From e60683a0d553b6488c564863f4e48954944fb0f8 Mon Sep 17 00:00:00 2001
From: bigbiff bigbiff <bigbiff@teamw.in>
Date: Fri, 22 Feb 2013 20:55:50 -0500
Subject: use libblkid to get filesystem type we can now use libblkid to detect
 exfat

---
 libblkid/exfat.c | 146 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 146 insertions(+)
 create mode 100644 libblkid/exfat.c

(limited to 'libblkid/exfat.c')

diff --git a/libblkid/exfat.c b/libblkid/exfat.c
new file mode 100644
index 000000000..215c67114
--- /dev/null
+++ b/libblkid/exfat.c
@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2010 Andrew Nayenko <resver@gmail.com>
+ *
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ */
+#include "superblocks.h"
+
+struct exfat_super_block {
+	uint8_t jump[3];
+	uint8_t oem_name[8];
+	uint8_t	__unused1[53];
+	uint64_t block_start;
+	uint64_t block_count;
+	uint32_t fat_block_start;
+	uint32_t fat_block_count;
+	uint32_t cluster_block_start;
+	uint32_t cluster_count;
+	uint32_t rootdir_cluster;
+	uint8_t volume_serial[4];
+	struct {
+		uint8_t minor;
+		uint8_t major;
+	} version;
+	uint16_t volume_state;
+	uint8_t block_bits;
+	uint8_t bpc_bits;
+	uint8_t fat_count;
+	uint8_t drive_no;
+	uint8_t allocated_percent;
+} __attribute__((__packed__));
+
+struct exfat_entry_label {
+	uint8_t type;
+	uint8_t length;
+	uint8_t name[30];
+} __attribute__((__packed__));
+
+#define BLOCK_SIZE(sb) (1 << (sb)->block_bits)
+#define CLUSTER_SIZE(sb) (BLOCK_SIZE(sb) << (sb)->bpc_bits)
+#define EXFAT_FIRST_DATA_CLUSTER 2
+#define EXFAT_LAST_DATA_CLUSTER 0xffffff6
+#define EXFAT_ENTRY_SIZE 32
+
+#define EXFAT_ENTRY_EOD		0x00
+#define EXFAT_ENTRY_LABEL	0x83
+
+static blkid_loff_t block_to_offset(const struct exfat_super_block *sb,
+		blkid_loff_t block)
+{
+	return (blkid_loff_t) block << sb->block_bits;
+}
+
+static blkid_loff_t cluster_to_block(const struct exfat_super_block *sb,
+		uint32_t cluster)
+{
+	return le32_to_cpu(sb->cluster_block_start) +
+			((blkid_loff_t) (cluster - EXFAT_FIRST_DATA_CLUSTER)
+					<< sb->bpc_bits);
+}
+
+static blkid_loff_t cluster_to_offset(const struct exfat_super_block *sb,
+		uint32_t cluster)
+{
+	return block_to_offset(sb, cluster_to_block(sb, cluster));
+}
+
+static uint32_t next_cluster(blkid_probe pr,
+		const struct exfat_super_block *sb, uint32_t cluster)
+{
+	uint32_t *next;
+	blkid_loff_t fat_offset;
+
+	fat_offset = block_to_offset(sb, le32_to_cpu(sb->fat_block_start))
+		+ (blkid_loff_t) cluster * sizeof(cluster);
+	next = (uint32_t *) blkid_probe_get_buffer(pr, fat_offset,
+			sizeof(uint32_t));
+	if (!next)
+		return 0;
+	return le32_to_cpu(*next);
+}
+
+static struct exfat_entry_label *find_label(blkid_probe pr,
+		const struct exfat_super_block *sb)
+{
+	uint32_t cluster = le32_to_cpu(sb->rootdir_cluster);
+	blkid_loff_t offset = cluster_to_offset(sb, cluster);
+	uint8_t *entry;
+
+	for (;;) {
+		entry = (uint8_t *) blkid_probe_get_buffer(pr, offset,
+				EXFAT_ENTRY_SIZE);
+		if (!entry)
+			return NULL;
+		if (entry[0] == EXFAT_ENTRY_EOD)
+			return NULL;
+		if (entry[0] == EXFAT_ENTRY_LABEL)
+			return (struct exfat_entry_label *) entry;
+		offset += EXFAT_ENTRY_SIZE;
+		if (offset % CLUSTER_SIZE(sb) == 0) {
+			cluster = next_cluster(pr, sb, cluster);
+			if (cluster < EXFAT_FIRST_DATA_CLUSTER)
+				return NULL;
+			if (cluster > EXFAT_LAST_DATA_CLUSTER)
+				return NULL;
+			offset = cluster_to_offset(sb, cluster);
+		}
+	}
+}
+
+static int probe_exfat(blkid_probe pr, const struct blkid_idmag *mag)
+{
+	struct exfat_super_block *sb;
+	struct exfat_entry_label *label;
+
+	sb = blkid_probe_get_sb(pr, mag, struct exfat_super_block);
+	if (!sb)
+		return -1;
+
+	label = find_label(pr, sb);
+	if (label)
+		blkid_probe_set_utf8label(pr, label->name,
+				min(label->length * 2, 30), BLKID_ENC_UTF16LE);
+
+	blkid_probe_sprintf_uuid(pr, sb->volume_serial, 4,
+			"%02hhX%02hhX-%02hhX%02hhX",
+			sb->volume_serial[3], sb->volume_serial[2],
+			sb->volume_serial[1], sb->volume_serial[0]);
+
+	blkid_probe_sprintf_version(pr, "%u.%u",
+			sb->version.major, sb->version.minor);
+
+	return 0;
+}
+
+const struct blkid_idinfo exfat_idinfo =
+{
+	.name		= "exfat",
+	.usage		= BLKID_USAGE_FILESYSTEM,
+	.probefunc	= probe_exfat,
+	.magics		=
+	{
+		{ .magic = "EXFAT   ", .len = 8, .sboff = 3 },
+		{ NULL }
+	}
+};
-- 
cgit v1.2.3