Page MenuHomeFreeBSD
Files F169471215

D47855.diff
No OneTemporary
Actions

D47855.diff
View Options

diff --git a/usr.sbin/fstyp/fstyp.c b/usr.sbin/fstyp/fstyp.c
--- a/usr.sbin/fstyp/fstyp.c
+++ b/usr.sbin/fstyp/fstyp.c
@@ -54,25 +54,55 @@
typedef int (*fstyp_function)(FILE *, char *, size_t);
+/*
+ * The ordering of fstypes[] is not arbitrary.
+ *
+ * fstyp checks the existence of a file system header to determine the
+ * type of file system on a given device. For different file systems,
+ * these headers reside at different offsets within the device.
+ *
+ * For example, the header for an MS-DOS file system begins at offset 0,
+ * whereas a header for UFS *normally* begins at offset 64k. If a device
+ * was constructed as MS-DOS and then repurposed as UFS (via newfs), it
+ * is possible the MS-DOS header will still be intact. To prevent
+ * misidentifying the file system, it is desirable to check the header
+ * with the largest offset first (i.e., UFS before MS-DOS).
+ */
static struct {
const char *name;
fstyp_function function;
bool unmountable;
const char *precache_encoding;
} fstypes[] = {
- { "apfs", &fstyp_apfs, true, NULL },
- { "befs", &fstyp_befs, false, NULL },
+ /* last sector of geli device */
+ { "geli", &fstyp_geli, true, NULL },
+ /*
+ * ufs headers have four different areas, searched in this order:
+ * offsets: 64k, 8k, 0k, 256k + 8192 bytes
+ */
+ { "ufs", &fstyp_ufs, false, NULL },
+ /* offset 32768 + 512 bytes */
{ "cd9660", &fstyp_cd9660, false, NULL },
- { "exfat", &fstyp_exfat, false, EXFAT_ENC },
+ /* offset 1024 + 512 bytes */
+ { "hfs+", &fstyp_hfsp, false, NULL },
+ /* offset 1024 + 512 bytes */
{ "ext2fs", &fstyp_ext2fs, false, NULL },
- { "geli", &fstyp_geli, true, NULL },
+ /* offset 512 + 36 bytes */
+ { "befs", &fstyp_befs, false, NULL },
+ /* offset 0 + 40 bytes */
+ { "apfs", &fstyp_apfs, true, NULL },
+ /* offset 0 + 512 bytes (for initial signature check) */
+ { "exfat", &fstyp_exfat, false, EXFAT_ENC },
+ /* offset 0 + 1928 bytes */
{ "hammer", &fstyp_hammer, true, NULL },
+ /* offset 0 + 65536 bytes (for initial signature check) */
{ "hammer2", &fstyp_hammer2, true, NULL },
- { "hfs+", &fstyp_hfsp, false, NULL },
+ /* offset 0 + 512 bytes (for initial signature check) */
{ "msdosfs", &fstyp_msdosfs, false, NULL },
+ /* offset 0 + 512 bytes (for initial signature check) */
{ "ntfs", &fstyp_ntfs, false, NTFS_ENC },
- { "ufs", &fstyp_ufs, false, NULL },
#ifdef HAVE_ZFS
+ /* offset 0 + 256k */
{ "zfs", &fstyp_zfs, true, NULL },
#endif
{ NULL, NULL, NULL, NULL }

File Metadata

Mime Type
text/plain
Expires
Wed, Sep 2, 3:14 PM (6 h, 23 m)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
37849657
Default Alt Text
D47855.diff (2 KB)

Event Timeline