Tribblix: manual page: media

MEDIA_GETATTR(3VOLMGT) Volume Management Library Functions

NAME

media_getattr, media_setattr - get and set media attributes

SYNOPSIS

cc [ flag ... ] file ... -lvolmgt [ library ... ]
#include <volmgt.h>

char *media_getattr(char *vol_path, char *attr);

int media_setattr(char *vol_path, char *attr, char *value);

DESCRIPTION

This function is obsolete. The management of removable media by the
Volume Management feature, including vold, has been replaced by
software that supports the Hardware Abstraction Layer (HAL).
Programmatic support for HAL is through the HAL APIs, which are
documented on the HAL web site. See hal(7). The return value of this
function is undefined.

media_setattr() and media_getattr() respectively set and get
attribute-value pairs (called properties) on a per-volume basis.

Volume management supports system properties and user properties.
System properties are ones that volume management predefines. Some of
these system properties are writable, but only by the user that owns
the volume being specified, and some system properties are read only:

Attribute Writable Value Description
------------------------------------------------------------------------------------------------------
s-access RO "seq", "rand" sequential or random access
s-density RO "low", "medium", "high" media density
s-parts RO comma separated list of slice numbers list of partitions on this volume
s-location RO pathname volume management pathname to media
s-mejectable RO "true", "false" whether or not media is manually
ejectable
s-rmoneject R/W "true", "false" should media access points be
removed from database upon ejection
s-enxio R/W "true", "false" if set return ENXIO when media
access attempted

Properties can also be defined by the user. In this case the value
can be any string the user wishes.

RETURN VALUES

The return from this function is undefined.

ERRORS

Both media_getattr() and media_setattr() can fail returning a null
pointer if an open(2) of the specified vol_path fails, if an fstat(2)
of that pathname fails, or if that pathname is not a block or
character special device.

media_getattr() can also fail if the specified attribute was not
found, and media_setattr() can also fail if the caller doesn't have
permission to set the attribute, either because it's is a system
attribute, or because the caller doesn't own the specified volume.

EXAMPLES

Example 1: Using media_getattr()

The following example checks to see if the volume called fred that
volume management is managing can be ejected by means of software, or
if it can only be manually ejected:

if (media_getattr("/rdsk/fred", "s-mejectable") != NULL) {
(void) printf("\"fred\" must be manually ejected\n");
} else {
(void) printf("software can eject \"fred\"\n");
}

This example shows setting the s-enxio property for the floppy volume
currently in the first floppy drive:

int res;
if ((res = media_setattr("/dev/aliases/floppy0", "s-enxio",
"true")) == 0) {
(void) printf("can't set s-enxio flag for floppy0\n");
}

ATTRIBUTES