/*      $NetBSD: readufs_ffs.c,v 1.16 2026/03/13 21:13:45 andvar Exp $  */
/*      from Id: readufs_ffs.c,v 1.6 2003/04/08 09:19:32 itohy Exp      */

/*
 * FS specific support for 4.2BSD Fast Filesystem
 *
 * Written in 1999, 2002, 2003 by ITOH Yasufumi.
 * Public domain.
 *
 * Intended to be used for boot programs (first stage).
 * DON'T ADD ANY FANCY FEATURE.  THIS SHALL BE COMPACT.
 */

#include "readufs.h"

#include <ufs/ffs/fs.h>

static int get_ffs_inode(ino32_t ino, union ufs_dinode *dibuf);

#define fsi     (*ufsinfo)
#define fsi_ffs fsi.fs_u.u_ffs

/*
 * Read and check superblock.
 * If it is an FFS, save information from the superblock.
 */
int
try_ffs(void)
{
        union {
                struct fs       sblk;
                unsigned char   pad[SBLOCKSIZE];
        } buf;
        struct ufs_info *ufsinfo = &ufs_info;
        static const int sblocs[] = SBLOCKSEARCH;
        const int *sbl;
        int magic;

#ifdef DEBUG_WITH_STDIO
        printf("trying FFS\n");
#endif
        /* read FFS superblock */
        for (sbl = sblocs; ; sbl++) {
                if (*sbl == -1)
                        return 1;

                RAW_READ(&buf, (daddr_t) btodb(*sbl), SBLOCKSIZE);

                magic = buf.sblk.fs_magic;
#ifdef DEBUG_WITH_STDIO
                printf("FFS: sblk: pos %d magic 0x%x\n", btodb(*sbl), magic);
#endif
#ifdef USE_UFS1
                if (magic == FS_UFS1_MAGIC
                    && !(buf.sblk.fs_old_flags & FS_FLAGS_UPDATED)) {
                        if (*sbl == SBLOCK_UFS2)
                                /* might be an alternate superblock */
                                continue;
                        break;
                }
#endif
                if (*sbl != buf.sblk.fs_sblockloc)
                        /* must be an alternate superblock */
                        continue;

#ifdef USE_UFS1
                if (magic == FS_UFS1_MAGIC) {
                        break;
                }
#endif
#ifdef USE_UFS2
                if (magic == FS_UFS2_MAGIC || magic == FS_UFS2EA_MAGIC) {
#ifdef USE_UFS1
                        fsi.ufstype = UFSTYPE_UFS2;
#endif
                        break;
                }
#endif
        }

        /*
         * XXX <ufs/ffs/fs.h> always uses fs_magic
         * (UFS1 only or UFS2 only is impossible)
         */
        fsi_ffs.magic = magic;
#ifdef DEBUG_WITH_STDIO
        printf("FFS: detected UFS%d format\n",
               (magic == FS_UFS2_MAGIC || magic == FS_UFS2EA_MAGIC) + 1);
#endif

        /* This partition looks like an FFS. */
        fsi.fstype = UFSTYPE_FFS;
        fsi.get_inode = get_ffs_inode;

        /* Get information from the superblock. */
        fsi.bsize = buf.sblk.fs_bsize;
        fsi.fsbtodb = buf.sblk.fs_fsbtodb;
        fsi.nindir = buf.sblk.fs_nindir;

        fsi_ffs.iblkno = buf.sblk.fs_iblkno;
        fsi_ffs.old_cgoffset = buf.sblk.fs_old_cgoffset;
        fsi_ffs.old_cgmask = buf.sblk.fs_old_cgmask;
        fsi_ffs.fragshift = buf.sblk.fs_fragshift;
        fsi_ffs.inopb = buf.sblk.fs_inopb;
        fsi_ffs.ipg = buf.sblk.fs_ipg;
        fsi_ffs.fpg = buf.sblk.fs_fpg;

        return 0;
}

/* for inode macros */
#define fs_ipg          fs_u.u_ffs.ipg
#define fs_iblkno       fs_u.u_ffs.iblkno
#define fs_old_cgoffset fs_u.u_ffs.old_cgoffset
#define fs_old_cgmask   fs_u.u_ffs.old_cgmask
#define fs_fpg          fs_u.u_ffs.fpg
#define fs_magic        fs_u.u_ffs.magic
#define fs_inopb        fs_u.u_ffs.inopb
#define fs_fragshift    fs_u.u_ffs.fragshift
#define fs_fsbtodb      fsbtodb

/*
 * Get inode from disk.
 */
static int
get_ffs_inode(ino32_t ino, union ufs_dinode *dibuf)
{
        struct ufs_info *ufsinfo = &ufs_info;
        union ufs_dinode *buf = alloca((size_t) fsi.bsize);
        union ufs_dinode *di;
        unsigned ioff;

        RAW_READ(buf, FFS_FSBTODB(&fsi, ino_to_fsba(&fsi, ino)),
                        (size_t) fsi.bsize);

        ioff = ino_to_fsbo(&fsi, ino);

#if defined(USE_UFS1) && defined(USE_UFS2)
        if (ufsinfo->ufstype == UFSTYPE_UFS1)
                di = (void *) &(&buf->di1)[ioff];
        else {
                di = (void *) &(&buf->di2)[ioff];

                /* XXX for DI_SIZE() macro */
                di->di1.di_size = di->di2.di_size;
        }
#else
        di = &buf[ioff];
#endif

#ifdef DEBUG_WITH_STDIO
        printf("FFS: dinode(%d): mode 0%o, nlink %d, size %u\n",
                ino, di->di_common.di_mode, di->di_common.di_nlink,
                (unsigned) DI_SIZE(di));
#endif

        if (di->di_common.di_mode == 0)
                return 1;       /* unused inode (file is not found) */

        *dibuf = *di;

        return 0;
}