.\" -*- mode: troff; coding: utf-8 -*- .\" Automatically generated by Podwrapper::Man 1.20.1 (Pod::Simple 3.43) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>. .ie n \{\ . ds C` "" . ds C' "" 'br\} .el\{\ . ds C` . ds C' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is >0, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. Of course, you'll have to process the .\" output yourself in some meaningful fashion. .\" .\" Avoid warning from groff about undefined register 'F'. .de IX .. .nr rF 0 .if \n(.g .if rF .nr rF 1 .if (\n(rF:(\n(.g==0)) \{\ . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF .\" ======================================================================== .\" .IX Title "nbd_shutdown 3" .TH nbd_shutdown 3 2024-05-08 libnbd-1.20.1 LIBNBD .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH NAME nbd_shutdown \- disconnect from the NBD server .SH SYNOPSIS .IX Header "SYNOPSIS" .Vb 1 \& #include \& \& int nbd_shutdown ( \& struct nbd_handle *h, uint32_t flags \& ); .Ve .SH DESCRIPTION .IX Header "DESCRIPTION" Issue the disconnect command to the NBD server. This is a nice way to tell the server we are going away, but from the client's point of view has no advantage over abruptly closing the connection (see \fBnbd_close\fR\|(3)). .PP This function works whether or not the handle is ready for transmission of commands. If more fine-grained control is needed, see \fBnbd_aio_opt_abort\fR\|(3) and \fBnbd_aio_disconnect\fR\|(3). .PP The \f(CW\*(C`flags\*(C'\fR argument is a bitmask, including zero or more of the following shutdown flags: .ie n .IP """LIBNBD_SHUTDOWN_ABANDON_PENDING"" = 0x10000" 4 .el .IP "\f(CWLIBNBD_SHUTDOWN_ABANDON_PENDING\fR = 0x10000" 4 .IX Item "LIBNBD_SHUTDOWN_ABANDON_PENDING = 0x10000" If there are any pending requests which have not yet been sent to the server (see \fBnbd_aio_in_flight\fR\|(3)), abandon them without sending them to the server, rather than the usual practice of issuing those commands before informing the server of the intent to disconnect. .PP For convenience, the constant \f(CW\*(C`LIBNBD_SHUTDOWN_MASK\*(C'\fR is available to describe all shutdown flags recognized by this build of libnbd. A future version of the library may add new flags. .SH "RETURN VALUE" .IX Header "RETURN VALUE" If the call is successful the function returns \f(CW0\fR. .SH ERRORS .IX Header "ERRORS" On error \f(CW\-1\fR is returned. .PP Refer to "ERROR HANDLING" in \fBlibnbd\fR\|(3) for how to get further details of the error. .PP The following parameters must not be NULL: \f(CW\*(C`h\*(C'\fR. For more information see "Non-NULL parameters" in \fBlibnbd\fR\|(3). .SH "HANDLE STATE" .IX Header "HANDLE STATE" nbd_shutdown can be called when the handle is in the following states: .PP .Vb 8 \& ┌─────────────────────────────────────┬─────────────────────────┐ \& │ Handle created, before connecting │ ❌ error │ \& │ Connecting │ ❌ error │ \& │ Connecting & handshaking (opt_mode) │ ✅ allowed │ \& │ Connected to the server │ ✅ allowed │ \& │ Connection shut down │ ❌ error │ \& │ Handle dead │ ❌ error │ \& └─────────────────────────────────────┴─────────────────────────┘ .Ve .SH VERSION .IX Header "VERSION" This function first appeared in libnbd 1.0. .PP If you need to test if this function is available at compile time check if the following macro is defined: .PP .Vb 1 \& #define LIBNBD_HAVE_NBD_SHUTDOWN 1 .Ve .SH EXAMPLE .IX Header "EXAMPLE" This example is also available as \fIexamples/reads\-and\-writes.c\fR in the libnbd source code. .PP .Vb 10 \& /* This example shows how to do synchronous reads \& * and writes randomly over the first megabyte of an \& * NBD server. Note this will destroy any existing \& * content on the NBD server. \& * \& * To test it with nbdkit and a RAM disk: \& * \& * nbdkit \-U \- memory 1M \e \& * \-\-run \*(Aq./simple\-reads\-and\-writes $unixsocket\*(Aq \& */ \& \& #include \& #include \& #include \& #include \& #include \& #include \& \& #include \& \& int \& main (int argc, char *argv[]) \& { \& struct nbd_handle *nbd; \& char buf[512]; \& size_t i; \& int64_t exportsize; \& uint64_t offset; \& \& srand (time (NULL)); \& \& if (argc != 2) { \& fprintf (stderr, "%s socket\en", argv[0]); \& exit (EXIT_FAILURE); \& } \& \& /* Create the libnbd handle. */ \& nbd = nbd_create (); \& if (nbd == NULL) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& \& /* Connect to the NBD server over a \& * Unix domain socket. \& */ \& if (nbd_connect_unix (nbd, argv[1]) == \-1) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& \& /* Get the size of the disk and check \& * it\*(Aqs large enough. \& */ \& exportsize = nbd_get_size (nbd); \& if (exportsize == \-1) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& assert (exportsize >= sizeof buf); \& \& /* Check that the server is writable. */ \& if (nbd_is_read_only (nbd) == 1) { \& fprintf (stderr, "%s: " \& "error: this NBD export is read\-only\en", \& argv[0]); \& exit (EXIT_FAILURE); \& } \& \& for (i = 0; i < sizeof buf; ++i) \& buf[i] = rand (); \& \& /* 1000 writes. */ \& for (i = 0; i < 1000; ++i) { \& offset = rand () % (exportsize \- sizeof buf); \& \& if (nbd_pwrite (nbd, buf, sizeof buf, \& offset, 0) == \-1) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& } \& \& /* 1000 reads and writes. */ \& for (i = 0; i < 1000; ++i) { \& offset = rand () % (exportsize \- sizeof buf); \& if (nbd_pread (nbd, buf, sizeof buf, \& offset, 0) == \-1) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& \& offset = rand () % (exportsize \- sizeof buf); \& if (nbd_pwrite (nbd, buf, sizeof buf, \& offset, 0) == \-1) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& } \& \& /* Sends a graceful shutdown to the server. */ \& if (nbd_shutdown (nbd, 0) == \-1) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& \& nbd_close (nbd); \& \& exit (EXIT_SUCCESS); \& } .Ve .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBnbd_aio_disconnect\fR\|(3), \&\fBnbd_aio_in_flight\fR\|(3), \&\fBnbd_aio_opt_abort\fR\|(3), \&\fBnbd_close\fR\|(3), \&\fBnbd_create\fR\|(3), \&\fBlibnbd\fR\|(3). .SH AUTHORS .IX Header "AUTHORS" Eric Blake .PP Richard W.M. Jones .SH COPYRIGHT .IX Header "COPYRIGHT" Copyright Red Hat .SH LICENSE .IX Header "LICENSE" This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. .PP This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. .PP You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110\-1301 USA