Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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$FreeBSD: head/share/man/man9/g_data.9 125699 2004-02-11 10:06:18Z pjd $

.Dd January 16, 2004 .Dt g_data 9 .Os .Sh NAME .Nm g_read_data , .Nm g_write_data .Nd "read/write data through consumer" .Sh SYNOPSIS n geom/geom.h .Ft "void *" .Fn g_read_data "struct g_consumer *cp" "off_t offset" "off_t length" "int *error" .Ft int .Fn g_write_data "struct g_consumer *cp" "off_t offset" "void *ptr" "off_t length" .Sh DESCRIPTION The .Fn g_read_data reads .Fa length bytes of data from a provider through attached consumer .Fa cp starting at offset .Fa offset . Memory for data is allocated inside .Fn g_read_data with .Fn g_malloc , and should therefor be freed by the caller with the .Fn g_free function after use. If the operation fails, an error value will be stored in the .Fa error argument if it is not .Dv NULL .

p The .Fn g_write_data writes .Fa length bytes of data from address .Fa ptr starting at offset .Fa offset to a provider through the attached consumer .Fa cp . .Sh RESTRICTIONS/CONDITIONS Length of data should be a multiple of the sectorsize for the provider and less than or equal to .Dv DFLTPHYS .Dv ( DFLTPHYS is defined in n sys/param.h ) .

p The topology lock must not be held. .Sh RETURN VALUES .Fn g_read_data returns a pointer to the read data or .Dv NULL if an error occured. In that case an error value is stored in the .Fa error argument unsless it is .Dv NULL .

p .Fn g_write_data returns the value 0 if successful; otherwise an error code is returned. .Sh ERRORS Possible errors: l -tag -width Er t Bq Er EIO Can not read data. .El .Sh SEE ALSO .Xr DECLARE_GEOM_CLASS 9 , .Xr geom 4 , .Xr g_attach 9 , .Xr g_bio 9 , .Xr g_consumer 9 , .Xr g_event 9 , .Xr g_geom 9 , .Xr g_provider 9 , .Xr g_provider_by_name 9 , .Xr g_wither_geom 9 .Sh AUTHORS .An -nosplit This manual page was written by .An Pawel Jakub Dawidek Aq pjd@FreeBSD.org .