Add check_clean() function

Signed-off-by: Doug Ledford <dledford@redhat.com>

3 files changed, 40 insertions, 6 deletions

diff --git a/Incremental.c b/Incremental.c
index 8bc455d..d3dd0c3 100644
--- a/Incremental.c
+++ b/Incremental.c
@@ -941,7 +941,7 @@ static int IncrementalNewDisk(char *devname, int verbose, int export,
 			      struct domain_ent *domain)
 {
 	struct stat stb;
-	int dfd;
+	int dfd, rv;
 
 	dfd = dev_open_check(devname, O_RDONLY|O_EXCL, &stb);
 	if (dfd < 0) 
@@ -954,8 +954,11 @@ static int IncrementalNewDisk(char *devname, int verbose, int export,
 		close(dfd);
 		return 1;
 	}
-	if (domain->handler->check_table(dfd, verbose, export, domain) == 0)
+
+	if (domain->handler->check_table(dfd, verbose, export, domain) == 0) {
+		close(dfd);
 		return 0;
+	}
 	/*
 	 * OK, at this point we have a valid block device without a
 	 * superblock, the partition table doesn't match, and we are a
@@ -965,10 +968,11 @@ static int IncrementalNewDisk(char *devname, int verbose, int export,
 	 * last 4k of the device must be one of three patterns: 0x00, 0x5a,
 	 * or 0xff.
 	 */
-	if (force(domain))
-		return domain->handler->write_table(dfd, verbose, export,
-						    domain);
-	return 0;
+	if (check_clean(dfd) || force(domain)) {
+		rv = domain->handler->write_table(dfd, verbose, export, domain);
+	}
+	close(dfd);
+	return rv;
 }
 
 /*
diff --git a/mdadm.h b/mdadm.h
index 118056d..b1e74db 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -893,6 +893,7 @@ extern int parse_layout_faulty(char *layout);
 extern int check_ext2(int fd, char *name);
 extern int check_reiser(int fd, char *name);
 extern int check_raid(int fd, char *name);
+extern int check_clean(int fd);
 extern int check_partitions(int fd, char *dname, unsigned long long freesize);
 
 extern int get_mdp_major(void);
diff --git a/util.c b/util.c
index b9c428b..3c8dbcb 100644
--- a/util.c
+++ b/util.c
@@ -511,6 +511,35 @@ int check_raid(int fd, char *name)
 	return 1;
 }
 
+int check_clean(int dfd)
+{
+	void *head, *tail, *pattern;
+	int i=0, head_clean=0, tail_clean=0;
+	unsigned char patterns[]={0x00,0x5a,0xff};
+
+	head = malloc(4096);
+	tail = malloc(4096);
+	pattern = malloc(4096);
+	if (!head || !tail || !pattern)
+		return 0;
+	if (lseek(dfd, 0, SEEK_SET) == -1)
+		return 0;
+	if (read(dfd, head, 4096) != 4096)
+		return 0;
+	if (lseek(dfd, -4096, SEEK_END) == -1)
+		return 0;
+	if (read(dfd, tail, 4096) != 4096)
+		return 0;
+	while (i < 3) {
+		memset(pattern, patterns[i++], 4096);
+		if (memcmp(head, pattern, 4096) == 0)
+			head_clean++;
+		if (memcmp(tail, pattern, 4096) == 0)
+			tail_clean++;
+	}
+	return (head_clean && tail_clean);
+}
+
 int ask(char *mesg)
 {
 	char *add = "";