1 files changed, 134 insertions, 0 deletions
diff --git a/usr.bin/top/username.c b/usr.bin/top/username.c
new file mode 100644
index 000000000000..37ccfe60c3ef
--- /dev/null
+++ b/usr.bin/top/username.c
@@ -0,0 +1,134 @@
+/*
+ *  Top users/processes display for Unix
+ *
+ *  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 <sys/param.h>
+
+#include <pwd.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "utils.h"
+#include "username.h"
+
+struct hash_el {
+    int  uid;
+    char name[MAXLOGNAME];
+};
+
+#define    is_empty_hash(x)	(hash_table[x].name[0] == 0)
+
+/* simple minded hashing function */
+#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! */
+static struct hash_el hash_table[Table_size];
+
+
+char *
+username(int uid)
+{
+    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(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);
+}
+
+/* wecare 1 = enter it always, 0 = nice to have */
+int
+enter_user(int uid, char name[], bool wecare)
+{
+    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.
+ */
+
+int
+get_user(int uid)
+{
+    struct passwd *pwd;
+
+    /* no performance penalty for using getpwuid makes it easy */
+    if ((pwd = getpwuid(uid)) != NULL)
+    {
+		return(enter_user(pwd->pw_uid, pwd->pw_name, 1));
+    }
+
+    /* if we can't find the name at all, then use the uid as the name */
+    return(enter_user(uid, itoa7(uid), 1));
+}