1 files changed, 236 insertions, 0 deletions
diff --git a/src/interface/efi/efi_settings.c b/src/interface/efi/efi_settings.c
new file mode 100644
index 0000000..cde0ff8
--- /dev/null
+++ b/src/interface/efi/efi_settings.c
@@ -0,0 +1,236 @@
+/*
+ * Copyright (C) 2023 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+/**
+ * @file
+ *
+ * EFI variable settings
+ *
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <ipxe/settings.h>
+#include <ipxe/init.h>
+#include <ipxe/efi/efi.h>
+#include <ipxe/efi/efi_strings.h>
+
+/** EFI variable settings scope */
+static const struct settings_scope efivars_scope;
+
+/** EFI variable settings */
+static struct settings efivars;
+
+/**
+ * Check applicability of EFI variable setting
+ *
+ * @v settings		Settings block
+ * @v setting		Setting
+ * @ret applies		Setting applies within this settings block
+ */
+static int efivars_applies ( struct settings *settings __unused,
+			     const struct setting *setting ) {
+
+	return ( setting->scope == &efivars_scope );
+}
+
+/**
+ * Find first matching EFI variable name
+ *
+ * @v wname		Name
+ * @v guid		GUID to fill in
+ * @ret rc		Return status code
+ */
+static int efivars_find ( const CHAR16 *wname, EFI_GUID *guid ) {
+	EFI_RUNTIME_SERVICES *rs = efi_systab->RuntimeServices;
+	size_t wname_len = ( ( wcslen ( wname ) + 1 ) * sizeof ( wname[0] ) );
+	CHAR16 *buf;
+	CHAR16 *tmp;
+	UINTN size;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Allocate single wNUL for first call to GetNextVariableName() */
+	size = sizeof ( buf[0] );
+	buf = zalloc ( size );
+	if ( ! buf )
+		return -ENOMEM;
+
+	/* Iterate over all veriables */
+	while ( 1 ) {
+
+		/* Get next variable name */
+		efirc = rs->GetNextVariableName ( &size, buf, guid );
+		if ( efirc == EFI_BUFFER_TOO_SMALL ) {
+			tmp = realloc ( buf, size );
+			if ( ! tmp ) {
+				rc = -ENOMEM;
+				break;
+			}
+			buf = tmp;
+			efirc = rs->GetNextVariableName ( &size, buf, guid );
+		}
+		if ( efirc == EFI_NOT_FOUND ) {
+			rc = -ENOENT;
+			break;
+		}
+		if ( efirc != 0 ) {
+			rc = -EEFI ( efirc );
+			DBGC ( &efivars, "EFIVARS %s:%ls could not fetch next "
+			       "variable name: %s\n",
+			       efi_guid_ntoa ( guid ), buf, strerror ( rc ) );
+			break;
+		}
+		DBGC2 ( &efivars, "EFIVARS %s:%ls exists\n",
+			efi_guid_ntoa ( guid ), buf );
+
+		/* Check for matching variable name */
+		if ( memcmp ( wname, buf, wname_len ) == 0 ) {
+			rc = 0;
+			break;
+		}
+	}
+
+	/* Free temporary buffer */
+	free ( buf );
+
+	return rc;
+}
+
+/**
+ * Fetch value of EFI variable setting
+ *
+ * @v settings		Settings block
+ * @v setting		Setting to fetch
+ * @v data		Buffer to fill with setting data
+ * @v len		Length of buffer
+ * @ret len		Length of setting data, or negative error
+ */
+static int efivars_fetch ( struct settings *settings __unused,
+			   struct setting *setting, void *data, size_t len ) {
+	EFI_RUNTIME_SERVICES *rs = efi_systab->RuntimeServices;
+	size_t name_len = strlen ( setting->name );
+	CHAR16 wname[ name_len + 1 /* wNUL */ ];
+	EFI_GUID guid;
+	UINT32 attrs;
+	UINTN size;
+	void *buf;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Convert name to UCS-2 */
+	efi_snprintf ( wname, sizeof ( wname ), "%s", setting->name );
+
+	/* Find variable GUID */
+	if ( ( rc = efivars_find ( wname, &guid ) ) != 0 )
+		goto err_find;
+
+	/* Get variable length */
+	size = 0;
+	if ( ( efirc = rs->GetVariable ( wname, &guid, &attrs, &size,
+					 NULL ) != EFI_BUFFER_TOO_SMALL ) ) {
+		rc = -EEFI ( efirc );
+		DBGC ( &efivars, "EFIVARS %s:%ls could not get size: %s\n",
+		       efi_guid_ntoa ( &guid ), wname, strerror ( rc ) );
+		goto err_len;
+	}
+
+	/* Allocate temporary buffer, since GetVariable() is not
+	 * guaranteed to return partial data for an underlength
+	 * buffer.
+	 */
+	buf = malloc ( size );
+	if ( ! buf ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+
+	/* Get variable value */
+	if ( ( efirc = rs->GetVariable ( wname, &guid, &attrs, &size,
+					 buf ) ) != 0 ) {
+		rc = -EEFI ( efirc );
+		DBGC ( &efivars, "EFIVARS %s:%ls could not get %zd bytes: "
+		       "%s\n", efi_guid_ntoa ( &guid ), wname,
+		       ( ( size_t ) size ), strerror ( rc ) );
+		goto err_get;
+	}
+	DBGC ( &efivars, "EFIVARS %s:%ls:\n", efi_guid_ntoa ( &guid ), wname );
+	DBGC_HDA ( &efivars, 0, buf, size );
+
+	/* Return setting value */
+	if ( len > size )
+		len = size;
+	memcpy ( data, buf, len );
+	if ( ! setting->type )
+		setting->type = &setting_type_hex;
+
+	/* Free temporary buffer */
+	free ( buf );
+
+	return size;
+
+ err_get:
+	free ( buf );
+ err_alloc:
+ err_len:
+ err_find:
+	return rc;
+}
+
+/** EFI variable settings operations */
+static struct settings_operations efivars_operations = {
+	.applies = efivars_applies,
+	.fetch = efivars_fetch,
+};
+
+/** EFI variable settings */
+static struct settings efivars = {
+	.refcnt = NULL,
+	.siblings = LIST_HEAD_INIT ( efivars.siblings ),
+	.children = LIST_HEAD_INIT ( efivars.children ),
+	.op = &efivars_operations,
+	.default_scope = &efivars_scope,
+};
+
+/**
+ * Initialise EFI variable settings
+ *
+ */
+static void efivars_init ( void ) {
+	int rc;
+
+	/* Register settings block */
+	if ( ( rc = register_settings ( &efivars, NULL, "efi" ) ) != 0 ) {
+		DBGC ( &efivars, "EFIVARS could not register: %s\n",
+		       strerror ( rc ) );
+		return;
+	}
+}
+
+/** EFI variable settings initialiser */
+struct init_fn efivars_init_fn __init_fn ( INIT_NORMAL ) = {
+	.initialise = efivars_init,
+};