Make fsck and fsck_msdosfs WARNS=6 clean

- sprinkle const
- add volatile qualifier to avoid vfork clobbering

Inspired by:	NetBSD
PR:		bin/139802
Reviewed by:	ed

4 files changed, 3 insertions, 4 deletions

diff --git a/sbin/fsck_msdosfs/Makefile b/sbin/fsck_msdosfs/Makefile
index ddb8e8a..f9dd9fa 100644
--- a/sbin/fsck_msdosfs/Makefile
+++ b/sbin/fsck_msdosfs/Makefile
@@ -9,6 +9,5 @@ MAN=	fsck_msdosfs.8
 SRCS=	main.c check.c boot.c fat.c dir.c fsutil.c
 
 CFLAGS+= -I${FSCK}
-WARNS?=	2
 
 .include <bsd.prog.mk>
diff --git a/sbin/fsck_msdosfs/boot.c b/sbin/fsck_msdosfs/boot.c
index 97d9419..3195183 100644
--- a/sbin/fsck_msdosfs/boot.c
+++ b/sbin/fsck_msdosfs/boot.c
@@ -48,7 +48,7 @@ readboot(int dosfs, struct bootblock *boot)
 	int ret = FSOK;
 	int i;
 	
-	if (read(dosfs, block, sizeof block) != sizeof block) {
+	if ((size_t)read(dosfs, block, sizeof block) != sizeof block) {
 		perr("could not read boot block");
 		return FSFATAL;
 	}
diff --git a/sbin/fsck_msdosfs/ext.h b/sbin/fsck_msdosfs/ext.h
index a4fd19b..681cde9 100644
--- a/sbin/fsck_msdosfs/ext.h
+++ b/sbin/fsck_msdosfs/ext.h
@@ -133,7 +133,7 @@ void finishlf(void);
 /*
  * Return the type of a reserved cluster as text
  */
-char *rsrvdcltype(cl_t);
+const char *rsrvdcltype(cl_t);
 
 /*
  * Clear a cluster chain in a FAT
diff --git a/sbin/fsck_msdosfs/fat.c b/sbin/fsck_msdosfs/fat.c
index 837bd69..d2d1444 100644
--- a/sbin/fsck_msdosfs/fat.c
+++ b/sbin/fsck_msdosfs/fat.c
@@ -320,7 +320,7 @@ readfat(int fs, struct bootblock *boot, u_int no, struct fatEntry **fp)
 /*
  * Get type of reserved cluster
  */
-char *
+const char *
 rsrvdcltype(cl_t cl)
 {
 	if (cl == CLUST_FREE)