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         extern struct passwd *getpwuid ();
  63
  64         if (uid != saveuid) {
  65                 saveuid = uid;
  66                 saveuname[0] = '\0';
  67                 pw = getpwuid(uid);
  68                 if (pw)
  69                         strncpy(saveuname, pw->pw_name, TUNMLEN);
  70         }
  71         strncpy(uname, saveuname, TUNMLEN);
  72 }
  73
  74 int
  75 finduid(uname)
  76         char    uname[TUNMLEN];
  77 {
  78         struct passwd   *pw;
  79         extern struct passwd *getpwnam();
  80
  81         if (uname[0] != saveuname[0]    /* Quick test w/o proc call */
  82             || 0!=strncmp(uname, saveuname, TUNMLEN)) {
  83                 strncpy(saveuname, uname, TUNMLEN);
  84                 pw = getpwnam(uname);
  85                 if (pw) {
  86                         saveuid = pw->pw_uid;
  87                 } else {
  88                         saveuid = myuid;
  89                 }
  90         }
  91         return saveuid;
  92 }
  93
  94
  95 void
  96 findgname(gname, gid)
  97         char    gname[TGNMLEN];
  98         int     gid;
  99 {
 100         struct group    *gr;
 101         extern struct group *getgrgid ();
 102
 103         if (gid != savegid) {
 104                 savegid = gid;
 105                 savegname[0] = '\0';
 106                 (void)setgrent();
 107                 gr = getgrgid(gid);
 108                 if (gr)
 109                         strncpy(savegname, gr->gr_name, TGNMLEN);
 110         }
 111         (void) strncpy(gname, savegname, TGNMLEN);
 112 }
 113
 114
 115 int
 116 findgid(gname)
 117         char    gname[TUNMLEN];
 118 {
 119         struct group    *gr;
 120         extern struct group *getgrnam();
 121
 122         if (gname[0] != savegname[0]    /* Quick test w/o proc call */
 123             || 0!=strncmp(gname, savegname, TUNMLEN)) {
 124                 strncpy(savegname, gname, TUNMLEN);
 125                 gr = getgrnam(gname);
 126                 if (gr) {
 127                         savegid = gr->gr_gid;
 128                 } else {
 129                         savegid = mygid;
 130                 }
 131         }
 132         return savegid;
 133 }
 134 #endif