1 files changed, 134 insertions, 0 deletions
diff --git a/common/uuid.c b/common/uuid.c
new file mode 100644
index 000000000..ac6db50a0
--- /dev/null
+++ b/common/uuid.c
@@ -0,0 +1,134 @@
+/*
+ * Copyright (c) 2021, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <common/debug.h>
+#include <common/uuid.h>
+
+/* Return the hex nibble value of a char */
+static int8_t hex_val(char hex)
+{
+	int8_t val = 0;
+
+	if ((hex >= '0') && (hex <= '9')) {
+		val = (int8_t)(hex - '0');
+	} else if ((hex >= 'a') && (hex <= 'f')) {
+		val = (int8_t)(hex - 'a' + 0xa);
+	} else if ((hex >= 'A') && (hex <= 'F')) {
+		val = (int8_t)(hex - 'A' + 0xa);
+	} else {
+		val = -1;
+	}
+
+	return val;
+}
+
+/*
+ * Read hex_src_len hex characters from hex_src, convert to bytes and
+ * store in buffer pointed to by dest
+ */
+static int read_hex(uint8_t *dest, char *hex_src, unsigned int hex_src_len)
+{
+	int8_t nibble;
+	uint8_t byte;
+
+	/*
+	 * The string length must be a multiple of 2 to represent an
+	 * exact number of bytes.
+	 */
+	assert((hex_src_len % 2U) == 0U);
+
+	for (unsigned int i = 0U; i < (hex_src_len / 2U); i++) {
+		nibble = 0;
+		byte = 0U;
+
+		nibble = hex_val(hex_src[2U * i]);
+		if (nibble < 0) {
+			return -1;
+		}
+		byte = (uint8_t)nibble;
+		byte <<= 4U;
+
+		nibble = hex_val(hex_src[(2U * i) + 1U]);
+		if (nibble < 0) {
+			return -1;
+		}
+		byte |= (uint8_t)nibble;
+
+		*dest = byte;
+		dest++;
+	}
+
+	return 0;
+}
+
+/* Parse UUIDs of the form aabbccdd-eeff-4099-8877-665544332211 */
+int read_uuid(uint8_t *dest, char *uuid)
+{
+	int err;
+	uint8_t *dest_start = dest;
+
+	/* Check that we have enough characters */
+	if (strnlen(uuid, UUID_STRING_LENGTH) != UUID_STRING_LENGTH) {
+		WARN("UUID string is too short\n");
+		return -EINVAL;
+	}
+
+	/* aabbccdd */
+	err = read_hex(dest, uuid, 8);
+	uuid += 8;
+	dest += 4;
+
+	/* Check for '-' */
+	err |= ((*uuid == '-') ? 0 : -1);
+	uuid++;
+
+	/* eeff */
+	err |= read_hex(dest, uuid, 4);
+	uuid += 4;
+	dest += 2;
+
+	/* Check for '-' */
+	err |= ((*uuid == '-') ? 0 : -1);
+	uuid++;
+
+	/* 4099 */
+	err |= read_hex(dest, uuid, 4);
+	uuid += 4;
+	dest += 2;
+
+	/* Check for '-' */
+	err |= ((*uuid == '-') ? 0 : -1);
+	uuid++;
+
+	/* 8877 */
+	err |= read_hex(dest, uuid, 4);
+	uuid += 4;
+	dest += 2;
+
+	/* Check for '-' */
+	err |= ((*uuid == '-') ? 0 : -1);
+	uuid++;
+
+	/* 665544332211 */
+	err |= read_hex(dest, uuid, 12);
+	uuid += 12;
+	dest += 6;
+
+	if (err < 0) {
+		WARN("Error parsing UUID\n");
+		/* Clear the buffer on error */
+		memset((void *)dest_start, '\0', UUID_BYTES_LENGTH * sizeof(uint8_t));
+		return -EINVAL;
+	}
+
+	return 0;
+}
+