NAME¶
g_read_data
,
g_write_data
—
read/write data from/to GEOM consumer
SYNOPSIS¶
#include
<geom/geom.h>
void *
g_read_data
(
struct
g_consumer *cp,
off_t offset,
off_t length,
int
*error);
int
g_write_data
(
struct
g_consumer *cp,
off_t offset,
void *ptr,
off_t
length);
DESCRIPTION¶
The
g_read_data
() function reads
length bytes of data from the provider
attached to consumer
cp, starting at offset
offset. The buffer returned from
g_read_data
() is allocated with
g_malloc
(), so it should be freed by the
caller with
g_free
() after use. If the
operation fails, an error value will be stored in the
error argument if it is not
NULL
.
The
g_write_data
() function writes
length bytes of data from the buffer pointed
to by
ptr to the provider attached to
consumer
cp, starting at offset
offset.
RESTRICTIONS/CONDITIONS¶
The
length argument should be a multiple of the
provider's sectorsize and less than or equal to
DFLTPHYS
(
DFLTPHYS
is defined in
<sys/param.h>
).
The topology lock must not be held.
RETURN VALUES¶
The
g_read_data
() function returns a pointer
to a data buffer or
NULL
if an error
occurred. In that case an error value is stored in the
error argument unless it is
NULL
.
The
g_write_data
() function returns 0 if
successful; otherwise an error code is returned.
ERRORS¶
Possible errors:
- [
EIO
]
- An I/O error occurred while reading from or writing to the consumer.
SEE ALSO¶
geom(4),
DECLARE_GEOM_CLASS(9),
g_access(9),
g_attach(9),
g_bio(9),
g_consumer(9),
g_event(9),
g_geom(9),
g_provider(9),
g_provider_by_name(9),
g_wither_geom(9)
AUTHORS¶
This manual page was written by
Pawel Jakub
Dawidek ⟨pjd@FreeBSD.org⟩.