Loop: libblockdev Reference Manual for libblockdev 3.1.1.

Loop

Loop — plugin for operations with loop devices

Functions

gboolean	bd_loop_init ()
void	bd_loop_close ()
GQuark	bd_loop_error_quark ()
BDLoopInfo *	bd_loop_info ()
BDLoopInfo *	bd_loop_info_copy ()
void	bd_loop_info_free ()
gchar *	bd_loop_get_loop_name ()
gboolean	bd_loop_setup ()
gboolean	bd_loop_setup_from_fd ()
gboolean	bd_loop_teardown ()
gboolean	bd_loop_set_autoclear ()
gboolean	bd_loop_is_tech_avail ()

Types and Values

#define	BD_LOOP_ERROR
enum	BDLoopError
	BDLoopInfo
enum	BDLoopTech
enum	BDLoopTechMode

Includes

#include <loop.h>

Description

A plugin for operations with loop devices. All sizes passed in/out to/from the functions are in bytes.

Functions

bd_loop_init ()

gboolean
bd_loop_init (void);

Initializes the plugin. **This function is called automatically by the library's initialization functions.**

bd_loop_close ()

void
bd_loop_close (void);

Cleans up after the plugin. **This function is called automatically by the library's functions that unload it.**

bd_loop_error_quark ()

GQuark
bd_loop_error_quark (void);

[skip]

bd_loop_info ()

BDLoopInfo *
bd_loop_info (const gchar *loop,
              GError **error);

Parameters

loop	name of the loop device to get information about (e.g. "loop0")
error	place to store error (if any).	[out][optional]

Returns

information about the loop device or NULL in case of error

Tech category: BD_LOOP_TECH_LOOP-BD_LOOP_TECH_MODE_QUERY.

[transfer full]

bd_loop_info_copy ()

BDLoopInfo *
bd_loop_info_copy (BDLoopInfo *info);

Creates a new copy of info .

[skip]

Parameters

info

BDLoopInfo to copy.

[nullable]

bd_loop_info_free ()

void
bd_loop_info_free (BDLoopInfo *info);

Frees info .

[skip]

Parameters

info

BDLoopInfo to free.

[nullable]

bd_loop_get_loop_name ()

gchar *
bd_loop_get_loop_name (const gchar *file,
                       GError **error);

Parameters

file	path of the backing file to get loop name for
error	place to store error (if any).	[out][optional]

Returns

name of the loop device associated with the given file

Tech category: BD_LOOP_TECH_LOOP-BD_LOOP_TECH_MODE_QUERY.

[transfer full]

bd_loop_setup ()

gboolean
bd_loop_setup (const gchar *file,
               guint64 offset,
               guint64 size,
               gboolean read_only,
               gboolean part_scan,
               guint64 sector_size,
               const gchar **loop_name,
               GError **error);

Parameters

file	file to setup as a loop device
offset	offset of the start of the device (in `file` )
size	maximum size of the device (or 0 to leave unspecified)
read_only	whether to setup as read-only (`TRUE`) or read-write (`FALSE`)
part_scan	whether to enforce partition scan on the newly created device or not
sector_size	logical sector size for the loop device in bytes (or 0 for default)
loop_name	if not `NULL`, it is used to store the name of the loop device.	[optional][out]
error	place to store error (if any).	[out][optional]

Returns

whether the file was successfully setup as a loop device or not

Tech category: BD_LOOP_TECH_LOOP-BD_LOOP_TECH_MODE_CREATE

bd_loop_setup_from_fd ()

gboolean
bd_loop_setup_from_fd (gint fd,
                       guint64 offset,
                       guint64 size,
                       gboolean read_only,
                       gboolean part_scan,
                       guint64 sector_size,
                       const gchar **loop_name,
                       GError **error);

Parameters

fd	file descriptor for a file to setup as a new loop device
offset	offset of the start of the device (in file given by `fd` )
size	maximum size of the device (or 0 to leave unspecified)
read_only	whether to setup as read-only (`TRUE`) or read-write (`FALSE`)
part_scan	whether to enforce partition scan on the newly created device or not
sector_size	logical sector size for the loop device in bytes (or 0 for default)
loop_name	if not `NULL`, it is used to store the name of the loop device.	[optional][out]
error	place to store error (if any).	[out][optional]

Returns

whether an new loop device was successfully setup for fd or not

Tech category: BD_LOOP_TECH_LOOP-BD_LOOP_TECH_MODE_CREATE

bd_loop_teardown ()

gboolean
bd_loop_teardown (const gchar *loop,
                  GError **error);

Parameters

loop	path or name of the loop device to tear down
error	place to store error (if any).	[out][optional]

Returns

whether the loop device was successfully torn down or not

Tech category: BD_LOOP_TECH_LOOP-BD_LOOP_TECH_MODE_DESTROY

bd_loop_set_autoclear ()

gboolean
bd_loop_set_autoclear (const gchar *loop,
                       gboolean autoclear,
                       GError **error);

Parameters

loop	path or name of the loop device
autoclear	whether to set or unset the autoclear flag
error	place to store error (if any).	[out][optional]

Returns

whether the autoclear flag was successfully set on the loop device or not

Tech category: BD_LOOP_TECH_LOOP-BD_LOOP_TECH_MODE_MODIFY

bd_loop_is_tech_avail ()

gboolean
bd_loop_is_tech_avail (BDLoopTech tech,
                       guint64 mode,
                       GError **error);

Parameters

tech	the queried tech
mode	a bit mask of queried modes of operation (BDLoopTechMode) for `tech`
error	place to store error (details about why the `tech` -`mode` combination is not available).	[out][optional]

Returns

whether the tech -mode combination is available -- supported by the plugin implementation and having all the runtime dependencies available

Types and Values

BD_LOOP_ERROR

#define             BD_LOOP_ERROR

enum BDLoopError

Members

BD_LOOP_ERROR_TECH_UNAVAIL
BD_LOOP_ERROR_FAIL
BD_LOOP_ERROR_DEVICE

BDLoopInfo

typedef struct {
    gchar *backing_file;
    guint64 offset;
    gboolean autoclear;
    gboolean direct_io;
    gboolean part_scan;
    gboolean read_only;
} BDLoopInfo;

Members

gchar *`backing_file`;	backing file for the give loop device;
guint64 `offset`;	offset of the start of the device (in `backing_file` );
gboolean `autoclear`;	whether the autoclear flag is set or not;
gboolean `direct_io`;	whether direct IO is enabled or not;
gboolean `part_scan`;	whether the partition scan is enforced or not;
gboolean `read_only`;	whether the device is read-only or not;

enum BDLoopTech

Members

BD_LOOP_TECH_LOOP

enum BDLoopTechMode

Members

BD_LOOP_TECH_MODE_CREATE
BD_LOOP_TECH_MODE_DESTROY
BD_LOOP_TECH_MODE_MODIFY
BD_LOOP_TECH_MODE_QUERY