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 Library 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 Library General Public License for more details.

 * Namespace: finduname, finduid, findgname, findgid.
 */

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

#include "names.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 )

int
finduid (char *uname)
{
    struct passwd *pw;

    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;
}

int
findgid (char *gname)
{
    struct group *gr;

    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;
}