hurd/hurdlookup.c

   1 /* Copyright (C) 1992-2020 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <hurd.h>
  19 #include <hurd/lookup.h>
  20 #include <string.h>
  21 #include <fcntl.h>
  22
  23
  24 /* Translate the error from dir_lookup into the error the user sees.  */
  25 static inline error_t
  26 lookup_error (error_t error)
  27 {
  28   switch (error)
  29     {
  30     case EOPNOTSUPP:
  31     case MIG_BAD_ID:
  32       /* These indicate that the server does not understand dir_lookup
  33          at all.  If it were a directory, it would, by definition.  */
  34       return ENOTDIR;
  35     default:
  36       return error;
  37     }
  38 }
  39
  40 error_t
  41 __hurd_file_name_lookup (error_t (*use_init_port)
  42                            (int which, error_t (*operate) (file_t)),
  43                          file_t (*get_dtable_port) (int fd),
  44                          error_t (*lookup)
  45                            (file_t dir, const char *name, int flags, mode_t mode,
  46                             retry_type *do_retry, string_t retry_name,
  47                             mach_port_t *result),
  48                          const char *file_name, int flags, mode_t mode,
  49                          file_t *result)
  50 {
  51   error_t err;
  52   enum retry_type doretry;
  53   char retryname[1024];         /* XXX string_t LOSES! */
  54   int startport;
  55
  56   error_t lookup_op (mach_port_t startdir)
  57     {
  58       return lookup_error ((*lookup) (startdir, file_name, flags, mode,
  59                                       &doretry, retryname, result));
  60     }
  61
  62   if (! lookup)
  63     lookup = __dir_lookup;
  64
  65   if (file_name[0] == '\0')
  66     return ENOENT;
  67
  68   startport = (file_name[0] == '/') ? INIT_PORT_CRDIR : INIT_PORT_CWDIR;
  69   while (file_name[0] == '/')
  70     file_name++;
  71
  72   if (flags & O_NOFOLLOW)       /* See lookup-retry.c about O_NOFOLLOW.  */
  73     flags |= O_NOTRANS;
  74
  75   if (flags & O_DIRECTORY && (flags & O_NOFOLLOW) == 0)
  76     {
  77       /* The caller wants to require that the file we look up is a directory.
  78          We can do this without an extra RPC by appending a trailing slash
  79          to the file name we look up.  */
  80       size_t len = strlen (file_name);
  81       if (len == 0)
  82         file_name = "/";
  83       else if (file_name[len - 1] != '/')
  84         {
  85           char *n = alloca (len + 2);
  86           memcpy (n, file_name, len);
  87           n[len] = '/';
  88           n[len + 1] = '\0';
  89           file_name = n;
  90         }
  91     }
  92
  93   err = (*use_init_port) (startport, &lookup_op);
  94   if (! err)
  95     err = __hurd_file_name_lookup_retry (use_init_port, get_dtable_port,
  96                                          lookup, doretry, retryname,
  97                                          flags, mode, result);
  98
  99   return err;
 100 }
 101 weak_alias (__hurd_file_name_lookup, hurd_file_name_lookup)
 102
 103 error_t
 104 __hurd_file_name_split (error_t (*use_init_port)
 105                           (int which, error_t (*operate) (file_t)),
 106                         file_t (*get_dtable_port) (int fd),
 107                         error_t (*lookup)
 108                           (file_t dir, const char *name, int flags, mode_t mode,
 109                            retry_type *do_retry, string_t retry_name,
 110                            mach_port_t *result),
 111                         const char *file_name,
 112                         file_t *dir, char **name)
 113 {
 114   error_t addref (file_t crdir)
 115     {
 116       *dir = crdir;
 117       return __mach_port_mod_refs (__mach_task_self (),
 118                                    crdir, MACH_PORT_RIGHT_SEND, +1);
 119     }
 120
 121   const char *lastslash = strrchr (file_name, '/');
 122
 123   if (lastslash != NULL)
 124     {
 125       if (lastslash == file_name)
 126         {
 127           /* "/foobar" => crdir + "foobar".  */
 128           *name = (char *) file_name + 1;
 129           return (*use_init_port) (INIT_PORT_CRDIR, &addref);
 130         }
 131       else
 132         {
 133           /* "/dir1/dir2/.../file".  */
 134           char dirname[lastslash - file_name + 1];
 135           memcpy (dirname, file_name, lastslash - file_name);
 136           dirname[lastslash - file_name] = '\0';
 137           *name = (char *) lastslash + 1;
 138           return
 139             __hurd_file_name_lookup (use_init_port, get_dtable_port, lookup,
 140                                      dirname, 0, 0, dir);
 141         }
 142     }
 143   else if (file_name[0] == '\0')
 144     return ENOENT;
 145   else
 146     {
 147       /* "foobar" => cwdir + "foobar".  */
 148       *name = (char *) file_name;
 149       return (*use_init_port) (INIT_PORT_CWDIR, &addref);
 150     }
 151 }
 152 weak_alias (__hurd_file_name_split, hurd_file_name_split)
 153
 154 /* This is the same as hurd_file_name_split, except that it ignores
 155    trailing slashes (so *NAME is never "").  */
 156 error_t
 157 __hurd_directory_name_split (error_t (*use_init_port)
 158                              (int which, error_t (*operate) (file_t)),
 159                              file_t (*get_dtable_port) (int fd),
 160                              error_t (*lookup)
 161                              (file_t dir, const char *name, int flags, mode_t mode,
 162                               retry_type *do_retry, string_t retry_name,
 163                               mach_port_t *result),
 164                              const char *file_name,
 165                              file_t *dir, char **name)
 166 {
 167   error_t addref (file_t crdir)
 168     {
 169       *dir = crdir;
 170       return __mach_port_mod_refs (__mach_task_self (),
 171                                    crdir, MACH_PORT_RIGHT_SEND, +1);
 172     }
 173
 174   const char *lastslash = strrchr (file_name, '/');
 175
 176   if (lastslash != NULL && lastslash[1] == '\0')
 177     {
 178       /* Trailing slash doesn't count.  Look back further.  */
 179
 180       /* Back up over all trailing slashes.  */
 181       while (lastslash > file_name && *lastslash == '/')
 182         --lastslash;
 183
 184       /* Find the last one earlier in the string, before the trailing ones.  */
 185       lastslash = __memrchr (file_name, '/', lastslash - file_name);
 186     }
 187
 188   if (lastslash != NULL)
 189     {
 190       if (lastslash == file_name)
 191         {
 192           /* "/foobar" => crdir + "foobar".  */
 193           *name = (char *) file_name + 1;
 194           return (*use_init_port) (INIT_PORT_CRDIR, &addref);
 195         }
 196       else
 197         {
 198           /* "/dir1/dir2/.../file".  */
 199           char dirname[lastslash - file_name + 1];
 200           memcpy (dirname, file_name, lastslash - file_name);
 201           dirname[lastslash - file_name] = '\0';
 202           *name = (char *) lastslash + 1;
 203           return
 204             __hurd_file_name_lookup (use_init_port, get_dtable_port, lookup,
 205                                      dirname, 0, 0, dir);
 206         }
 207     }
 208   else if (file_name[0] == '\0')
 209     return ENOENT;
 210   else
 211     {
 212       /* "foobar" => cwdir + "foobar".  */
 213       *name = (char *) file_name;
 214       return (*use_init_port) (INIT_PORT_CWDIR, &addref);
 215     }
 216 }
 217 weak_alias (__hurd_directory_name_split, hurd_directory_name_split)
 218
 219 \f
 220 file_t
 221 __file_name_lookup (const char *file_name, int flags, mode_t mode)
 222 {
 223   error_t err;
 224   file_t result;
 225
 226   err = __hurd_file_name_lookup (&_hurd_ports_use, &__getdport, 0,
 227                                  file_name, flags, mode & ~_hurd_umask,
 228                                  &result);
 229
 230   return err ? (__hurd_fail (err), MACH_PORT_NULL) : result;
 231 }
 232 weak_alias (__file_name_lookup, file_name_lookup)
 233
 234
 235 file_t
 236 __file_name_split (const char *file_name, char **name)
 237 {
 238   error_t err;
 239   file_t result;
 240
 241   err = __hurd_file_name_split (&_hurd_ports_use, &__getdport, 0,
 242                                 file_name, &result, name);
 243
 244   return err ? (__hurd_fail (err), MACH_PORT_NULL) : result;
 245 }
 246 weak_alias (__file_name_split, file_name_split)
 247
 248 file_t
 249 __directory_name_split (const char *directory_name, char **name)
 250 {
 251   error_t err;
 252   file_t result;
 253
 254   err = __hurd_directory_name_split (&_hurd_ports_use, &__getdport, 0,
 255                                      directory_name, &result, name);
 256
 257   return err ? (__hurd_fail (err), MACH_PORT_NULL) : result;
 258 }
 259 weak_alias (__directory_name_split, directory_name_split)
 260
 261
 262 file_t
 263 __file_name_lookup_under (file_t startdir,
 264                           const char *file_name, int flags, mode_t mode)
 265 {
 266   error_t err;
 267   file_t result;
 268
 269   error_t use_init_port (int which, error_t (*operate) (mach_port_t))
 270     {
 271       return (which == INIT_PORT_CWDIR ? (*operate) (startdir)
 272               : _hurd_ports_use (which, operate));
 273     }
 274
 275   err = __hurd_file_name_lookup (&use_init_port, &__getdport, 0,
 276                                  file_name, flags, mode & ~_hurd_umask,
 277                                  &result);
 278
 279   return err ? (__hurd_fail (err), MACH_PORT_NULL) : result;
 280 }
 281 weak_alias (__file_name_lookup_under, file_name_lookup_under)