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G_DATA (9) | Kernel routines | Unix Manual Pages | :man

NAME

g_read_data, g_write_data - "read/write data from/to GEOM consumer"

CONTENTS

Synopsis
Description
Restrictions/conditions
Return Values
Errors
See Also
Authors

SYNOPSIS


.In geom/geom.h "void *"
.Fo g_read_data "struct g_consumer *cp" "off_t offset" "off_t length" "int *error"
.Fc int
.Fo g_write_data "struct g_consumer *cp" "off_t offset" "void *ptr" "off_t length"
.Fc

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
.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


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