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+.. _util.h:
+
+**util.h**
+
+
+libnvme utility functions
+
+
+
+.. c:enum:: nvme_connect_err
+
+   nvme connect error codes
+
+**Constants**
+
+``ENVME_CONNECT_RESOLVE``
+  failed to resolve host
+
+``ENVME_CONNECT_ADDRFAM``
+  unrecognized address family
+
+``ENVME_CONNECT_TRADDR``
+  failed to get traddr
+
+``ENVME_CONNECT_TARG``
+  need a transport (-t) argument
+
+``ENVME_CONNECT_AARG``
+  need a address (-a) argument
+
+``ENVME_CONNECT_OPEN``
+  failed to open nvme-fabrics device
+
+``ENVME_CONNECT_WRITE``
+  failed to write to nvme-fabrics device
+
+``ENVME_CONNECT_READ``
+  failed to read from nvme-fabrics device
+
+``ENVME_CONNECT_PARSE``
+  failed to parse ctrl info
+
+``ENVME_CONNECT_INVAL_TR``
+  invalid transport type
+
+``ENVME_CONNECT_LOOKUP_SUBSYS_NAME``
+  failed to lookup subsystem name
+
+``ENVME_CONNECT_LOOKUP_SUBSYS``
+  failed to lookup subsystem
+
+``ENVME_CONNECT_ALREADY``
+  the connect attempt failed, already connected
+
+``ENVME_CONNECT_INVAL``
+  invalid arguments/configuration
+
+``ENVME_CONNECT_ADDRINUSE``
+  hostnqn already in use
+
+``ENVME_CONNECT_NODEV``
+  invalid interface
+
+``ENVME_CONNECT_OPNOTSUPP``
+  not supported
+
+``ENVME_CONNECT_CONNREFUSED``
+  connection refused
+
+
+.. c:function:: __u8 nvme_status_to_errno (int status, bool fabrics)
+
+   Converts nvme return status to errno
+
+**Parameters**
+
+``int status``
+  Return status from an nvme passthrough command
+
+``bool fabrics``
+  Set to true if :c:type:`status` is to a fabrics target.
+
+**Return**
+
+An errno representing the nvme status if it is an nvme status field,
+or unchanged status is < 0 since errno is already set.
+
+
+.. c:function:: const char * nvme_status_to_string (int status, bool fabrics)
+
+   Returns string describing nvme return status.
+
+**Parameters**
+
+``int status``
+  Return status from an nvme passthrough command
+
+``bool fabrics``
+  Set to true if :c:type:`status` is to a fabrics target.
+
+**Return**
+
+String representation of the nvme status if it is an nvme status field,
+or a standard errno string if status is < 0.
+
+
+.. c:function:: const char * nvme_errno_to_string (int err)
+
+   Returns string describing nvme connect failures
+
+**Parameters**
+
+``int err``
+  Returned error code from nvme_add_ctrl()
+
+**Return**
+
+String representation of the nvme connect error codes
+
+
+.. c:function:: void nvme_init_ctrl_list (struct nvme_ctrl_list *cntlist, __u16 num_ctrls, __u16 *ctrlist)
+
+   Initialize an nvme_ctrl_list structure from an array.
+
+**Parameters**
+
+``struct nvme_ctrl_list *cntlist``
+  The controller list structure to initialize
+
+``__u16 num_ctrls``
+  The number of controllers in the array, :c:type:`ctrlist`.
+
+``__u16 *ctrlist``
+  An array of controller identifiers in CPU native endian.
+
+**Description**
+
+This is intended to be used with any command that takes a controller list
+argument. See nvme_ns_attach_ctrls() and nvme_ns_detach().
+
+
+.. c:function:: void nvme_init_dsm_range (struct nvme_dsm_range *dsm, __u32 *ctx_attrs, __u32 *llbas, __u64 *slbas, __u16 nr_ranges)
+
+   Constructs a data set range structure
+
+**Parameters**
+
+``struct nvme_dsm_range *dsm``
+  DSM range array
+
+``__u32 *ctx_attrs``
+  Array of context attributes
+
+``__u32 *llbas``
+  Array of length in logical blocks
+
+``__u64 *slbas``
+  Array of starting logical blocks
+
+``__u16 nr_ranges``
+  The size of the dsm arrays
+
+**Description**
+
+Each array must be the same size of size 'nr_ranges'. This is intended to be
+used with constructing a payload for nvme_dsm().
+
+**Return**
+
+The nvme command status if a response was received or -errno
+otherwise.
+
+
+.. c:function:: void nvme_init_copy_range (struct nvme_copy_range *copy, __u16 *nlbs, __u64 *slbas, __u32 *eilbrts, __u32 *elbatms, __u32 *elbats, __u16 nr)
+
+   Constructs a copy range structure
+
+**Parameters**
+
+``struct nvme_copy_range *copy``
+  Copy range array
+
+``__u16 *nlbs``
+  Number of logical blocks
+
+``__u64 *slbas``
+  Starting LBA
+
+``__u32 *eilbrts``
+  Expected initial logical block reference tag
+
+``__u32 *elbatms``
+  Expected logical block application tag mask
+
+``__u32 *elbats``
+  Expected logical block application tag
+
+``__u16 nr``
+  Number of descriptors to construct
+
+
+.. c:function:: void nvme_init_copy_range_f1 (struct nvme_copy_range_f1 *copy, __u16 *nlbs, __u64 *slbas, __u64 *eilbrts, __u32 *elbatms, __u32 *elbats, __u16 nr)
+
+   Constructs a copy range f1 structure
+
+**Parameters**
+
+``struct nvme_copy_range_f1 *copy``
+  Copy range array
+
+``__u16 *nlbs``
+  Number of logical blocks
+
+``__u64 *slbas``
+  Starting LBA
+
+``__u64 *eilbrts``
+  Expected initial logical block reference tag
+
+``__u32 *elbatms``
+  Expected logical block application tag mask
+
+``__u32 *elbats``
+  Expected logical block application tag
+
+``__u16 nr``
+  Number of descriptors to construct
+
+
+.. c:function:: int nvme_get_feature_length (int fid, __u32 cdw11, __u32 *len)
+
+   Retreive the command payload length for a specific feature identifier
+
+**Parameters**
+
+``int fid``
+  Feature identifier, see :c:type:`enum nvme_features_id <nvme_features_id>`.
+
+``__u32 cdw11``
+  The cdw11 value may affect the transfer (only known fid is
+  ``NVME_FEAT_FID_HOST_ID``)
+
+``__u32 *len``
+  On success, set to this features payload length in bytes.
+
+**Return**
+
+0 on success, -1 with errno set to EINVAL if the function did not
+recognize :c:type:`fid`.
+
+
+.. c:function:: int nvme_get_feature_length2 (int fid, __u32 cdw11, enum nvme_data_tfr dir, __u32 *len)
+
+   Retreive the command payload length for a specific feature identifier
+
+**Parameters**
+
+``int fid``
+  Feature identifier, see :c:type:`enum nvme_features_id <nvme_features_id>`.
+
+``__u32 cdw11``
+  The cdw11 value may affect the transfer (only known fid is
+  ``NVME_FEAT_FID_HOST_ID``)
+
+``enum nvme_data_tfr dir``
+  Data transfer direction: false - host to controller, true -
+  controller to host may affect the transfer (only known fid is
+  ``NVME_FEAT_FID_HOST_MEM_BUF``).
+
+``__u32 *len``
+  On success, set to this features payload length in bytes.
+
+**Return**
+
+0 on success, -1 with errno set to EINVAL if the function did not
+recognize :c:type:`fid`.
+
+
+.. c:function:: int nvme_get_directive_receive_length (enum nvme_directive_dtype dtype, enum nvme_directive_receive_doper doper, __u32 *len)
+
+   Get directive receive length
+
+**Parameters**
+
+``enum nvme_directive_dtype dtype``
+  Directive type, see :c:type:`enum nvme_directive_dtype <nvme_directive_dtype>`
+
+``enum nvme_directive_receive_doper doper``
+  Directive receive operation, see :c:type:`enum nvme_directive_receive_doper <nvme_directive_receive_doper>`
+
+``__u32 *len``
+  On success, set to this directives payload length in bytes.
+
+**Return**
+
+0 on success, -1 with errno set to EINVAL if the function did not
+recognize :c:type:`dtype` or :c:type:`doper`.
+
+
+.. c:function:: size_t get_entity_name (char *buffer, size_t bufsz)
+
+   Get Entity Name (ENAME).
+
+**Parameters**
+
+``char *buffer``
+  The buffer where the ENAME will be saved as an ASCII string.
+
+``size_t bufsz``
+  The size of **buffer**.
+
+**Description**
+
+Per TP8010, ENAME is defined as the name associated with the host (i.e.
+hostname).
+
+**Return**
+
+Number of characters copied to **buffer**.
+
+
+.. c:function:: size_t get_entity_version (char *buffer, size_t bufsz)
+
+   Get Entity Version (EVER).
+
+**Parameters**
+
+``char *buffer``
+  The buffer where the EVER will be saved as an ASCII string.
+
+``size_t bufsz``
+  The size of **buffer**.
+
+**Description**
+
+EVER is defined as the operating system name and version as an ASCII
+string. This function reads different files from the file system and
+builds a string as follows: [os type] [os release] [distro release]
+
+    E.g. "Linux 5.17.0-rc1 SLES 15.4"
+
+**Return**
+
+Number of characters copied to **buffer**.
+
+
+.. c:function:: char * kv_strip (char *kv)
+
+   Strip blanks from key value string
+
+**Parameters**
+
+``char *kv``
+  The key-value string to strip
+
+**Description**
+
+Strip leading/trailing blanks as well as trailing comments from the
+Key=Value string pointed to by **kv**.
+
+**Return**
+
+A pointer to the stripped string. Note that the original string,
+**kv**, gets modified.
+
+
+.. c:function:: char * kv_keymatch (const char *kv, const char *key)
+
+   Look for key in key value string
+
+**Parameters**
+
+``const char *kv``
+  The key=value string to search for the presence of **key**
+
+``const char *key``
+  The key to look for
+
+**Description**
+
+Look for **key** in the Key=Value pair pointed to by **k** and return a
+pointer to the Value if **key** is found.
+
+Check if **kv** starts with **key**. If it does then make sure that we
+have a whole-word match on the **key**, and if we do, return a pointer
+to the first character of value (i.e. skip leading spaces, tabs,
+and equal sign)
+
+**Return**
+
+A pointer to the first character of "value" if a match is found.
+NULL otherwise.
+
+
+.. c:function:: char * startswith (const char *s, const char *prefix)
+
+   Checks that a string starts with a given prefix.
+
+**Parameters**
+
+``const char *s``
+  The string to check
+
+``const char *prefix``
+  A string that **s** could be starting with
+
+**Return**
+
+If **s** starts with **prefix**, then return a pointer within **s** at
+the first character after the matched **prefix**. NULL otherwise.
+
+
+.. c:macro:: round_up
+
+``round_up (val, mult)``
+
+   Round a value **val** to the next multiple specified by **mult**.
+
+**Parameters**
+
+``val``
+  Value to round
+
+``mult``
+  Multiple to round to.
+
+**Description**
+
+usage: int x = round_up(13, sizeof(__u32)); // 13 -> 16
+
+
+.. c:function:: __u16 nvmf_exat_len (size_t val_len)
+
+   Return length rounded up by 4
+
+**Parameters**
+
+``size_t val_len``
+  Value length
+
+**Description**
+
+Return the size in bytes, rounded to a multiple of 4 (e.g., size of
+__u32), of the buffer needed to hold the exat value of size
+**val_len**.
+
+**Return**
+
+Length rounded up by 4
+
+
+.. c:function:: __u16 nvmf_exat_size (size_t val_len)
+
+   Return min aligned size to hold value
+
+**Parameters**
+
+``size_t val_len``
+  This is the length of the data to be copied to the "exatval"
+  field of a "struct nvmf_ext_attr".
+
+**Description**
+
+Return the size of the "struct nvmf_ext_attr" needed to hold
+a value of size **val_len**.
+
+**Return**
+
+The size in bytes, rounded to a multiple of 4 (i.e. size of
+__u32), of the "struct nvmf_ext_attr" required to hold a string of
+length **val_len**.
+
+
+.. c:function:: struct nvmf_ext_attr * nvmf_exat_ptr_next (struct nvmf_ext_attr *p)
+
+   Increment **p** to the next element in the array.
+
+**Parameters**
+
+``struct nvmf_ext_attr *p``
+  Pointer to an element of an array of "struct nvmf_ext_attr".
+
+**Description**
+
+Extended attributes are saved to an array of "struct nvmf_ext_attr"
+where each element of the array is of variable size. In order to
+move to the next element in the array one must increment the
+pointer to the current element (**p**) by the size of the current
+element.
+
+**Return**
+
+Pointer to the next element in the array.
+
+
+
+
+.. c:enum:: nvme_version
+
+   Selector for version to be returned by **nvme_get_version**
+
+**Constants**
+
+``NVME_VERSION_PROJECT``
+  Project release version
+
+``NVME_VERSION_GIT``
+  Git reference
+
+
+.. c:function:: const char * nvme_get_version (enum nvme_version type)
+
+   Return version libnvme string
+
+**Parameters**
+
+``enum nvme_version type``
+  Selects which version type (see **struct** nvme_version)
+
+**Return**
+
+Returns version string for known types or else "n/a"
+
+
+.. c:function:: int nvme_uuid_to_string (unsigned char uuid[NVME_UUID_LEN], char *str)
+
+   Return string represenation of encoded UUID
+
+**Parameters**
+
+``unsigned char uuid[NVME_UUID_LEN]``
+  Binary encoded input UUID
+
+``char *str``
+  Output string represenation of UUID
+
+**Return**
+
+Returns error code if type conversion fails.
+
+
+.. c:function:: int nvme_uuid_from_string (const char *str, unsigned char uuid[NVME_UUID_LEN])
+
+   Return encoded UUID represenation of string UUID
+
+**Parameters**
+
+``const char *str``
+  Output string represenation of UUID
+
+``unsigned char uuid[NVME_UUID_LEN]``
+  Binary encoded input UUID
+
+**Return**
+
+Returns error code if type conversion fails.
+
+
+.. c:function:: int nvme_uuid_random (unsigned char uuid[NVME_UUID_LEN])
+
+   Generate random UUID
+
+**Parameters**
+
+``unsigned char uuid[NVME_UUID_LEN]``
+  Generated random UUID
+
+**Description**
+
+Generate random number according
+https://www.rfc-editor.org/rfc/rfc4122#section-4.4
+
+**Return**
+
+Returns error code if generating of random number fails.
+
+