1 /* 2 * Top users/processes display for Unix 3 * 4 * This program may be freely redistributed, 5 * but this entire comment MUST remain intact. 6 * 7 * Copyright (c) 1984, 1989, William LeFebvre, Rice University 8 * Copyright (c) 1989, 1990, 1992, William LeFebvre, Northwestern University 9 * 10 * $FreeBSD$ 11 */ 12 13 /* 14 * Username translation code for top. 15 * 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. 21 * 22 * Changes to these have been provided by John Gilmore (gnu@toad.com). 23 * 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. 30 */ 31 32 #include <sys/param.h> 33 #include <sys/types.h> 34 35 #include <pwd.h> 36 #include <stdio.h> 37 #include <stdlib.h> 38 #include <string.h> 39 40 #include "utils.h" 41 #include "username.h" 42 43 struct hash_el { 44 int uid; 45 char name[MAXLOGNAME]; 46 }; 47 48 #define is_empty_hash(x) (hash_table[x].name[0] == 0) 49 50 /* simple minded hashing function */ 51 /* Uid "nobody" is -2 results in hashit(-2) = -2 which is out of bounds for 52 the hash_table. Applied abs() function to fix. 2/16/96 tpugh 53 */ 54 #define hashit(i) (abs(i) % Table_size) 55 56 /* K&R requires that statically declared tables be initialized to zero. */ 57 /* We depend on that for hash_table and YOUR compiler had BETTER do it! */ 58 static struct hash_el hash_table[Table_size]; 59 60 61 char *username(uid) 62 63 int uid; 64 65 { 66 int hashindex; 67 68 hashindex = hashit(uid); 69 if (is_empty_hash(hashindex) || (hash_table[hashindex].uid != uid)) 70 { 71 /* not here or not right -- get it out of passwd */ 72 hashindex = get_user(uid); 73 } 74 return(hash_table[hashindex].name); 75 } 76 77 int userid(username) 78 79 char *username; 80 81 { 82 struct passwd *pwd; 83 84 /* Eventually we want this to enter everything in the hash table, 85 but for now we just do it simply and remember just the result. 86 */ 87 88 if ((pwd = getpwnam(username)) == NULL) 89 { 90 return(-1); 91 } 92 93 /* enter the result in the hash table */ 94 enter_user(pwd->pw_uid, username, 1); 95 96 /* return our result */ 97 return(pwd->pw_uid); 98 } 99 100 int enter_user(uid, name, wecare) 101 102 int uid; 103 char *name; 104 int wecare; /* 1 = enter it always, 0 = nice to have */ 105 106 { 107 int hashindex; 108 109 #ifdef DEBUG 110 fprintf(stderr, "enter_hash(%d, %s, %d)\n", uid, name, wecare); 111 #endif 112 113 hashindex = hashit(uid); 114 115 if (!is_empty_hash(hashindex)) 116 { 117 if (!wecare) 118 return 0; /* Don't clobber a slot for trash */ 119 if (hash_table[hashindex].uid == uid) 120 return(hashindex); /* Fortuitous find */ 121 } 122 123 /* empty or wrong slot -- fill it with new value */ 124 hash_table[hashindex].uid = uid; 125 (void) strncpy(hash_table[hashindex].name, name, MAXLOGNAME - 1); 126 return(hashindex); 127 } 128 129 /* 130 * Get a userid->name mapping from the system. 131 * If the passwd database is hashed (#define RANDOM_PW), we 132 * just handle this uid. 133 */ 134 135 int 136 get_user(int uid) 137 { 138 struct passwd *pwd; 139 140 /* no performance penalty for using getpwuid makes it easy */ 141 if ((pwd = getpwuid(uid)) != NULL) 142 { 143 return(enter_user(pwd->pw_uid, pwd->pw_name, 1)); 144 } 145 146 /* if we can't find the name at all, then use the uid as the name */ 147 return(enter_user(uid, itoa7(uid), 1)); 148 } 149