123 lines
3.1 KiB
C
123 lines
3.1 KiB
C
/* nbd-client.c - network block device client
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*
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* Copyright 2010 Rob Landley <rob@landley.net>
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*
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* Not in SUSv4.
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// This little dance is because a NEWTOY with - in the name tries to do
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// things like prototype "nbd-client_main" which isn't a valid symbol. So
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// we hide the underscore name and OLDTOY the name we want.
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USE_NBD_CLIENT(NEWTOY(nbd_client, "<3>3b#<1>4294967295=4096ns", 0))
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USE_NBD_CLIENT(OLDTOY(nbd-client, nbd_client, TOYFLAG_USR|TOYFLAG_BIN))
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config NBD_CLIENT
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bool "nbd-client"
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default y
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help
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usage: nbd-client [-ns] [-b BLKSZ] HOST PORT DEVICE
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-b Block size (default 4096)
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-n Do not daemonize
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-s nbd swap support (lock server into memory)
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*/
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/* TODO:
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usage: nbd-client [-Sp] [-t SECS] [-N name] HOST PORT DEVICE
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-t timeout in seconds
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-S sdp
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-p persist
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-d DEVICE
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-c DEVICE
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*/
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#define FOR_nbd_client
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#include "toys.h"
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#include <linux/nbd.h>
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GLOBALS(
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long b;
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int nbd;
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)
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static void sig_cleanup(int catch)
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{
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// Flush on the way out
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ioctl(TT.nbd, NBD_CLEAR_QUE);
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ioctl(TT.nbd, NBD_CLEAR_SOCK);
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_exit(catch ? 128+catch : 0);
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}
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void nbd_client_main(void)
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{
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int sock = -1, flags, temp;
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unsigned long timeout = 0;
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char *host=toys.optargs[0], *port=toys.optargs[1], *device=toys.optargs[2];
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unsigned long long devsize;
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// Daemonize in a nommu-friendly way, but retain stderr
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if (toys.stacktop && !FLAG(n)) {
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dup2(2, 222);
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xvdaemon();
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}
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dup2(222, 2);
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close(222);
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TT.nbd = xopen(device, O_RDWR);
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xsignal(SIGINT, sig_cleanup);
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xsignal(SIGTERM, sig_cleanup);
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for (;;) {
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// Find and connect to server
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sock = xconnectany(xgetaddrinfo(host, port, AF_UNSPEC, SOCK_STREAM, 0, 0));
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temp = 1;
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setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, &temp, sizeof(int));
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// Read login data
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xreadall(sock, toybuf, 152);
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if (smemcmp(toybuf, "NBDMAGIC\x00\x00\x42\x02\x81\x86\x12\x53", 16))
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error_exit("bad login %s:%s", host, port);
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devsize = SWAP_BE64(*(unsigned long long *)(toybuf+16));
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flags = SWAP_BE32(*(int *)(toybuf+24));
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// Use 4k block size
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ioctl(TT.nbd, NBD_SET_BLKSIZE, TT.b);
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ioctl(TT.nbd, NBD_SET_SIZE_BLOCKS, devsize/TT.b); // rounds down
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ioctl(TT.nbd, NBD_CLEAR_SOCK);
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// Locally respect read only exports
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flags = (flags>>1)&1;
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xioctl(TT.nbd, BLKROSET, &flags);
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if (timeout && ioctl(TT.nbd, NBD_SET_TIMEOUT, timeout)<0) break;
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if (ioctl(TT.nbd, NBD_SET_SOCK, sock) < 0) break;
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if (FLAG(s)) mlockall(MCL_CURRENT|MCL_FUTURE);
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// Open the device to force reread of the partition table.
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if (!CFG_TOYBOX_FORK || !xfork()) {
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char *s = strrchr(device, '/');
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int i;
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// Give device up to 10 seconds to come up
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sprintf(toybuf, "/sys/block/%.32s/pid", s ? s+1 : device);
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for (i=0; i<100; i++) {
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if (access(toybuf, F_OK)) break;
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msleep(100);
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}
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close(open(device, O_RDONLY));
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if (CFG_TOYBOX_FORK) _exit(0);
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}
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// Process NBD requests until further notice.
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if (ioctl(TT.nbd, NBD_DO_IT)>=0 || errno==EBADR) break;
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close(sock);
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ioctl(TT.nbd, NBD_CLEAR_QUE);
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}
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// Flush queue and exit.
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if (CFG_TOYBOX_FREE) close(TT.nbd);
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}
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