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EFI_GET_VARIABLE(3)   DragonFly 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
       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-sytle 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_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>

                                Thu Aug 20 2012            EFI_GET_VARIABLE(3)

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