Man page - efi_variables_supported(3)

Packages contains this manual

Package:  libefivar-dev
apt-get install libefivar-dev

Manuals in package:
• efi_variable_export(3)
• efi_variable_import(3)
• efi_variable_get_data(3)
• efi_variable_set_attributes(3)
• efi_append_variable(3)
• efi_variable_realize(3)
• efi_set_variable(3)
• efi_variable_set_guid(3)
• efi_str_to_guid(3)
• efi_symbol_to_guid(3)
• efi_variable_set_data(3)
• efi_get_variable_size(3)
• efi_variable_get_guid(3)
• efi_get_next_variable_name(3)
• efi_variables_supported(3)
• efi_get_variable_attributes(3)
• efi_variable_get_name(3)
• efi_get_variable(3)
• efi_variable_get_attributes(3)
• efi_variable_t(3)
• efi_name_to_guid(3)
• efi_guid_to_id_guid(3)
• efi_del_variable(3)
• efi_variable_set_name(3)
• efi_variable_free(3)
• efi_guid_to_symbol(3)
• efi_variable_alloc(3)
• efi_guid_to_str(3)
• efi_guid_to_name(3)
Documentations in package:
• libefivar-dev

Manual

EFI_GET_VARIABLE

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
AUTHORS

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NAME

efi_variables_supported, efi_del_variable, efi_get_variable, efi_get_variable_attributes, efi_get_variable_size, efi_set_variable - manipulate UEFI variables

SYNOPSIS

#include <efivar.h>

int efi_variables_supported(void);
int efi_del_variable(efi_guid_t guid , const char *name );

int efi_get_variable(efi_guid_t guid , const char * name ,

					void ** data , ssize_t * data_size ,
					uint32_t * attributes );

int efi_get_variable_attributes(efi_guid_t guid , const char * name ,

uint32_t * attributes );

int efi_get_variable_exists(efi_guid_t guid , const char *name );

int efi_get_variable_size(efi_guid_t guid , const char * name ,

size_t * size );

int efi_append_variable(efi_guid_t guid , const char * name ,

					void * data , size_t data_size ,
					uint32_t attributes );

int efi_set_variable(efi_guid_t guid , const char * name ,

					void * data , size_t data_size ,
					uint32_t attributes , mode_t mode );

int efi_get_next_variable_name(efi_guid_t ** guid , char ** name );

int efi_str_to_guid(const char * s , efi_guid_t * guid );

int efi_guid_to_str(const efi_guid_t * guid , char ** sp );

int efi_name_to_guid(const char * name , efi_guid_t * guid );

int efi_id_guid_to_guid(const char * id_guid , efi_guid_t * guid );

int efi_guid_to_name(efi_guid_t * guid , char ** name );

int efi_guid_to_id_guid(efi_guid_t * guid , char ** id_guid );

int efi_guid_to_symbol(efi_guid_t * guid , char ** symbol );
int efi_symbol_to_guid(const char * symbol , efi_guid_t * guid );

DESCRIPTION

efi_variables_supported () tests if the UEFI variable facility is supported on the current machine.

efi_del_variable () deletes the variable specified by guid and name .

efi_get_variable () gets the variable specified by guid and name . The value is stored in data , its size in data_size , and its attributes are stored in attributes .

efi_get_variable_attributes () gets attributes for the variable specified by guid and name .

efi_get_variable_exists () gets if the variable specified by guid and name exists.

efi_get_variable_size () gets the size of the data for the variable specified by guid and name .

efi_append_variable () appends data of size size to the variable specified by guid and name .

efi_set_variable () sets the variable specified by guid and name , and sets the file mode to mode , subject to umask. Note that the mode will not persist across a reboot, and that the permissions only apply if on systems using efivarfs.

efi_get_next_variable_name () iterates across the currently extant variables, passing back a guid and name.

efi_str_to_guid () parses a UEFI GUID from string form to an efi_guid_t the caller provides

efi_guid_to_str () Creates a string representation of a UEFI GUID. If sp is NULL, it returns how big the string would be. If sp is not NULL but *sp is NULL, it allocates a string and returns it with. It is the caller’s responsibility to free this string. If sp is not NULL and *sp is not NULL, efi_guid_to_str () assumes there is an allocation of suitable size and uses it.

efi_name_to_guid () translates from a well known name to an efi_guid_t the caller provides.

efi_guid_to_name () translates from an efi_guid_t to a well known name. If the supplied GUID does not have a well known name, this function is equivalent to efi_guid_to_str ().

efi_guid_to_id_guid () translates from an efi_guid_t to an {ID GUID}. If the supplied GUID has a well known name, the {ID GUID} will be of the form "{name_here}". If not, it will be of the form "{66b2af1c-6211-4082-95cb-9f73a4795a7e}".

efi_id_guid_to_guid () translates from an {ID GUID} to an efi_guid_t the caller provides.

efi_guid_to_symbol () translates from an efi_guid_t to a unique (within libefivar) C-style symbol name. These symbol names are useful for printing as a unique, easily parsed identifier, and are also provide by the library and its header files.

efi_symbol_to_guid () translates from a libefivar efi_guid_$FOO symbol name to an efi_guid_t the caller provides.

RETURN VALUE

efi_variables_supported () returns true if variables are supported on the running hardware, and false if they are not.

efi_get_next_variable_name () returns 0 when iteration has completed, 1 when iteration has not completed, and -1 on error. In the event of an error, errno (3) is set appropriately.

efi_del_variable (), efi_get_variable (), efi_get_variable_attributes (), efi_get_variable_exists (), efi_get_variable_size (), efi_append_variable (), efi_set_variable (), efi_str_to_guid (), efi_guid_to_str (), efi_name_to_guid (), and efi_guid_to_name () return negative on error and zero on success.

AUTHORS

Peter Jones <pjones@redhat.com>

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