213 lines
6.2 KiB
C
213 lines
6.2 KiB
C
/* $NetBSD: username.c,v 1.5 2003/06/23 13:05:53 agc Exp $ */
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/*
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* Top users/processes display for Unix
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* Version 3
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*
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* Copyright (c) 1984, 1989, William LeFebvre, Rice University
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* Copyright (c) 1989, 1990, 1992, William LeFebvre, Northwestern University
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR OR HIS EMPLOYER BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Username translation code for top.
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*
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* These routines handle uid to username mapping.
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* They use a hashing table scheme to reduce reading overhead.
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* For the time being, these are very straightforward hashing routines.
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* Maybe someday I'll put in something better. But with the advent of
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* "random access" password files, it might not be worth the effort.
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*
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* Changes to these have been provided by John Gilmore (gnu@toad.com).
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*
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* The hash has been simplified in this release, to avoid the
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* table overflow problems of previous releases. If the value
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* at the initial hash location is not right, it is replaced
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* by the right value. Collisions will cause us to call getpw*
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* but hey, this is a cache, not the Library of Congress.
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* This makes the table size independent of the passwd file size.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__RCSID("$NetBSD: username.c,v 1.5 2003/06/23 13:05:53 agc Exp $");
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#endif
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#include <stdio.h>
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#include <pwd.h>
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#include "os.h"
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#include "top.local.h"
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#include "utils.h"
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#include "username.h"
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struct hash_el {
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int uid;
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char name[9];
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};
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#define is_empty_hash(x) (hash_table[x].name[0] == 0)
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/* simple minded hashing function */
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/* Uid "nobody" is -2 results in hashit(-2) = -2 which is out of bounds for
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the hash_table. Applied abs() function to fix. 2/16/96 tpugh
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*/
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#define hashit(i) (abs(i) % Table_size)
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/* K&R requires that statically declared tables be initialized to zero. */
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/* We depend on that for hash_table and YOUR compiler had BETTER do it! */
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struct hash_el hash_table[Table_size];
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void
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init_hash()
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{
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/*
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* There used to be some steps we had to take to initialize things.
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* We don't need to do that anymore, but we will leave this stub in
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* just in case future changes require initialization steps.
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*/
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}
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char *username(uid)
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register int uid;
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{
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register int hashindex;
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hashindex = hashit(uid);
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if (is_empty_hash(hashindex) || (hash_table[hashindex].uid != uid))
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{
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/* not here or not right -- get it out of passwd */
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hashindex = get_user(uid);
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}
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return(hash_table[hashindex].name);
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}
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int userid(username)
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char *username;
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{
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struct passwd *pwd;
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/* Eventually we want this to enter everything in the hash table,
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but for now we just do it simply and remember just the result.
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*/
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if ((pwd = getpwnam(username)) == NULL)
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{
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return(-1);
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}
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/* enter the result in the hash table */
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enter_user(pwd->pw_uid, username, 1);
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/* return our result */
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return(pwd->pw_uid);
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}
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int enter_user(uid, name, wecare)
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register int uid;
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register char *name;
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int wecare; /* 1 = enter it always, 0 = nice to have */
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{
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register int hashindex;
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#ifdef DEBUG
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fprintf(stderr, "enter_hash(%d, %s, %d)\n", uid, name, wecare);
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#endif
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hashindex = hashit(uid);
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if (!is_empty_hash(hashindex))
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{
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if (!wecare)
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return 0; /* Don't clobber a slot for trash */
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if (hash_table[hashindex].uid == uid)
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return(hashindex); /* Fortuitous find */
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}
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/* empty or wrong slot -- fill it with new value */
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hash_table[hashindex].uid = uid;
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(void) strncpy(hash_table[hashindex].name, name, 8);
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return(hashindex);
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}
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/*
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* Get a userid->name mapping from the system.
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* If the passwd database is hashed (#define RANDOM_PW), we
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* just handle this uid. Otherwise we scan the passwd file
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* and cache any entries we pass over while looking.
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*/
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int get_user(uid)
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register int uid;
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{
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struct passwd *pwd;
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#ifdef RANDOM_PW
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/* no performance penalty for using getpwuid makes it easy */
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if ((pwd = getpwuid(uid)) != NULL)
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{
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return(enter_user(pwd->pw_uid, pwd->pw_name, 1));
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}
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#else
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int from_start = 0;
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/*
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* If we just called getpwuid each time, things would be very slow
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* since that just iterates through the passwd file each time. So,
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* we walk through the file instead (using getpwent) and cache each
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* entry as we go. Once the right record is found, we cache it and
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* return immediately. The next time we come in, getpwent will get
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* the next record. In theory, we never have to read the passwd file
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* a second time (because we cache everything we read). But in
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* practice, the cache may not be large enough, so if we don't find
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* it the first time we have to scan the file a second time. This
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* is not very efficient, but it will do for now.
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*/
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while (from_start++ < 2)
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{
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while ((pwd = getpwent()) != NULL)
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{
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if (pwd->pw_uid == uid)
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{
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return(enter_user(pwd->pw_uid, pwd->pw_name, 1));
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}
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(void) enter_user(pwd->pw_uid, pwd->pw_name, 0);
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}
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/* try again */
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setpwent();
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}
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#endif
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/* if we can't find the name at all, then use the uid as the name */
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return(enter_user(uid, itoa7(uid), 1));
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}
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