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EFI_GET_VARIABLE(3) - man page online | library functions

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Thu Aug 20 2012
EFI_GET_VARIABLE(3)                  Library Functions Manual                 EFI_GET_VARIABLE(3)

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_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); 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_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. If the optional mode parameter is given, it will use those permissions to create the file, subject to umask. 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 suit‐ able 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-sytle symbol name. These symbol names are useful for printing as a unique, easily parsed iden‐ tifier, 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_vari‐ able_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 <@redhat.com>
Thu Aug 20 2012 EFI_GET_VARIABLE(3)
This manual Reference Other manuals
efi_get_variable(3) referred by efi_variable_t(3)
refer to errno(3)