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$FreeBSD$
.Dd January 29, 2010 .Dt LIBEFI 3 .Os .Sh NAME .Nm efi_getvar , efi_nextvarname , efi_setvar .Nd "interface for accessing the EFI variable services" .Sh LIBRARY .Lb libefi .Sh SYNOPSIS n libefi.h .Ft int .Fo efi_getvar .Fa "char *name" "uuid_t *vendor" "uint32_t *attrib" .Fa "size_t *datasize" "void *data" .Fc .Ft int .Fn efi_nextvarname "size_t *namesize" "char *name" "uuid_t *vendor" .Ft int .Fo efi_setvar .Fa "char *name" "uuid_t *vendor" "uint32_t attrib" .Fa "size_t datasize" "void *data" .Fc .Sh DESCRIPTION The .Nm libefi library provides access to a select set of the runtime services of the Extensible Firmware Interface (EFI).
p The .Fn efi_nextvarname function is used to enumerate the variables. The .Fa namesize parameter needs to be set to the size of the buffer pointed to by .Fa name . On return, .Fa namesize is set to the length of the variable name (including the terminating .Ql \e0 ) irrespective of whether the buffer was big enough. The buffer pointed to by .Fa name contains the full or partial variable name on return. Only on successful completion of the request is the .Fa vendor updated. The values returned should be passed to successive calls to .Fn efi_nextvarname until all variables have been enumerated.
p The variable name and vendor as returned by .Fn efi_nextvarname can be passed to .Fn efi_getvar to obtain the value and attribute of the variable. The buffer that is to contain the value is specified by .Fa data and the size of the buffer is given by .Fa datasize . The attribute pointed to by .Fa attrib consists of the bit values defined by the EFI specification.
p Variables can be created, modified and deleted using the .Fn efi_setvar function. All new variables must be non-volatile and runtime accessible in order for the request to succeed. Note that for runtime accessable variables the boottime accessable bit must be set as well. To delete a variable, set .Fa datasize to 0.
p The vendor UUID is used to avoid collisions between variable names of different vendors. Variables created for use by .Fx should use the .Dv EFI_FREEBSD_VARIABLE UUID as defined in the n libefi.h header file. .Sh RETURN VALUES Upon successful completion, these functions return 0. Otherwise, the error number is returned. These functions will fail if: l -tag -width Er t Bq Er EACCES Insufficient permissions to access the EFI services. t Bq Er EILSEQ The variable name is not in UTF-8. t Bq Er EINVAL The request has invalid parameters. t Bq Er ENOENT The variable does not exist or no more variables exist. t Bq Er ENOMEM Temporary storage could not be allocated. t Bq Er EOVERFLOW The variable name is too long or the data is too big to fit in the buffer provided. .El .Sh SEE ALSO .Xr errno 2 , .Xr uuid 3 .Sh HISTORY The .Nm libefi library first appeared in .Fx 9.0 for the ia64 architecture. .Sh AUTHORS The .Nm libefi library and this manual page were written by .An Marcel Moolenaar Aq marcel@FreeBSD.org .