Kernel Functions for Drivers ldiopenbydev(9F)
NAME
ldiopenbydev, ldiopenbyname, ldiopenbydevid,
ldiclose - open and close devices
SYNOPSIS
#include
int ldiopenbydev(devt *devp, int otyp, int flag, credt *cr,
ldihandlet *lhp, ldiidentt li);
int ldiopenbyname(char *pathname, int flag, credt *cr,
ldihandlet *lhp, ldiidentt li);
int ldiopenbydevid(ddidevidt devid, char *minorname, int flag,
credt *cr, ldihandlet *lhp, ldiidentt li);
int ldiclose(ldihandlet lh, int flag, cred t *cr);
PARAMETERS
lh Layered handle
lhp Pointer to a layered handle that is returned
upon a successful open.
li LDI identifier.
cr Pointer to the credential structure used to
open a device.
devp Pointer to a device number.
pathname Pathname to a device.
devid Device ID.
minorname Minor device node name.
otyp Flag passed to the driver indicating which
interface is open. Valid settings are:
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Kernel Functions for Drivers ldiopenbydev(9F)
OTYPBLK Open the device block interface.
OTYPCHR Open the device character inter-
face.
Only one OTYP flag can be specified. To open
streams devices, specify OTYPCHR.
flag Bit field that instructs the driver on how to
open the device. Valid settings are:
FEXCL Open the device with exclusive
access; fail all other attempts to
open the device.
FNDELAY Open the device and return immedi-
ately. Do not block the open even
if something is wrong.
FREAD Open the device with read-only per-
mission. (If ORed with FWRITE,
allow both read and write access).
FWRITE Open a device with write-only per-
mission (if ORed with FREAD, then
allow both read and write access).
FNOCTY Open the device. If the device is a
tty, do not attempt to open it as a
session-controlling tty.
DESCRIPTION
The ldiopenbydev(), ldiopenbyname() and
ldiopenbydevid() functions allow a caller to open a
block, character, or streams device. Upon a successful open,
a layered handle to the device is returned via the layered
handle pointed to by lhp. The ldi identifier passed to these
functions is previously allocated with
ldiidentfromstream(9F), ldiidentfromdev(9F), and
ldiidentfromdip(9F).
The ldiopenbydev() function opens a device specified by
the devt pointed to by devp. Upon successful open, the
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Kernel Functions for Drivers ldiopenbydev(9F)
caller should check the value of the devt to see if it has
changed. (Cloning devices will change this value during
opens.) When opening a streams device, otyp must be
OTYPCHR.
The ldiopenbydevid() function opens a device by devid.
The caller must specify the minor node name to open.
The ldiopenbyname() function opens a device by pathname.
Pathname is a null terminated string in the kernel address
space. Pathname must be an absolute path, meaning that it
must begin with '/'. The format of the pathname supplied to
this function is either a /devices path or any other
filesystem path to a device node. Opens utilizing /devices
paths are supported before root is mounted. Opens utilizing
other filesystem paths to device nodes are supported only if
root is already mounted.
The ldiclose() function closes a layered handle that was
obtained with either ldiopenbydev(), ldiopenbyname(),
or ldiopenbydevid(). After ldiclose() returns the lay-
ered handle, the lh that was previously passed in is no
longer valid.
RETURN VALUES
The ldiclose() function returns 0 for success. EINVAL is
returned for invalid input parameters. Otherwise, any other
error number may be returned by the device.
The ldiopenbydev() and ldiopenbydevid() functions
return 0 upon success. If a failure occurs before the device
is open, possible return values are shown below. Otherwise
any other error number may be returned by the device.
EINVAL Invalid input parameters.
ENODEV Requested device does not exist.
ENXIO Unsupported device operation or access mode.
The ldiopenbyname() function returns 0 upon success. If a
failure occurs before the device is open, possible return
values are shown below. Otherwise any other error number may
be returned by the device.
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Kernel Functions for Drivers ldiopenbydev(9F)
EINVAL Invalid input parameters.
ENODEV Requested device path does not exist.
EACES Search permission is denied on a component of the
path prefix, or the file exists and the permis-
sions specified by cr are denied.
ENXIO Unsupported device operation or access mode.
CONTEXT
These functions may be called from user or kernel context.
These functions should not be called from a device's attach,
detach, or power entry point. This could result in a system
crash or deadlock.
SEE ALSO
scsivhci(7D), ldiidentfromdev(9F),
ldiidentfromdip(9F), ldiidentfromstream(9F)
NOTES
Use only OTYPCHR or OTYPBLK options when you use the
ldiopenbydev() and ldiopenbydevid() functions to open
a device. Other flags, including OTYPLYR, have been depre-
cated and should not be used with these interfaces.
The caller should be aware of cases when multiple paths to a
single device may exist. (This can occur for scsi disk dev-
ices if scsivhci(7D)) is disabled or a disk is connected to
multiple controllers not supported by scsivhci(7D).
In these cases, ldiopenbydevid() returns a device handle
that corresponds to a particular path to a target device.
This path may not be the same across multiple calls to
ldiopenbydevid(). Device handles associated with the
same device but different access paths should have different
filesystem device paths and devt values.
In the cases where multiple paths to a device exist and
access to the device has not been virtualized via MPXIO (as
with scsi disk devices not accessed via scsivhci(7D)), the
LDI does not provide any path fail-over capabilities. If the
caller wishes to do their own path management and failover
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Kernel Functions for Drivers ldiopenbydev(9F)
they should open all available paths to a device via
ldiopenbyname().
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