hurd/xattr.c

   1 /* Support for *xattr interfaces on GNU/Hurd.
   2    Copyright (C) 2006-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <hurd.h>
  20 #include <hurd/xattr.h>
  21 #include <string.h>
  22 #include <sys/mman.h>
  23
  24 /* Right now we support only a fixed set of xattr names for Hurd features.
  25    There are no RPC interfaces for free-form xattr names and values.
  26
  27    Name                 Value encoding
  28    ----                 ----- --------
  29    gnu.author           empty if st_author==st_uid
  30                         uid_t giving st_author value
  31    gnu.translator       empty if no passive translator
  32                         translator and arguments: "/hurd/foo\0arg1\0arg2\0"
  33 */
  34
  35 error_t
  36 _hurd_xattr_get (io_t port, const char *name, void *value, size_t *size)
  37 {
  38   if (strncmp (name, "gnu.", 4))
  39     return EOPNOTSUPP;
  40   name += 4;
  41
  42   if (!strcmp (name, "author"))
  43     {
  44       struct stat64 st;
  45       error_t err = __io_stat (port, &st);
  46       if (err)
  47         return err;
  48       if (st.st_author == st.st_uid)
  49         *size = 0;
  50       else if (value)
  51         {
  52           if (*size < sizeof st.st_author)
  53             return ERANGE;
  54           memcpy (value, &st.st_author, sizeof st.st_author);
  55         }
  56       *size = sizeof st.st_author;
  57       return 0;
  58     }
  59
  60   if (!strcmp (name, "translator"))
  61     {
  62       char *buf = value;
  63       mach_msg_type_number_t bufsz = value ? *size : 0;
  64       error_t err = __file_get_translator (port, &buf, &bufsz);
  65       if (err)
  66         return err;
  67       if (value != NULL && *size < bufsz)
  68         {
  69           if (buf != value)
  70             __munmap (buf, bufsz);
  71           return ERANGE;
  72         }
  73       if (buf != value && bufsz > 0)
  74         {
  75           if (value != NULL)
  76             memcpy (value, buf, bufsz);
  77           __munmap (buf, bufsz);
  78         }
  79       *size = bufsz;
  80       return 0;
  81     }
  82
  83   return EOPNOTSUPP;
  84 }
  85
  86 error_t
  87 _hurd_xattr_set (io_t port, const char *name, const void *value, size_t size,
  88                  int flags)
  89 {
  90   if (strncmp (name, "gnu.", 4))
  91     return EOPNOTSUPP;
  92   name += 4;
  93
  94   if (!strcmp (name, "author"))
  95     switch (size)
  96       {
  97       default:
  98         return EINVAL;
  99       case 0:                   /* "Clear" author by setting to st_uid. */
 100         {
 101           struct stat64 st;
 102           error_t err = __io_stat (port, &st);
 103           if (err)
 104             return err;
 105           if (st.st_author == st.st_uid)
 106             {
 107               /* Nothing to do.  */
 108               if (flags & XATTR_REPLACE)
 109                 return ENODATA;
 110               return 0;
 111             }
 112           if (flags & XATTR_CREATE)
 113             return EEXIST;
 114           return __file_chauthor (port, st.st_uid);
 115         }
 116       case sizeof (uid_t):      /* Set the author.  */
 117         {
 118           uid_t id;
 119           memcpy (&id, value, sizeof id);
 120           if (flags & (XATTR_CREATE|XATTR_REPLACE))
 121             {
 122               struct stat64 st;
 123               error_t err = __io_stat (port, &st);
 124               if (err)
 125                 return err;
 126               if (st.st_author == st.st_uid)
 127                 {
 128                   if (flags & XATTR_REPLACE)
 129                     return ENODATA;
 130                 }
 131               else if (flags & XATTR_CREATE)
 132                 return EEXIST;
 133               if (st.st_author == id)
 134                 /* Nothing to do.  */
 135                 return 0;
 136             }
 137           return __file_chauthor (port, id);
 138         }
 139       }
 140
 141   if (!strcmp (name, "translator"))
 142     {
 143       if (flags & XATTR_REPLACE)
 144         {
 145           /* Must make sure it's already there.  */
 146           char *buf = NULL;
 147           mach_msg_type_number_t bufsz = 0;
 148           error_t err = __file_get_translator (port, &buf, &bufsz);
 149           if (err)
 150             return err;
 151           if (bufsz > 0)
 152             {
 153               __munmap (buf, bufsz);
 154               return ENODATA;
 155             }
 156         }
 157       return __file_set_translator (port,
 158                                     FS_TRANS_SET | ((flags & XATTR_CREATE)
 159                                                     ? FS_TRANS_EXCL : 0), 0, 0,
 160                                     value, size,
 161                                     MACH_PORT_NULL, MACH_MSG_TYPE_COPY_SEND);
 162     }
 163
 164   return EOPNOTSUPP;
 165 }
 166
 167 error_t
 168 _hurd_xattr_remove (io_t port, const char *name)
 169 {
 170   return _hurd_xattr_set (port, name, NULL, 0, XATTR_REPLACE);
 171 }
 172
 173 error_t
 174 _hurd_xattr_list (io_t port, void *buffer, size_t *size)
 175 {
 176   size_t total = 0;
 177   char *bufp = buffer;
 178   inline void add (const char *name, size_t len)
 179     {
 180       total += len;
 181       if (bufp != NULL && total <= *size)
 182         bufp = __mempcpy (bufp, name, len);
 183     }
 184 #define add(s) add (s, sizeof s)
 185
 186   struct stat64 st;
 187   error_t err = __io_stat (port, &st);
 188   if (err)
 189     return err;
 190
 191   if (st.st_author != st.st_uid)
 192     add ("gnu.author");
 193   if (st.st_mode & S_IPTRANS)
 194     add ("gnu.translator");
 195
 196   if (buffer != NULL && total > *size)
 197     return ERANGE;
 198   *size = total;
 199   return 0;
 200 }