[settings] Add "base64" setting type

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/settings.c

 #include <ipxe/uuid.h>
 #include <ipxe/uri.h>
 #include <ipxe/base16.h>
+#include <ipxe/base64.h>
 #include <ipxe/pci.h>
 #include <ipxe/init.h>
 #include <ipxe/version.h>
 	.format = format_hex_raw_setting,
 };
 
+/**
+ * Parse Base64-encoded setting value
+ *
+ * @v type		Setting type
+ * @v value		Formatted setting value
+ * @v buf		Buffer to contain raw value
+ * @v len		Length of buffer
+ * @v size		Integer size, in bytes
+ * @ret len		Length of raw value, or negative error
+ */
+static int parse_base64_setting ( const struct setting_type *type __unused,
+				  const char *value, void *buf, size_t len ) {
+
+	return base64_decode ( value, buf, len );
+}
+
+/**
+ * Format Base64-encoded setting value
+ *
+ * @v type		Setting type
+ * @v raw		Raw setting value
+ * @v raw_len		Length of raw setting value
+ * @v buf		Buffer to contain formatted value
+ * @v len		Length of buffer
+ * @ret len		Length of formatted value, or negative error
+ */
+static int format_base64_setting ( const struct setting_type *type __unused,
+				   const void *raw, size_t raw_len,
+				   char *buf, size_t len ) {
+
+	return base64_encode ( raw, raw_len, buf, len );
+}
+
+/** A Base64-encoded setting */
+const struct setting_type setting_type_base64 __setting_type = {
+	.name = "base64",
+	.parse = parse_base64_setting,
+	.format = format_base64_setting,
+};
+
 /**
  * Format UUID setting value
  *

src/include/ipxe/settings.h

 extern const struct setting_type setting_type_hex __setting_type;
 extern const struct setting_type setting_type_hexhyp __setting_type;
 extern const struct setting_type setting_type_hexraw __setting_type;
+extern const struct setting_type setting_type_base64 __setting_type;
 extern const struct setting_type setting_type_uuid __setting_type;
 extern const struct setting_type setting_type_busdevfn __setting_type;
 extern const struct setting_type setting_type_dnssl __setting_type;

src/tests/settings_test.c

 	.type = &setting_type_hexraw,
 };
 
+/** Test Base64 setting type */
+static struct setting test_base64_setting = {
+	.name = "test_base64",
+	.type = &setting_type_base64,
+};
+
 /** Test UUID setting type */
 static struct setting test_uuid_setting = {
 	.name = "test_uuid",
 			  0x17, 0x06, 0x39, 0x6b, 0xf4, 0x48, 0x4e ),
 		    "9e4b6eef36b646fe8f1706396bf4484e" );
 
+	/* "base64" setting type */
+	storef_ok ( &test_settings, &test_base64_setting,
+		    "cGFzc6\nNwaHJhc2U= ",
+		    RAW ( 0x70, 0x61, 0x73, 0x73, 0xa3, 0x70, 0x68, 0x72, 0x61,
+			  0x73, 0x65 ) );
+	fetchf_ok ( &test_settings, &test_base64_setting,
+		    RAW ( 0x80, 0x81, 0x82, 0x83, 0x84, 0x00, 0xff ),
+		    "gIGCg4QA/w==" );
+
 	/* "uuid" setting type (no store capability) */
 	fetchf_ok ( &test_settings, &test_uuid_setting,
 		    RAW ( 0x1a, 0x6a, 0x74, 0x9d, 0x0e, 0xda, 0x46, 0x1a,0xa8,