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 void finduname (char *uname, int uid)
  62 {
  63     struct passwd *pw;
  64
  65     if (uid != saveuid) {
  66         saveuid = uid;
  67         saveuname[0] = '\0';
  68         pw = getpwuid (uid);
  69         if (pw)
  70             strncpy (saveuname, pw->pw_name, TUNMLEN);
  71     }
  72     strncpy (uname, saveuname, TUNMLEN);
  73 }
  74
  75 int finduid (char *uname)
  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 findgname (char *gname, int gid)
  95 {
  96     struct group *gr;
  97
  98     if (gid != savegid) {
  99         savegid = gid;
 100         savegname[0] = '\0';
 101         (void) setgrent ();
 102         gr = getgrgid (gid);
 103         if (gr)
 104             strncpy (savegname, gr->gr_name, TGNMLEN);
 105     }
 106     (void) strncpy (gname, savegname, TGNMLEN);
 107 }
 108
 109
 110 int findgid (char *gname)
 111 {
 112     struct group *gr;
 113     extern struct group *getgrnam ();
 114
 115     if (gname[0] != savegname[0]/* Quick test w/o proc call */
 116         ||0 != strncmp (gname, savegname, TUNMLEN)) {
 117         strncpy (savegname, gname, TUNMLEN);
 118         gr = getgrnam (gname);
 119         if (gr) {
 120             savegid = gr->gr_gid;
 121         } else {
 122             savegid = mygid;
 123         }
 124     }
 125     return savegid;
 126 }