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135 lines
3.3 KiB
C
135 lines
3.3 KiB
C
/*
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* Top users/processes display for Unix
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*
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* This program may be freely redistributed,
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* but this entire comment MUST remain intact.
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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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/*
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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/param.h>
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#include <pwd.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.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[MAXLOGNAME];
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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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#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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static struct hash_el hash_table[Table_size];
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char *
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username(int uid)
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{
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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
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userid(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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/* wecare 1 = enter it always, 0 = nice to have */
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int
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enter_user(int uid, char name[], bool wecare)
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{
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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, MAXLOGNAME - 1);
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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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*/
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int
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get_user(int uid)
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{
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struct passwd *pwd;
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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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/* 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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