fs/sysv/namei.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/sysv/namei.c
   4  *
   5  *  minix/namei.c
   6  *  Copyright (C) 1991, 1992  Linus Torvalds
   7  *
   8  *  coh/namei.c
   9  *  Copyright (C) 1993  Pascal Haible, Bruno Haible
  10  *
  11  *  sysv/namei.c
  12  *  Copyright (C) 1993  Bruno Haible
  13  *  Copyright (C) 1997, 1998  Krzysztof G. Baranowski
  14  */
  15
  16 #include <linux/pagemap.h>
  17 #include "sysv.h"
  18
  19 static int add_nondir(struct dentry *dentry, struct inode *inode)
  20 {
  21         int err = sysv_add_link(dentry, inode);
  22         if (!err) {
  23                 d_instantiate(dentry, inode);
  24                 return 0;
  25         }
  26         inode_dec_link_count(inode);
  27         iput(inode);
  28         return err;
  29 }
  30
  31 static int sysv_hash(const struct dentry *dentry, struct qstr *qstr)
  32 {
  33         /* Truncate the name in place, avoids having to define a compare
  34            function. */
  35         if (qstr->len > SYSV_NAMELEN) {
  36                 qstr->len = SYSV_NAMELEN;
  37                 qstr->hash = full_name_hash(dentry, qstr->name, qstr->len);
  38         }
  39         return 0;
  40 }
  41
  42 const struct dentry_operations sysv_dentry_operations = {
  43         .d_hash         = sysv_hash,
  44 };
  45
  46 static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
  47 {
  48         struct inode * inode = NULL;
  49         ino_t ino;
  50
  51         if (dentry->d_name.len > SYSV_NAMELEN)
  52                 return ERR_PTR(-ENAMETOOLONG);
  53         ino = sysv_inode_by_name(dentry);
  54
  55         if (ino) {
  56                 inode = sysv_iget(dir->i_sb, ino);
  57                 if (IS_ERR(inode))
  58                         return ERR_CAST(inode);
  59         }
  60         d_add(dentry, inode);
  61         return NULL;
  62 }
  63
  64 static int sysv_mknod(struct inode * dir, struct dentry * dentry, umode_t mode, dev_t rdev)
  65 {
  66         struct inode * inode;
  67         int err;
  68
  69         if (!old_valid_dev(rdev))
  70                 return -EINVAL;
  71
  72         inode = sysv_new_inode(dir, mode);
  73         err = PTR_ERR(inode);
  74
  75         if (!IS_ERR(inode)) {
  76                 sysv_set_inode(inode, rdev);
  77                 mark_inode_dirty(inode);
  78                 err = add_nondir(dentry, inode);
  79         }
  80         return err;
  81 }
  82
  83 static int sysv_create(struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
  84 {
  85         return sysv_mknod(dir, dentry, mode, 0);
  86 }
  87
  88 static int sysv_symlink(struct inode * dir, struct dentry * dentry,
  89         const char * symname)
  90 {
  91         int err = -ENAMETOOLONG;
  92         int l = strlen(symname)+1;
  93         struct inode * inode;
  94
  95         if (l > dir->i_sb->s_blocksize)
  96                 goto out;
  97
  98         inode = sysv_new_inode(dir, S_IFLNK|0777);
  99         err = PTR_ERR(inode);
 100         if (IS_ERR(inode))
 101                 goto out;
 102
 103         sysv_set_inode(inode, 0);
 104         err = page_symlink(inode, symname, l);
 105         if (err)
 106                 goto out_fail;
 107
 108         mark_inode_dirty(inode);
 109         err = add_nondir(dentry, inode);
 110 out:
 111         return err;
 112
 113 out_fail:
 114         inode_dec_link_count(inode);
 115         iput(inode);
 116         goto out;
 117 }
 118
 119 static int sysv_link(struct dentry * old_dentry, struct inode * dir,
 120         struct dentry * dentry)
 121 {
 122         struct inode *inode = d_inode(old_dentry);
 123
 124         inode->i_ctime = current_time(inode);
 125         inode_inc_link_count(inode);
 126         ihold(inode);
 127
 128         return add_nondir(dentry, inode);
 129 }
 130
 131 static int sysv_mkdir(struct inode * dir, struct dentry *dentry, umode_t mode)
 132 {
 133         struct inode * inode;
 134         int err;
 135
 136         inode_inc_link_count(dir);
 137
 138         inode = sysv_new_inode(dir, S_IFDIR|mode);
 139         err = PTR_ERR(inode);
 140         if (IS_ERR(inode))
 141                 goto out_dir;
 142
 143         sysv_set_inode(inode, 0);
 144
 145         inode_inc_link_count(inode);
 146
 147         err = sysv_make_empty(inode, dir);
 148         if (err)
 149                 goto out_fail;
 150
 151         err = sysv_add_link(dentry, inode);
 152         if (err)
 153                 goto out_fail;
 154
 155         d_instantiate(dentry, inode);
 156 out:
 157         return err;
 158
 159 out_fail:
 160         inode_dec_link_count(inode);
 161         inode_dec_link_count(inode);
 162         iput(inode);
 163 out_dir:
 164         inode_dec_link_count(dir);
 165         goto out;
 166 }
 167
 168 static int sysv_unlink(struct inode * dir, struct dentry * dentry)
 169 {
 170         struct inode * inode = d_inode(dentry);
 171         struct page * page;
 172         struct sysv_dir_entry * de;
 173         int err = -ENOENT;
 174
 175         de = sysv_find_entry(dentry, &page);
 176         if (!de)
 177                 goto out;
 178
 179         err = sysv_delete_entry (de, page);
 180         if (err)
 181                 goto out;
 182
 183         inode->i_ctime = dir->i_ctime;
 184         inode_dec_link_count(inode);
 185 out:
 186         return err;
 187 }
 188
 189 static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
 190 {
 191         struct inode *inode = d_inode(dentry);
 192         int err = -ENOTEMPTY;
 193
 194         if (sysv_empty_dir(inode)) {
 195                 err = sysv_unlink(dir, dentry);
 196                 if (!err) {
 197                         inode->i_size = 0;
 198                         inode_dec_link_count(inode);
 199                         inode_dec_link_count(dir);
 200                 }
 201         }
 202         return err;
 203 }
 204
 205 /*
 206  * Anybody can rename anything with this: the permission checks are left to the
 207  * higher-level routines.
 208  */
 209 static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
 210                        struct inode * new_dir, struct dentry * new_dentry,
 211                        unsigned int flags)
 212 {
 213         struct inode * old_inode = d_inode(old_dentry);
 214         struct inode * new_inode = d_inode(new_dentry);
 215         struct page * dir_page = NULL;
 216         struct sysv_dir_entry * dir_de = NULL;
 217         struct page * old_page;
 218         struct sysv_dir_entry * old_de;
 219         int err = -ENOENT;
 220
 221         if (flags & ~RENAME_NOREPLACE)
 222                 return -EINVAL;
 223
 224         old_de = sysv_find_entry(old_dentry, &old_page);
 225         if (!old_de)
 226                 goto out;
 227
 228         if (S_ISDIR(old_inode->i_mode)) {
 229                 err = -EIO;
 230                 dir_de = sysv_dotdot(old_inode, &dir_page);
 231                 if (!dir_de)
 232                         goto out_old;
 233         }
 234
 235         if (new_inode) {
 236                 struct page * new_page;
 237                 struct sysv_dir_entry * new_de;
 238
 239                 err = -ENOTEMPTY;
 240                 if (dir_de && !sysv_empty_dir(new_inode))
 241                         goto out_dir;
 242
 243                 err = -ENOENT;
 244                 new_de = sysv_find_entry(new_dentry, &new_page);
 245                 if (!new_de)
 246                         goto out_dir;
 247                 sysv_set_link(new_de, new_page, old_inode);
 248                 new_inode->i_ctime = current_time(new_inode);
 249                 if (dir_de)
 250                         drop_nlink(new_inode);
 251                 inode_dec_link_count(new_inode);
 252         } else {
 253                 err = sysv_add_link(new_dentry, old_inode);
 254                 if (err)
 255                         goto out_dir;
 256                 if (dir_de)
 257                         inode_inc_link_count(new_dir);
 258         }
 259
 260         sysv_delete_entry(old_de, old_page);
 261         mark_inode_dirty(old_inode);
 262
 263         if (dir_de) {
 264                 sysv_set_link(dir_de, dir_page, new_dir);
 265                 inode_dec_link_count(old_dir);
 266         }
 267         return 0;
 268
 269 out_dir:
 270         if (dir_de) {
 271                 kunmap(dir_page);
 272                 put_page(dir_page);
 273         }
 274 out_old:
 275         kunmap(old_page);
 276         put_page(old_page);
 277 out:
 278         return err;
 279 }
 280
 281 /*
 282  * directories can handle most operations...
 283  */
 284 const struct inode_operations sysv_dir_inode_operations = {
 285         .create         = sysv_create,
 286         .lookup         = sysv_lookup,
 287         .link           = sysv_link,
 288         .unlink         = sysv_unlink,
 289         .symlink        = sysv_symlink,
 290         .mkdir          = sysv_mkdir,
 291         .rmdir          = sysv_rmdir,
 292         .mknod          = sysv_mknod,
 293         .rename         = sysv_rename,
 294         .getattr        = sysv_getattr,
 295 };