[PATCH v1 35/54] efi: loader: protocol: add efi_device_path_to_text support

[Ahmad Fatoum]

For use by EFI payloads that don't want to convert device paths into
strings themselves, the loader can provide a protocol with access to its
own routines. device_path_to_str(), which we already in the EFI payload
can fill that role, so add a protocol that calls into it.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 efi/loader/protocols/Kconfig               |   7 ++
 efi/loader/protocols/Makefile              |   1 +
 efi/loader/protocols/device_path_to_text.c | 130 +++++++++++++++++++++
 include/efi/protocol/devicepath.h          |  11 ++
 4 files changed, 149 insertions(+)
 create mode 100644 efi/loader/protocols/device_path_to_text.c

diff --git a/efi/loader/protocols/Kconfig b/efi/loader/protocols/Kconfig
index 3405de1acdfb..ba6f562b7585 100644
--- a/efi/loader/protocols/Kconfig
+++ b/efi/loader/protocols/Kconfig
@@ -39,6 +39,13 @@ config EFI_LOADER_RNG
 	  Provide a EFI_RNG_PROTOCOL implementation using the hardware random
 	  number generator of the platform.
 
+config EFI_LOADER_DEVICE_PATH_TO_TEXT
+	bool "Device path to text protocol"
+	default y
+	help
+	  The device path to text protocol converts device nodes and paths to
+	  human readable strings.
+
 config EFI_LOADER_DEVICE_PATH_UTIL
 	bool "Device path utilities protocol"
 	default y
diff --git a/efi/loader/protocols/Makefile b/efi/loader/protocols/Makefile
index b5ec5cf5dd46..a323927b89e3 100644
--- a/efi/loader/protocols/Makefile
+++ b/efi/loader/protocols/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_EFI_LOADER_HII) += hii.o hii_config.o
 obj-$(CONFIG_EFI_LOADER_UNICODE_COLLATION_PROTOCOL2) += unicode_collation.o
 obj-$(CONFIG_EFI_LOADER_RNG) += rng.o
 obj-$(CONFIG_EFI_LOADER_DEVICE_PATH_UTIL) += device_path_utilities.o
+obj-$(CONFIG_EFI_LOADER_DEVICE_PATH_TO_TEXT) += device_path_to_text.o
diff --git a/efi/loader/protocols/device_path_to_text.c b/efi/loader/protocols/device_path_to_text.c
new file mode 100644
index 000000000000..d2907915469c
--- /dev/null
+++ b/efi/loader/protocols/device_path_to_text.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  EFI device path interface
+ *
+ *  Copyright (c) 2017 Heinrich Schuchardt
+ */
+
+#include <charset.h>
+#include <efi/devicepath.h>
+#include <efi/loader/devicepath.h>
+#include <efi/protocol/devicepath.h>
+#include <efi/loader/object.h>
+#include <efi/loader/trace.h>
+#include <efi/loader.h>
+#include <efi/guid.h>
+#include <efi/error.h>
+#include <init.h>
+
+/**
+ * efi_str_to_u16() - convert ASCII string to UTF-16
+ *
+ * A u16 buffer is allocated from pool. The ASCII string is copied to the u16
+ * buffer.
+ *
+ * @str:	ASCII string
+ * Return:	UTF-16 string. NULL if out of memory.
+ */
+static u16 *efi_str_to_u16(const char *str)
+{
+	size_t len;
+	u16 *out, *dst;
+	efi_status_t ret;
+
+	if (!str)
+		return NULL;
+
+	len = sizeof(u16) * (utf8_utf16_strlen(str) + 1);
+	ret = efi_allocate_pool(EFI_BOOT_SERVICES_DATA, len, (void **)&out, "DP");
+	if (ret != EFI_SUCCESS)
+		return NULL;
+	dst = out;
+	utf8_utf16_strcpy(&dst, str);
+	return out;
+}
+
+static uint16_t EFIAPI *__efi_convert_device_path_to_text(
+		const struct efi_device_path *dp,
+		bool all_nodes)
+{
+	char *str;
+	uint16_t *text;
+
+	if (!dp)
+		return NULL;
+
+	str = device_path_to_str(dp, all_nodes);
+	text = efi_str_to_u16(str);
+	free(str);
+
+	return text;
+}
+
+/*
+ * This function implements the ConvertDeviceNodeToText service of the
+ * EFI_DEVICE_PATH_TO_TEXT_PROTOCOL.
+ * See the Unified Extensible Firmware Interface (UEFI) specification
+ * for details.
+ *
+ * device_node		device node to be converted
+ * display_only		true if the shorter text representation shall be used
+ * allow_shortcuts	true if shortcut forms may be used
+ * Return:		text representation of the device path
+ *			NULL if out of memory of device_path is NULL
+ */
+static uint16_t EFIAPI *efi_convert_device_node_to_text(
+		const struct efi_device_path *device_node,
+		bool display_only,
+		bool allow_shortcuts)
+{
+	uint16_t *text;
+
+	EFI_ENTRY("%p, %d, %d", device_node, display_only, allow_shortcuts);
+
+	text = __efi_convert_device_path_to_text(device_node, false);
+
+	EFI_EXIT(EFI_SUCCESS);
+
+	return text;
+}
+
+/*
+ * This function implements the ConvertDevicePathToText service of the
+ * EFI_DEVICE_PATH_TO_TEXT_PROTOCOL.
+ * See the Unified Extensible Firmware Interface (UEFI) specification
+ * for details.
+ *
+ * device_path		device path to be converted
+ * display_only		true if the shorter text representation shall be used
+ * allow_shortcuts	true if shortcut forms may be used
+ * Return:		text representation of the device path
+ *			NULL if out of memory of device_path is NULL
+ */
+static uint16_t EFIAPI *efi_convert_device_path_to_text(
+		const struct efi_device_path *device_path,
+		bool display_only,
+		bool allow_shortcuts)
+{
+	uint16_t *text;
+
+	EFI_ENTRY("%p, %d, %d", device_path, display_only, allow_shortcuts);
+
+	text = __efi_convert_device_path_to_text(device_path, true);
+
+	EFI_EXIT(EFI_SUCCESS);
+
+	return text;
+}
+
+static const struct efi_device_path_to_text_protocol efi_device_path_to_text = {
+	.convert_device_node_to_text = efi_convert_device_node_to_text,
+	.convert_device_path_to_text = efi_convert_device_path_to_text,
+};
+
+static int efi_device_path_to_text_init(void)
+{
+	efi_add_root_node_protocol_deferred(&efi_device_path_to_text_protocol_guid,
+					    &efi_device_path_to_text);
+	return 0;
+}
+postcore_initcall(efi_device_path_to_text_init);
diff --git a/include/efi/protocol/devicepath.h b/include/efi/protocol/devicepath.h
index 19a35888f9cc..ca0cbd94d5ce 100644
--- a/include/efi/protocol/devicepath.h
+++ b/include/efi/protocol/devicepath.h
@@ -4,6 +4,17 @@
 
 #include <efi/types.h>
 
+struct efi_device_path_to_text_protocol {
+	uint16_t *(EFIAPI *convert_device_node_to_text)(
+			const struct efi_device_path *device_node,
+			bool display_only,
+			bool allow_shortcuts);
+	uint16_t *(EFIAPI *convert_device_path_to_text)(
+			const struct efi_device_path *device_path,
+			bool display_only,
+			bool allow_shortcuts);
+};
+
 struct efi_device_path_utilities_protocol {
 	size_t (EFIAPI *get_device_path_size)(
 		const struct efi_device_path *device_path);
-- 
2.47.3