.\" Automatically generated by Podwrapper::Man 1.6.1 (Pod::Simple 3.40) .\" .\" 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 .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. 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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_set_opt_mode 3" .TH nbd_set_opt_mode 3 "2021-02-09" "libnbd-1.6.1" "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_set_opt_mode \- control option mode, for pausing during option negotiation .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include \& \& int nbd_set_opt_mode (struct nbd_handle *h, bool enable); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" Set this flag to true in order to request that a connection command \&\f(CW\*(C`nbd_connect_*\*(C'\fR will pause for negotiation options rather than proceeding all the way to the ready state, when communicating with a newstyle server. This setting has no effect when connecting to an oldstyle server. .PP When option mode is enabled, you have fine-grained control over which options are negotiated, compared to the default of the server negotiating everything on your behalf using settings made before starting the connection. To leave the mode and proceed on to the ready state, you must use \fBnbd_opt_go\fR\|(3) successfully; a failed \&\fBnbd_opt_go\fR\|(3) returns to the negotiating state to allow a change of export name before trying again. You may also use \fBnbd_opt_abort\fR\|(3) to end the connection without finishing negotiation. .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\*(C`\-1\*(C'\fR is returned. .PP Refer to \*(L"\s-1ERROR HANDLING\*(R"\s0 in \fBlibnbd\fR\|(3) for how to get further details of the error. .SH "HANDLE STATE" .IX Header "HANDLE STATE" The handle must be newly created, otherwise this call will return an error. .SH "VERSION" .IX Header "VERSION" This function first appeared in libnbd 1.4. .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_SET_OPT_MODE 1 .Ve .SH "EXAMPLE" .IX Header "EXAMPLE" This example is also available as \fIexamples/list\-exports.c\fR in the libnbd source code. .PP .Vb 10 \& /* This example shows how to list NBD exports. \& * \& * To test this with qemu\-nbd: \& * $ qemu\-nbd \-x "hello" \-t \-k /tmp/sock disk.img \& * $ ./run examples/list\-exports /tmp/sock \& * [0] hello \& * Which export to connect to (\-1 to quit)? 0 \& * Connecting to hello ... \& * /tmp/sock: hello: size = 2048 bytes \& * \& * To test this with nbdkit (requires 1.22): \& * $ nbdkit \-U /tmp/sock sh \- <<\eEOF \& * case $1 in \& * list_exports) echo NAMES; echo foo; echo foobar ;; \& * open) echo "$3" ;; \& * get_size) echo "$2" | wc \-c ;; \& * pread) echo "$2" | dd bs=1 skip=$4 count=$3 ;; \& * *) exit 2 ;; \& * esac \& * EOF \& * $ ./run examples/list\-exports /tmp/sock \& * [0] foo \& * [1] foobar \& * Which export to connect to (\-1 to quit)? 1 \& * Connecting to foobar ... \& * /tmp/sock: foobar: size = 7 bytes \& */ \& \& #include \& #include \& #include \& #include \& #include \& #include \& \& #include \& \& struct export_list { \& int i; \& char **names; \& }; \& \& /* Callback function for nbd_opt_list */ \& static int \& list_one (void *opaque, const char *name, \& const char *description) \& { \& struct export_list *l = opaque; \& char **names; \& \& printf ("[%d] %s\en", l\->i, name); \& if (*description) \& printf(" (%s)\en", description); \& names = realloc (l\->names, \& (l\->i + 1) * sizeof *names); \& if (!names) { \& perror ("realloc"); \& exit (EXIT_FAILURE); \& } \& names[l\->i] = strdup (name); \& if (!names[l\->i]) { \& perror ("strdup"); \& exit (EXIT_FAILURE); \& } \& l\->names = names; \& l\->i++; \& return 0; \& } \& \& int \& main (int argc, char *argv[]) \& { \& struct nbd_handle *nbd; \& int i; \& const char *name; \& int64_t size; \& struct export_list list = { 0 }; \& \& 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); \& } \& \& /* Set opt mode. */ \& nbd_set_opt_mode (nbd, true); \& \& /* Connect to the NBD server over a \& * Unix domain socket. If we did not \& * end up in option mode, then a \& * listing is not possible. \& */ \& if (nbd_connect_unix (nbd, argv[1]) == \-1) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& if (!nbd_aio_is_negotiating (nbd)) { \& fprintf (stderr, "Server does not support " \& "listing exports.\en"); \& exit (EXIT_FAILURE); \& } \& \& /* Print the export list. */ \& if (nbd_opt_list (nbd, \& (nbd_list_callback) { \& .callback = list_one, \& .user_data = &list, }) == \-1) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& \& /* Display the list of exports. */ \& printf ("Which export to connect to? "); \& if (scanf ("%d", &i) != 1) exit (EXIT_FAILURE); \& if (i == \-1) { \& if (nbd_opt_abort (nbd) == \-1) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& nbd_close (nbd); \& exit (EXIT_SUCCESS); \& } \& if (i < 0 || i >= list.i) { \& fprintf (stderr, "index %d out of range", i); \& exit (EXIT_FAILURE); \& } \& name = list.names[i]; \& printf ("Connecting to %s ...\en", name); \& \& /* Resume connecting to the chosen export. */ \& if (nbd_set_export_name (nbd, name) == \-1 || \& nbd_opt_go (nbd) == \-1) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& if (!nbd_aio_is_ready (nbd)) { \& fprintf (stderr, "server closed early\en"); \& exit (EXIT_FAILURE); \& } \& \& /* Read the size in bytes and print it. */ \& size = nbd_get_size (nbd); \& if (size == \-1) { \& fprintf (stderr, "%s\en", nbd_get_error ()); \& exit (EXIT_FAILURE); \& } \& printf ("%s: %s: size = %" PRIi64 " bytes\en", \& argv[1], name, size); \& \& /* Close the libnbd handle. */ \& nbd_close (nbd); \& \& for (i = 0; i < list.i; i++) \& free (list.names[i]); \& free (list.names); \& \& exit (EXIT_SUCCESS); \& } .Ve .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBnbd_aio_is_negotiating\fR\|(3), \&\fBnbd_create\fR\|(3), \&\fBnbd_get_opt_mode\fR\|(3), \&\fBnbd_opt_abort\fR\|(3), \&\fBnbd_opt_go\fR\|(3), \&\fBnbd_opt_info\fR\|(3), \&\fBnbd_opt_list\fR\|(3), \&\fBnbd_opt_list_meta_context\fR\|(3), \&\fBlibnbd\fR\|(3). .SH "AUTHORS" .IX Header "AUTHORS" Eric Blake .PP Richard W.M. Jones .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright (C) 2019\-2020 Red Hat Inc. .SH "LICENSE" .IX Header "LICENSE" This library is free software; you can redistribute it and/or modify it under the terms of the \s-1GNU\s0 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 \s-1WITHOUT ANY WARRANTY\s0; without even the implied warranty of \&\s-1MERCHANTABILITY\s0 or \s-1FITNESS FOR A PARTICULAR PURPOSE.\s0 See the \s-1GNU\s0 Lesser General Public License for more details. .PP You should have received a copy of the \s-1GNU\s0 Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, \s-1MA 02110\-1301 USA\s0