mc/vfs/names.c

/* Look up user and/or group names.
   Copyright (C) 1988, 1992 Free Software Foundation

   From GNU Tar.
   
GNU Tar is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Tar is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Tar; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

/*
 * Look up user and/or group names.
 *
 * This file should be modified for non-unix systems to do something
 * reasonable.
 */

#include <config.h>
#include <sys/types.h>
#include <string.h>
#include <unistd.h>
#define TAR_NAMES
#include "tar.h"
#include "names.h"

#include <stdio.h>
#include <pwd.h>
#include <grp.h>

#ifndef TUNMLEN 
#define TUNMLEN 256
#endif
#ifndef TGNMLEN
#define TGNMLEN 256
#endif

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;

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

/*
 * Look up a user or group name from a uid/gid, maintaining a cache.
 * FIXME, for now it's a one-entry cache.
 * FIXME2, the "-993" is to reduce the chance of a hit on the first lookup.
 *
 * This is ifdef'd because on Suns, it drags in about 38K of "yellow
 * pages" code, roughly doubling the program size.  Thanks guys.
 */
void finduname (char *uname, int uid)
{
    struct passwd *pw;
#ifndef HAVE_GETPWUID
    extern struct passwd *getpwuid ();
#endif

    if (uid != saveuid) {
	saveuid = uid;
	saveuname[0] = '\0';
	pw = getpwuid (uid);
	if (pw)
	    strncpy (saveuname, pw->pw_name, TUNMLEN);
    }
    strncpy (uname, saveuname, TUNMLEN);
}

int finduid (char *uname)
{
    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;
}


void findgname (char *gname, int gid)
{
    struct group *gr;
#ifndef HAVE_GETGRGID
    extern struct group *getgrgid ();
#endif

    if (gid != savegid) {
	savegid = gid;
	savegname[0] = '\0';
	(void) setgrent ();
	gr = getgrgid (gid);
	if (gr)
	    strncpy (savegname, gr->gr_name, TGNMLEN);
    }
    (void) strncpy (gname, savegname, TGNMLEN);
}


int findgid (char *gname)
{
    struct group *gr;
    extern struct group *getgrnam ();
    
    if (gname[0] != savegname[0]/* Quick test w/o proc call */
	||0 != strncmp (gname, savegname, TUNMLEN)) {
	strncpy (savegname, gname, TUNMLEN);
	gr = getgrnam (gname);
	if (gr) {
	    savegid = gr->gr_gid;
	} else {
	    savegid = mygid;
	}
    }
    return savegid;
}