Add command to set an environment variable to an EFI variable

We may want to make things conditional on EFI variable state

Signed-off-by: Matthew Garrett <mgarrett@aurora.tech>
Reviewed-by: Simon Glass <sjg@chromium.org>

cmd/Kconfig

@@ -761,6 +761,10 @@ config CMD_NVEDIT_SELECT
 	help
 	  Select the compiled-in persistent storage of environment variables.
 
+config CMD_EFI_GET_ENV
+	bool "efi get env"
+	help
+	  Set an environment variable to the contents of an EFI variable
 endmenu
 
 menu "Memory commands"

cmd/Makefile

@@ -70,6 +70,7 @@ obj-$(CONFIG_CMD_EEPROM) += eeprom.o
 obj-$(CONFIG_EFI) += efi.o efi_common.o
 obj-$(CONFIG_CMD_EFIDEBUG) += efidebug.o efi_common.o
 obj-$(CONFIG_CMD_EFICONFIG) += eficonfig.o
+obj-$(CONFIG_CMD_EFI_GET_ENV) += efigetenv.o
 ifdef CONFIG_CMD_EFICONFIG
 ifdef CONFIG_EFI_MM_COMM_TEE
 obj-$(CONFIG_EFI_SECURE_BOOT) += eficonfig_sbkey.o

cmd/efigetenv.c

@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include <charset.h>
+#include <command.h>
+#include <efi_loader.h>
+#include <efi_variable.h>
+#include <env.h>
+#include <hexdump.h>
+#include <malloc.h>
+#include <uuid.h>
+
+/* Set a U-Boot environment variable to the contents of a UEFI variable */
+int do_efi_get_env(struct cmd_tbl *cmdtb, int flat, int argc, char *const argv[])
+{
+	u16 *var_name = NULL;
+	char *strdata = NULL;
+	efi_uintn_t size = 0;
+	bool var_content_is_utf16_string = false;
+	efi_status_t ret;
+	efi_guid_t guid;
+	u8 *data = NULL;
+	u32 attributes;
+	size_t len;
+	u64 time;
+	u16 *p;
+
+	ret = efi_init_obj_list();
+	if (ret != EFI_SUCCESS) {
+		printf("Error: Cannot initialize UEFI sub-system, r = %lu\n",
+		       ret & ~EFI_ERROR_MASK);
+		return CMD_RET_FAILURE;
+	}
+
+	argv++;
+	argc--;
+
+	if (argc != 3 && argc != 4)
+		return CMD_RET_USAGE;
+
+	if (argc == 4) {
+		if (strcmp(argv[0], "-s"))
+			return CMD_RET_USAGE;
+		var_content_is_utf16_string = true;
+		argv++;
+		argc--;
+	}
+
+	len = utf8_utf16_strnlen(argv[0], strlen(argv[0]));
+	var_name = malloc((len + 1) * 2);
+	if (!var_name) {
+		printf("## Out of memory\n");
+		return CMD_RET_FAILURE;
+	}
+	p = var_name;
+	utf8_utf16_strncpy(&p, argv[0], len + 1);
+
+	if (uuid_str_to_bin(argv[1], guid.b, UUID_STR_FORMAT_GUID)) {
+		ret = CMD_RET_USAGE;
+		goto out;
+	}
+
+	ret = efi_get_variable_int(var_name, &guid, &attributes, &size, data,
+				   &time);
+	if (ret == EFI_BUFFER_TOO_SMALL) {
+		data = malloc(size);
+		if (!data) {
+			printf("## Out of memory\n");
+			ret = CMD_RET_FAILURE;
+			goto out;
+		}
+		ret = efi_get_variable_int(var_name, &guid, &attributes,
+					   &size, data, &time);
+	}
+
+	if (ret == EFI_NOT_FOUND) {
+		printf("Error: \"%ls\" not defined\n", var_name);
+		ret = CMD_RET_FAILURE;
+		goto out;
+	}
+
+	if (ret != EFI_SUCCESS) {
+		printf("Error: Cannot read variable, r = %lu\n",
+		       ret & ~EFI_ERROR_MASK);
+		ret = CMD_RET_FAILURE;
+		goto out;
+	}
+
+	if (var_content_is_utf16_string) {
+		char *p;
+
+		len = utf16_utf8_strnlen((u16 *)data, size / 2);
+		strdata = malloc(len + 1);
+		if (!strdata) {
+			printf("## Out of memory\n");
+			ret = CMD_RET_FAILURE;
+			goto out;
+		}
+		p = strdata;
+		utf16_utf8_strncpy(&p, (u16 *)data, size / 2);
+	} else {
+		len = size * 2;
+		strdata = malloc(len + 1);
+		if (!strdata) {
+			printf("## Out of memory\n");
+			ret = CMD_RET_FAILURE;
+			goto out;
+		}
+		bin2hex(strdata, data, size);
+	}
+
+	strdata[len] = '\0';
+
+	ret = env_set(argv[2], strdata);
+	if (ret) {
+		ret = CMD_RET_FAILURE;
+		goto out;
+	}
+
+	ret = CMD_RET_SUCCESS;
+out:
+	free(strdata);
+	free(data);
+	free(var_name);
+
+	return ret;
+}
+
+U_BOOT_CMD(
+	efigetenv, 5, 4, do_efi_get_env,
+	"set environment variable to content of EFI variable",
+	"[-s] name guid envvar\n"
+	"    - set environment variable 'envvar' to the EFI variable 'name'-'guid'\n"
+	"      \"-s\": Interpret the EFI variable value as a UTF-16 string\n"
+);