DEVID_GET(3DEVID) Device ID Library Functions DEVID_GET(3DEVID)

NAME

devid_get, devid_free, devid_get_minor_name, devid_deviceid_to_nmlist,
devid_free_nmlist, devid_compare, devid_sizeof, devid_valid,
devid_str_encode, devid_str_decode, devid_str_from_path, devid_str_free
- device ID interfaces for user applications

SYNOPSIS

Device ID Library (libdevid, -ldevid)
#include <devid.h>

int
devid_get(int fd, ddi_devid_t *retdevid);

void
devid_free(ddi_devid_t devid);

int
devid_get_minor_name(int fd, char **retminor_name);

int
devid_deviceid_to_nmlist(char *search_path, ddi_devid_t devid,
char *minor_name, devid_nmlist_t **retlist);

void
devid_free_nmlist(devid_nmlist_t *list);

int
devid_compare(ddi_devid_t devid1, ddi_devid_t devid2);

size_t
devid_sizeof(ddi_devid_t devid);

int
devid_valid(ddi_devid_t devid);

char *
devid_str_encode(ddi_devid_t devid, char *minor_name);

int
devid_str_decode(char *devidstr, ddi_devid_t *retdevid,
char **retminor_name);

char *
devid_str_from_path(const char *path);

void
devid_str_free(char *str);

DESCRIPTION

These functions provide unique identifiers (device ID) for devices.
Applications and device drivers use these functions to identify and
locate devices, independent of the device's physical connection or its
logical device name or number.

The devid_get() function returns in retdevid the device ID for the
device associated with the open file descriptor fd, which refers to any
device. It returns an error if the device does not have an associated
device ID. The caller must free the memory allocated for retdevid
using the devid_free() function.

The devid_free() function frees the space that was allocated for the
returned devid by devid_get() and devid_str_decode().

The devid_get_minor_name() function returns the minor name, in
retminor_name, for the device associated with the open file descriptor
fd. This name is specific to the particular minor number, but is
"instance number" specific. The caller of this function must free the
memory allocated for the returned retminor_name string using
devid_str_free().

The devid_deviceid_to_nmlist() function returns an array of
devid_nmlist structures, where each entry matches the devid and
minor_name passed in. If the minor_name specified is one of the
special values (DEVID_MINOR_NAME_ALL, DEVID_MINOR_NAME_ALL_CHR, or
DEVID_MINOR_NAME_ALL_BLK), then all minor names associated with devid
which also meet the special minor_name filtering requirements are
returned. The devid_nmlist structure contains the device name and
device number. The last entry of the array contains a null pointer for
the devname and NODEV for the device number. This function traverses
the file tree, starting at search_path. For each device with a
matching device ID and minor name tuple, a device name and device
number are added to the retlist. If no matches are found, an error is
returned. The caller of this function must free the memory allocated
for the returned array with the devid_free_nmlist() function. This
function may take a long time to complete if called with the device ID
of an unattached device.

The devid_free_nmlist() function frees the memory allocated by the
devid_deviceid_to_nmlist() function and returned in the retlist.

The devid_compare() function compares two device IDs and determines
both equality and sort order. The function returns an integer greater
than 0 if the device ID pointed to by devid1 is greater than the device
ID pointed to by devid2. It returns 0 if the device ID pointed to by
devid1 is equal to the device ID pointed to by devid2. It returns an
integer less than 0 if the device ID pointed to by devid1 is less than
the device ID pointed to by devid2. This function is the only valid
mechanism to determine the equality of two devids. This function may
indicate equality for arguments which by simple inspection appear
different.

The devid_sizeof() function returns the size of devid in bytes.

The devid_valid() function validates the format of a devid. It returns
1 if the format is valid, and 0 if invalid. This check may not be as
complete as the corresponding kernel function ddi_devid_valid() (see
ddi_devid_compare(9F)).

The devid_str_encode() function encodes a devid and minor_name into a
null-terminated ASCII string, returning a pointer to that string. To
avoid shell conflicts, the devid portion of the string is limited to
uppercase and lowercase letters, digits, and the plus ("+"), minus
("-"), period ("."), equals ("="), underscore ("_"), tilde ("~"), and
comma (",") characters. If there is an ASCII quote character in the
binary form of a devid, the string representation will be in hex_id
form, not ascii_id form. The comma (",") character is added for "id1,"
at the head of the string devid. If both a devid and a minor_name are
non-null, a slash ("/") is used to separate the devid from the
minor_name in the encoded string. If minor_name is null, only the
devid is encoded. If the devid is null then the special string "id0"
is returned. Note that you cannot compare the returned string against
another string with strcmp(3C) to determine devid equality. The string
returned must be freed by calling devid_str_free().

The devid_str_from_path() is similar to devid_str_encode(), but takes a
path argument instead. If path includes the minor name, it will be
encoded as well. The string returned must be freed by calling
devid_str_free().

The devid_str_decode() function takes a string previously produced by
the devid_str_encode() or ddi_devid_str_encode() (see
ddi_devid_compare(9F)) function and decodes the contained device ID and
minor name, allocating and returning pointers to the extracted parts
via the retdevid and retminor_name arguments. If the special devidstr
"id0" was specified, the returned device ID and minor name will both be
null. A non-null returned devid must be freed by the caller by the
devid_free() function. A non-null returned minor name must be freed by
calling devid_str_free().

The devid_str_free() function frees the character string returned by
devid_str_encode() and the retminor_name argument returned by
devid_str_decode() and devid_get_minor_name().

RETURN VALUES

Upon successful completion, the devid_get(), devid_get_minor_name(),
devid_str_decode(), and devid_deviceid_to_nmlist() functions return 0.
Otherwise, they return -1.

The devid_compare() function returns the following values:

-1 The device ID pointed to by devid1 is less than the device ID
pointed to by devid2.

0 The device ID pointed to by devid1 is equal to the device ID
pointed to by devid2.

1 The device ID pointed to by devid1 is greater than the device
ID pointed to by devid2.

The devid_sizeof() function returns the size of devid in bytes. If
devid is null, the number of bytes that must be allocated and
initialized to determine the size of a complete device ID is returned.

The devid_valid() function returns 1 if the devid is valid and 0 if the
devid is invalid.

The devid_str_encode() and devid_str_from_path() functions return NULL
to indicate failure. Failure may be caused by attempting to encode an
invalid string. If the return value is non-null, the caller must free
the returned string by using the devid_str_free() function.

EXAMPLES

Example 1 Using devid_get(), devid_get_minor_name(), and
devid_str_encode()
The following example shows the proper use of devid_get(),
devid_get_minor_name(), and devid_str_encode() to free the
space allocated for devid, minor_name and encoded devid.

int fd;
ddi_devid_t devid;
char *minor_name, *devidstr;

if ((fd = open("/dev/dsk/c0t3d0s0", O_RDONLY|O_NDELAY)) < 0) {
...
}
if (devid_get(fd, &devid) != 0) {
...
}
if (devid_get_minor_name(fd, &minor_name) != 0) {
...
}
if ((devidstr = devid_str_encode(devid, minor_name)) == 0) {
...
}
printf("devid %s\n", devidstr);
devid_str_free(devidstr);
devid_free(devid);
devid_str_free(minor_name);

Example 2 Using devid_deviceid_to_nmlist() and devid_free_nmlist()
The following example shows the proper use of
devid_deviceid_to_nmlist() and devid_free_nmlist():

devid_nmlist_t *list = NULL;
int err;

if (devid_deviceid_to_nmlist("/dev/rdsk", devid,
minor_name, &list))
return (-1);
/* loop through list and process device names and numbers */
devid_free_nmlist(list);

MT-LEVEL
MT-Safe

INTERFACE STABILITY

Stable

SEE ALSO

free(3C), libdevid(3LIB), attributes(7), ddi_devid_compare(9F)

illumos January 25, 2017 illumos