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/*
* Copyright 2010 Rob Landley <rob@landley.net>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//config:config NBDCLIENT
//config: bool "nbd-client (4.6 kb)"
//config: default y
//config: help
//config: Network block device client
//applet:IF_NBDCLIENT(APPLET_NOEXEC(nbd-client, nbdclient, BB_DIR_USR_SBIN, BB_SUID_DROP, nbdclient))
//kbuild:lib-$(CONFIG_NBDCLIENT) += nbd-client.o
#include "libbb.h"
#include <netinet/tcp.h>
#include <linux/fs.h>
#define NBD_SET_SOCK _IO(0xab, 0)
#define NBD_SET_BLKSIZE _IO(0xab, 1)
#define NBD_SET_SIZE _IO(0xab, 2)
#define NBD_DO_IT _IO(0xab, 3)
#define NBD_CLEAR_SOCK _IO(0xab, 4)
#define NBD_CLEAR_QUEUE _IO(0xab, 5)
#define NBD_PRINT_DEBUG _IO(0xab, 6)
#define NBD_SET_SIZE_BLOCKS _IO(0xab, 7)
#define NBD_DISCONNECT _IO(0xab, 8)
#define NBD_SET_TIMEOUT _IO(0xab, 9)
//usage:#define nbdclient_trivial_usage
//usage: "HOST PORT BLOCKDEV"
//usage:#define nbdclient_full_usage "\n\n"
//usage: "Connect to HOST and provide a network block device on BLOCKDEV"
//TODO: more compat with nbd-client version 2.9.13 -
//Usage: nbd-client [bs=blocksize] [timeout=sec] host port nbd_device [-swap] [-persist] [-nofork]
//Or : nbd-client -d nbd_device
//Or : nbd-client -c nbd_device
//Default value for blocksize is 1024 (recommended for ethernet)
//Allowed values for blocksize are 512,1024,2048,4096
//Note, that kernel 2.4.2 and older ones do not work correctly with
//blocksizes other than 1024 without patches
int nbdclient_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int nbdclient_main(int argc UNUSED_PARAM, char **argv)
{
unsigned long timeout = 0;
#if BB_MMU
int nofork = 0;
#endif
char *host, *port, *device;
struct nbd_header_t {
uint64_t magic1; // "NBDMAGIC"
uint64_t magic2; // 0x420281861253 big endian
uint64_t devsize;
uint32_t flags;
char data[124];
} nbd_header;
BUILD_BUG_ON(offsetof(struct nbd_header_t, data) != 8+8+8+4);
// Parse command line stuff (just a stub now)
if (!argv[1] || !argv[2] || !argv[3] || argv[4])
bb_show_usage();
#if !BB_MMU
bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv);
#endif
host = argv[1];
port = argv[2];
device = argv[3];
// Repeat until spanked (-persist behavior)
for (;;) {
int sock, nbd;
int ro;
// Make sure the /dev/nbd exists
nbd = xopen(device, O_RDWR);
// Find and connect to server
sock = create_and_connect_stream_or_die(host, xatou16(port));
setsockopt_1(sock, IPPROTO_TCP, TCP_NODELAY);
// Log on to the server
xread(sock, &nbd_header, 8+8+8+4 + 124);
if (memcmp(&nbd_header.magic1, "NBDMAGIC""\x00\x00\x42\x02\x81\x86\x12\x53", 16) != 0)
bb_error_msg_and_die("login failed");
// Set 4k block size. Everything uses that these days
ioctl(nbd, NBD_SET_BLKSIZE, 4096);
ioctl(nbd, NBD_SET_SIZE_BLOCKS, SWAP_BE64(nbd_header.devsize) / 4096);
ioctl(nbd, NBD_CLEAR_SOCK);
// If the sucker was exported read only, respect that locally
ro = (nbd_header.flags & SWAP_BE32(2)) / SWAP_BE32(2);
if (ioctl(nbd, BLKROSET, &ro) < 0)
bb_perror_msg_and_die("BLKROSET");
if (timeout)
if (ioctl(nbd, NBD_SET_TIMEOUT, timeout))
bb_perror_msg_and_die("NBD_SET_TIMEOUT");
if (ioctl(nbd, NBD_SET_SOCK, sock))
bb_perror_msg_and_die("NBD_SET_SOCK");
// if (swap) mlockall(MCL_CURRENT|MCL_FUTURE);
#if BB_MMU
// Open the device to force reread of the partition table.
// Need to do it in a separate process, since open(device)
// needs some other process to sit in ioctl(nbd, NBD_DO_IT).
if (fork() == 0) {
char *s = strrchr(device, '/');
sprintf(nbd_header.data, "/sys/block/%.32s/pid", s ? s + 1 : device);
// Is it up yet?
for (;;) {
int fd = open(nbd_header.data, O_RDONLY);
if (fd >= 0) {
//close(fd);
break;
}
sleep(1);
}
open(device, O_RDONLY);
return 0;
}
// Daemonize here
if (!nofork) {
daemon(0, 0);
nofork = 1;
}
#endif
// This turns us (the process that calls this ioctl)
// into a dedicated NBD request handler.
// We block here for a long time.
// When exactly ioctl returns? On a signal,
// or if someone does ioctl(NBD_DISCONNECT) [nbd-client -d].
if (ioctl(nbd, NBD_DO_IT) >= 0 || errno == EBADR) {
// Flush queue and exit
ioctl(nbd, NBD_CLEAR_QUEUE);
ioctl(nbd, NBD_CLEAR_SOCK);
break;
}
close(sock);
close(nbd);
}
return 0;
}
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