/contrib/top/username.c
C | 189 lines | 85 code | 35 blank | 69 comment | 17 complexity | f140f21cf7e14cbae2f2340739e95d64 MD5 | raw file
Possible License(s): MPL-2.0-no-copyleft-exception, BSD-3-Clause, LGPL-2.0, LGPL-2.1, BSD-2-Clause, 0BSD, JSON, AGPL-1.0, GPL-2.0
- /*
- * Top users/processes display for Unix
- * Version 3
- *
- * This program may be freely redistributed,
- * but this entire comment MUST remain intact.
- *
- * Copyright (c) 1984, 1989, William LeFebvre, Rice University
- * Copyright (c) 1989, 1990, 1992, William LeFebvre, Northwestern University
- *
- * $FreeBSD$
- */
- /*
- * Username translation code for top.
- *
- * These routines handle uid to username mapping.
- * They use a hashing table scheme to reduce reading overhead.
- * For the time being, these are very straightforward hashing routines.
- * Maybe someday I'll put in something better. But with the advent of
- * "random access" password files, it might not be worth the effort.
- *
- * Changes to these have been provided by John Gilmore (gnu@toad.com).
- *
- * The hash has been simplified in this release, to avoid the
- * table overflow problems of previous releases. If the value
- * at the initial hash location is not right, it is replaced
- * by the right value. Collisions will cause us to call getpw*
- * but hey, this is a cache, not the Library of Congress.
- * This makes the table size independent of the passwd file size.
- */
- #include <sys/param.h>
- #include <sys/types.h>
- #include <stdio.h>
- #include <pwd.h>
- #include "top.local.h"
- #include "utils.h"
- struct hash_el {
- int uid;
- char name[MAXLOGNAME];
- };
- #define is_empty_hash(x) (hash_table[x].name[0] == 0)
- /* simple minded hashing function */
- /* Uid "nobody" is -2 results in hashit(-2) = -2 which is out of bounds for
- the hash_table. Applied abs() function to fix. 2/16/96 tpugh
- */
- #define hashit(i) (abs(i) % Table_size)
- /* K&R requires that statically declared tables be initialized to zero. */
- /* We depend on that for hash_table and YOUR compiler had BETTER do it! */
- struct hash_el hash_table[Table_size];
- init_hash()
- {
- /*
- * There used to be some steps we had to take to initialize things.
- * We don't need to do that anymore, but we will leave this stub in
- * just in case future changes require initialization steps.
- */
- }
- char *username(uid)
- register int uid;
- {
- register int hashindex;
- hashindex = hashit(uid);
- if (is_empty_hash(hashindex) || (hash_table[hashindex].uid != uid))
- {
- /* not here or not right -- get it out of passwd */
- hashindex = get_user(uid);
- }
- return(hash_table[hashindex].name);
- }
- int userid(username)
- char *username;
- {
- struct passwd *pwd;
- /* Eventually we want this to enter everything in the hash table,
- but for now we just do it simply and remember just the result.
- */
- if ((pwd = getpwnam(username)) == NULL)
- {
- return(-1);
- }
- /* enter the result in the hash table */
- enter_user(pwd->pw_uid, username, 1);
- /* return our result */
- return(pwd->pw_uid);
- }
- int enter_user(uid, name, wecare)
- register int uid;
- register char *name;
- int wecare; /* 1 = enter it always, 0 = nice to have */
- {
- register int hashindex;
- #ifdef DEBUG
- fprintf(stderr, "enter_hash(%d, %s, %d)\n", uid, name, wecare);
- #endif
- hashindex = hashit(uid);
- if (!is_empty_hash(hashindex))
- {
- if (!wecare)
- return 0; /* Don't clobber a slot for trash */
- if (hash_table[hashindex].uid == uid)
- return(hashindex); /* Fortuitous find */
- }
- /* empty or wrong slot -- fill it with new value */
- hash_table[hashindex].uid = uid;
- (void) strncpy(hash_table[hashindex].name, name, MAXLOGNAME - 1);
- return(hashindex);
- }
- /*
- * Get a userid->name mapping from the system.
- * If the passwd database is hashed (#define RANDOM_PW), we
- * just handle this uid. Otherwise we scan the passwd file
- * and cache any entries we pass over while looking.
- */
- int get_user(uid)
- register int uid;
- {
- struct passwd *pwd;
- #ifdef RANDOM_PW
- /* no performance penalty for using getpwuid makes it easy */
- if ((pwd = getpwuid(uid)) != NULL)
- {
- return(enter_user(pwd->pw_uid, pwd->pw_name, 1));
- }
- #else
- int from_start = 0;
- /*
- * If we just called getpwuid each time, things would be very slow
- * since that just iterates through the passwd file each time. So,
- * we walk through the file instead (using getpwent) and cache each
- * entry as we go. Once the right record is found, we cache it and
- * return immediately. The next time we come in, getpwent will get
- * the next record. In theory, we never have to read the passwd file
- * a second time (because we cache everything we read). But in
- * practice, the cache may not be large enough, so if we don't find
- * it the first time we have to scan the file a second time. This
- * is not very efficient, but it will do for now.
- */
- while (from_start++ < 2)
- {
- while ((pwd = getpwent()) != NULL)
- {
- if (pwd->pw_uid == uid)
- {
- return(enter_user(pwd->pw_uid, pwd->pw_name, 1));
- }
- (void) enter_user(pwd->pw_uid, pwd->pw_name, 0);
- }
- /* try again */
- setpwent();
- }
- #endif
- /* if we can't find the name at all, then use the uid as the name */
- return(enter_user(uid, itoa7(uid), 1));
- }