exfatprogs: tune: use sector size extracted from the boot sector

Eric Sandeen reported exfat dump image is damaged when tune.exfat was
executed against exfat dump image created in 4K native device.

# fsck/fsck.exfat /root/test.img
exfatprogs version : 1.1.1
/root/test.img: clean. directories 1, files 0
# tune/tune.exfat -I 0x1234  /root/test.img
exfatprogs version : 1.1.1
New volume serial : 0x1234
# fsck/fsck.exfat /root/test.img
exfatprogs version : 1.1.1
checksum of boot region is not correct. 0x3eedc5, but expected
0xe59577e3
boot region is corrupted. try to restore the region from backup. Fix
(y/N)? n

This patch read boot sector with 4KB(for 4K native) size, and use the
sector size extracted from the boot sector.

Reported-by: Eric Sandeen <[email protected]>
Signed-off-by: Namjae Jeon <[email protected]>

include/libexfat.h

@@ -43,6 +43,8 @@
 #define EXFAT_GET_VOLUME_SERIAL		0x03
 #define EXFAT_SET_VOLUME_SERIAL		0x04
 
+#define EXFAT_MAX_SECTOR_SIZE		4096
+
 enum {
 	BOOT_SEC_IDX = 0,
 	EXBOOT_SEC_IDX,
@@ -107,7 +109,7 @@ int exfat_write_sector(struct exfat_blk_dev *bd, void *buf,
 int exfat_write_checksum_sector(struct exfat_blk_dev *bd,
 		unsigned int checksum, bool is_backup);
 char *exfat_conv_volume_label(struct exfat_dentry *vol_entry);
-int exfat_show_volume_serial(struct exfat_blk_dev *bd);
+int exfat_show_volume_serial(int fd);
 int exfat_set_volume_serial(struct exfat_blk_dev *bd,
 		struct exfat_user_input *ui);
 unsigned int exfat_clus_to_blk_dev_off(struct exfat_blk_dev *bd,

label/label.c

@@ -90,7 +90,7 @@ int main(int argc, char *argv[])
 	if (serial_mode) {
 		/* Mode to change or display volume serial */
 		if (flags == EXFAT_GET_VOLUME_SERIAL) {
-			ret = exfat_show_volume_serial(&bd);
+			ret = exfat_show_volume_serial(bd.dev_fd);
 		} else if (flags == EXFAT_SET_VOLUME_SERIAL) {
 			ui.volume_serial = strtoul(argv[3], NULL, 0);
 			ret = exfat_set_volume_serial(&bd, &ui);

lib/libexfat.c

@@ -358,26 +358,27 @@ off_t exfat_get_root_entry_offset(struct exfat_blk_dev *bd)
 {
 	struct pbr *bs;
 	int nbytes;
-	unsigned int cluster_size;
+	unsigned int cluster_size, sector_size;
 	off_t root_clu_off;
 
-	bs = (struct pbr *)malloc(sizeof(struct pbr));
+	bs = (struct pbr *)malloc(EXFAT_MAX_SECTOR_SIZE);
 	if (!bs) {
 		exfat_err("failed to allocate memory\n");
 		return -ENOMEM;
 	}
 
-	nbytes = exfat_read(bd->dev_fd, bs, sizeof(struct pbr), 0);
-	if (nbytes != sizeof(struct pbr)) {
+	nbytes = exfat_read(bd->dev_fd, bs, EXFAT_MAX_SECTOR_SIZE, 0);
+	if (nbytes != EXFAT_MAX_SECTOR_SIZE) {
 		exfat_err("boot sector read failed: %d\n", errno);
 		free(bs);
 		return -1;
 	}
 
-	cluster_size = (1 << bs->bsx.sect_per_clus_bits) * bd->sector_size;
-	root_clu_off = le32_to_cpu(bs->bsx.clu_offset) * bd->sector_size +
-		le32_to_cpu(bs->bsx.root_cluster - EXFAT_RESERVED_CLUSTERS)
-		* cluster_size;
+	sector_size = 1 << bs->bsx.sect_size_bits;
+	cluster_size = (1 << bs->bsx.sect_per_clus_bits) * sector_size;
+	root_clu_off = le32_to_cpu(bs->bsx.clu_offset) * sector_size +
+		le32_to_cpu(bs->bsx.root_cluster - EXFAT_RESERVED_CLUSTERS) *
+		cluster_size;
 	free(bs);
 
 	return root_clu_off;
@@ -528,19 +529,19 @@ int exfat_write_checksum_sector(struct exfat_blk_dev *bd,
 	return ret;
 }
 
-int exfat_show_volume_serial(struct exfat_blk_dev *bd)
+int exfat_show_volume_serial(int fd)
 {
 	struct pbr *ppbr;
 	int ret;
 
-	ppbr = malloc(bd->sector_size);
+	ppbr = malloc(EXFAT_MAX_SECTOR_SIZE);
 	if (!ppbr) {
 		exfat_err("Cannot allocate pbr: out of memory\n");
 		return -1;
 	}
 
 	/* read main boot sector */
-	ret = exfat_read_sector(bd, (char *)ppbr, BOOT_SEC_IDX);
+	ret = exfat_read(fd, (char *)ppbr, EXFAT_MAX_SECTOR_SIZE, 0);
 	if (ret < 0) {
 		exfat_err("main boot sector read failed\n");
 		ret = -1;
@@ -600,20 +601,22 @@ int exfat_set_volume_serial(struct exfat_blk_dev *bd,
 	int ret;
 	struct pbr *ppbr;
 
-	ppbr = malloc(bd->sector_size);
+	ppbr = malloc(EXFAT_MAX_SECTOR_SIZE);
 	if (!ppbr) {
 		exfat_err("Cannot allocate pbr: out of memory\n");
 		return -1;
 	}
 
 	/* read main boot sector */
-	ret = exfat_read_sector(bd, (char *)ppbr, BOOT_SEC_IDX);
+	ret = exfat_read(bd->dev_fd, (char *)ppbr, EXFAT_MAX_SECTOR_SIZE,
+			BOOT_SEC_IDX);
 	if (ret < 0) {
 		exfat_err("main boot sector read failed\n");
 		ret = -1;
 		goto free_ppbr;
 	}
 
+	bd->sector_size = 1 << ppbr->bsx.sect_size_bits;
 	ppbr->bsx.vol_serial = ui->volume_serial;
 
 	/* update main boot sector */

tune/tune.c

@@ -102,7 +102,7 @@ int main(int argc, char *argv[])
 
 	/* Mode to change or display volume serial */
 	if (flags == EXFAT_GET_VOLUME_SERIAL) {
-		ret = exfat_show_volume_serial(&bd);
+		ret = exfat_show_volume_serial(bd.dev_fd);
 		goto close_fd_out;
 	} else if (flags == EXFAT_SET_VOLUME_SERIAL) {
 		ret = exfat_set_volume_serial(&bd, &ui);