ref: 66892eb133865ec02faa8e64cdfa2f867f9e1e87
dir: /sys/src/ape/cmd/pax/names.c/
/* $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 ([email protected])
*
* 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);
}