Home | History | Annotate | Download | only in ext2fs 
      1 /*
      2  * link.c --- create links in a ext2fs directory
      3  *
      4  * Copyright (C) 1993, 1994 Theodore Ts'o.
      5  *
      6  * %Begin-Header%
      7  * This file may be redistributed under the terms of the GNU Public
      8  * License.
      9  * %End-Header%
     10  */
     11 
     12 #include <stdio.h>
     13 #include <string.h>
     14 #if HAVE_UNISTD_H
     15 #include <unistd.h>
     16 #endif
     17 
     18 #include "ext2_fs.h"
     19 #include "ext2fs.h"
     20 
     21 struct link_struct  {
     22 	const char	*name;
     23 	int		namelen;
     24 	ext2_ino_t	inode;
     25 	int		flags;
     26 	int		done;
     27 	struct ext2_super_block *sb;
     28 };
     29 
     30 static int link_proc(struct ext2_dir_entry *dirent,
     31 		     int	offset,
     32 		     int	blocksize,
     33 		     char	*buf,
     34 		     void	*priv_data)
     35 {
     36 	struct link_struct *ls = (struct link_struct *) priv_data;
     37 	struct ext2_dir_entry *next;
     38 	int rec_len, min_rec_len;
     39 	int ret = 0;
     40 
     41 	rec_len = EXT2_DIR_REC_LEN(ls->namelen);
     42 
     43 	/*
     44 	 * See if the following directory entry (if any) is unused;
     45 	 * if so, absorb it into this one.
     46 	 */
     47 	next = (struct ext2_dir_entry *) (buf + offset + dirent->rec_len);
     48 	if ((offset + dirent->rec_len < blocksize - 8) &&
     49 	    (next->inode == 0) &&
     50 	    (offset + dirent->rec_len + next->rec_len <= blocksize)) {
     51 		dirent->rec_len += next->rec_len;
     52 		ret = DIRENT_CHANGED;
     53 	}
     54 
     55 	/*
     56 	 * If the directory entry is used, see if we can split the
     57 	 * directory entry to make room for the new name.  If so,
     58 	 * truncate it and return.
     59 	 */
     60 	if (dirent->inode) {
     61 		min_rec_len = EXT2_DIR_REC_LEN(dirent->name_len & 0xFF);
     62 		if (dirent->rec_len < (min_rec_len + rec_len))
     63 			return ret;
     64 		rec_len = dirent->rec_len - min_rec_len;
     65 		dirent->rec_len = min_rec_len;
     66 		next = (struct ext2_dir_entry *) (buf + offset +
     67 						  dirent->rec_len);
     68 		next->inode = 0;
     69 		next->name_len = 0;
     70 		next->rec_len = rec_len;
     71 		return DIRENT_CHANGED;
     72 	}
     73 
     74 	/*
     75 	 * If we get this far, then the directory entry is not used.
     76 	 * See if we can fit the request entry in.  If so, do it.
     77 	 */
     78 	if (dirent->rec_len < rec_len)
     79 		return ret;
     80 	dirent->inode = ls->inode;
     81 	dirent->name_len = ls->namelen;
     82 	strncpy(dirent->name, ls->name, ls->namelen);
     83 	if (ls->sb->s_feature_incompat & EXT2_FEATURE_INCOMPAT_FILETYPE)
     84 		dirent->name_len |= (ls->flags & 0x7) << 8;
     85 
     86 	ls->done++;
     87 	return DIRENT_ABORT|DIRENT_CHANGED;
     88 }
     89 
     90 /*
     91  * Note: the low 3 bits of the flags field are used as the directory
     92  * entry filetype.
     93  */
     94 #ifdef __TURBOC__
     95  #pragma argsused
     96 #endif
     97 errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
     98 		      ext2_ino_t ino, int flags)
     99 {
    100 	errcode_t		retval;
    101 	struct link_struct	ls;
    102 	struct ext2_inode	inode;
    103 
    104 	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
    105 
    106 	if (!(fs->flags & EXT2_FLAG_RW))
    107 		return EXT2_ET_RO_FILSYS;
    108 
    109 	ls.name = name;
    110 	ls.namelen = name ? strlen(name) : 0;
    111 	ls.inode = ino;
    112 	ls.flags = flags;
    113 	ls.done = 0;
    114 	ls.sb = fs->super;
    115 
    116 	retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY,
    117 				    0, link_proc, &ls);
    118 	if (retval)
    119 		return retval;
    120 
    121 	if (!ls.done)
    122 		return EXT2_ET_DIR_NO_SPACE;
    123 
    124 	if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
    125 		return retval;
    126 
    127 	if (inode.i_flags & EXT2_INDEX_FL) {
    128 		inode.i_flags &= ~EXT2_INDEX_FL;
    129 		if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)
    130 			return retval;
    131 	}
    132 
    133 	return 0;
    134 }
    135