vfs/names.c

   1 /* Look up user and/or group names.
   2    Copyright (C) 1988, 1992 Free Software Foundation
   3
   4    From GNU Tar.
   5
   6 GNU Tar is free software; you can redistribute it and/or modify it
   7 under the terms of the GNU Library General Public License as published
   8 by 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 Library General Public License for more details.
  15
  16  * Namespace: finduname, finduid, findgname, findgid.
  17  */
  18
  19 /*
  20  * Look up user and/or group names.
  21  *
  22  * This file should be modified for non-unix systems to do something
  23  * reasonable.
  24  */
  25
  26 #include <config.h>
  27 #include <sys/types.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30 #define TAR_NAMES
  31 #include "tar.h"
  32 #include "names.h"
  33
  34 #include <stdio.h>
  35 #include <pwd.h>
  36 #include <grp.h>
  37
  38 #ifndef TUNMLEN
  39 #define TUNMLEN 256
  40 #endif
  41 #ifndef TGNMLEN
  42 #define TGNMLEN 256
  43 #endif
  44
  45 static int saveuid = -993;
  46 static char saveuname[TUNMLEN];
  47 static int my_uid = -993;
  48
  49 static int savegid = -993;
  50 static char savegname[TGNMLEN];
  51 static int my_gid = -993;
  52
  53 #define myuid   ( my_uid < 0? (my_uid = getuid()): my_uid )
  54 #define mygid   ( my_gid < 0? (my_gid = getgid()): my_gid )
  55
  56 /*
  57  * Look up a user or group name from a uid/gid, maintaining a cache.
  58  * FIXME, for now it's a one-entry cache.
  59  * FIXME2, the "-993" is to reduce the chance of a hit on the first lookup.
  60  *
  61  * This is ifdef'd because on Suns, it drags in about 38K of "yellow
  62  * pages" code, roughly doubling the program size.  Thanks guys.
  63  */
  64 void finduname (char *uname, int uid)
  65 {
  66     struct passwd *pw;
  67 #ifndef HAVE_GETPWUID
  68     extern struct passwd *getpwuid ();
  69 #endif
  70
  71     if (uid != saveuid) {
  72         saveuid = uid;
  73         saveuname[0] = '\0';
  74         pw = getpwuid (uid);
  75         if (pw)
  76             strncpy (saveuname, pw->pw_name, TUNMLEN);
  77     }
  78     strncpy (uname, saveuname, TUNMLEN);
  79 }
  80
  81 int finduid (char *uname)
  82 {
  83     struct passwd *pw;
  84     extern struct passwd *getpwnam ();
  85
  86     if (uname[0] != saveuname[0]/* Quick test w/o proc call */
  87         ||0 != strncmp (uname, saveuname, TUNMLEN)) {
  88         strncpy (saveuname, uname, TUNMLEN);
  89         pw = getpwnam (uname);
  90         if (pw) {
  91             saveuid = pw->pw_uid;
  92         } else {
  93             saveuid = myuid;
  94         }
  95     }
  96     return saveuid;
  97 }
  98
  99
 100 void findgname (char *gname, 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 findgid (char *gname)
 120 {
 121     struct group *gr;
 122     extern struct group *getgrnam ();
 123
 124     if (gname[0] != savegname[0]/* Quick test w/o proc call */
 125         ||0 != strncmp (gname, savegname, TUNMLEN)) {
 126         strncpy (savegname, gname, TUNMLEN);
 127         gr = getgrnam (gname);
 128         if (gr) {
 129             savegid = gr->gr_gid;
 130         } else {
 131             savegid = mygid;
 132         }
 133     }
 134     return savegid;
 135 }