nbd_get_uri3

Usage

 #include <libnbd.h>
 char * nbd_get_uri (
          struct nbd_handle *h
        );

Overview

This makes a best effort attempt to construct an NBD URI which could be used to connect back to the same server (using nbd_connect_uri(3)).

In some cases there is not enough information in the handle to successfully create a URI (eg. if you connected with nbd_connect_socket(3)). In such cases the call returns "NULL" and further diagnostic information is available via nbd_get_errno(3) and nbd_get_error(3) as usual.

Even if a URI is returned it is not guaranteed to work, and it may not be optimal.

nbdinfo(1) --uri option is a way to access this API from shell scripts.

Return value

This call returns a string. The caller must free the returned string to avoid a memory leak.

Errors

On error "NULL" is returned.

Refer to "ERROR HANDLING" in libnbd(3) for how to get further details of the error.

The following parameters must not be NULL: "h". For more information see "Non-NULL parameters" in libnbd(3).

Handle state

nbd_get_uri can be called when the handle is in the following states:

 ┌─────────────────────────────────────┬─────────────────────────┐
 │ Handle created, before connecting   │ ❌ error                │
 │ Connecting                          │ ✅ allowed              │
 │ Connecting & handshaking (opt_mode) │ ✅ allowed              │
 │ Connected to the server             │ ✅ allowed              │
 │ Connection shut down                │ ✅ allowed              │
 │ Handle dead                         │ ✅ allowed              │
 └─────────────────────────────────────┴─────────────────────────┘

Version

This function first appeared in libnbd 1.8.

If you need to test if this function is available at compile time check if the following macro is defined:

 #define LIBNBD_HAVE_NBD_GET_URI 1