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man pages section 3: Extended Library Functions, Volume 4

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Updated: Thursday, June 13, 2019
 
 

volmgt_acquire(3VOLMGT)

Name

volmgt_acquire - reserve removable media device

Synopsis

cc [ flag ... ] file ... –lvolmgt [ library ... ]
#include <sys/types.h>

#include <volmgt.h>

int volmgt_acquire(char *dev, char *id, int ovr, char **err, pid_t *
pidp);

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This function is obsolete. The management of removable media by the Volume Management feature, including vold, has been replaced by software that supports the Hardware Abstraction Layer (HAL).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

The volmgt_acquire() routine reserves the removable media device specified as dev. volmgt_acquire() operates in two different modes, depending on whether or not volume management is running.

If volume management is running, volmgt_acquire() attempts to reserve the removable media device specified as dev. Specify dev as either a symbolic device name or a physical device pathname.

If volume management is not running, volmgt_acquire() requires callers to specify a physical device pathname for dev. Specifying dev as a symbolic device name is not acceptable. In this mode, volmgt_acquire() relies entirely on the major and minor numbers of the device to determine whether or not the device is reserved.

If dev is free, volmgt_acquire() updates the internal device reservation database with the caller's process id (pid) and the specified id string.

If dev is reserved by another process, the reservation attempt fails and volmgt_acquire():

  • sets errno to EBUSY

  • fills the caller's id value in the array pointed to by err

  • fills in the pid to which the pointer pidp points with the pid of the process which holds the reservation, if the supplied pidp is non-zero.

If the override ovr is non-zero, the call overrides the device reservation.

Return Values

The return from this function is undefined.

Errors

The volmgt_acquire() routine fails if one or more of the following are true:

EINVAL

One of the specified arguments is invalid or missing.

EBUSY

dev is already reserved by another process (and ovr was not set to a non-zero value)

Attributes

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

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

See Also

free(3C), malloc(3C), volmgt_release(3VOLMGT), attributes(7), hal(7)

Notes

When returning a string through err, volmgt_acquire() allocates a memory area using malloc(3C). Use free(3C) to release the memory area when no longer needed.

The ovr argument is intended to allow callers to override the current device reservation. It is assumed that the calling application has determined that the current reservation can safely be cleared.