LXR toybox/toys/other/nbd

   1/* nbd-client.c - network block device client
   2 *
   3 * Copyright 2010 Rob Landley <rob@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.
  10USE_NBD_CLIENT(NEWTOY(nbd_client, "<3>3ns", 0))
  11USE_NBD_CLIENT(OLDTOY(nbd-client, nbd_client, TOYFLAG_USR|TOYFLAG_BIN))
  12
  13config 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
  40void 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