Add a "I know it points to my foot!" -f option.

PR:		3288
Reviewed by:	phk
Submitted by:	Martin Kammerhofer <dada@freepass.tu-graz.ac.at>

1 files changed, 36 insertions, 10 deletions

diff --git a/release/write_mfs_in_kernel.c b/release/write_mfs_in_kernel.c
index 358c7d943c33..93934de995cf 100644
--- a/release/write_mfs_in_kernel.c
+++ b/release/write_mfs_in_kernel.c
@@ -6,7 +6,7 @@
  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
  * ----------------------------------------------------------------------------
  *
- * $Id$
+ * $Id: write_mfs_in_kernel.c,v 1.3 1997/02/22 14:10:31 peter Exp $
  *
  * This program patches a filesystem into a kernel made with MFS_ROOT
  * option.
@@ -21,17 +21,33 @@
 #include <sys/stat.h>
 #include <ufs/ffs/fs.h>
 
+static int force = 0;	/* don't check for zeros, may corrupt kernel */
+
+int
 main(int argc, char **argv)
 {
-	unsigned char *buf_kernel, *buf_fs, *p,*q;
-	int fd_kernel, fd_fs;
+	unsigned char *buf_kernel, *buf_fs, *p,*q, *prog;
+	int fd_kernel, fd_fs, ch, errs=0;
 	struct stat st_kernel, st_fs;
 	u_long l;
 
-	if (argc < 3) {
-		fprintf(stderr,"Usage:\n\t%s kernel fs\n");
+	prog= *argv;
+	while ((ch = getopt(argc, argv, "f")) != EOF)
+		switch(ch) {                                                       
+		case 'f':                                                          
+			force = 1 - force;
+			break;   
+		default:
+			errs++;
+		}
+	argc -= optind;
+	argv += optind;
+
+	if (errs || argc != 2) {
+		fprintf(stderr,"Usage:\n\t%s [-f] kernel fs\n", prog);
 		exit(2);
 	}
+	--argv;	/* original prog did not use getopt(3) */
 	fd_kernel = open(argv[1],O_RDWR);
 	if (fd_kernel < 0) { perror(argv[1]); exit(2); }
 	fstat(fd_kernel,&st_kernel);
@@ -51,16 +67,17 @@ main(int argc, char **argv)
 			goto found;
 	fprintf(stderr,"MFS filesystem signature not found in %s\n",argv[1]);
 	exit(1);
-    found:
-	for(l=0,q= p + SBOFF; l < st_fs.st_size - SBOFF ; l++,q++ )
-		if (*q)
-			goto fail;
+found:
+	if (!force)
+		for(l=0,q= p + SBOFF; l < st_fs.st_size - SBOFF ; l++,q++ )
+			if (*q)
+				goto fail;
 	memcpy(p+SBOFF,buf_fs+SBOFF,st_fs.st_size-SBOFF);
 	lseek(fd_kernel,0L,SEEK_SET);
 	if (st_kernel.st_size != write(fd_kernel,buf_kernel,st_kernel.st_size))
 		{ perror(argv[1]); exit(2); }
 	exit(0);
-    fail:
+fail:
 	l += SBOFF;
 	fprintf(stderr,"Obstruction in kernel after %ld bytes (%ld Kbyte)\n",
 		l, l/1024);
@@ -68,3 +85,12 @@ main(int argc, char **argv)
 		(u_long)st_fs.st_size, (u_long)st_fs.st_size/1024);
 	exit(1);
 }
+
+/*
+ * I added a '-f' option to force writing the image into the kernel, even when
+ * there is already data (i.e. not zero) in the written area. This is useful
+ * to rewrite a changed MFS-image. Beware: If the written image is larger than
+ * the space reserved in the kernel (with option MFS_ROOT) then
+ * THIS WILL CORRUPT THE KERNEL!
+ *
+ */