[git commit master 1/1] nbd-client: new applet
Denys Vlasenko
vda.linux at googlemail.com
Thu Sep 23 00:03:47 UTC 2010
commit: http://git.busybox.net/busybox/commit/?id=1fc20c446fde454bbff690a17b0b89de5e127d96
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master
function old new delta
nbdclient_main - 537 +537
daemon - 162 +162
packed_usage 27682 27724 +42
applet_names 2355 2366 +11
bbconfig_config_bz2 4918 4922 +4
applet_main 1376 1380 +4
applet_nameofs 688 690 +2
applet_install_loc 172 173 +1
------------------------------------------------------------------------------
(add/remove: 4/0 grow/shrink: 6/0 up/down: 763/0) Total: 763 bytes
Signed-off-by: Rob Landley <rob at landley.net>
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
networking/nbd-client.c | 153 +++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 153 insertions(+), 0 deletions(-)
create mode 100644 networking/nbd-client.c
diff --git a/networking/nbd-client.c b/networking/nbd-client.c
new file mode 100644
index 0000000..5ac190c
--- /dev/null
+++ b/networking/nbd-client.c
@@ -0,0 +1,153 @@
+/*
+ * Copyright 2010 Rob Landley <rob at landley.net>
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
+ */
+#include "libbb.h"
+#include <netinet/tcp.h>
+#include <linux/fs.h>
+
+//applet:IF_NBDCLIENT(APPLET_ODDNAME(nbd-client, nbdclient, _BB_DIR_USR_SBIN, _BB_SUID_DROP, nbdclient))
+
+//kbuild:lib-$(CONFIG_NBDCLIENT) += nbd-client.o
+
+//config:config NBDCLIENT
+//config: bool "nbd-client"
+//config: default y
+//config: help
+//config: Network block device client
+
+#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, char **argv)
+{
+ unsigned long timeout = 0;
+ int nofork = 0;
+ 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;
+ struct bug_check {
+ char c[offsetof(struct nbd_header_t, data) == 8+8+8+4 ? 1 : -1];
+ };
+
+ // Parse command line stuff (just a stub now)
+ if (argc != 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(sock, IPPROTO_TCP, TCP_NODELAY, &const_int_1, sizeof(const_int_1));
+
+ // 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;
+}
--
1.7.1
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