MEDIA_GETATTR(3VOLMGT) Volume Management Library Functions


media_getattr, media_setattr - get and set media attributes


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);


This function is obsolete.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Volume Management feature, including vold, has been replaced by software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(5). 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
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.


The return from this function is undefined.


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.


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");


See attributes(5) for descriptions of the following attributes:

|MT-Level | MT-Safe |
|Interface Stability | Obsolete |


lstat(2), open(2), readlink(2), stat(2), free(3C), malloc(3C),
media_findname(3VOLMGT), volmgt_check(3VOLMGT), volmgt_inuse(3VOLMGT),
volmgt_root(3VOLMGT), volmgt_running(3VOLMGT), volmgt_symname(3VOLMGT),
attributes(5), hal(5)