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authorJason Downs <downsj@cvs.openbsd.org>1997-08-14 14:00:29 +0000
committerJason Downs <downsj@cvs.openbsd.org>1997-08-14 14:00:29 +0000
commit6e46887b7158d427eebc23ab135222ed4df2bdf0 (patch)
tree3c75f1ac16fc0820700961b0f91b18496054cb6d /usr.bin/top/username.c
parent44dbc9719c1c86a71535213a3f43c4cee4a4b770 (diff)
top 3.4, with a few changes. Still needs more work.
Diffstat (limited to 'usr.bin/top/username.c')
-rw-r--r--usr.bin/top/username.c187
1 files changed, 187 insertions, 0 deletions
diff --git a/usr.bin/top/username.c b/usr.bin/top/username.c
new file mode 100644
index 00000000000..e7e88c72f57
--- /dev/null
+++ b/usr.bin/top/username.c
@@ -0,0 +1,187 @@
+/* $OpenBSD: username.c,v 1.1 1997/08/14 14:00:27 downsj Exp $ */
+
+/*
+ * 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
+ */
+
+/*
+ * 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 <stdio.h>
+#include <pwd.h>
+
+#include "top.local.h"
+#include "utils.h"
+
+struct hash_el {
+ int uid;
+ char name[9];
+};
+
+#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, 8);
+ 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));
+}