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/* $Source: /u/mark/src/pax/RCS/names.c,v $

 *

 * $Revision: 1.2 $

 *

 * names.c - Look up user and/or group names. 

 *

 * DESCRIPTION

 *

 *	These functions support UID and GID name lookup.  The results are

 *	cached to improve performance.

 *

 * AUTHOR

 *

 *	Mark H. Colburn, NAPS International (mark@jhereg.mn.org)

 *

 * Sponsored by The USENIX Association for public distribution. 

 *

 * Copyright (c) 1989 Mark H. Colburn.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms are permitted

 * provided that the above copyright notice is duplicated in all such 

 * forms and that any documentation, advertising materials, and other 

 * materials related to such distribution and use acknowledge that the 

 * software was developed * by Mark H. Colburn and sponsored by The 

 * USENIX Association. 

 *

 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

 *

 * $Log:	names.c,v $

 * Revision 1.2  89/02/12  10:05:05  mark

 * 1.2 release fixes

 * 

 * Revision 1.1  88/12/23  18:02:19  mark

 * Initial revision

 * 

 */

#ifndef lint

static char *ident = "$Id: names.c,v 1.2 89/02/12 10:05:05 mark Exp $";

static char *copyright = "Copyright (c) 1989 Mark H. Colburn.\nAll rights reserved.\n";

#endif /* ! lint */

/* Headers */

#include "pax.h"

/* Defines */

#define myuid	( my_uid < 0? (my_uid = getuid()): my_uid )

#define	mygid	( my_gid < 0? (my_gid = getgid()): my_gid )

/* Internal Identifiers */

static int      saveuid = -993;

static char     saveuname[TUNMLEN];

static int      my_uid = -993;

static int      savegid = -993;

static char     savegname[TGNMLEN];

static int      my_gid = -993;

/* finduname - find a user or group name from a uid or gid

 *

 * DESCRIPTION

 *

 * 	Look up a user name from a uid/gid, maintaining a cache. 

 *

 * PARAMETERS

 *

 *	char	uname[]		- name (to be returned to user)

 *	int	uuid		- id of name to find

 *

 *

 * RETURNS

 *

 *	Returns a name which is associated with the user id given.  If there

 *	is not name which corresponds to the user-id given, then a pointer

 *	to a string of zero length is returned.

 *	

 * FIXME

 *

 * 	1. for now it's a one-entry cache. 

 *	2. The "-993" is to reduce the chance of a hit on the first lookup. 

 */

#ifdef __STDC__

char *finduname(int uuid)

#else

char *finduname(uuid)

int             uuid;

#endif

{

    struct passwd  *pw;

    if (uuid != saveuid) {

	saveuid = uuid;

	saveuname[0] = '\0';

	pw = getpwuid(uuid);

	if (pw) {

	    strncpy(saveuname, pw->pw_name, TUNMLEN);

	}

    }

    return(saveuname);

}

/* finduid - get the uid for a given user name

 *

 * DESCRIPTION

 *

 *	This does just the opposit of finduname.  Given a user name it

 *	finds the corresponding UID for that name.

 *

 * PARAMETERS

 *

 *	char	uname[]		- username to find a UID for

 *

 * RETURNS

 *

 *	The UID which corresponds to the uname given, if any.  If no UID

 *	could be found, then the UID which corrsponds the user running the

 *	program is returned.

 *

 */

#ifdef __STDC__

int finduid(char *uname)

#else

int finduid(uname)

char            *uname;

#endif

{

    struct passwd  *pw;

    extern struct passwd *getpwnam();

    if (uname[0] != saveuname[0]/* Quick test w/o proc call */

	||0 != strncmp(uname, saveuname, TUNMLEN)) {

	strncpy(saveuname, uname, TUNMLEN);

	pw = getpwnam(uname);

	if (pw) {

	    saveuid = pw->pw_uid;

	} else {

	    saveuid = myuid;

	}

    }

    return (saveuid);

}

/* findgname - look up a group name from a gid

 *

 * DESCRIPTION

 *

 * 	Look up a group name from a gid, maintaining a cache.

 *	

 *

 * PARAMETERS

 *

 *	int	ggid		- goupid of group to find

 *

 * RETURNS

 *

 *	A string which is associated with the group ID given.  If no name

 *	can be found, a string of zero length is returned.

 */

#ifdef __STDC__

char *findgname(int ggid)

#else

char *findgname(ggid)

int             ggid;

#endif

{

    struct group   *gr;

    if (ggid != savegid) {

	savegid = ggid;

	savegname[0] = '\0';

#ifndef _POSIX_SOURCE

	setgrent();

#endif

	gr = getgrgid(ggid);

	if (gr) {

	    strncpy(savegname, gr->gr_name, TGNMLEN);

	}

    }

    return(savegname);

}

/* findgid - get the gid for a given group name

 *

 * DESCRIPTION

 *

 *	This does just the opposit of finduname.  Given a group name it

 *	finds the corresponding GID for that name.

 *

 * PARAMETERS

 *

 *	char	uname[]		- groupname to find a GID for

 *

 * RETURNS

 *

 *	The GID which corresponds to the uname given, if any.  If no GID

 *	could be found, then the GID which corrsponds the group running the

 *	program is returned.

 *

 */

#ifdef __STDC__

int findgid(char *gname)

#else

int findgid(gname)

char           *gname;

#endif

{

    struct group   *gr;

    /* Quick test w/o proc call */

    if (gname[0] != savegname[0] || strncmp(gname, savegname, TUNMLEN) != 0) {

	strncpy(savegname, gname, TUNMLEN);

	gr = getgrnam(gname);

	if (gr) {

	    savegid = gr->gr_gid;

	} else {

	    savegid = mygid;

	}

    }

    return (savegid);

}