media_getattr(3VOLMGT)Volume Management Library Functionmedia_getattr(3VOLMGT)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);
DESCRIPTIONmedia_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. Sys‐
tem 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
Upon successful completion media_getattr() returns a pointer to the
value corresponding to the specified attribute. A null pointer is
returned if the specified volume does not exist, if the specified
attribute for that volume doesn't exist, if the specified attribute is
boolean and its value is false, or if malloc(3C) fails to allocate
space for the return value.
media_setattr() returns 1 upon success, and 0 upon failure.
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.
Additionally, either routine can fail returning the following error
values:
ENXIO The Volume Management daemon, vold, is not running
EINTR The routine was interrupted by the user before finishing
EXAMPLES
Example 1 Using media_getattr()
The following example checks to see if the volume called fred that Vol‐
ume Management is managing can be ejected by means of software, or if
it can only be manually ejected:
if (media_getattr("/vol/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("/vol/dev/aliases/floppy0", "s-enxio",
"true")) == 0) {
(void) printf("can't set s-enxio flag for floppy0\n");
}
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOcc(1B), vold(1M), 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)NOTES
Upon success media_getattr() returns a pointer to a string which has
been allocated, and should be freed when no longer in use (see
free(3C)).
SunOS 5.10 31 Dec 1996 media_getattr(3VOLMGT)
