2 * Top users/processes display for Unix
4 * This program may be freely redistributed,
5 * but this entire comment MUST remain intact.
7 * Copyright (c) 1984, 1989, William LeFebvre, Rice University
8 * Copyright (c) 1989, 1990, 1992, William LeFebvre, Northwestern University
14 * Username translation code for top.
16 * These routines handle uid to username mapping.
17 * They use a hashing table scheme to reduce reading overhead.
18 * For the time being, these are very straightforward hashing routines.
19 * Maybe someday I'll put in something better. But with the advent of
20 * "random access" password files, it might not be worth the effort.
22 * Changes to these have been provided by John Gilmore (gnu@toad.com).
24 * The hash has been simplified in this release, to avoid the
25 * table overflow problems of previous releases. If the value
26 * at the initial hash location is not right, it is replaced
27 * by the right value. Collisions will cause us to call getpw*
28 * but hey, this is a cache, not the Library of Congress.
29 * This makes the table size independent of the passwd file size.
32 #include <sys/param.h>
45 char name[MAXLOGNAME];
48 #define is_empty_hash(x) (hash_table[x].name[0] == 0)
50 /* simple minded hashing function */
51 #define hashit(i) (abs(i) % Table_size)
53 /* K&R requires that statically declared tables be initialized to zero. */
54 /* We depend on that for hash_table and YOUR compiler had BETTER do it! */
55 static struct hash_el hash_table[Table_size];
63 hashindex = hashit(uid);
64 if (is_empty_hash(hashindex) || (hash_table[hashindex].uid != uid))
66 /* not here or not right -- get it out of passwd */
67 hashindex = get_user(uid);
69 return(hash_table[hashindex].name);
73 userid(char username_[])
77 /* Eventually we want this to enter everything in the hash table,
78 but for now we just do it simply and remember just the result.
81 if ((pwd = getpwnam(username_)) == NULL)
86 /* enter the result in the hash table */
87 enter_user(pwd->pw_uid, username_, 1);
89 /* return our result */
93 /* wecare 1 = enter it always, 0 = nice to have */
95 enter_user(int uid, char name[], bool wecare)
100 fprintf(stderr, "enter_hash(%d, %s, %d)\n", uid, name, wecare);
103 hashindex = hashit(uid);
105 if (!is_empty_hash(hashindex))
108 return (0); /* Don't clobber a slot for trash */
109 if (hash_table[hashindex].uid == uid)
110 return(hashindex); /* Fortuitous find */
113 /* empty or wrong slot -- fill it with new value */
114 hash_table[hashindex].uid = uid;
115 (void) strncpy(hash_table[hashindex].name, name, MAXLOGNAME - 1);
120 * Get a userid->name mapping from the system.
128 /* no performance penalty for using getpwuid makes it easy */
129 if ((pwd = getpwuid(uid)) != NULL)
131 return(enter_user(pwd->pw_uid, pwd->pw_name, 1));
134 /* if we can't find the name at all, then use the uid as the name */
135 return(enter_user(uid, itoa7(uid), 1));