fstyp(8): Detect APFS containers

APFS NXSBs are more like slices (or zvols?) than individual filesystem,
but go ahead and detect them nicely as well.

usr.sbin/fstyp/Makefile

@@ -3,7 +3,7 @@
 .include <src.opts.mk>
 
 PROG=	fstyp
-SRCS=	cd9660.c exfat.c ext2fs.c fstyp.c geli.c hfsplus.c msdosfs.c ntfs.c ufs.c
+SRCS=	apfs.c cd9660.c exfat.c ext2fs.c fstyp.c geli.c hfsplus.c msdosfs.c ntfs.c ufs.c
 
 .if ${MK_ZFS} != "no"
 SRCS +=	zfs.c

usr.sbin/fstyp/apfs.c

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2019 Conrad Meyer <cem@FreeBSD.org>.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <assert.h>
+#include <err.h>
+#include <errno.h>
+#include <iconv.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "fstyp.h"
+
+/*
+ * This really detects the container format, which might be best supported by
+ * geom_part or a special GEOM class.
+ *
+ * https://developer.apple.com/support/downloads/Apple-File-System-Reference.pdf
+ */
+
+#define	NX_CKSUM_SZ		8
+
+typedef uint64_t nx_oid_t;
+
+typedef uint64_t nx_xid_t;
+
+struct nx_obj {
+	uint8_t		o_cksum[NX_CKSUM_SZ];	/* Fletcher 64 */
+	nx_oid_t	o_oid;
+	nx_xid_t	o_xid;
+	uint32_t	o_type;
+	uint32_t	o_subtype;
+};
+
+/* nx_obj::o_oid */
+#define	OID_NX_SUPERBLOCK	1
+
+/* nx_obj::o_type: */
+#define	OBJECT_TYPE_MASK		0x0000ffff
+#define	OBJECT_TYPE_NX_SUPERBLOCK	0x00000001
+#define	OBJECT_TYPE_FLAGS_MASK		0xffff0000
+#define	OBJ_STORAGETYPE_MASK		0xc0000000
+#define	OBJECT_TYPE_FLAGS_DEFINED_MASK	0xf8000000
+#define	OBJ_STORAGE_VIRTUAL		0x00000000
+#define	OBJ_STORAGE_EPHEMERAL		0x80000000
+#define	OBJ_STORAGE_PHYSICAL		0x40000000
+#define	OBJ_NOHEADER			0x20000000
+#define	OBJ_ENCRYPTED			0x10000000
+#define	OBJ_NONPERSISTENT		0x08000000
+
+struct nx_superblock {
+	struct nx_obj	nx_o;
+	char		nx_magic[4];
+	/* ... other stuff that doesn't matter */
+};
+
+int
+fstyp_apfs(FILE *fp, char *label, size_t size)
+{
+	struct nx_superblock *csb;
+	int retval;
+
+	retval = 1;
+	csb = read_buf(fp, 0, sizeof(*csb));
+	if (csb == NULL)
+		goto fail;
+
+	/* Ideally, checksum the SB here. */
+	if (strncmp(csb->nx_magic, "NXSB", 4) != 0 ||
+	    csb->nx_o.o_oid != OID_NX_SUPERBLOCK ||
+	    (csb->nx_o.o_type & OBJECT_TYPE_MASK) != OBJECT_TYPE_NX_SUPERBLOCK)
+		goto fail;
+
+	retval = 0;
+
+	/* No label support yet. */
+
+fail:
+	free(csb);
+	return (retval);
+}

usr.sbin/fstyp/fstyp.c

@@ -62,6 +62,7 @@ static struct {
 	bool		unmountable;
 	char		*precache_encoding;
 } fstypes[] = {
+	{ "apfs", &fstyp_apfs, true, NULL },
 	{ "cd9660", &fstyp_cd9660, false, NULL },
 	{ "exfat", &fstyp_exfat, false, EXFAT_ENC },
 	{ "ext2fs", &fstyp_ext2fs, false, NULL },

usr.sbin/fstyp/fstyp.h

@@ -50,6 +50,7 @@ void	*read_buf(FILE *fp, off_t off, size_t len);
 char	*checked_strdup(const char *s);
 void	rtrim(char *label, size_t size);
 
+int	fstyp_apfs(FILE *fp, char *label, size_t size);
 int	fstyp_cd9660(FILE *fp, char *label, size_t size);
 int	fstyp_exfat(FILE *fp, char *label, size_t size);
 int	fstyp_ext2fs(FILE *fp, char *label, size_t size);