g_data (9)
Leading comments
Copyright (c) 2004-2005 Pawel Jakub Dawidek <pjd@FreeBSD.org> All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the...
NAME
g_read_data g_write_data - read/write data from/to GEOM consumerSYNOPSIS
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 FcDESCRIPTION
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 NULLThe 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 NULLThe 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.