Dogcows Code - chaz/tar/blob - src/names.c

   1 /* Look up user and/or group names.
   2    Copyright (C) 1988 Free Software Foundation
   3
   4 This file is part of GNU Tar.
   5
   6 GNU Tar is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Tar is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Tar; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20 /*
  21  * Look up user and/or group names.
  22  *
  23  * This file should be modified for non-unix systems to do something
  24  * reasonable.
  25  *
  26  * @(#)names.c 1.3 10/30/87 - gnu
  27  */
  28 #include <sys/types.h>
  29 #include "tar.h"
  30
  31 extern  char    *strncpy();
  32
  33 #ifndef NONAMES
  34 /* Whole module goes away if NONAMES defined.  Otherwise... */
  35 #include <pwd.h>
  36 #include <grp.h>
  37
  38 static int      saveuid = -993;
  39 static char     saveuname[TUNMLEN];
  40 static int      my_uid = -993;
  41
  42 static int      savegid = -993;
  43 static char     savegname[TGNMLEN];
  44 static int      my_gid = -993;
  45
  46 #define myuid   ( my_uid < 0? (my_uid = getuid()): my_uid )
  47 #define mygid   ( my_gid < 0? (my_gid = getgid()): my_gid )
  48
  49 /*
  50  * Look up a user or group name from a uid/gid, maintaining a cache.
  51  * FIXME, for now it's a one-entry cache.
  52  * FIXME2, the "-993" is to reduce the chance of a hit on the first lookup.
  53  *
  54  * This is ifdef'd because on Suns, it drags in about 38K of "yellow
  55  * pages" code, roughly doubling the program size.  Thanks guys.
  56  */
  57 void
  58 finduname(uname, uid)
  59         char    uname[TUNMLEN];
  60         int     uid;
  61 {
  62         struct passwd   *pw;
  63         extern struct passwd *getpwuid ();
  64
  65         if (uid != saveuid) {
  66                 saveuid = uid;
  67                 saveuname[0] = '\0';
  68                 pw = getpwuid(uid);
  69                 if (pw)
  70                         strncpy(saveuname, pw->pw_name, TUNMLEN);
  71         }
  72         strncpy(uname, saveuname, TUNMLEN);
  73 }
  74
  75 int
  76 finduid(uname)
  77         char    uname[TUNMLEN];
  78 {
  79         struct passwd   *pw;
  80         extern struct passwd *getpwnam();
  81
  82         if (uname[0] != saveuname[0]    /* Quick test w/o proc call */
  83             || 0!=strncmp(uname, saveuname, TUNMLEN)) {
  84                 strncpy(saveuname, uname, TUNMLEN);
  85                 pw = getpwnam(uname);
  86                 if (pw) {
  87                         saveuid = pw->pw_uid;
  88                 } else {
  89                         saveuid = myuid;
  90                 }
  91         }
  92         return saveuid;
  93 }
  94
  95
  96 void
  97 findgname(gname, gid)
  98         char    gname[TGNMLEN];
  99         int     gid;
 100 {
 101         struct group    *gr;
 102         extern struct group *getgrgid ();
 103
 104         if (gid != savegid) {
 105                 savegid = gid;
 106                 savegname[0] = '\0';
 107                 (void)setgrent();
 108                 gr = getgrgid(gid);
 109                 if (gr)
 110                         strncpy(savegname, gr->gr_name, TGNMLEN);
 111         }
 112         (void) strncpy(gname, savegname, TGNMLEN);
 113 }
 114
 115
 116 int
 117 findgid(gname)
 118         char    gname[TUNMLEN];
 119 {
 120         struct group    *gr;
 121         extern struct group *getgrnam();
 122
 123         if (gname[0] != savegname[0]    /* Quick test w/o proc call */
 124             || 0!=strncmp(gname, savegname, TUNMLEN)) {
 125                 strncpy(savegname, gname, TUNMLEN);
 126                 gr = getgrnam(gname);
 127                 if (gr) {
 128                         savegid = gr->gr_gid;
 129                 } else {
 130                         savegid = mygid;
 131                 }
 132         }
 133         return savegid;
 134 }
 135 #endif