media_getattr(3X)
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);
MT-LEVEL
MT-Safe
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 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 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 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
The following example checks to see if the volume called fred that Volume Management is managing can be ejected via 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");
}
SEE ALSO
cc(1B), vold(1M), lstat(2), open(2), readlink(2), stat(2), free(3C), malloc(3C), media_findname(3X), volmgt_check(3X), volmgt_inuse(3X), volmgt_root(3X), volmgt_running(3X), volmgt_symname(3X)
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 5.5.1 — Last change: 23 Aug 1995