X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=qemu%2Froms%2Fopenbios%2Ffs%2Fgrubfs%2Ffsys_ext2fs.c;fp=qemu%2Froms%2Fopenbios%2Ffs%2Fgrubfs%2Ffsys_ext2fs.c;h=05425bbd34e72792f3aff22003769cc57d300304;hb=e44e3482bdb4d0ebde2d8b41830ac2cdb07948fb;hp=0000000000000000000000000000000000000000;hpb=9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00;p=kvmfornfv.git

diff --git a/qemu/roms/openbios/fs/grubfs/fsys_ext2fs.c b/qemu/roms/openbios/fs/grubfs/fsys_ext2fs.c
new file mode 100644
index 000000000..05425bbd3
--- /dev/null
+++ b/qemu/roms/openbios/fs/grubfs/fsys_ext2fs.c
@@ -0,0 +1,794 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 1999, 2001  Free Software Foundation, Inc.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+ *  MA 02110-1301, USA.
+ */
+
+#ifdef FSYS_EXT2FS
+
+#include "config.h"
+#include "shared.h"
+#include "filesys.h"
+#include "libc/byteorder.h"
+
+#ifdef CONFIG_DEBUG_EXT2FS
+#define E2DEBUG
+#endif
+
+static int mapblock1, mapblock2;
+
+/* sizes are always in bytes, BLOCK values are always in DEV_BSIZE (sectors) */
+#define DEV_BSIZE 512
+
+/* include/linux/fs.h */
+#define BLOCK_SIZE 1024		/* initial block size for superblock read */
+/* made up, defaults to 1 but can be passed via mount_opts */
+#define WHICH_SUPER 1
+/* kind of from fs/ext2/super.c */
+#define SBLOCK (WHICH_SUPER * BLOCK_SIZE / DEV_BSIZE)	/* = 2 */
+
+/* include/asm-i386/types.h */
+typedef __signed__ char __s8;
+typedef unsigned char __u8;
+typedef __signed__ short __s16;
+typedef unsigned short __u16;
+typedef __signed__ int __s32;
+typedef unsigned int __u32;
+
+/*
+ * Constants relative to the data blocks, from ext2_fs.h
+ */
+#define EXT2_NDIR_BLOCKS                12
+#define EXT2_IND_BLOCK                  EXT2_NDIR_BLOCKS
+#define EXT2_DIND_BLOCK                 (EXT2_IND_BLOCK + 1)
+#define EXT2_TIND_BLOCK                 (EXT2_DIND_BLOCK + 1)
+#define EXT2_N_BLOCKS                   (EXT2_TIND_BLOCK + 1)
+
+/* include/linux/ext2_fs.h */
+struct ext2_super_block
+  {
+    __u32 s_inodes_count;	/* Inodes count */
+    __u32 s_blocks_count;	/* Blocks count */
+    __u32 s_r_blocks_count;	/* Reserved blocks count */
+    __u32 s_free_blocks_count;	/* Free blocks count */
+    __u32 s_free_inodes_count;	/* Free inodes count */
+    __u32 s_first_data_block;	/* First Data Block */
+    __u32 s_log_block_size;	/* Block size */
+    __s32 s_log_frag_size;	/* Fragment size */
+    __u32 s_blocks_per_group;	/* # Blocks per group */
+    __u32 s_frags_per_group;	/* # Fragments per group */
+    __u32 s_inodes_per_group;	/* # Inodes per group */
+    __u32 s_mtime;		/* Mount time */
+    __u32 s_wtime;		/* Write time */
+    __u16 s_mnt_count;		/* Mount count */
+    __s16 s_max_mnt_count;	/* Maximal mount count */
+    __u16 s_magic;		/* Magic signature */
+    __u16 s_state;		/* File system state */
+    __u16 s_errors;		/* Behaviour when detecting errors */
+    __u16 s_pad;
+    __u32 s_lastcheck;		/* time of last check */
+    __u32 s_checkinterval;	/* max. time between checks */
+    __u32 s_creator_os;		/* OS */
+    __u32 s_rev_level;		/* Revision level */
+    __u16 s_def_resuid;		/* Default uid for reserved blocks */
+    __u16 s_def_resgid;		/* Default gid for reserved blocks */
+    __u32 s_reserved[235];	/* Padding to the end of the block */
+  };
+
+struct ext2_group_desc
+  {
+    __u32 bg_block_bitmap;	/* Blocks bitmap block */
+    __u32 bg_inode_bitmap;	/* Inodes bitmap block */
+    __u32 bg_inode_table;	/* Inodes table block */
+    __u16 bg_free_blocks_count;	/* Free blocks count */
+    __u16 bg_free_inodes_count;	/* Free inodes count */
+    __u16 bg_used_dirs_count;	/* Directories count */
+    __u16 bg_pad;
+    __u32 bg_reserved[3];
+  };
+
+struct ext2_inode
+  {
+    __u16 i_mode;		/* File mode */
+    __u16 i_uid;		/* Owner Uid */
+    __u32 i_size;		/* 4: Size in bytes */
+    __u32 i_atime;		/* Access time */
+    __u32 i_ctime;		/* 12: Creation time */
+    __u32 i_mtime;		/* Modification time */
+    __u32 i_dtime;		/* 20: Deletion Time */
+    __u16 i_gid;		/* Group Id */
+    __u16 i_links_count;	/* 24: Links count */
+    __u32 i_blocks;		/* Blocks count */
+    __u32 i_flags;		/* 32: File flags */
+    union
+      {
+	struct
+	  {
+	    __u32 l_i_reserved1;
+	  }
+	linux1;
+	struct
+	  {
+	    __u32 h_i_translator;
+	  }
+	hurd1;
+	struct
+	  {
+	    __u32 m_i_reserved1;
+	  }
+	masix1;
+      }
+    osd1;			/* OS dependent 1 */
+    __u32 i_block[EXT2_N_BLOCKS];	/* 40: Pointers to blocks */
+    __u32 i_version;		/* File version (for NFS) */
+    __u32 i_file_acl;		/* File ACL */
+    __u32 i_dir_acl;		/* Directory ACL */
+    __u32 i_faddr;		/* Fragment address */
+    union
+      {
+	struct
+	  {
+	    __u8 l_i_frag;	/* Fragment number */
+	    __u8 l_i_fsize;	/* Fragment size */
+	    __u16 i_pad1;
+	    __u32 l_i_reserved2[2];
+	  }
+	linux2;
+	struct
+	  {
+	    __u8 h_i_frag;	/* Fragment number */
+	    __u8 h_i_fsize;	/* Fragment size */
+	    __u16 h_i_mode_high;
+	    __u16 h_i_uid_high;
+	    __u16 h_i_gid_high;
+	    __u32 h_i_author;
+	  }
+	hurd2;
+	struct
+	  {
+	    __u8 m_i_frag;	/* Fragment number */
+	    __u8 m_i_fsize;	/* Fragment size */
+	    __u16 m_pad1;
+	    __u32 m_i_reserved2[2];
+	  }
+	masix2;
+      }
+    osd2;			/* OS dependent 2 */
+  };
+
+/* linux/posix_type.h */
+typedef long linux_off_t;
+
+/* linux/ext2fs.h */
+#define EXT2_NAME_LEN 255
+struct ext2_dir_entry
+  {
+    __u32 inode;		/* Inode number */
+    __u16 rec_len;		/* Directory entry length */
+    __u8 name_len;		/* Name length */
+    __u8 file_type;
+    char name[EXT2_NAME_LEN];	/* File name */
+  };
+
+/* ext2/super.c */
+#define EXT2_SUPER_MAGIC      0xEF53	/* include/linux/ext2_fs.h */
+#define EXT2_ROOT_INO              2	/* include/linux/ext2_fs.h */
+#define PATH_MAX                1024	/* include/linux/limits.h */
+#define MAX_LINK_COUNT             5	/* number of symbolic links to follow */
+
+/* made up, these are pointers into FSYS_BUF */
+/* read once, always stays there: */
+#define SUPERBLOCK \
+    ((struct ext2_super_block *)(FSYS_BUF))
+#define GROUP_DESC \
+    ((struct ext2_group_desc *) \
+     ((char *)SUPERBLOCK + sizeof(struct ext2_super_block)))
+#define INODE \
+    ((struct ext2_inode *)((char *)GROUP_DESC + EXT2_BLOCK_SIZE(SUPERBLOCK)))
+#define DATABLOCK1 \
+    ((char *)((char *)INODE + sizeof(struct ext2_inode)))
+#define DATABLOCK2 \
+    ((char *)((char *)DATABLOCK1 + EXT2_BLOCK_SIZE(SUPERBLOCK)))
+
+/* linux/ext2_fs.h */
+#define EXT2_ADDR_PER_BLOCK(s)          (EXT2_BLOCK_SIZE(s) / sizeof (__u32))
+#define EXT2_ADDR_PER_BLOCK_BITS(s)	(log2(EXT2_ADDR_PER_BLOCK(s)))
+
+/* linux/ext2_fs.h */
+#define EXT2_BLOCK_SIZE_BITS(s)        (__le32_to_cpu((s)->s_log_block_size) + 10)
+/* kind of from ext2/super.c */
+#define EXT2_BLOCK_SIZE(s)	(1 << EXT2_BLOCK_SIZE_BITS(s))
+/* linux/ext2fs.h */
+#define EXT2_DESC_PER_BLOCK(s) \
+     (EXT2_BLOCK_SIZE(s) / sizeof (struct ext2_group_desc))
+/* linux/stat.h */
+#define S_IFMT  00170000
+#define S_IFLNK  0120000
+#define S_IFREG  0100000
+#define S_IFDIR  0040000
+#define S_ISLNK(m)	(((m) & S_IFMT) == S_IFLNK)
+#define S_ISREG(m)      (((m) & S_IFMT) == S_IFREG)
+#define S_ISDIR(m)      (((m) & S_IFMT) == S_IFDIR)
+
+#ifdef E2DEBUG
+void
+dump_super(struct ext2_super_block *s)
+{
+    printf(" superblock 0x%x:\n", s);
+    printf("  inodes=%d\n", __le32_to_cpu(s->s_inodes_count));
+    printf("  blocks=%d\n", __le32_to_cpu(s->s_blocks_count));
+    printf("  reserved=%d\n", __le32_to_cpu(s->s_r_blocks_count));
+    printf("  i_free=%d\n", __le32_to_cpu(s->s_free_inodes_count));
+    printf("  b_free=%d\n", __le32_to_cpu(s->s_free_blocks_count));
+    printf("  first=%d\n", __le32_to_cpu(s->s_first_data_block));
+    printf("  log_b_size=%d, b_size=%d\n", __le32_to_cpu(s->s_log_block_size), EXT2_BLOCK_SIZE(s));
+    printf("  log_f_size=%d\n", __le32_to_cpu(s->s_log_frag_size));
+    printf("  bpg=%d\n", __le32_to_cpu(s->s_blocks_per_group));
+    printf("  fpg=%d\n", __le32_to_cpu(s->s_frags_per_group));
+    printf("  ipg=%d\n", __le32_to_cpu(s->s_inodes_per_group));
+}
+
+void
+dump_group_desc(struct ext2_group_desc *g)
+{
+    printf(" group_desc 0x%x:\n", g);
+    printf("  b_bmap block=%d\n", __le32_to_cpu(g->bg_block_bitmap));
+    printf("  i_bmap block=%d\n", __le32_to_cpu(g->bg_inode_bitmap));
+    printf("  i_tab block=%d\n", __le32_to_cpu(g->bg_inode_table));
+    printf("  free_blks=%d\n", __le16_to_cpu(g->bg_free_blocks_count));
+    printf("  free_inodes=%d\n", __le16_to_cpu(g->bg_free_inodes_count));
+    printf("  used_dirs=%d\n", __le16_to_cpu(g->bg_used_dirs_count));
+}
+
+void
+dump_inode(struct ext2_inode *i)
+{
+    printf(" inode 0x%x:\n", i);
+    printf("  mode=%o\n", __le16_to_cpu(i->i_mode));
+    printf("  uid=%d\n", __le16_to_cpu(i->i_uid));
+    printf("  gid=%d\n", __le16_to_cpu(i->i_gid));
+    printf("  size=%d\n", __le32_to_cpu(i->i_size));
+    printf("  atime=%d\n", __le32_to_cpu(i->i_atime));
+    printf("  ctime=%d\n", __le32_to_cpu(i->i_ctime));
+    printf("  mtime=%d\n", __le32_to_cpu(i->i_mtime));
+    printf("  dtime=%d\n", __le32_to_cpu(i->i_dtime));
+    printf("  links=%d\n", __le16_to_cpu(i->i_links_count));
+    printf("  blocks=%d\n", __le32_to_cpu(i->i_blocks));
+    printf("  flags=%d\n", __le32_to_cpu(i->i_flags));
+}
+
+void
+dump_inode_data(unsigned char *inode, int len)
+{
+  static char hexdigit[] = "0123456789abcdef";
+  unsigned char *i;
+  for (i = inode;
+       i < (inode + len);
+       i++)
+    {
+      printf ("%c", hexdigit[*i >> 4]);
+      printf ("%c", hexdigit[*i % 16]);
+      if (!((i + 1 - inode) % 16))
+	{
+	  printf ("\n");
+	}
+      else
+	{
+	  printf (" ");
+	}
+    }
+}
+#endif
+
+/* check filesystem types and read superblock into memory buffer */
+int
+ext2fs_mount (void)
+{
+  int retval = 1;
+
+  if ((((current_drive & 0x80) || (current_slice != 0))
+       && (current_slice != PC_SLICE_TYPE_EXT2FS)
+       && (current_slice != PC_SLICE_TYPE_LINUX_RAID)
+       && (! IS_PC_SLICE_TYPE_BSD_WITH_FS (current_slice, FS_EXT2FS))
+       && (! IS_PC_SLICE_TYPE_BSD_WITH_FS (current_slice, FS_OTHER)))
+      || part_length < (SBLOCK + (sizeof (struct ext2_super_block) / DEV_BSIZE))
+      || !devread (SBLOCK, 0, sizeof (struct ext2_super_block),
+		   (char *) SUPERBLOCK)
+      || __le16_to_cpu(SUPERBLOCK->s_magic) != EXT2_SUPER_MAGIC)
+      retval = 0;
+
+  return retval;
+}
+
+/* Takes a file system block number and reads it into BUFFER. */
+static int
+ext2_rdfsb (int fsblock, char * buffer)
+{
+#ifdef E2DEBUG
+  printf ("ext2_rdfsb: fsblock %d, devblock %d, size %d\n", fsblock,
+	  fsblock * (EXT2_BLOCK_SIZE (SUPERBLOCK) / DEV_BSIZE),
+	  EXT2_BLOCK_SIZE (SUPERBLOCK));
+#endif /* E2DEBUG */
+  return devread (fsblock * (EXT2_BLOCK_SIZE (SUPERBLOCK) / DEV_BSIZE), 0,
+		  EXT2_BLOCK_SIZE (SUPERBLOCK), (char *) buffer);
+}
+
+/* from
+  ext2/inode.c:ext2_bmap()
+*/
+/* Maps LOGICAL_BLOCK (the file offset divided by the blocksize) into
+   a physical block (the location in the file system) via an inode. */
+static int
+ext2fs_block_map (int logical_block)
+{
+
+#ifdef E2DEBUG
+  printf ("ext2fs_block_map(%d)\n", logical_block);
+#endif /* E2DEBUG */
+
+  /* if it is directly pointed to by the inode, return that physical addr */
+  if (logical_block < EXT2_NDIR_BLOCKS)
+    {
+#ifdef E2DEBUG
+      printf ("ext2fs_block_map: returning %d\n", __le32_to_cpu(INODE->i_block[logical_block]));
+#endif /* E2DEBUG */
+      return __le32_to_cpu(INODE->i_block[logical_block]);
+    }
+  /* else */
+  logical_block -= EXT2_NDIR_BLOCKS;
+  /* try the indirect block */
+  if (logical_block < EXT2_ADDR_PER_BLOCK (SUPERBLOCK))
+    {
+      if (mapblock1 != 1
+	  && !ext2_rdfsb (__le32_to_cpu(INODE->i_block[EXT2_IND_BLOCK]), DATABLOCK1))
+	{
+	  errnum = ERR_FSYS_CORRUPT;
+	  return -1;
+	}
+      mapblock1 = 1;
+      return __le32_to_cpu(((__u32 *) DATABLOCK1)[logical_block]);
+    }
+  /* else */
+  logical_block -= EXT2_ADDR_PER_BLOCK (SUPERBLOCK);
+  /* now try the double indirect block */
+  if (logical_block < (1 << (EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK) * 2)))
+    {
+      int bnum;
+      if (mapblock1 != 2
+	  && !ext2_rdfsb (__le32_to_cpu(INODE->i_block[EXT2_DIND_BLOCK]), DATABLOCK1))
+	{
+	  errnum = ERR_FSYS_CORRUPT;
+	  return -1;
+	}
+      mapblock1 = 2;
+      if ((bnum = __le32_to_cpu(((__u32 *) DATABLOCK1)
+		   [logical_block >> EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK)]))
+	  != mapblock2
+	  && !ext2_rdfsb (bnum, DATABLOCK2))
+	{
+	  errnum = ERR_FSYS_CORRUPT;
+	  return -1;
+	}
+      mapblock2 = bnum;
+      return __le32_to_cpu(((__u32 *) DATABLOCK2)
+	[logical_block & (EXT2_ADDR_PER_BLOCK (SUPERBLOCK) - 1)]);
+    }
+  /* else */
+  mapblock2 = -1;
+  logical_block -= (1 << (EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK) * 2));
+  if (mapblock1 != 3
+      && !ext2_rdfsb (__le32_to_cpu(INODE->i_block[EXT2_TIND_BLOCK]), DATABLOCK1))
+    {
+      errnum = ERR_FSYS_CORRUPT;
+      return -1;
+    }
+  mapblock1 = 3;
+  if (!ext2_rdfsb (__le32_to_cpu(((__u32 *) DATABLOCK1)
+		   [logical_block >> (EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK)
+				      * 2)]),
+		   DATABLOCK2))
+    {
+      errnum = ERR_FSYS_CORRUPT;
+      return -1;
+    }
+  if (!ext2_rdfsb (__le32_to_cpu(((__u32 *) DATABLOCK2)
+		   [(logical_block >> EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK))
+		    & (EXT2_ADDR_PER_BLOCK (SUPERBLOCK) - 1)]),
+		   DATABLOCK2))
+    {
+      errnum = ERR_FSYS_CORRUPT;
+      return -1;
+    }
+  return __le32_to_cpu(((__u32 *) DATABLOCK2)
+    [logical_block & (EXT2_ADDR_PER_BLOCK (SUPERBLOCK) - 1)]);
+}
+
+/* preconditions: all preconds of ext2fs_block_map */
+int
+ext2fs_read (char *buf, int len)
+{
+  int logical_block;
+  int offset;
+  int map;
+  int ret = 0;
+  int size = 0;
+
+#ifdef E2DEBUG
+  printf("ext2fs_read(0x%x, %d)\n", buf, len);
+  dump_inode(INODE);
+  dump_inode_data((unsigned char *)INODE, sizeof (struct ext2_inode));
+#endif /* E2DEBUG */
+  while (len > 0)
+    {
+      /* find the (logical) block component of our location */
+      logical_block = filepos >> EXT2_BLOCK_SIZE_BITS (SUPERBLOCK);
+      offset = filepos & (EXT2_BLOCK_SIZE (SUPERBLOCK) - 1);
+      map = ext2fs_block_map (logical_block);
+#ifdef E2DEBUG
+      printf ("map=%d\n", map);
+#endif /* E2DEBUG */
+      if (map < 0)
+	break;
+
+      size = EXT2_BLOCK_SIZE (SUPERBLOCK);
+      size -= offset;
+      if (size > len)
+	size = len;
+
+      disk_read_func = disk_read_hook;
+
+      devread (map * (EXT2_BLOCK_SIZE (SUPERBLOCK) / DEV_BSIZE),
+	       offset, size, buf);
+
+      disk_read_func = NULL;
+
+      buf += size;
+      len -= size;
+      filepos += size;
+      ret += size;
+    }
+
+  if (errnum)
+    ret = 0;
+
+  return ret;
+}
+
+
+/* Based on:
+   def_blk_fops points to
+   blkdev_open, which calls (I think):
+   sys_open()
+   do_open()
+   open_namei()
+   dir_namei() which accesses current->fs->root
+     fs->root was set during original mount:
+     (something)... which calls (I think):
+     ext2_read_super()
+     iget()
+     __iget()
+     read_inode()
+     ext2_read_inode()
+       uses desc_per_block_bits, which is set in ext2_read_super()
+       also uses group descriptors loaded during ext2_read_super()
+   lookup()
+   ext2_lookup()
+   ext2_find_entry()
+   ext2_getblk()
+
+*/
+
+/* preconditions: ext2fs_mount already executed, therefore supblk in buffer
+ *   known as SUPERBLOCK
+ * returns: 0 if error, nonzero iff we were able to find the file successfully
+ * postconditions: on a nonzero return, buffer known as INODE contains the
+ *   inode of the file we were trying to look up
+ * side effects: messes up GROUP_DESC buffer area
+ */
+int
+ext2fs_dir (char *dirname)
+{
+  int current_ino = EXT2_ROOT_INO;	/* start at the root */
+  int updir_ino = current_ino;	/* the parent of the current directory */
+  int group_id;			/* which group the inode is in */
+  int group_desc;		/* fs pointer to that group */
+  int desc;			/* index within that group */
+  int ino_blk;			/* fs pointer of the inode's information */
+  int str_chk = 0;		/* used to hold the results of a string compare */
+  struct ext2_group_desc *gdp;
+  struct ext2_inode *raw_inode;	/* inode info corresponding to current_ino */
+
+  char linkbuf[PATH_MAX];	/* buffer for following symbolic links */
+  int link_count = 0;
+
+  char *rest;
+  char ch;			/* temp char holder */
+
+  int off;			/* offset within block of directory entry (off mod blocksize) */
+  int loc;			/* location within a directory */
+  int blk;			/* which data blk within dir entry (off div blocksize) */
+  long map;			/* fs pointer of a particular block from dir entry */
+  struct ext2_dir_entry *dp;	/* pointer to directory entry */
+
+  /* loop invariants:
+     current_ino = inode to lookup
+     dirname = pointer to filename component we are cur looking up within
+     the directory known pointed to by current_ino (if any)
+   */
+
+#ifdef E2DEBUG
+  printf("****** ext2fs_dir(%s)\n", dirname);
+  dump_super(SUPERBLOCK);
+#endif /* E2DEBUG */
+
+  while (1)
+    {
+#ifdef E2DEBUG
+      printf ("ext2fs_dir: inode %d\n", current_ino);
+      printf ("ext2fs_dir: dirname=%s\n", dirname);
+#endif /* E2DEBUG */
+
+      /* look up an inode */
+      group_id = (current_ino - 1) / __le32_to_cpu(SUPERBLOCK->s_inodes_per_group);
+      group_desc = group_id >> log2 (EXT2_DESC_PER_BLOCK (SUPERBLOCK));
+      desc = group_id & (EXT2_DESC_PER_BLOCK (SUPERBLOCK) - 1);
+#ifdef E2DEBUG
+      printf ("ext2fs_dir: ipg=%d, dpb=%d\n", __le32_to_cpu(SUPERBLOCK->s_inodes_per_group),
+	      EXT2_DESC_PER_BLOCK (SUPERBLOCK));
+      printf ("ext2fs_dir: group_id=%d group_desc=%d desc=%d\n", group_id, group_desc, desc);
+#endif /* E2DEBUG */
+      if (!ext2_rdfsb (
+			(WHICH_SUPER + group_desc + __le32_to_cpu(SUPERBLOCK->s_first_data_block)),
+			(char*) GROUP_DESC))
+	{
+	  return 0;
+	}
+
+#ifdef E2DEBUG
+      dump_group_desc(GROUP_DESC);
+#endif /* E2DEBUG */
+
+      gdp = GROUP_DESC;
+      ino_blk = __le32_to_cpu(gdp[desc].bg_inode_table) +
+	(((current_ino - 1) % __le32_to_cpu(SUPERBLOCK->s_inodes_per_group))
+	 >> log2 (EXT2_BLOCK_SIZE (SUPERBLOCK) / sizeof (struct ext2_inode)));
+#ifdef E2DEBUG
+      printf ("ext2fs_dir: itab_blk=%d, i_in_grp=%d, log2=%d\n",
+	 __le32_to_cpu(gdp[desc].bg_inode_table),
+	 ((current_ino - 1) % __le32_to_cpu(SUPERBLOCK->s_inodes_per_group)),
+	 log2 (EXT2_BLOCK_SIZE (SUPERBLOCK) / sizeof (struct ext2_inode)));
+      printf ("ext2fs_dir: inode table fsblock=%d\n", ino_blk);
+#endif /* E2DEBUG */
+      if (!ext2_rdfsb (ino_blk, (char *)INODE))
+	{
+	  return 0;
+	}
+
+      /* reset indirect blocks! */
+      mapblock2 = mapblock1 = -1;
+
+      raw_inode = INODE +
+	((current_ino - 1)
+	 & (EXT2_BLOCK_SIZE (SUPERBLOCK) / sizeof (struct ext2_inode) - 1));
+#ifdef E2DEBUG
+      printf ("ext2fs_dir: ipb=%d, sizeof(inode)=%d\n",
+	      (EXT2_BLOCK_SIZE (SUPERBLOCK) / sizeof (struct ext2_inode)),
+	      sizeof (struct ext2_inode));
+      printf ("ext2fs_dir: inode=%x, raw_inode=%x\n", INODE, raw_inode);
+      printf ("ext2fs_dir: offset into inode table block=%d\n", (int) raw_inode - (int) INODE);
+      dump_inode(raw_inode);
+      dump_inode_data((unsigned char *)INODE, EXT2_BLOCK_SIZE(SUPERBLOCK));
+      printf ("ext2fs_dir: first word=%x\n", *((int *) raw_inode));
+#endif /* E2DEBUG */
+
+      /* copy inode to fixed location */
+      memmove ((void *) INODE, (void *) raw_inode, sizeof (struct ext2_inode));
+
+#ifdef E2DEBUG
+      dump_inode(INODE);
+      printf ("ext2fs_dir: first word=%x\n", *((int *) INODE));
+#endif /* E2DEBUG */
+
+      /* If we've got a symbolic link, then chase it. */
+      if (S_ISLNK (__le16_to_cpu(INODE->i_mode)))
+	{
+	  int len;
+	  if (++link_count > MAX_LINK_COUNT)
+	    {
+	      errnum = ERR_SYMLINK_LOOP;
+	      return 0;
+	    }
+
+	  /* Find out how long our remaining name is. */
+	  len = 0;
+	  while (dirname[len] && !isspace (dirname[len]))
+	    len++;
+
+	  /* Get the symlink size. */
+	  filemax = __le32_to_cpu(INODE->i_size);
+	  if (filemax + len > sizeof (linkbuf) - 2)
+	    {
+	      errnum = ERR_FILELENGTH;
+	      return 0;
+	    }
+
+	  if (len)
+	    {
+	      /* Copy the remaining name to the end of the symlink data.
+	         Note that DIRNAME and LINKBUF may overlap! */
+	      memmove (linkbuf + filemax, dirname, len);
+	    }
+	  linkbuf[filemax + len] = '\0';
+
+	  /* Read the symlink data. */
+	  if (__le32_to_cpu(INODE->i_blocks))
+	    {
+	      /* Read the necessary blocks, and reset the file pointer. */
+	      len = file_read (linkbuf, filemax);
+	      filepos = 0;
+	      if (!len)
+		return 0;
+	    }
+	  else
+	    {
+	      /* Copy the data directly from the inode. */
+	      len = filemax;
+	      memmove (linkbuf, (char *) INODE->i_block, len);
+	    }
+
+#ifdef E2DEBUG
+	  printf ("ext2fs_dir: symlink=%s\n", linkbuf);
+#endif
+
+	  dirname = linkbuf;
+	  if (*dirname == '/')
+	    {
+	      /* It's an absolute link, so look it up in root. */
+	      current_ino = EXT2_ROOT_INO;
+	      updir_ino = current_ino;
+	    }
+	  else
+	    {
+	      /* Relative, so look it up in our parent directory. */
+	      current_ino = updir_ino;
+	    }
+
+	  /* Try again using the new name. */
+	  continue;
+	}
+
+      /* if end of filename, INODE points to the file's inode */
+      if (!*dirname || isspace (*dirname))
+	{
+	  if (!S_ISREG (__le16_to_cpu(INODE->i_mode)))
+	    {
+	      errnum = ERR_BAD_FILETYPE;
+	      return 0;
+	    }
+
+	  filemax = __le32_to_cpu(INODE->i_size);
+	  return 1;
+	}
+
+      /* else we have to traverse a directory */
+      updir_ino = current_ino;
+
+      /* skip over slashes */
+      while (*dirname == '/')
+	dirname++;
+
+      /* if this isn't a directory of sufficient size to hold our file, abort */
+      if (!(__le32_to_cpu(INODE->i_size)) || !S_ISDIR (__le16_to_cpu(INODE->i_mode)))
+	{
+	  errnum = ERR_BAD_FILETYPE;
+	  return 0;
+	}
+
+      /* skip to next slash or end of filename (space) */
+      for (rest = dirname; (ch = *rest) && !isspace (ch) && ch != '/';
+	   rest++);
+
+      /* look through this directory and find the next filename component */
+      /* invariant: rest points to slash after the next filename component */
+      *rest = 0;
+      loc = 0;
+
+      do
+	{
+
+#ifdef E2DEBUG
+	  printf ("ext2fs_dir: dirname=%s, rest=%s, loc=%d\n", dirname, rest, loc);
+#endif /* E2DEBUG */
+
+	  /* if our location/byte offset into the directory exceeds the size,
+	     give up */
+	  if (loc >= __le32_to_cpu(INODE->i_size))
+	    {
+	      if (print_possibilities < 0)
+		{
+# if 0
+		  putchar ('\n');
+# endif
+		}
+	      else
+		{
+		  errnum = ERR_FILE_NOT_FOUND;
+		  *rest = ch;
+		}
+	      return (print_possibilities < 0);
+	    }
+
+	  /* else, find the (logical) block component of our location */
+	  blk = loc >> EXT2_BLOCK_SIZE_BITS (SUPERBLOCK);
+
+	  /* we know which logical block of the directory entry we are looking
+	     for, now we have to translate that to the physical (fs) block on
+	     the disk */
+	  map = ext2fs_block_map (blk);
+#ifdef E2DEBUG
+	  printf ("ext2fs_dir: fs block=%d\n", map);
+#endif /* E2DEBUG */
+	  mapblock2 = -1;
+	  if ((map < 0) || !ext2_rdfsb (map, DATABLOCK2))
+	    {
+	      errnum = ERR_FSYS_CORRUPT;
+	      *rest = ch;
+	      return 0;
+	    }
+	  off = loc & (EXT2_BLOCK_SIZE (SUPERBLOCK) - 1);
+	  dp = (struct ext2_dir_entry *) (DATABLOCK2 + off);
+	  /* advance loc prematurely to next on-disk directory entry  */
+	  loc += __le16_to_cpu(dp->rec_len);
+
+	  /* NOTE: ext2fs filenames are NOT null-terminated */
+
+#ifdef E2DEBUG
+	  printf ("ext2fs_dir: directory entry ino=%d\n", __le32_to_cpu(dp->inode));
+	  if (__le32_to_cpu(dp->inode))
+	    printf ("entry=%s\n", dp->name);
+#endif /* E2DEBUG */
+
+	  if (__le32_to_cpu(dp->inode))
+	    {
+	      int saved_c = dp->name[dp->name_len];
+
+	      dp->name[dp->name_len] = 0;
+	      str_chk = substring (dirname, dp->name);
+
+# ifndef STAGE1_5
+	      if (print_possibilities && ch != '/'
+		  && (!*dirname || str_chk <= 0))
+		{
+		  if (print_possibilities > 0)
+		    print_possibilities = -print_possibilities;
+		  print_a_completion (dp->name);
+		}
+# endif
+
+	      dp->name[dp->name_len] = saved_c;
+	    }
+
+	}
+      while (!__le32_to_cpu(dp->inode) || (str_chk || (print_possibilities && ch != '/')));
+
+      current_ino = __le32_to_cpu(dp->inode);
+      *(dirname = rest) = ch;
+    }
+  /* never get here */
+}
+
+#endif /* FSYS_EXT2_FS */