[PATCH v3 3/5] efi_loader: utility function to check the variable name is "Boot####"

[Masahisa Kojima]

Some commands need to enumerate the existing UEFI load
option variable("Boot####"). This commit transfers some code
from cmd/efidebug.c to lib/efi_loder/, then exposes
efi_varname_is_load_option() function to check whether
the UEFI variable name is "Boot####".

Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
v2->v3:
- add static qualifier to u16_tohex()

Newly created in v2

 cmd/efidebug.c              | 23 +----------------------
 include/efi_loader.h        |  1 +
 lib/efi_loader/efi_helper.c | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 22 deletions(-)

diff --git a/cmd/efidebug.c b/cmd/efidebug.c
index ef239bb34b..ceb3aa5cee 100644
--- a/cmd/efidebug.c
+++ b/cmd/efidebug.c
@@ -1010,17 +1010,6 @@ static void show_efi_boot_opt(u16 *varname16)
 	}
 }
 
-static int u16_tohex(u16 c)
-{
-	if (c >= '0' && c <= '9')
-		return c - '0';
-	if (c >= 'A' && c <= 'F')
-		return c - 'A' + 10;
-
-	/* not hexadecimal */
-	return -1;
-}
-
 /**
  * show_efi_boot_dump() - dump all UEFI load options
  *
@@ -1041,7 +1030,6 @@ static int do_efi_boot_dump(struct cmd_tbl *cmdtp, int flag,
 	u16 *var_name16, *p;
 	efi_uintn_t buf_size, size;
 	efi_guid_t guid;
-	int id, i, digit;
 	efi_status_t ret;
 
 	if (argc > 1)
@@ -1074,16 +1062,7 @@ static int do_efi_boot_dump(struct cmd_tbl *cmdtp, int flag,
 			return CMD_RET_FAILURE;
 		}
 
-		if (memcmp(var_name16, u"Boot", 8))
-			continue;
-
-		for (id = 0, i = 0; i < 4; i++) {
-			digit = u16_tohex(var_name16[4 + i]);
-			if (digit < 0)
-				break;
-			id = (id << 4) + digit;
-		}
-		if (i == 4 && !var_name16[8])
+		if (efi_varname_is_load_option(var_name16, NULL))
 			show_efi_boot_opt(var_name16);
 	}
 
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 0c6c95ba46..0899e293e5 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -707,6 +707,7 @@ int algo_to_len(const char *algo);
 
 int efi_link_dev(efi_handle_t handle, struct udevice *dev);
 int efi_unlink_dev(efi_handle_t handle);
+bool efi_varname_is_load_option(u16 *var_name16, int *index);
 
 /**
  * efi_size_in_pages() - convert size in bytes to size in pages
diff --git a/lib/efi_loader/efi_helper.c b/lib/efi_loader/efi_helper.c
index c71e87d118..788cb9faec 100644
--- a/lib/efi_loader/efi_helper.c
+++ b/lib/efi_loader/efi_helper.c
@@ -190,3 +190,36 @@ int efi_unlink_dev(efi_handle_t handle)
 
 	return 0;
 }
+
+static int u16_tohex(u16 c)
+{
+	if (c >= '0' && c <= '9')
+		return c - '0';
+	if (c >= 'A' && c <= 'F')
+		return c - 'A' + 10;
+
+	/* not hexadecimal */
+	return -1;
+}
+
+bool efi_varname_is_load_option(u16 *var_name16, int *index)
+{
+	int id, i, digit;
+
+	if (memcmp(var_name16, u"Boot", 8))
+		return false;
+
+	for (id = 0, i = 0; i < 4; i++) {
+		digit = u16_tohex(var_name16[4 + i]);
+		if (digit < 0)
+			break;
+		id = (id << 4) + digit;
+	}
+	if (i == 4 && !var_name16[8]) {
+		if (index)
+			*index = id;
+		return true;
+	}
+
+	return false;
+}
-- 
2.17.1