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1 files changed, 129 insertions, 0 deletions

diff --git a/src/ext4_mbr.c b/src/ext4_mbr.c
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--- /dev/null
+++ b/src/ext4_mbr.c
@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2015 Grzegorz Kostka (kostka.grzegorz@gmail.com)
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup lwext4
+ * @{
+ */
+/**
+ * @file  ext4_mbr.c
+ * @brief Master boot record parser
+ */
+
+#include "ext4_config.h"
+#include "ext4_types.h"
+#include "ext4_debug.h"
+#include "ext4_mbr.h"
+
+#include <inttypes.h>
+#include <string.h>
+
+#define MBR_SIGNATURE 0xAA55
+
+#pragma pack(push, 1)
+
+struct ext4_part_entry {
+	uint8_t status;
+	uint8_t chs1[3];
+	uint8_t type;
+	uint8_t chs2[3];
+	uint32_t first_lba;
+	uint32_t sectors;
+};
+
+struct ext4_mbr {
+	uint8_t bootstrap[446];
+	struct ext4_part_entry part_entry[4];
+	uint16_t signature;
+};
+
+#pragma pack(pop)
+
+int ext4_mbr_scan(struct ext4_blockdev *parent, struct ext4_mbr_bdevs *bdevs)
+{
+	int r;
+	size_t i;
+
+	ext4_dbg(DEBUG_MBR, DBG_INFO "ext4_mbr_scan\n");
+	memset(bdevs, 0, sizeof(struct ext4_mbr_bdevs));
+	r = ext4_block_init(parent);
+	if (r != EOK)
+		return r;
+
+	r = ext4_block_readbytes(parent, 0, parent->bdif->ph_bbuf, 512);
+	if (r != EOK) {
+		goto blockdev_fini;
+	}
+
+	const struct ext4_mbr *mbr = (void *)parent->bdif->ph_bbuf;
+
+	if (to_le16(mbr->signature) != MBR_SIGNATURE) {
+		ext4_dbg(DEBUG_MBR, DBG_ERROR "ext4_mbr_scan: unknown "
+			 "signature: 0x%x\n", to_le16(mbr->signature));
+		r = ENOENT;
+		goto blockdev_fini;
+	}
+
+	/*Show bootstrap code*/
+	ext4_dbg(DEBUG_MBR, "mbr_part: bootstrap:");
+	for (i = 0; i < sizeof(mbr->bootstrap); ++i) {
+		if (!(i & 0xF))
+				ext4_dbg(DEBUG_MBR | DEBUG_NOPREFIX, "\n");
+		ext4_dbg(DEBUG_MBR | DEBUG_NOPREFIX, "%02x, ", mbr->bootstrap[i]);
+	}
+
+	ext4_dbg(DEBUG_MBR | DEBUG_NOPREFIX, "\n\n");
+	for (i = 0; i < 4; ++i) {
+		const struct ext4_part_entry *pe = &mbr->part_entry[i];
+		ext4_dbg(DEBUG_MBR, "mbr_part: %d\n", (int)i);
+		ext4_dbg(DEBUG_MBR, "\tstatus: 0x%x\n", pe->status);
+		ext4_dbg(DEBUG_MBR, "\ttype 0x%x:\n", pe->type);
+		ext4_dbg(DEBUG_MBR, "\tfirst_lba: 0x%"PRIx32"\n", pe->first_lba);
+		ext4_dbg(DEBUG_MBR, "\tsectors: 0x%"PRIx32"\n", pe->sectors);
+
+		if (!pe->sectors)
+			continue; /*Empty entry*/
+
+		if (pe->type != 0x83)
+			continue; /*Unsupported entry. 0x83 - linux native*/
+
+		bdevs->partitions[i].bdif = parent->bdif;
+		bdevs->partitions[i].part_offset =
+			(uint64_t)pe->first_lba * parent->bdif->ph_bsize;
+		bdevs->partitions[i].part_size =
+			(uint64_t)pe->sectors * parent->bdif->ph_bsize;
+	}
+
+	blockdev_fini:
+	ext4_block_fini(parent);
+	return r;
+}
+
+/**
+ * @}
+ */
+