libblkid: arch independent minix detection

It seems that on-disk MINIX FS superblock is native-endian.

Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=833841
Signed-off-by: Karel Zak <kzak@redhat.com>

2 files changed, 97 insertions, 29 deletions

diff --git a/include/minix.h b/include/minix.h
index 57be23921..f28991ce9 100644
--- a/include/minix.h
+++ b/include/minix.h
@@ -73,10 +73,13 @@ struct minix3_super_block {
 #define MINIX_VALID_FS       0x0001          /* Clean fs. */
 #define MINIX_ERROR_FS       0x0002          /* fs has errors. */
 
-#define MINIX_SUPER_MAGIC    0x137F          /* original minix fs */
-#define MINIX_SUPER_MAGIC2   0x138F          /* minix fs, 30 char names */
-#define MINIX2_SUPER_MAGIC   0x2468	     /* minix V2 fs */
+
+#define MINIX_SUPER_MAGIC    0x137F          /* minix V1 fs, 14 char names */
+#define MINIX_SUPER_MAGIC2   0x138F          /* minix V1 fs, 30 char names */
+
+#define MINIX2_SUPER_MAGIC   0x2468	     /* minix V2 fs, 14 char names */
 #define MINIX2_SUPER_MAGIC2  0x2478	     /* minix V2 fs, 30 char names */
+
 #define MINIX3_SUPER_MAGIC   0x4d5a          /* minix V3 fs (60 char names) */
 
 #endif /* UTIL_LINUX_MINIX_H */
diff --git a/libblkid/src/superblocks/minix.c b/libblkid/src/superblocks/minix.c
index 54e71396b..0e7cd934f 100644
--- a/libblkid/src/superblocks/minix.c
+++ b/libblkid/src/superblocks/minix.c
@@ -3,7 +3,7 @@
  * Copyright (C) 1999, 2000, 2003 by Theodore Ts'o
  * Copyright (C) 2001 by Andreas Dilger
  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
- * Copyright (C) 2008 Karel Zak <kzak@redhat.com>
+ * Copyright (C) 2008-2013 Karel Zak <kzak@redhat.com>
  *
  * This file may be redistributed under the terms of the
  * GNU Lesser General Public License.
@@ -13,50 +13,103 @@
 #include "superblocks.h"
 #include "minix.h"
 
-static int probe_minix(blkid_probe pr, const struct blkid_idmag *mag)
+#define minix_swab16(doit, num)	((uint16_t) (doit ? swab16(num) : num))
+#define minix_swab32(doit, num)	((uint32_t) (doit ? swab32(num) : num))
+
+static int get_minix_version(const unsigned char *data, int *other_endian)
 {
-	unsigned char *ext;
-	int version;
+	struct minix_super_block *sb = (struct minix_super_block *) data;
+	struct minix3_super_block *sb3 = (struct minix3_super_block *) data;
+	int version = 0;
 
-	/* for more details see magic strings below */
-	switch(mag->magic[1]) {
-	case '\023':
+	*other_endian = 0;
+
+	switch (sb->s_magic) {
+	case MINIX_SUPER_MAGIC:
+	case MINIX_SUPER_MAGIC2:
 		version = 1;
 		break;
-	case '\044':
+	case MINIX2_SUPER_MAGIC:
+	case MINIX2_SUPER_MAGIC2:
 		version = 2;
 		break;
-	case '\115':
-		version = 3;
-		break;
 	default:
-		return -1;
+		if (sb3->s_magic == MINIX3_SUPER_MAGIC)
+			version = 3;
 		break;
 	}
 
+	if (!version) {
+		*other_endian = 1;
+
+		switch (swab16(sb->s_magic)) {
+		case MINIX_SUPER_MAGIC:
+		case MINIX_SUPER_MAGIC2:
+			version = 1;
+			break;
+		case MINIX2_SUPER_MAGIC:
+		case MINIX2_SUPER_MAGIC2:
+			version = 2;
+			break;
+		default:
+			if (sb3->s_magic == MINIX3_SUPER_MAGIC)
+				version = 3;
+			break;
+		}
+	}
+	if (!version)
+		return -1;
+
+	DBG(LOWPROBE, blkid_debug("minix version %d detected [%s]", version,
+#if defined(WORDS_BIGENDIAN)
+	*other_endian ? "LE" : "BE"
+#else
+	*other_endian ? "BE" : "LE"
+#endif
+	));
+	return version;
+}
+
+static int probe_minix(blkid_probe pr, const struct blkid_idmag *mag)
+{
+	unsigned char *ext;
+	const unsigned char *data;
+	int version = 0, swabme = 0;
+
+	data = blkid_probe_get_buffer(pr, 1024,
+			max(sizeof(struct minix_super_block),
+			    sizeof(struct minix3_super_block)));
+	if (!data)
+		return -1;
+	version = get_minix_version(data, &swabme);
+	if (version < 1)
+		return -1;
+
 	if (version <= 2) {
-		struct minix_super_block *sb;
-		uint32_t zones;
+		struct minix_super_block *sb = (struct minix_super_block *) data;
+		int zones, ninodes, imaps, zmaps, firstz;
 
-		sb = blkid_probe_get_sb(pr, mag, struct minix_super_block);
-		if (!sb || sb->s_imap_blocks == 0 || sb->s_zmap_blocks == 0)
+		if (sb->s_imap_blocks == 0 || sb->s_zmap_blocks == 0)
 			return -1;
 
-		zones = version == 2 ? sb->s_zones : sb->s_nzones;
+		zones = version == 2 ? minix_swab32(swabme, sb->s_zones) :
+				       minix_swab16(swabme, sb->s_nzones);
+		ninodes = minix_swab16(swabme, sb->s_ninodes);
+		imaps   = minix_swab16(swabme, sb->s_imap_blocks);
+		zmaps   = minix_swab16(swabme, sb->s_zmap_blocks);
+		firstz  = minix_swab16(swabme, sb->s_firstdatazone);
 
 		/* sanity checks to be sure that the FS is really minix */
-		if (sb->s_imap_blocks * MINIX_BLOCK_SIZE * 8 < sb->s_ninodes + 1)
+		if (imaps * MINIX_BLOCK_SIZE * 8 < ninodes + 1)
 			return -1;
-		if (sb->s_zmap_blocks * MINIX_BLOCK_SIZE * 8 < zones - sb->s_firstdatazone + 1)
+		if (zmaps * MINIX_BLOCK_SIZE * 8 < zones - firstz + 1)
 			return -1;
 
 	} else if (version == 3) {
-		struct minix3_super_block *sb;
+		struct minix3_super_block *sb = (struct minix3_super_block *) data;
 
-		sb = blkid_probe_get_sb(pr, mag, struct minix3_super_block);
-		if (!sb || sb->s_imap_blocks == 0 || sb->s_zmap_blocks == 0)
+		if (sb->s_imap_blocks == 0 || sb->s_zmap_blocks == 0)
 			return -1;
-
 	}
 
 	/* unfortunately, some parts of ext3 is sometimes possible to
@@ -78,16 +131,28 @@ const struct blkid_idinfo minix_idinfo =
 	.probefunc	= probe_minix,
 	.magics		=
 	{
-		/* version 1 */
+		/* version 1 - LE */
 		{ .magic = "\177\023", .len = 2, .kboff = 1, .sboff = 0x10 },
 		{ .magic = "\217\023", .len = 2, .kboff = 1, .sboff = 0x10 },
 
-		/* version 2 */
+		/* version 1 - BE */
+		{ .magic = "\023\177", .len = 2, .kboff = 1, .sboff = 0x10 },
+		{ .magic = "\023\217", .len = 2, .kboff = 1, .sboff = 0x10 },
+
+		/* version 2 - LE */
 		{ .magic = "\150\044", .len = 2, .kboff = 1, .sboff = 0x10 },
 		{ .magic = "\170\044", .len = 2, .kboff = 1, .sboff = 0x10 },
 
-		/* version 3 */
+		/* version 2 - BE */
+		{ .magic = "\044\150", .len = 2, .kboff = 1, .sboff = 0x10 },
+		{ .magic = "\044\170", .len = 2, .kboff = 1, .sboff = 0x10 },
+
+		/* version 3 - LE */
 		{ .magic = "\132\115", .len = 2, .kboff = 1, .sboff = 0x18 },
+
+		/* version 3 - BE */
+		{ .magic = "\115\132", .len = 2, .kboff = 1, .sboff = 0x18 },
+
 		{ NULL }
 	}
 };