lib/libc/gen/pwcache.c

   1 /*
   2  * Copyright (c) 1989, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)pwcache.c        8.1 (Berkeley) 6/4/93
  30  * $FreeBSD: src/lib/libc/gen/pwcache.c,v 1.10 2002/03/22 02:35:47 imp Exp $
  31  * $DragonFly: src/lib/libc/gen/pwcache.c,v 1.5 2005/11/13 00:07:42 swildner Exp $
  32  */
  33
  34 #include <sys/types.h>
  35
  36 #include <grp.h>
  37 #include <pwd.h>
  38 #include <stdio.h>
  39 #include <string.h>
  40 #include <utmp.h>
  41
  42 #define NCACHE  64                      /* power of 2 */
  43 #define MASK    (NCACHE - 1)            /* bits to store with */
  44
  45 const char *
  46 user_from_uid(uid_t uid, int nouser)
  47 {
  48         static struct ncache {
  49                 uid_t   uid;
  50                 int     found;
  51                 char    name[UT_NAMESIZE + 1];
  52         } c_uid[NCACHE];
  53         static int pwopen;
  54         struct passwd *pw;
  55         struct ncache *cp;
  56
  57         cp = c_uid + (uid & MASK);
  58         if (cp->uid != uid || !*cp->name) {
  59                 if (pwopen == 0) {
  60                         setpassent(1);
  61                         pwopen = 1;
  62                 }
  63                 pw = getpwuid(uid);
  64                 cp->uid = uid;
  65                 if (pw != NULL) {
  66                         cp->found = 1;
  67                         strncpy(cp->name, pw->pw_name, UT_NAMESIZE);
  68                         cp->name[UT_NAMESIZE] = '\0';
  69                 } else {
  70                         cp->found = 0;
  71                         snprintf(cp->name, UT_NAMESIZE, "%u", uid);
  72                         if (nouser)
  73                                 return (NULL);
  74                 }
  75         }
  76         return ((nouser && !cp->found) ? NULL : cp->name);
  77 }
  78
  79 const char *
  80 group_from_gid(gid_t gid, int nogroup)
  81 {
  82         static struct ncache {
  83                 gid_t   gid;
  84                 int     found;
  85                 char    name[UT_NAMESIZE + 1];
  86         } c_gid[NCACHE];
  87         static int gropen;
  88         struct group *gr;
  89         struct ncache *cp;
  90
  91         cp = c_gid + (gid & MASK);
  92         if (cp->gid != gid || !*cp->name) {
  93                 if (gropen == 0) {
  94                         setgroupent(1);
  95                         gropen = 1;
  96                 }
  97                 gr = getgrgid(gid);
  98                 cp->gid = gid;
  99                 if (gr != NULL) {
 100                         cp->found = 1;
 101                         strncpy(cp->name, gr->gr_name, UT_NAMESIZE);
 102                         cp->name[UT_NAMESIZE] = '\0';
 103                 } else {
 104                         cp->found = 0;
 105                         snprintf(cp->name, UT_NAMESIZE, "%u", gid);
 106                         if (nogroup)
 107                                 return (NULL);
 108                 }
 109         }
 110         return ((nogroup && !cp->found) ? NULL : cp->name);
 111 }