.TH "libnvmf_host_get_ids" 9 "libnvmf_host_get_ids" "September 2026" "libnvme API manual" LINUX
.SH NAME
libnvmf_host_get_ids \- Retrieve host ids from various sources
.SH SYNOPSIS
.B "int" libnvmf_host_get_ids
.BI "(struct libnvme_global_ctx *ctx "  ","
.BI "const char *hostnqn_arg "  ","
.BI "const char *hostid_arg "  ","
.BI "char **hostnqn "  ","
.BI "char **hostid "  ");"
.SH ARGUMENTS
.IP "ctx" 12
struct libnvme_global_ctx object
.IP "hostnqn_arg" 12
Input hostnqn (command line) argument
.IP "hostid_arg" 12
Input hostid (command line) argument
.IP "hostnqn" 12
Output hostnqn; may be NULL if the caller does not need it
.IP "hostid" 12
Output hostid; may be NULL if the caller does not need it
.SH "DESCRIPTION"
libnvmf_host_get_ids figures out which hostnqn/hostid is to be used.
There are several sources where this information can be retrieved.

The order is:

- Start with hostnqn/hostid given on the command line
(\fIhostnqn_arg\fP, \fIhostid_arg\fP), if any
- Otherwise, use the first host already resolved in \fIctx\fP's host
list, if any
- Otherwise, use \fIctx\fP's own hostnqn/hostid default, or
/etc/nvme/hostnqn and /etc/nvme/hostid if \fIctx\fP has none
- Otherwise, if hostnqn is known but hostid is not, and hostnqn
has a "uuid:" component, derive hostid from it
- As a last resort, derive a still-missing hostid from DMI or
device-tree information (or generate a random one), then build
a hostnqn from that hostid if one is still missing

The function also checks that hostnqn and hostid match, logging a
debug warning if not. The Linux NVMe implementation expects a 1:1
matching between the IDs.
.SH "RETURN"
0 on success (\fIhostnqn\fP and \fIhostid\fP contain valid strings
which the caller needs to free), or negative error code otherwise.