media_getattr(3VOLMGT) Volume Management Library Functions media_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);
DESCRIPTION
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 list of partitions on this volume
slice numbers
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 doesn't 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 per-
mission 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 Volume 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
");
} else {
(void) printf("software can eject "fred"
");
}
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
");
}
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|MT-Level |MT-Safe |
+-----------------------------+-----------------------------+
SEE ALSO
cc(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)