Make msdosfs support the dirty flag in FAT16 and FAT32.

Enable lockf support.

PR:		55861
Submitted by:	Jun Su <junsu@m-net.arbornet.org> (original version)
Reviewed by:	make universe

4 files changed, 66 insertions, 10 deletions

diff --git a/sbin/fsck_msdosfs/check.c b/sbin/fsck_msdosfs/check.c
index 28b1588..72e5b0a 100644
--- a/sbin/fsck_msdosfs/check.c
+++ b/sbin/fsck_msdosfs/check.c
@@ -84,6 +84,13 @@ checkfilesys(const char *fname)
 		return 8;
 	}
 
+	if (checkdirty(dosfs, &boot) && !force)	{
+		if (preen) printf("%s: ", fname);
+		printf("FILESYSTEM CLEAN; SKIPPING CHECKS\n");
+		ret = 0;
+		goto out;
+	}
+
 	if (!preen)  {
 		if (boot.ValidFat < 0)
 			printf("** Phase 1 - Read and Compare FATs\n");
@@ -191,3 +198,48 @@ checkfilesys(const char *fname)
 
 	return ret;
 }
+
+int checkdirty(int fs, struct bootblock *boot)
+{
+	off_t off;
+	u_char *buffer;
+	int ret = 0;
+	
+	if (boot->ClustMask == CLUST12_MASK)
+		return 0;	
+
+	off = boot->ResSectors;
+	off *= boot->BytesPerSec;
+	
+	buffer = malloc(boot->BytesPerSec);
+	if (buffer == NULL) {
+		perror("No space for FAT");
+		return 1;
+	}
+
+	if (lseek(fs, off, SEEK_SET) != off) {
+		perror("Unable to read FAT");
+		goto err;
+	}
+
+	if (read(fs, buffer, boot->BytesPerSec)
+	    != boot->BytesPerSec) {
+		perror("Unable to read FAT");
+		goto err;
+	}
+
+	 if (buffer[0] == boot->Media && buffer[1] == 0xff
+                    && buffer[2] == 0xff
+                    && ((boot->ClustMask == CLUST16_MASK && buffer[3] == 0x7f)
+                        || (boot->ClustMask == CLUST32_MASK
+                            && buffer[3] == 0x0f && buffer[4] == 0xff
+                            && buffer[5] == 0xff && buffer[6] == 0xff
+                            && buffer[7] == 0x07)))
+		ret = 0;
+	else
+		ret = 1;
+
+err:
+	free(buffer);
+	return ret;
+}
diff --git a/sbin/fsck_msdosfs/ext.h b/sbin/fsck_msdosfs/ext.h
index ce67792..9eb4098 100644
--- a/sbin/fsck_msdosfs/ext.h
+++ b/sbin/fsck_msdosfs/ext.h
@@ -48,6 +48,7 @@ extern int alwaysno;	/* assume "no" for all questions */
 extern int alwaysyes;	/* assume "yes" for all questions */
 extern int preen;	/* we are preening */
 extern int rdonly;	/* device is opened read only (supersedes above) */
+extern int force;
 
 extern struct dosDirEntry *rootDir;
 
@@ -85,6 +86,12 @@ int readboot(int, struct bootblock *);
 int writefsinfo(int, struct bootblock *);
 
 /*
+ * Check the dirty flag. If clean return 1, otherwise return 0. 
+ * If it is FAT12, return 0 always.
+ */
+int checkdirty(int, struct bootblock *);
+
+/*
  * Read one of the FAT copies and return a pointer to the new
  * allocated array holding our description of it.
  */
diff --git a/sbin/fsck_msdosfs/fsck_msdosfs.8 b/sbin/fsck_msdosfs/fsck_msdosfs.8
index 7b2985d..d07e53d 100644
--- a/sbin/fsck_msdosfs/fsck_msdosfs.8
+++ b/sbin/fsck_msdosfs/fsck_msdosfs.8
@@ -88,11 +88,9 @@ immediately in foreground, or if its cleaning can be deferred to background.
 FAT (MS-DOS) file systems must always be cleaned in the foreground.
 A non-zero exit code is always returned for this option.
 .It Fl f
-This option is ignored by
-.Nm ,
-and is present only for compatibility with programs that
-check other file system types for consistency, such as
-.Xr fsck_ffs 8 .
+Force
+.Nm 
+to check 'clean' file systems when preening.
 .It Fl n
 Causes
 .Nm
diff --git a/sbin/fsck_msdosfs/main.c b/sbin/fsck_msdosfs/main.c
index cbfe6da..bef877b 100644
--- a/sbin/fsck_msdosfs/main.c
+++ b/sbin/fsck_msdosfs/main.c
@@ -53,6 +53,7 @@ int alwaysno;		/* assume "no" for all questions */
 int alwaysyes;		/* assume "yes" for all questions */
 int preen;		/* set when preening */
 int rdonly;		/* device is opened read only (supersedes above) */
+int force;		/* force check even the fs is clean */
 
 static void usage(void) __dead2;
 
@@ -67,14 +68,12 @@ main(int argc, char **argv)
 {
 	int ret = 0, erg;
 	int ch;
-
+	
+	force = 0;
 	while ((ch = getopt(argc, argv, "fFnpy")) != -1) {
 		switch (ch) {
 		case 'f':
-			/*
-			 * We are always forced, since we don't
-			 * have a clean flag
-			 */
+			force = 1;
 			break;
 		case 'F':
 			/* We can never run in background */