temp;
     52 
     53     // Find and connect to server
     54 
     55     sock = xconnect(xgetaddrinfo(host, port, AF_UNSPEC, SOCK_STREAM, 0, 0));
     56     temp = 1;
     57     setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, &temp, sizeof(int));
     58 
     59     // Read login data
     60 
     61     xreadall(sock, toybuf, 152);
     62     if (memcmp(toybuf, "NBDMAGIC\x00\x00\x42\x02\x81\x86\x12\x53", 16))
     63       error_exit("bad login %s:%s", host, port);
     64     devsize = SWAP_BE64(*(uint64_t *)(toybuf+16));
     65     flags = SWAP_BE32(*(int *)(toybuf+24));
     66 
     67     // Set 4k block size.  Everything uses that these days.
     68     ioctl(nbd, NBD_SET_BLKSIZE, 4096);
     69     ioctl(nbd, NBD_SET_SIZE_BLOCKS, devsize/4096);
     70     ioctl(nbd, NBD_CLEAR_SOCK);
     71 
     72     // If the sucker was exported read only, respect that locally.
     73     temp = (flags & 2) ? 1 : 0;
     74     xioctl(nbd, BLKROSET, &temp);
     75 
     76     if (timeout && ioctl(nbd, NBD_SET_TIMEOUT, timeout)<0) break;
     77     if (ioctl(nbd, NBD_SET_SOCK, sock) < 0) break;
     78 
     79     if (toys.optflags & FLAG_s) mlockall(MCL_CURRENT|MCL_FUTURE);
     80 
     81     // Open the device to force reread of the partition table.
     82     if ((toys.optflags & FLAG_n) || !xfork()) {
     83       char *s = strrchr(device, '/');
     84       int i;
     85 
     86       sprintf(toybuf, "/sys/block/%.32s/pid", s ? s+1 : device);
     87       // Is it up yet? (Give it 10 seconds.)
     88       for (i=0; i<100; i++) {
     89         temp = open(toybuf, O_RDONLY);
     90         if (temp == -1) msleep(100);
     91         else {
     92           close(temp);
     93           break;
     94         }
     95       }
     96       close(open(device, O_RDONLY));
     97       if (!(toys.optflags & FLAG_n)) exit(0);
     98     }
     99 
    100     // Daemonize here.
    101 
    102     if (daemon(0,0)) perror_exit("daemonize");
    103 
    104     // Process NBD requests until further notice.
    105 
    106     if (ioctl(nbd, NBD_DO_IT)>=0 || errno==EBADR) break;
    107     close(sock);
    108   }
    109 
    110   // Flush queue and exit.
    111   ioctl(nbd, NBD_CLEAR_QUE);
    112   ioctl(nbd, NBD_CLEAR_SOCK);
    113   if (CFG_TOYBOX_FREE) close(nbd);
    114 }
    115