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

[Ilias Apalodimas]

On Sun, Mar 14, 2021 at 09:01:48AM +0100, Heinrich Schuchardt wrote:
> On 3/14/21 8:34 AM, Ilias Apalodimas wrote:
> > 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.
> 
> Unfortunately we cannot call the efi_get_file_size() function in
> lib/efi_loader/efi_file.c directly because a driver might have installed
> a different implementation of a simple file protocol.
> 
> We should have different names for the functions, e.g. efi_file_size()
> and efi_get_file_size().
> 
> But still I think lib/efi_loader/efi_file.c would be a better place for
> the new function. We will be able to reuse it in:
> 
> * efi_capsule_read_file()
> * efi_load_image_from_file()

Sure, I'll rename this to efi_file_size() and move it in lib/efi_loader/efi_file.c

> 
> Best regards
> 
> Heinrich
> 
> > 
> > > 
> > > 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;
> > > > +}
> > > > 
> > > 
>