2 * Copyright 2010 Rob Landley <rob@landley.net>
4 * Licensed under GPLv2, see file LICENSE in this source tree.
7 #include <netinet/tcp.h>
10 //applet:IF_NBDCLIENT(APPLET_ODDNAME(nbd-client, nbdclient, BB_DIR_USR_SBIN, BB_SUID_DROP, nbdclient))
12 //kbuild:lib-$(CONFIG_NBDCLIENT) += nbd-client.o
14 //config:config NBDCLIENT
15 //config: bool "nbd-client"
18 //config: Network block device client
20 #define NBD_SET_SOCK _IO(0xab, 0)
21 #define NBD_SET_BLKSIZE _IO(0xab, 1)
22 #define NBD_SET_SIZE _IO(0xab, 2)
23 #define NBD_DO_IT _IO(0xab, 3)
24 #define NBD_CLEAR_SOCK _IO(0xab, 4)
25 #define NBD_CLEAR_QUEUE _IO(0xab, 5)
26 #define NBD_PRINT_DEBUG _IO(0xab, 6)
27 #define NBD_SET_SIZE_BLOCKS _IO(0xab, 7)
28 #define NBD_DISCONNECT _IO(0xab, 8)
29 #define NBD_SET_TIMEOUT _IO(0xab, 9)
31 //usage:#define nbdclient_trivial_usage
32 //usage: "HOST PORT BLOCKDEV"
33 //usage:#define nbdclient_full_usage "\n\n"
34 //usage: "Connect to HOST and provide a network block device on BLOCKDEV"
36 //TODO: more compat with nbd-client version 2.9.13 -
37 //Usage: nbd-client [bs=blocksize] [timeout=sec] host port nbd_device [-swap] [-persist] [-nofork]
38 //Or : nbd-client -d nbd_device
39 //Or : nbd-client -c nbd_device
40 //Default value for blocksize is 1024 (recommended for ethernet)
41 //Allowed values for blocksize are 512,1024,2048,4096
42 //Note, that kernel 2.4.2 and older ones do not work correctly with
43 //blocksizes other than 1024 without patches
45 int nbdclient_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
46 int nbdclient_main(int argc, char **argv)
48 unsigned long timeout = 0;
52 char *host, *port, *device;
54 uint64_t magic1; // "NBDMAGIC"
55 uint64_t magic2; // 0x420281861253 big endian
61 char c[offsetof(struct nbd_header_t, data) == 8+8+8+4 ? 1 : -1];
64 // Parse command line stuff (just a stub now)
69 bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv);
76 // Repeat until spanked (-persist behavior)
81 // Make sure the /dev/nbd exists
82 nbd = xopen(device, O_RDWR);
84 // Find and connect to server
85 sock = create_and_connect_stream_or_die(host, xatou16(port));
86 setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, &const_int_1, sizeof(const_int_1));
88 // Log on to the server
89 xread(sock, &nbd_header, 8+8+8+4 + 124);
90 if (memcmp(&nbd_header.magic1, "NBDMAGIC""\x00\x00\x42\x02\x81\x86\x12\x53", 16) != 0)
91 bb_error_msg_and_die("login failed");
93 // Set 4k block size. Everything uses that these days
94 ioctl(nbd, NBD_SET_BLKSIZE, 4096);
95 ioctl(nbd, NBD_SET_SIZE_BLOCKS, SWAP_BE64(nbd_header.devsize) / 4096);
96 ioctl(nbd, NBD_CLEAR_SOCK);
98 // If the sucker was exported read only, respect that locally
99 ro = (nbd_header.flags & SWAP_BE32(2)) / SWAP_BE32(2);
100 if (ioctl(nbd, BLKROSET, &ro) < 0)
101 bb_perror_msg_and_die("BLKROSET");
104 if (ioctl(nbd, NBD_SET_TIMEOUT, timeout))
105 bb_perror_msg_and_die("NBD_SET_TIMEOUT");
106 if (ioctl(nbd, NBD_SET_SOCK, sock))
107 bb_perror_msg_and_die("NBD_SET_SOCK");
109 // if (swap) mlockall(MCL_CURRENT|MCL_FUTURE);
112 // Open the device to force reread of the partition table.
113 // Need to do it in a separate process, since open(device)
114 // needs some other process to sit in ioctl(nbd, NBD_DO_IT).
116 char *s = strrchr(device, '/');
117 sprintf(nbd_header.data, "/sys/block/%.32s/pid", s ? s + 1 : device);
120 int fd = open(nbd_header.data, O_RDONLY);
127 open(device, O_RDONLY);
138 // This turns us (the process that calls this ioctl)
139 // into a dedicated NBD request handler.
140 // We block here for a long time.
141 // When exactly ioctl returns? On a signal,
142 // or if someone does ioctl(NBD_DISCONNECT) [nbd-client -d].
143 if (ioctl(nbd, NBD_DO_IT) >= 0 || errno == EBADR) {
144 // Flush queue and exit
145 ioctl(nbd, NBD_CLEAR_QUEUE);
146 ioctl(nbd, NBD_CLEAR_SOCK);