sbin/newfs_msdos: add support for exFAT file systems

Add support for the creation of exFAT file systems, if invoked as
newfs_exfat.

Reviewed by:	olce
Approved by:	olce, mckusick
MFC after:	4 weeks
Relnotes:	yes
Differential Revision:	https://reviews.freebsd.org/D48727

sbin/newfs_msdos/Makefile

@@ -5,6 +5,13 @@ PROG=	newfs_msdos
 MAN=	newfs_msdos.8
 SRCS=	newfs_msdos.c mkfs_msdos.c
 
+LINKS=  ${BINDIR}/newfs_msdos ${BINDIR}/newfs_exfat
+MLINKS=	newfs_msdos.8 newfs_exfat.8
+
+.if ${MK_ICONV} == "yes"
+CFLAGS+=-DWITH_ICONV
+.endif
+
 # XXX - this is verboten
 .if ${MACHINE_CPUARCH} == "arm"
 WARNS?= 3

sbin/newfs_msdos/mkfs_msdos.h

@@ -55,7 +55,7 @@ AOPT('m', uint8_t, media_descriptor, 0, "Media descriptor") \
 AOPT('n', uint8_t, num_FAT, 1, "Number of FATs") \
 AOPT('o', uint32_t, hidden_sectors, 0, "Hidden sectors") \
 AOPT('r', uint16_t, reserved_sectors, 1, "Reserved sectors") \
-AOPT('s', uint32_t, size, 1, "File System size") \
+AOPT('s', uint64_t, size, 1, "File System size") \
 AOPT('u', uint16_t, sectors_per_track, 1, "Sectors per track")
 
 struct msdos_options {
@@ -66,6 +66,7 @@ ALLOPTS
 	uint32_t volume_id_set:1;
 	uint32_t media_descriptor_set:1;
 	uint32_t hidden_sectors_set:1;
+	uint32_t exfat:1;
 };
 
 int mkfs_msdos(const char *, const char *, const struct msdos_options *);

sbin/newfs_msdos/newfs_msdos.8

@@ -23,12 +23,13 @@
 .\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 .\" IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd June 6, 2024
+.Dd August 5, 2025
 .Dt NEWFS_MSDOS 8
 .Os
 .Sh NAME
-.Nm newfs_msdos
-.Nd construct a new MS-DOS (FAT) file system
+.Nm newfs_msdos ,
+.Nm newfs_exfat
+.Nd construct a new FAT or exFAT file system
 .Sh SYNOPSIS
 .Nm
 .Op Fl N
@@ -58,10 +59,28 @@
 .Op Fl u Ar track-size
 .Ar special
 .Op Ar disktype
+.Nm newfs_exfat
+.Op Fl N
+.Op Fl @ Ar offset
+.Op Fl A
+.Op Fl B Ar boot
+.Op Fl C Ar create-size
+.Op Fl I Ar VolumeID
+.Op Fl L Ar label
+.Op Fl S Ar sector-size
+.Op Fl T Ar timestamp
+.Op Fl a Ar FAT-size
+.Op Fl b Ar block-size
+.Op Fl c Ar cluster-size
+.Op Fl n Ar FATs
+.Op Fl s Ar total
+.Ar special
+.Op Ar disktype
 .Sh DESCRIPTION
 The
 .Nm
-utility creates a FAT12, FAT16, or FAT32 file system on device or file named
+utility creates a FAT12, FAT16, FAT32, or exFAT file system on device or file
+named
 .Ar special ,
 using
 .Xr disktab 5
@@ -222,11 +241,13 @@ struct bsxbpb {
 };
 .Ed
 .Sh LIMITATION
-The maximum file size is 4GB, even if the file system itself is bigger.
+The maximum size of a file on a FAT file system is 4GB, even if the file system
+itself is bigger.
+This limitation does not apply to exFAT file systems.
 .Sh EXIT STATUS
 Exit status is 0 on success and 1 on error.
 .Sh EXAMPLES
-Create a file system, using default parameters, on
+Create a FAT file system, using default parameters, on
 .Pa /dev/ada0s1 :
 .Bd -literal -offset indent
 newfs_msdos /dev/ada0s1
@@ -251,6 +272,13 @@ Create a 30MB image file, with the FAT partition starting
 .Bd -literal -offset indent
 newfs_msdos -C 30M -@63s ./somefile
 .Ed
+.Pp
+Create a 300MB exFAT image file with a block size of 65536
+bytes:
+.Bd -literal -offset indent
+newfs_exfat -C 300M -b 65536 /tmp/1.raw
+.Ed
+.Pp
 .Sh SEE ALSO
 .Xr msdosfs 4 ,
 .Xr gpart 8 ,
@@ -260,5 +288,9 @@ The
 .Nm
 utility first appeared in
 .Fx 3.0 .
+Support for the creation of exFAT file systems has been
+introduced in
+.Fx 15.0 .
 .Sh AUTHORS
 .An Robert Nordier Aq Mt rnordier@FreeBSD.org
+.An Stefan Eßer Aq Mt se@FreeBSD.org

sbin/newfs_msdos/newfs_msdos.c

@@ -31,6 +31,7 @@
 #include <sys/stat.h>
 #include <err.h>
 #include <errno.h>
+#include <libgen.h>
 #include <paths.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -42,12 +43,15 @@
 #define	argto1(arg, lo, msg)  argtou(arg, lo, 0xff, msg)
 #define	argto2(arg, lo, msg)  argtou(arg, lo, 0xffff, msg)
 #define	argto4(arg, lo, msg)  argtou(arg, lo, 0xffffffff, msg)
+#define	argto8(arg, lo, msg)  argtou(arg, lo, 0xffffffffffffffff, msg)
 #define	argtox(arg, lo, msg)  argtou(arg, lo, UINT_MAX, msg)
 
-static u_int argtou(const char *, u_int, u_int, const char *);
+static u_quad_t argtou(const char *, u_int, u_quad_t, const char *);
 static off_t argtooff(const char *, const char *);
 static void usage(void) __dead2;
 
+static const char *fsopts;
+
 static time_t
 get_tstamp(const char *b)
 {
@@ -65,13 +69,23 @@ get_tstamp(const char *b)
     return (time_t)l;
 }
 
+/*
+ * Check whether invoked as newfs_exfat.
+ */
+static int
+check_exfat(char *argv0)
+{
+	return (strstr(basename(argv0), "exfat") != NULL);
+}
+
 /*
  * Construct a FAT12, FAT16, or FAT32 file system.
  */
 int
 main(int argc, char *argv[])
 {
-    static const char opts[] = "@:NAB:C:F:I:L:O:S:a:b:c:e:f:h:i:k:m:n:o:r:s:T:u:";
+    static const char fatopts[] = "@:NAB:C:F:I:L:O:S:T:a:b:c:e:f:h:i:k:m:n:o:r:s:u:";
+    static const char exfatopts[] = "@:NAB:C:I:L:S:T:a:b:c:n:s:";
     struct msdos_options o;
     const char *fname, *dtype;
     char buf[MAXPATHLEN];
@@ -79,7 +93,10 @@ main(int argc, char *argv[])
 
     memset(&o, 0, sizeof(o));
 
-    while ((ch = getopt(argc, argv, opts)) != -1)
+    o.exfat = check_exfat(argv[0]);
+    fsopts = o.exfat ? exfatopts : fatopts;
+
+    while ((ch = getopt(argc, argv, fsopts)) != -1)
 	switch (ch) {
 	case '@':
 	    o.offset = argtooff(optarg, "offset");
@@ -157,7 +174,7 @@ main(int argc, char *argv[])
 	    o.reserved_sectors = argto2(optarg, 1, "reserved sectors");
 	    break;
 	case 's':
-	    o.size = argto4(optarg, 1, "file system size");
+	    o.size = argto8(optarg, 1, "file system size");
 	    break;
 	case 'T':
 	    o.timestamp_set = 1;
@@ -189,14 +206,14 @@ main(int argc, char *argv[])
 /*
  * Convert and check a numeric option argument.
  */
-static u_int
-argtou(const char *arg, u_int lo, u_int hi, const char *msg)
+static u_quad_t
+argtou(const char *arg, u_int lo, u_quad_t hi, const char *msg)
 {
     char *s;
-    u_long x;
+    u_quad_t x;
 
     errno = 0;
-    x = strtoul(arg, &s, 0);
+    x = strtoull(arg, &s, 0);
     if (errno || !*arg || *s || x < lo || x > hi)
 	errx(1, "%s: bad %s", arg, msg);
     return x;
@@ -271,6 +288,7 @@ ALLOPTS
 #undef AOPT
     };
     for (size_t i = 0; i < nitems(opts); i++)
-	fprintf(stderr, "\t-%c %s\n", opts[i].o, opts[i].h);
+	if (strchr(fsopts, opts[i].o) != NULL)
+	    fprintf(stderr, "\t-%c %s\n", opts[i].o, opts[i].h);
     exit(1);
 }