hurd/hurdlookup.c

   1 /* Copyright (C) 1992-2024 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/fd.h>
  20 #include <hurd/lookup.h>
  21 #include <string.h>
  22 #include <fcntl.h>
  23
  24
  25 /* Translate the error from dir_lookup into the error the user sees.  */
  26 static inline error_t
  27 lookup_error (error_t error)
  28 {
  29   switch (error)
  30     {
  31     case EOPNOTSUPP:
  32     case MIG_BAD_ID:
  33       /* These indicate that the server does not understand dir_lookup
  34          at all.  If it were a directory, it would, by definition.  */
  35       return ENOTDIR;
  36     default:
  37       return error;
  38     }
  39 }
  40
  41 error_t
  42 __hurd_file_name_lookup (error_t (*use_init_port)
  43                            (int which, error_t (*operate) (file_t)),
  44                          file_t (*get_dtable_port) (int fd),
  45                          error_t (*lookup)
  46                            (file_t dir, const char *name, int flags, mode_t mode,
  47                             retry_type *do_retry, string_t retry_name,
  48                             mach_port_t *result),
  49                          const char *file_name, int flags, mode_t mode,
  50                          file_t *result)
  51 {
  52   error_t err;
  53   enum retry_type doretry;
  54   char retryname[1024];         /* XXX string_t LOSES! */
  55   int startport;
  56
  57   error_t lookup_op (mach_port_t startdir)
  58     {
  59       return lookup_error ((*lookup) (startdir, file_name, flags, mode,
  60                                       &doretry, retryname, result));
  61     }
  62
  63   if (! lookup)
  64     lookup = __dir_lookup;
  65
  66   if (file_name[0] == '\0')
  67     return ENOENT;
  68
  69   startport = (file_name[0] == '/') ? INIT_PORT_CRDIR : INIT_PORT_CWDIR;
  70   while (file_name[0] == '/')
  71     file_name++;
  72
  73   if (flags & O_NOFOLLOW)       /* See lookup-retry.c about O_NOFOLLOW.  */
  74     flags |= O_NOTRANS;
  75
  76   if (flags & O_DIRECTORY && (flags & O_NOFOLLOW) == 0)
  77     {
  78       /* The caller wants to require that the file we look up is a directory.
  79          We can do this without an extra RPC by appending a trailing slash
  80          to the file name we look up.  */
  81       size_t len = strlen (file_name);
  82       if (len == 0)
  83         file_name = "/";
  84       else if (file_name[len - 1] != '/')
  85         {
  86           char *n = alloca (len + 2);
  87           memcpy (n, file_name, len);
  88           n[len] = '/';
  89           n[len + 1] = '\0';
  90           file_name = n;
  91         }
  92     }
  93
  94   err = (*use_init_port) (startport, &lookup_op);
  95   if (! err)
  96     err = __hurd_file_name_lookup_retry (use_init_port, get_dtable_port,
  97                                          lookup, doretry, retryname,
  98                                          flags, mode, result);
  99
 100   return err;
 101 }
 102 weak_alias (__hurd_file_name_lookup, hurd_file_name_lookup)
 103
 104 error_t
 105 __hurd_file_name_split (error_t (*use_init_port)
 106                           (int which, error_t (*operate) (file_t)),
 107                         file_t (*get_dtable_port) (int fd),
 108                         error_t (*lookup)
 109                           (file_t dir, const char *name, int flags, mode_t mode,
 110                            retry_type *do_retry, string_t retry_name,
 111                            mach_port_t *result),
 112                         const char *file_name,
 113                         file_t *dir, char **name)
 114 {
 115   error_t addref (file_t crdir)
 116     {
 117       *dir = crdir;
 118       return __mach_port_mod_refs (__mach_task_self (),
 119                                    crdir, MACH_PORT_RIGHT_SEND, +1);
 120     }
 121
 122   const char *lastslash = strrchr (file_name, '/');
 123
 124   if (lastslash != NULL)
 125     {
 126       if (lastslash == file_name)
 127         {
 128           /* "/foobar" => crdir + "foobar".  */
 129           *name = (char *) file_name + 1;
 130           return (*use_init_port) (INIT_PORT_CRDIR, &addref);
 131         }
 132       else
 133         {
 134           /* "/dir1/dir2/.../file".  */
 135           char dirname[lastslash - file_name + 1];
 136           memcpy (dirname, file_name, lastslash - file_name);
 137           dirname[lastslash - file_name] = '\0';
 138           *name = (char *) lastslash + 1;
 139           return
 140             __hurd_file_name_lookup (use_init_port, get_dtable_port, lookup,
 141                                      dirname, 0, 0, dir);
 142         }
 143     }
 144   else if (file_name[0] == '\0')
 145     return ENOENT;
 146   else
 147     {
 148       /* "foobar" => cwdir + "foobar".  */
 149       *name = (char *) file_name;
 150       return (*use_init_port) (INIT_PORT_CWDIR, &addref);
 151     }
 152 }
 153 weak_alias (__hurd_file_name_split, hurd_file_name_split)
 154
 155 /* This is the same as hurd_file_name_split, except that it ignores
 156    trailing slashes (so *NAME is never "").  */
 157 error_t
 158 __hurd_directory_name_split (error_t (*use_init_port)
 159                              (int which, error_t (*operate) (file_t)),
 160                              file_t (*get_dtable_port) (int fd),
 161                              error_t (*lookup)
 162                              (file_t dir, const char *name, int flags, mode_t mode,
 163                               retry_type *do_retry, string_t retry_name,
 164                               mach_port_t *result),
 165                              const char *file_name,
 166                              file_t *dir, char **name)
 167 {
 168   error_t addref (file_t crdir)
 169     {
 170       *dir = crdir;
 171       return __mach_port_mod_refs (__mach_task_self (),
 172                                    crdir, MACH_PORT_RIGHT_SEND, +1);
 173     }
 174
 175   const char *lastslash = strrchr (file_name, '/');
 176
 177   if (lastslash != NULL && lastslash[1] == '\0')
 178     {
 179       /* Trailing slash doesn't count.  Look back further.  */
 180
 181       /* Back up over all trailing slashes.  */
 182       while (lastslash > file_name && *lastslash == '/')
 183         --lastslash;
 184
 185       /* Find the last one earlier in the string, before the trailing ones.  */
 186       lastslash = __memrchr (file_name, '/', lastslash - file_name);
 187     }
 188
 189   if (lastslash != NULL)
 190     {
 191       if (lastslash == file_name)
 192         {
 193           /* "/foobar" => crdir + "foobar".  */
 194           *name = (char *) file_name + 1;
 195           return (*use_init_port) (INIT_PORT_CRDIR, &addref);
 196         }
 197       else
 198         {
 199           /* "/dir1/dir2/.../file".  */
 200           char dirname[lastslash - file_name + 1];
 201           memcpy (dirname, file_name, lastslash - file_name);
 202           dirname[lastslash - file_name] = '\0';
 203           *name = (char *) lastslash + 1;
 204           return
 205             __hurd_file_name_lookup (use_init_port, get_dtable_port, lookup,
 206                                      dirname, 0, 0, dir);
 207         }
 208     }
 209   else if (file_name[0] == '\0')
 210     return ENOENT;
 211   else
 212     {
 213       /* "foobar" => cwdir + "foobar".  */
 214       *name = (char *) file_name;
 215       return (*use_init_port) (INIT_PORT_CWDIR, &addref);
 216     }
 217 }
 218 weak_alias (__hurd_directory_name_split, hurd_directory_name_split)
 219
 220 \f
 221 file_t
 222 __file_name_lookup (const char *file_name, int flags, mode_t mode)
 223 {
 224   return __file_name_lookup_at (AT_FDCWD, 0, file_name, flags, mode);
 225 }
 226 weak_alias (__file_name_lookup, file_name_lookup)
 227
 228
 229 file_t
 230 __file_name_split (const char *file_name, char **name)
 231 {
 232   error_t err;
 233   file_t result;
 234
 235   err = __hurd_file_name_split (&_hurd_ports_use, &__getdport, 0,
 236                                 file_name, &result, name);
 237
 238   return err ? (__hurd_fail (err), MACH_PORT_NULL) : result;
 239 }
 240 weak_alias (__file_name_split, file_name_split)
 241
 242 file_t
 243 __directory_name_split (const char *directory_name, char **name)
 244 {
 245   error_t err;
 246   file_t result;
 247
 248   err = __hurd_directory_name_split (&_hurd_ports_use, &__getdport, 0,
 249                                      directory_name, &result, name);
 250
 251   return err ? (__hurd_fail (err), MACH_PORT_NULL) : result;
 252 }
 253 weak_alias (__directory_name_split, directory_name_split)
 254
 255
 256 file_t
 257 __file_name_lookup_under (file_t startdir,
 258                           const char *file_name, int flags, mode_t mode)
 259 {
 260   error_t err;
 261   file_t result;
 262
 263   error_t use_init_port (int which, error_t (*operate) (mach_port_t))
 264     {
 265       return (which == INIT_PORT_CWDIR ? (*operate) (startdir)
 266               : _hurd_ports_use (which, operate));
 267     }
 268
 269   err = __hurd_file_name_lookup (&use_init_port, &__getdport, 0,
 270                                  file_name, flags, mode & ~_hurd_umask,
 271                                  &result);
 272
 273   return err ? (__hurd_fail (err), MACH_PORT_NULL) : result;
 274 }
 275 weak_alias (__file_name_lookup_under, file_name_lookup_under)