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