Go to main content

man pages section 3: Extended Library Functions, Volume 4

Exit Print View

Updated: Thursday, June 13, 2019
 
 

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

This function is obsolete. The management of removable media by the Volume Management feature, including vold, has been replaced by software that supports the Hardware Abstraction Layer (HAL).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");
}

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
MT-Level
MT-Safe
Interface Stability
Obsolete

See Also

lstat(2), open(2), readlink(2), stat(2), free(3C), malloc(3C), volmgt_check(3VOLMGT), media_findname(3VOLMGT), volmgt_inuse(3VOLMGT), volmgt_root(3VOLMGT), volmgt_running(3VOLMGT), volmgt_symname(3VOLMGT), attributes(7), hal(7)