g_read_data(9) read/write data from/to GEOM consumer

Other Alias

g_write_data

SYNOPSIS

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

DESCRIPTION

The Fn g_read_data function reads Fa length bytes of data from the provider attached to consumer Fa cp , starting at offset Fa offset . The buffer returned from Fn g_read_data is allocated with Fn g_malloc , so it should be freed by the caller with Fn g_free after use. If the operation fails, an error value will be stored in the Fa error argument if it is not NULL

The Fn g_write_data function writes Fa length bytes of data from the buffer pointed to by Fa ptr to the provider attached to consumer Fa cp , starting at offset Fa offset .

RESTRICTIONS/CONDITIONS

The Fa 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 Fn 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 Fa error argument unless it is NULL

The Fn g_write_data function returns 0 if successful; otherwise an error code is returned.

ERRORS

Possible errors:

Bq Er EIO
An I/O error occurred while reading from or writing to the consumer.

AUTHORS

An -nosplit This manual page was written by An Pawel Jakub Dawidek Aq [email protected] .