nbd-client: new applet

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@landley.net>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/networking/nbd-client.c b/networking/nbd-client.c
new file mode 100644 (file)
index 0000000..5ac190c
--- /dev/null
+++ b/networking/nbd-client.c
@@ -0,0 +1,153 @@
+/*
+ * Copyright 2010 Rob Landley <rob@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;
+}