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

   1 /* Look up user and/or group names.
   2    Copyright (C) 1988, 1992 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
  27 #include <sys/types.h>
  28 #include "tar.h"
  29 #include "port.h"
  30
  31 #ifndef NONAMES
  32 /* Whole module goes away if NONAMES defined.  Otherwise... */
  33 #include <stdio.h>
  34 #include <pwd.h>
  35 #include <grp.h>
  36
  37 static int      saveuid = -993;
  38 static char     saveuname[TUNMLEN];
  39 static int      my_uid = -993;
  40
  41 static int      savegid = -993;
  42 static char     savegname[TGNMLEN];
  43 static int      my_gid = -993;
  44
  45 #define myuid   ( my_uid < 0? (my_uid = getuid()): my_uid )
  46 #define mygid   ( my_gid < 0? (my_gid = getgid()): my_gid )
  47
  48 /*
  49  * Look up a user or group name from a uid/gid, maintaining a cache.
  50  * FIXME, for now it's a one-entry cache.
  51  * FIXME2, the "-993" is to reduce the chance of a hit on the first lookup.
  52  *
  53  * This is ifdef'd because on Suns, it drags in about 38K of "yellow
  54  * pages" code, roughly doubling the program size.  Thanks guys.
  55  */
  56 void
  57 finduname(uname, uid)
  58         char    uname[TUNMLEN];
  59         int     uid;
  60 {
  61         struct passwd   *pw;
  62 #ifndef HAVE_GETPWUID
  63         extern struct passwd *getpwuid ();
  64 #endif
  65
  66         if (uid != saveuid) {
  67                 saveuid = uid;
  68                 saveuname[0] = '\0';
  69                 pw = getpwuid(uid);
  70                 if (pw)
  71                         strncpy(saveuname, pw->pw_name, TUNMLEN);
  72         }
  73         strncpy(uname, saveuname, TUNMLEN);
  74 }
  75
  76 int
  77 finduid(uname)
  78         char    uname[TUNMLEN];
  79 {
  80         struct passwd   *pw;
  81         extern struct passwd *getpwnam();
  82
  83         if (uname[0] != saveuname[0]    /* Quick test w/o proc call */
  84             || 0!=strncmp(uname, saveuname, TUNMLEN)) {
  85                 strncpy(saveuname, uname, TUNMLEN);
  86                 pw = getpwnam(uname);
  87                 if (pw) {
  88                         saveuid = pw->pw_uid;
  89                 } else {
  90                         saveuid = myuid;
  91                 }
  92         }
  93         return saveuid;
  94 }
  95
  96
  97 void
  98 findgname(gname, gid)
  99         char    gname[TGNMLEN];
 100         int     gid;
 101 {
 102         struct group    *gr;
 103 #ifndef HAVE_GETGRGID
 104         extern struct group *getgrgid ();
 105 #endif
 106
 107         if (gid != savegid) {
 108                 savegid = gid;
 109                 savegname[0] = '\0';
 110                 (void)setgrent();
 111                 gr = getgrgid(gid);
 112                 if (gr)
 113                         strncpy(savegname, gr->gr_name, TGNMLEN);
 114         }
 115         (void) strncpy(gname, savegname, TGNMLEN);
 116 }
 117
 118
 119 int
 120 findgid(gname)
 121         char    gname[TUNMLEN];
 122 {
 123         struct group    *gr;
 124         extern struct group *getgrnam();
 125
 126         if (gname[0] != savegname[0]    /* Quick test w/o proc call */
 127             || 0!=strncmp(gname, savegname, TUNMLEN)) {
 128                 strncpy(savegname, gname, TUNMLEN);
 129                 gr = getgrnam(gname);
 130                 if (gr) {
 131                         savegid = gr->gr_gid;
 132                 } else {
 133                         savegid = mygid;
 134                 }
 135         }
 136         return savegid;
 137 }
 138 #endif