From a719ab7780eb524ce96cb845637b692fc5ce81c8 Mon Sep 17 00:00:00 2001
From: Erik van der Kouwe <erik@minix3.org>
Date: Tue, 3 Aug 2010 06:28:58 +0000
Subject: [PATCH] Auto-detect ext2 partitions in mount

---
 commands/mount/mount.c         | 26 +++++++++++++++++---------
 commands/printroot/printroot.c | 15 +++++++--------
 include/minix/minlib.h         |  6 ++++++
 lib/libc/other/fsversion.c     | 27 +++++++++++++++++++--------
 4 files changed, 49 insertions(+), 25 deletions(-)

diff --git a/commands/mount/mount.c b/commands/mount/mount.c
index 38c2dd77c..0d6060b2f 100644
--- a/commands/mount/mount.c
+++ b/commands/mount/mount.c
@@ -61,6 +61,17 @@ char *argv[];
   device = argv[1];
   if (!strcmp(device, "none")) device = NULL;
 
+  /* auto-detect type */
+  v = fsversion(argv[1], "mount");
+  if (type == NULL) {
+	switch (v) {
+		case FSVERSION_MFS1:
+		case FSVERSION_MFS2: 
+		case FSVERSION_MFS3: type = "mfs"; break;		
+		case FSVERSION_EXT2: type = "ext2"; break;
+	}
+  }
+  
   if (mount(device, argv[2], mountflags, type, args) < 0) {
 	err = strerror(errno);
 	fprintf(stderr, "mount: Can't mount %s on %s: %s\n",
@@ -88,15 +99,12 @@ char *argv[];
   }
   /* For MFS, use a version number. Otherwise, use the FS type name. */
   if (type == NULL || !strcmp(type, MINIX_FS_TYPE)) {
-	v = fsversion(argv[1], "mount");
-	if (v == 1)
-		vs = "1";
-	else if (v == 2)
-		vs = "2";
-	else if (v == 3)
-		vs = "3";
-	else
-		vs = "0";
+	switch (v) {
+		case FSVERSION_MFS1: vs = "1"; break;
+		case FSVERSION_MFS2: vs = "2"; break;
+		case FSVERSION_MFS3: vs = "3"; break;		
+		default: vs = "0"; break;
+	}
   } else {
 	/* Keep the version field sufficiently short. */
 	if (strlen(type) < sizeof(version))
diff --git a/commands/printroot/printroot.c b/commands/printroot/printroot.c
index d9ad00c8f..b00fc44a8 100644
--- a/commands/printroot/printroot.c
+++ b/commands/printroot/printroot.c
@@ -73,13 +73,12 @@ int status;
   }
   write(1, MESSAGE, sizeof MESSAGE - 1);
   v = fsversion(name, "printroot");	/* determine file system version */
-  if (v == 1)
-	write(1, "1 rw\n", 5);
-  else if (v == 2)
-	write(1, "2 rw\n", 5);
-  else if (v == 3)
-	write(1, "3 rw\n", 5);
-  else
-	write(1, "0 rw\n", 5);
+  switch (v) {
+	case FSVERSION_MFS1: write(1, "1 rw\n", 5);	break;
+	case FSVERSION_MFS2: write(1, "2 rw\n", 5);	break;
+	case FSVERSION_MFS3: write(1, "3 rw\n", 5);	break;
+	case FSVERSION_EXT2: write(1, "ext2 rw\n", 8);	break;
+	default: write(1, "0 rw\n", 5);			break;
+  }
   exit(status);
 }
diff --git a/include/minix/minlib.h b/include/minix/minlib.h
index 9c9c3187e..b123e5f7d 100644
--- a/include/minix/minlib.h
+++ b/include/minix/minlib.h
@@ -21,4 +21,10 @@ _PROTOTYPE(int rewrite_mtab, (char *_prog_name));
 _PROTOTYPE(int get_mtab_entry, (char *_s1, char *_s2, char *_s3, char *_s4));
 _PROTOTYPE(int put_mtab_entry, (char *_s1, char *_s2, char *_s3, char *_s4));
 
+/* return values for fsversion */
+#define FSVERSION_MFS1	0x00001
+#define FSVERSION_MFS2	0x00002
+#define FSVERSION_MFS3	0x00003
+#define FSVERSION_EXT2	0x10002
+
 #endif
diff --git a/lib/libc/other/fsversion.c b/lib/libc/other/fsversion.c
index 3a0faa59f..49418995b 100644
--- a/lib/libc/other/fsversion.c
+++ b/lib/libc/other/fsversion.c
@@ -16,12 +16,20 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <stdio.h>
+#include <string.h>
 
 #include "mfs/const.h"
-#include "mfs/type.h"
-#include "mfs/super.h"
 
-static struct super_block super, *sp;
+static char super[SUPER_BLOCK_BYTES];
+
+#define MAGIC_OFFSET_MFS 0x18
+#define MAGIC_OFFSET_EXT 0x38
+#define MAGIC_VALUE_EXT2	0xef53
+
+static int check_super(off_t offset, unsigned short magic)
+{
+  return (memcmp(super + offset, &magic, sizeof(magic)) == 0) ? 1 : 0;
+}
 
 int fsversion(dev, prog)
 char *dev, *prog;
@@ -36,7 +44,7 @@ char *dev, *prog;
   }
 
   lseek(fd, (off_t) SUPER_BLOCK_BYTES, SEEK_SET);	/* skip boot block */
-  if (read(fd, (char *) &super, (unsigned) SUPER_SIZE) != SUPER_SIZE) {
+  if (read(fd, (char *) &super, sizeof(super)) != sizeof(super)) {
 	std_err(prog);
 	std_err(" cannot read super block on ");
 	perror(dev);
@@ -44,9 +52,12 @@ char *dev, *prog;
 	return(-1);
   }
   close(fd);
-  sp = &super;
-  if (sp->s_magic == SUPER_MAGIC) return(1);
-  if (sp->s_magic == SUPER_V2) return(2);
-  if (sp->s_magic == SUPER_V3) return(3);
+  
+  /* first check MFS, a valid MFS may look like EXT but not vice versa */
+  if (check_super(MAGIC_OFFSET_MFS, SUPER_MAGIC))	return FSVERSION_MFS1;
+  if (check_super(MAGIC_OFFSET_MFS, SUPER_V2))		return FSVERSION_MFS2;
+  if (check_super(MAGIC_OFFSET_MFS, SUPER_V3))		return FSVERSION_MFS3;
+  if (check_super(MAGIC_OFFSET_EXT, MAGIC_VALUE_EXT2))	return FSVERSION_EXT2;
+  
   return(-1);
 }