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G_DATA(9) FreeBSD Kernel Developer's Manual G_DATA(9)
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.
[EINTEGRITY] Corrupted data was detected while reading from 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>.
FreeBSD 14.0-RELEASE-p6 March 30, 2020 FreeBSD 14.0-RELEASE-p6