source: branches/3.2/mindi-busybox/networking/nbd-client.c @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 5 years ago
  • Update mindi-busybox to 1.21.1
  • Property svn:eol-style set to native
File size: 4.3 KB
RevLine 
[2725]1/*
2 * Copyright 2010 Rob Landley <rob@landley.net>
3 *
4 * Licensed under GPLv2, see file LICENSE in this source tree.
5 */
6#include "libbb.h"
7#include <netinet/tcp.h>
8#include <linux/fs.h>
9
[3232]10//applet:IF_NBDCLIENT(APPLET_ODDNAME(nbd-client, nbdclient, BB_DIR_USR_SBIN, BB_SUID_DROP, nbdclient))
[2725]11
12//kbuild:lib-$(CONFIG_NBDCLIENT) += nbd-client.o
13
14//config:config NBDCLIENT
15//config:   bool "nbd-client"
16//config:   default y
17//config:   help
18//config:     Network block device client
19
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)
30
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"
35
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
44
45int nbdclient_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
46int nbdclient_main(int argc, char **argv)
47{
48    unsigned long timeout = 0;
49#if BB_MMU
50    int nofork = 0;
51#endif
52    char *host, *port, *device;
53    struct nbd_header_t {
54        uint64_t magic1; // "NBDMAGIC"
55        uint64_t magic2; // 0x420281861253 big endian
56        uint64_t devsize;
57        uint32_t flags;
58        char data[124];
59    } nbd_header;
60    struct bug_check {
61        char c[offsetof(struct nbd_header_t, data) == 8+8+8+4 ? 1 : -1];
62    };
63
64    // Parse command line stuff (just a stub now)
65    if (argc != 4)
66        bb_show_usage();
67
68#if !BB_MMU
69    bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv);
70#endif
71
72    host = argv[1];
73    port = argv[2];
74    device = argv[3];
75
76    // Repeat until spanked (-persist behavior)
77    for (;;) {
78        int sock, nbd;
79        int ro;
80
81        // Make sure the /dev/nbd exists
82        nbd = xopen(device, O_RDWR);
83
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));
87
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");
92
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);
97
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");
102
103        if (timeout)
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");
108
109        // if (swap) mlockall(MCL_CURRENT|MCL_FUTURE);
110
111#if BB_MMU
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).
115        if (fork() == 0) {
116            char *s = strrchr(device, '/');
117            sprintf(nbd_header.data, "/sys/block/%.32s/pid", s ? s + 1 : device);
118            // Is it up yet?
119            for (;;) {
120                int fd = open(nbd_header.data, O_RDONLY);
121                if (fd >= 0) {
122                    //close(fd);
123                    break;
124                }
125                sleep(1);
126            }
127            open(device, O_RDONLY);
128            return 0;
129        }
130
131        // Daemonize here
132        if (!nofork) {
133            daemon(0, 0);
134            nofork = 1;
135        }
136#endif
137
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);
147            break;
148        }
149
150        close(sock);
151        close(nbd);
152    }
153
154    return 0;
155}
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