uidlist.c

   1 /*
   2    Copyright (C) Andrew Tridgell 1996
   3    Copyright (C) Paul Mackerras 1996
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software
  17    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18 */
  19
  20 /* handle the mapping of uid/gid and user/group names between systems.
  21    If the source username/group does not exist on the target then use
  22    the numeric ids. Never do any mapping for uid=0 or gid=0 as these
  23    are special.
  24 */
  25
  26 #include "rsync.h"
  27
  28 extern int preserve_uid;
  29 extern int preserve_gid;
  30 extern int numeric_ids;
  31 extern int am_root;
  32
  33 struct idlist {
  34         struct idlist *next;
  35         int id, id2;
  36         char *name;
  37 };
  38
  39 static struct idlist *uidlist;
  40 static struct idlist *gidlist;
  41
  42 static struct idlist *add_list(int id, char *name)
  43 {
  44         struct idlist *list = new(struct idlist);
  45         if (!list) out_of_memory("add_list");
  46         list->next = NULL;
  47         list->name = strdup(name);
  48         if (!list->name) out_of_memory("add_list");
  49         list->id = (int)id;
  50         return list;
  51 }
  52
  53
  54
  55 /* turn a uid into a user name */
  56 static char *uid_to_name(uid_t uid)
  57 {
  58         struct passwd *pass = getpwuid(uid);
  59         if (pass) return(pass->pw_name);
  60         return NULL;
  61 }
  62
  63 /* turn a gid into a group name */
  64 static char *gid_to_name(gid_t gid)
  65 {
  66         struct group *grp = getgrgid(gid);
  67         if (grp) return(grp->gr_name);
  68         return NULL;
  69 }
  70
  71 static int map_uid(int id, char *name)
  72 {
  73         uid_t uid;
  74         if (name_to_uid(name, &uid) && uid != 0)
  75                 return uid;
  76         return id;
  77 }
  78
  79 static int map_gid(int id, char *name)
  80 {
  81         gid_t gid;
  82         if (name_to_gid(name, &gid) && gid != 0)
  83                 return gid;
  84         return id;
  85 }
  86
  87 /* this function is a definate candidate for a faster algorithm */
  88 static uid_t match_uid(uid_t uid)
  89 {
  90         static uid_t last_in, last_out;
  91         struct idlist *list = uidlist;
  92
  93         if (uid == last_in) return last_out;
  94
  95         last_in = uid;
  96
  97         while (list) {
  98                 if (list->id == (int)uid) {
  99                         last_out = (uid_t)list->id2;
 100                         return last_out;
 101                 }
 102                 list = list->next;
 103         }
 104
 105         last_out = uid;
 106         return last_out;
 107 }
 108
 109 static gid_t match_gid(gid_t gid)
 110 {
 111         static gid_t last_in, last_out;
 112         struct idlist *list = gidlist;
 113
 114         if (gid == last_in) return last_out;
 115
 116         last_in = gid;
 117
 118         while (list) {
 119                 if (list->id == (int)gid) {
 120                         last_out = (gid_t)list->id2;
 121                         return last_out;
 122                 }
 123                 list = list->next;
 124         }
 125
 126         if (am_root)
 127                 last_out = gid;
 128         else
 129                 last_out = (gid_t) -1;
 130         return last_out;
 131 }
 132
 133 /* add a uid to the list of uids */
 134 void add_uid(uid_t uid)
 135 {
 136         struct idlist *list = uidlist;
 137         char *name;
 138
 139         if (numeric_ids) return;
 140
 141         /* don't map root */
 142         if (uid==0) return;
 143
 144         if (!list) {
 145                 if (!(name = uid_to_name(uid))) return;
 146                 uidlist = add_list((int)uid, name);
 147                 return;
 148         }
 149
 150         while (list->next) {
 151                 if (list->id == (int)uid) return;
 152                 list = list->next;
 153         }
 154
 155         if (list->id == (int)uid) return;
 156
 157         if (!(name = uid_to_name(uid))) return;
 158
 159         list->next = add_list((int)uid, name);
 160 }
 161
 162 /* add a gid to the list of gids */
 163 void add_gid(gid_t gid)
 164 {
 165         struct idlist *list = gidlist;
 166         char *name;
 167
 168         if (numeric_ids) return;
 169
 170         /* don't map root */
 171         if (gid==0) return;
 172
 173         if (!list) {
 174                 if (!(name = gid_to_name(gid))) return;
 175                 gidlist = add_list((int)gid, name);
 176                 return;
 177         }
 178
 179         while (list->next) {
 180                 if (list->id == (int)gid) return;
 181                 list = list->next;
 182         }
 183
 184         if (list->id == (int)gid) return;
 185
 186         if (!(name = gid_to_name(gid))) return;
 187
 188         list->next = add_list((int)gid, name);
 189 }
 190
 191
 192 /* send a complete uid/gid mapping to the peer */
 193 void send_uid_list(int f)
 194 {
 195         struct idlist *list;
 196
 197         if (numeric_ids) return;
 198
 199         if (preserve_uid) {
 200                 /* we send sequences of uid/byte-length/name */
 201                 list = uidlist;
 202                 while (list) {
 203                         int len = strlen(list->name);
 204                         write_int(f, list->id);
 205                         write_byte(f, len);
 206                         write_buf(f, list->name, len);
 207                         list = list->next;
 208                 }
 209
 210                 /* terminate the uid list with a 0 uid. We explicitly exclude
 211                    0 from the list */
 212                 write_int(f, 0);
 213         }
 214
 215         if (preserve_gid) {
 216                 list = gidlist;
 217                 while (list) {
 218                         int len = strlen(list->name);
 219                         write_int(f, list->id);
 220                         write_byte(f, len);
 221                         write_buf(f, list->name, len);
 222                         list = list->next;
 223                 }
 224                 write_int(f, 0);
 225         }
 226 }
 227
 228 /* recv a complete uid/gid mapping from the peer and map the uid/gid
 229    in the file list to local names */
 230 void recv_uid_list(int f, struct file_list *flist)
 231 {
 232         int id, i;
 233         char *name;
 234         struct idlist *list;
 235
 236         if (numeric_ids) return;
 237
 238         if (preserve_uid) {
 239                 /* read the uid list */
 240                 list = uidlist;
 241                 id = read_int(f);
 242                 while (id != 0) {
 243                         int len = read_byte(f);
 244                         name = new_array(char, len+1);
 245                         if (!name) out_of_memory("recv_uid_list");
 246                         read_sbuf(f, name, len);
 247                         if (!list) {
 248                                 uidlist = add_list(id, name);
 249                                 list = uidlist;
 250                         } else {
 251                                 list->next = add_list(id, name);
 252                                 list = list->next;
 253                         }
 254                         list->id2 = map_uid(id, name);
 255                         free(name);
 256                         id = read_int(f);
 257                 }
 258         }
 259
 260
 261         if (preserve_gid) {
 262                 /* and the gid list */
 263                 list = gidlist;
 264                 id = read_int(f);
 265                 while (id != 0) {
 266                         int len = read_byte(f);
 267                         name = new_array(char, len+1);
 268                         if (!name) out_of_memory("recv_uid_list");
 269                         read_sbuf(f, name, len);
 270                         if (!list) {
 271                                 gidlist = add_list(id, name);
 272                                 list = gidlist;
 273                         } else {
 274                                 list->next = add_list(id, name);
 275                                 list = list->next;
 276                         }
 277                         list->id2 = map_gid(id, name);
 278                         free(name);
 279                         id = read_int(f);
 280                 }
 281         }
 282
 283         if (!(am_root && preserve_uid) && !preserve_gid) return;
 284
 285         /* now convert the uid/gid of all files in the list to the mapped
 286            uid/gid */
 287         for (i=0;i<flist->count;i++) {
 288                 if (am_root && preserve_uid && flist->files[i]->uid != 0) {
 289                         flist->files[i]->uid = match_uid(flist->files[i]->uid);
 290                 }
 291                 if (preserve_gid && flist->files[i]->gid != 0) {
 292                         flist->files[i]->gid = match_gid(flist->files[i]->gid);
 293                 }
 294         }
 295 }