[PATCH 3/6 v2] efi_loader: Introduce helper functions for EFI

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

Hi Heinrich, 

On Sun, Mar 14, 2021 at 08:31:20AM +0100, Heinrich Schuchardt wrote:
> On 3/13/21 10:47 PM, Ilias Apalodimas wrote:
> > A following patch introduces a different logic for loading initrd's
> > based on the EFI_LOAD_FILE2_PROTOCOL.
> > +/**
> > + * efi_get_file_size() - Get the size of a file using an EFI file handle
> > + *
> > + * @handle:	EFI file handle
> > + * @size:	buffer to fill in the discovered size
> > + *
> > + * Return:	device path or NULL. Caller must free the returned value
> > + */
> > +efi_status_t efi_get_file_size(struct efi_file_handle *fh, efi_uintn_t *size)
> 
> Should this function be in lib/efi_loader/efi_file?

there's already a statically defined efi_get_file_size() in that file.  I can
rename that, just let me know what you prefer.

> 
> Best regards
> 
> Heinrich
> 
> > +{
> > +	struct efi_file_info *info = NULL;
> > +	efi_uintn_t bs = 0;
> > +	efi_status_t ret;
> > +
> > +	*size = 0;
> > +	ret = EFI_CALL(fh->getinfo(fh, (efi_guid_t *)&efi_file_info_guid, &bs,
> > +				   info));
> > +	if (ret != EFI_BUFFER_TOO_SMALL) {
> > +		ret = EFI_DEVICE_ERROR;
> > +		goto out;
> > +	}
> > +
> > +	info = malloc(bs);
> > +	if (!info) {
> > +		ret = EFI_OUT_OF_RESOURCES;
> > +		goto out;
> > +	}
> > +	ret = EFI_CALL(fh->getinfo(fh, (efi_guid_t *)&efi_file_info_guid, &bs,
> > +				   info));
> > +	if (ret != EFI_SUCCESS)
> > +		goto out;
> > +
> > +	*size = info->file_size;
> > +
> > +out:
> > +	free(info);
> > +	return ret;
> > +}
> > diff --git a/lib/efi_loader/efi_var_common.c b/lib/efi_loader/efi_var_common.c
> > index 1c7459266a38..b11ed91a74a4 100644
> > --- a/lib/efi_loader/efi_var_common.c
> > +++ b/lib/efi_loader/efi_var_common.c
> > @@ -9,6 +9,7 @@
> >   #include <common.h>
> >   #include <efi_loader.h>
> >   #include <efi_variable.h>
> > +#include <stdlib.h>
> > 
> >   enum efi_secure_mode {
> >   	EFI_MODE_SETUP,
> > @@ -343,3 +344,35 @@ enum efi_auth_var_type efi_auth_var_get_type(u16 *name, const efi_guid_t *guid)
> >   	}
> >   	return EFI_AUTH_VAR_NONE;
> >   }
> > +
> > +/**
> > + * efi_get_var() - read value of an EFI variable
> > + *
> > + * @name:	variable name
> > + * @start:	vendor GUID
> > + * @size:	size of allocated buffer
> > + *
> > + * Return:	buffer with variable data or NULL
> > + */
> > +void *efi_get_var(u16 *name, const efi_guid_t *vendor, efi_uintn_t *size)
> > +{
> > +	efi_status_t ret;
> > +	void *buf = NULL;
> > +
> > +	*size = 0;
> > +	ret = efi_get_variable_int(name, vendor, NULL, size, buf, NULL);
> > +	if (ret == EFI_BUFFER_TOO_SMALL) {
> > +		buf = malloc(*size);
> > +		if (!buf)
> > +			return NULL;
> > +		ret = efi_get_variable_int(name, vendor, NULL, size, buf, NULL);
> > +	}
> > +
> > +	if (ret != EFI_SUCCESS) {
> > +		free(buf);
> > +		*size = 0;
> > +		return NULL;
> > +	}
> > +
> > +	return buf;
> > +}
> > 
>