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/* idcache.c -- map user and group IDs, cached for speed
Copyright (C) 1985, 1988, 1989, 1990, 2004, 2007, 2010 Free Software
Foundation, Inc.
This program 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 3, or (at your option)
any later version.
This program 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 this program; if not, write to the Free
Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301 USA. */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdio.h>
#include <sys/types.h>
#include <xalloc.h>
#include <system.h>
#if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
#include <string.h>
#else
#include <strings.h>
#endif
#include <unistd.h>
struct userid
{
union
{
uid_t u;
gid_t g;
} id;
char *name;
struct userid *next;
};
static struct userid *user_alist;
/* The members of this list have names not in the local passwd file. */
static struct userid *nouser_alist;
/* Translate UID to a login name or a stringified number,
with cache. */
char *
getuser (uid_t uid)
{
register struct userid *tail;
struct passwd *pwent;
char usernum_string[20];
for (tail = user_alist; tail; tail = tail->next)
if (tail->id.u == uid)
return tail->name;
pwent = getpwuid (uid);
tail = (struct userid *) xmalloc (sizeof (struct userid));
tail->id.u = uid;
if (pwent == 0)
{
sprintf (usernum_string, "%u", (unsigned) uid);
tail->name = xstrdup (usernum_string);
}
else
tail->name = xstrdup (pwent->pw_name);
/* Add to the head of the list, so most recently used is first. */
tail->next = user_alist;
user_alist = tail;
return tail->name;
}
/* Translate USER to a UID, with cache.
Return NULL if there is no such user.
(We also cache which user names have no passwd entry,
so we don't keep looking them up.) */
uid_t *
getuidbyname (char *user)
{
register struct userid *tail;
struct passwd *pwent;
for (tail = user_alist; tail; tail = tail->next)
/* Avoid a function call for the most common case. */
if (*tail->name == *user && !strcmp (tail->name, user))
return &tail->id.u;
for (tail = nouser_alist; tail; tail = tail->next)
/* Avoid a function call for the most common case. */
if (*tail->name == *user && !strcmp (tail->name, user))
return 0;
pwent = getpwnam (user);
tail = (struct userid *) xmalloc (sizeof (struct userid));
tail->name = xstrdup (user);
/* Add to the head of the list, so most recently used is first. */
if (pwent)
{
tail->id.u = pwent->pw_uid;
tail->next = user_alist;
user_alist = tail;
return &tail->id.u;
}
tail->next = nouser_alist;
nouser_alist = tail;
return 0;
}
/* Use the same struct as for userids. */
static struct userid *group_alist;
static struct userid *nogroup_alist;
/* Translate GID to a group name or a stringified number,
with cache. */
char *
getgroup (gid_t gid)
{
register struct userid *tail;
struct group *grent;
char groupnum_string[20];
for (tail = group_alist; tail; tail = tail->next)
if (tail->id.g == gid)
return tail->name;
grent = getgrgid (gid);
tail = (struct userid *) xmalloc (sizeof (struct userid));
tail->id.g = gid;
if (grent == 0)
{
sprintf (groupnum_string, "%u", (unsigned int) gid);
tail->name = xstrdup (groupnum_string);
}
else
tail->name = xstrdup (grent->gr_name);
/* Add to the head of the list, so most recently used is first. */
tail->next = group_alist;
group_alist = tail;
return tail->name;
}
/* Translate GROUP to a UID, with cache.
Return NULL if there is no such group.
(We also cache which group names have no group entry,
so we don't keep looking them up.) */
gid_t *
getgidbyname (char *group)
{
register struct userid *tail;
struct group *grent;
for (tail = group_alist; tail; tail = tail->next)
/* Avoid a function call for the most common case. */
if (*tail->name == *group && !strcmp (tail->name, group))
return &tail->id.g;
for (tail = nogroup_alist; tail; tail = tail->next)
/* Avoid a function call for the most common case. */
if (*tail->name == *group && !strcmp (tail->name, group))
return 0;
grent = getgrnam (group);
tail = (struct userid *) xmalloc (sizeof (struct userid));
tail->name = xstrdup (group);
/* Add to the head of the list, so most recently used is first. */
if (grent)
{
tail->id.g = grent->gr_gid;
tail->next = group_alist;
group_alist = tail;
return &tail->id.g;
}
tail->next = nogroup_alist;
nogroup_alist = tail;
return 0;
}
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