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     {
  68       saveuid = uid;
  69       saveuname[0] = '\0';
  70       pw = getpwuid (uid);
  71       if (pw)
  72         strncpy (saveuname, pw->pw_name, TUNMLEN);
  73     }
  74   strncpy (uname, saveuname, TUNMLEN);
  75 }
  76
  77 int
  78 finduid (uname)
  79      char uname[TUNMLEN];
  80 {
  81   struct passwd *pw;
  82   extern struct passwd *getpwnam ();
  83
  84   if (uname[0] != saveuname[0]  /* Quick test w/o proc call */
  85       || 0 != strncmp (uname, saveuname, TUNMLEN))
  86     {
  87       strncpy (saveuname, uname, TUNMLEN);
  88       pw = getpwnam (uname);
  89       if (pw)
  90         {
  91           saveuid = pw->pw_uid;
  92         }
  93       else
  94         {
  95           saveuid = myuid;
  96         }
  97     }
  98   return saveuid;
  99 }
 100
 101
 102 void
 103 findgname (gname, gid)
 104      char gname[TGNMLEN];
 105      int gid;
 106 {
 107   struct group *gr;
 108 #ifndef HAVE_GETGRGID
 109   extern struct group *getgrgid ();
 110 #endif
 111
 112   if (gid != savegid)
 113     {
 114       savegid = gid;
 115       savegname[0] = '\0';
 116       (void) setgrent ();
 117       gr = getgrgid (gid);
 118       if (gr)
 119         strncpy (savegname, gr->gr_name, TGNMLEN);
 120     }
 121   (void) strncpy (gname, savegname, TGNMLEN);
 122 }
 123
 124
 125 int
 126 findgid (gname)
 127      char gname[TUNMLEN];
 128 {
 129   struct group *gr;
 130   extern struct group *getgrnam ();
 131
 132   if (gname[0] != savegname[0]  /* Quick test w/o proc call */
 133       || 0 != strncmp (gname, savegname, TUNMLEN))
 134     {
 135       strncpy (savegname, gname, TUNMLEN);
 136       gr = getgrnam (gname);
 137       if (gr)
 138         {
 139           savegid = gr->gr_gid;
 140         }
 141       else
 142         {
 143           savegid = mygid;
 144         }
 145     }
 146   return savegid;
 147 }
 148
 149 #endif