table of contents
G_DATA(9) | Kernel Developer's Manual | G_DATA(9) |
NAME¶
g_read_data, g_write_data — read/write data from/to GEOM consumerSYNOPSIS¶
#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 notNULL
.
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 toDFLTPHYS
(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 orNULL
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⟩.January 16, 2004 | Debian |