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readufs_ffs.c revision 1.4 
      1 /*	$NetBSD: readufs_ffs.c,v 1.4 2003/12/04 13:05:17 keihan Exp $	*/
      2 /*	from Id: readufs_ffs.c,v 1.6 2003/04/08 09:19:32 itohy Exp 	*/
      3 
      4 /*
      5  * FS specific support for 4.2BSD Fast Filesystem
      6  *
      7  * Written in 1999, 2002, 2003 by ITOH Yasufumi (itohy (at) NetBSD.org).
      8  * Public domain.
      9  *
     10  * Intended to be used for boot programs (first stage).
     11  * DON'T ADD ANY FANCY FEATURE.  THIS SHALL BE COMPACT.
     12  */
     13 
     14 #include "readufs.h"
     15 
     16 #include <ufs/ffs/fs.h>
     17 
     18 static int get_ffs_inode __P((ino_t ino, union ufs_dinode *dibuf));
     19 
     20 #define fsi	(*ufsinfo)
     21 #define fsi_ffs	fsi.fs_u.u_ffs
     22 
     23 /*
     24  * Read and check superblock.
     25  * If it is an FFS, save information from the superblock.
     26  */
     27 int
     28 try_ffs()
     29 {
     30 	union {
     31 		struct fs	sblk;
     32 		unsigned char	pad[SBLOCKSIZE];
     33 	} buf;
     34 	struct ufs_info *ufsinfo = &ufs_info;
     35 	static const int sblocs[] = SBLOCKSEARCH;
     36 	const int *sbl;
     37 	int magic;
     38 
     39 #ifdef DEBUG_WITH_STDIO
     40 	printf("trying FFS\n");
     41 #endif
     42 	/* read FFS superblock */
     43 	for (sbl = sblocs; ; sbl++) {
     44 		if (*sbl == -1)
     45 			return 1;
     46 
     47 		RAW_READ(&buf, (daddr_t) btodb(*sbl), SBLOCKSIZE);
     48 
     49 		magic = buf.sblk.fs_magic;
     50 #ifdef DEBUG_WITH_STDIO
     51 		printf("FFS: sblk: pos %d magic 0x%x\n", btodb(*sbl), magic);
     52 #endif
     53 
     54 #ifdef USE_UFS1
     55 		if (magic == FS_UFS1_MAGIC)
     56 			break;
     57 #endif
     58 #ifdef USE_UFS2
     59 		if (magic == FS_UFS2_MAGIC) {
     60 #ifdef USE_UFS1
     61 			fsi.ufstype = UFSTYPE_UFS2;
     62 #endif
     63 			break;
     64 		}
     65 #endif
     66 	}
     67 
     68 	/*
     69 	 * XXX <ufs/ffs/fs.h> always uses fs_magic
     70 	 * (UFS1 only or UFS2 only is impossible)
     71 	 */
     72 	fsi_ffs.magic = magic;
     73 #ifdef DEBUG_WITH_STDIO
     74 	printf("FFS: detected UFS%d format\n", (magic == FS_UFS2_MAGIC) + 1);
     75 #endif
     76 
     77 	/* This partition looks like an FFS. */
     78 	fsi.fstype = UFSTYPE_FFS;
     79 	fsi.get_inode = get_ffs_inode;
     80 
     81 	/* Get information from the superblock. */
     82 	fsi.bsize = buf.sblk.fs_bsize;
     83 	fsi.fsbtodb = buf.sblk.fs_fsbtodb;
     84 	fsi.nindir = buf.sblk.fs_nindir;
     85 
     86 	fsi_ffs.iblkno = buf.sblk.fs_iblkno;
     87 	fsi_ffs.old_cgoffset = buf.sblk.fs_old_cgoffset;
     88 	fsi_ffs.old_cgmask = buf.sblk.fs_old_cgmask;
     89 	fsi_ffs.fragshift = buf.sblk.fs_fragshift;
     90 	fsi_ffs.inopb = buf.sblk.fs_inopb;
     91 	fsi_ffs.ipg = buf.sblk.fs_ipg;
     92 	fsi_ffs.fpg = buf.sblk.fs_fpg;
     93 
     94 	return 0;
     95 }
     96 
     97 /* for inode macros */
     98 #define fs_ipg		fs_u.u_ffs.ipg
     99 #define fs_iblkno	fs_u.u_ffs.iblkno
    100 #define fs_old_cgoffset	fs_u.u_ffs.old_cgoffset
    101 #define fs_old_cgmask	fs_u.u_ffs.old_cgmask
    102 #define fs_fpg		fs_u.u_ffs.fpg
    103 #define fs_magic	fs_u.u_ffs.magic
    104 #define fs_inopb	fs_u.u_ffs.inopb
    105 #define fs_fragshift	fs_u.u_ffs.fragshift
    106 #define fs_fsbtodb	fsbtodb
    107 
    108 /*
    109  * Get inode from disk.
    110  */
    111 static int
    112 get_ffs_inode(ino, dibuf)
    113 	ino_t ino;
    114 	union ufs_dinode *dibuf;
    115 {
    116 	struct ufs_info *ufsinfo = &ufs_info;
    117 	union ufs_dinode *buf = alloca((size_t) fsi.bsize);
    118 	union ufs_dinode *di;
    119 	unsigned ioff;
    120 
    121 	RAW_READ(buf, fsbtodb(&fsi, ino_to_fsba(&fsi, ino)),
    122 			(size_t) fsi.bsize);
    123 
    124 	ioff = ino_to_fsbo(&fsi, ino);
    125 
    126 #if defined(USE_UFS1) && defined(USE_UFS2)
    127 	if (ufsinfo->ufstype == UFSTYPE_UFS1)
    128 		di = (void *) &(&buf->di1)[ioff];
    129 	else {
    130 		di = (void *) &(&buf->di2)[ioff];
    131 
    132 		/* XXX for DI_SIZE() macro */
    133 		di->di1.di_size = di->di2.di_size;
    134 	}
    135 #else
    136 	di = &buf[ioff];
    137 #endif
    138 
    139 #ifdef DEBUG_WITH_STDIO
    140 	printf("FFS: dinode(%d): mode 0%o, nlink %d, size %u\n",
    141 		ino, di->di_common.di_mode, di->di_common.di_nlink,
    142 		(unsigned) DI_SIZE(di));
    143 #endif
    144 
    145 	if (di->di_common.di_mode == 0)
    146 		return 1;	/* unused inode (file is not found) */
    147 
    148 	*dibuf = *di;
    149 
    150 	return 0;
    151 }
    152