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readufs_ffs.c revision 1.6 
      1 /*	$NetBSD: readufs_ffs.c,v 1.6 2004/03/21 12:46:57 dsl 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 		if (buf.sblk.fs_old_flags & FS_FLAGS_UPDATED) {
     54 			if (*sbl != buf.sblk.fs_sblockloc)
     55 				/* must be an alternate suberblock */
     56 				continue;
     57 		} else {
     58 			if (*sbl == SBLOCK_UFS2)
     59 				/* might be an alternate suberblock */
     60 				continue;
     61 		}
     62 
     63 #ifdef USE_UFS1
     64 		if (magic == FS_UFS1_MAGIC)
     65 			break;
     66 #endif
     67 #ifdef USE_UFS2
     68 		if (magic == FS_UFS2_MAGIC) {
     69 #ifdef USE_UFS1
     70 			fsi.ufstype = UFSTYPE_UFS2;
     71 #endif
     72 			break;
     73 		}
     74 #endif
     75 	}
     76 
     77 	/*
     78 	 * XXX <ufs/ffs/fs.h> always uses fs_magic
     79 	 * (UFS1 only or UFS2 only is impossible)
     80 	 */
     81 	fsi_ffs.magic = magic;
     82 #ifdef DEBUG_WITH_STDIO
     83 	printf("FFS: detected UFS%d format\n", (magic == FS_UFS2_MAGIC) + 1);
     84 #endif
     85 
     86 	/* This partition looks like an FFS. */
     87 	fsi.fstype = UFSTYPE_FFS;
     88 	fsi.get_inode = get_ffs_inode;
     89 
     90 	/* Get information from the superblock. */
     91 	fsi.bsize = buf.sblk.fs_bsize;
     92 	fsi.fsbtodb = buf.sblk.fs_fsbtodb;
     93 	fsi.nindir = buf.sblk.fs_nindir;
     94 
     95 	fsi_ffs.iblkno = buf.sblk.fs_iblkno;
     96 	fsi_ffs.old_cgoffset = buf.sblk.fs_old_cgoffset;
     97 	fsi_ffs.old_cgmask = buf.sblk.fs_old_cgmask;
     98 	fsi_ffs.fragshift = buf.sblk.fs_fragshift;
     99 	fsi_ffs.inopb = buf.sblk.fs_inopb;
    100 	fsi_ffs.ipg = buf.sblk.fs_ipg;
    101 	fsi_ffs.fpg = buf.sblk.fs_fpg;
    102 
    103 	return 0;
    104 }
    105 
    106 /* for inode macros */
    107 #define fs_ipg		fs_u.u_ffs.ipg
    108 #define fs_iblkno	fs_u.u_ffs.iblkno
    109 #define fs_old_cgoffset	fs_u.u_ffs.old_cgoffset
    110 #define fs_old_cgmask	fs_u.u_ffs.old_cgmask
    111 #define fs_fpg		fs_u.u_ffs.fpg
    112 #define fs_magic	fs_u.u_ffs.magic
    113 #define fs_inopb	fs_u.u_ffs.inopb
    114 #define fs_fragshift	fs_u.u_ffs.fragshift
    115 #define fs_fsbtodb	fsbtodb
    116 
    117 /*
    118  * Get inode from disk.
    119  */
    120 static int
    121 get_ffs_inode(ino, dibuf)
    122 	ino_t ino;
    123 	union ufs_dinode *dibuf;
    124 {
    125 	struct ufs_info *ufsinfo = &ufs_info;
    126 	union ufs_dinode *buf = alloca((size_t) fsi.bsize);
    127 	union ufs_dinode *di;
    128 	unsigned ioff;
    129 
    130 	RAW_READ(buf, fsbtodb(&fsi, ino_to_fsba(&fsi, ino)),
    131 			(size_t) fsi.bsize);
    132 
    133 	ioff = ino_to_fsbo(&fsi, ino);
    134 
    135 #if defined(USE_UFS1) && defined(USE_UFS2)
    136 	if (ufsinfo->ufstype == UFSTYPE_UFS1)
    137 		di = (void *) &(&buf->di1)[ioff];
    138 	else {
    139 		di = (void *) &(&buf->di2)[ioff];
    140 
    141 		/* XXX for DI_SIZE() macro */
    142 		di->di1.di_size = di->di2.di_size;
    143 	}
    144 #else
    145 	di = &buf[ioff];
    146 #endif
    147 
    148 #ifdef DEBUG_WITH_STDIO
    149 	printf("FFS: dinode(%d): mode 0%o, nlink %d, size %u\n",
    150 		ino, di->di_common.di_mode, di->di_common.di_nlink,
    151 		(unsigned) DI_SIZE(di));
    152 #endif
    153 
    154 	if (di->di_common.di_mode == 0)
    155 		return 1;	/* unused inode (file is not found) */
    156 
    157 	*dibuf = *di;
    158 
    159 	return 0;
    160 }
    161