mirror of
https://github.com/coreutils/coreutils.git
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201 lines
5.1 KiB
C
201 lines
5.1 KiB
C
/* idcache.c -- map user and group IDs, cached for speed
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Copyright (C) 1985, 1988, 1989, 1990, 1997, 1998, 2003, 2005 Free
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Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <stdio.h>
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#include <string.h>
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#include <sys/types.h>
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#include <pwd.h>
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#include <grp.h>
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#include <unistd.h>
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#include "xalloc.h"
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#ifdef __DJGPP__
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static char digits[] = "0123456789";
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#endif
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struct userid
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{
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union
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{
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uid_t u;
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gid_t g;
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} id;
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char *name;
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struct userid *next;
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};
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static struct userid *user_alist;
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/* The members of this list have names not in the local passwd file. */
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static struct userid *nouser_alist;
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/* Translate UID to a login name, with cache, or NULL if unresolved. */
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char *
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getuser (uid_t uid)
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{
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register struct userid *tail;
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struct passwd *pwent;
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for (tail = user_alist; tail; tail = tail->next)
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if (tail->id.u == uid)
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return tail->name;
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pwent = getpwuid (uid);
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tail = xmalloc (sizeof *tail);
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tail->id.u = uid;
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tail->name = pwent ? xstrdup (pwent->pw_name) : NULL;
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/* Add to the head of the list, so most recently used is first. */
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tail->next = user_alist;
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user_alist = tail;
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return tail->name;
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}
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/* Translate USER to a UID, with cache.
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Return NULL if there is no such user.
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(We also cache which user names have no passwd entry,
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so we don't keep looking them up.) */
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uid_t *
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getuidbyname (const char *user)
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{
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register struct userid *tail;
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struct passwd *pwent;
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for (tail = user_alist; tail; tail = tail->next)
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/* Avoid a function call for the most common case. */
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if (*tail->name == *user && !strcmp (tail->name, user))
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return &tail->id.u;
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for (tail = nouser_alist; tail; tail = tail->next)
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/* Avoid a function call for the most common case. */
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if (*tail->name == *user && !strcmp (tail->name, user))
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return 0;
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pwent = getpwnam (user);
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#ifdef __DJGPP__
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/* We need to pretend to be the user USER, to make
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pwd functions know about an arbitrary user name. */
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if (!pwent && strspn (user, digits) < strlen (user))
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{
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setenv ("USER", user, 1);
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pwent = getpwnam (user); /* now it will succeed */
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}
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#endif
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tail = xmalloc (sizeof *tail);
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tail->name = xstrdup (user);
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/* Add to the head of the list, so most recently used is first. */
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if (pwent)
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{
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tail->id.u = pwent->pw_uid;
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tail->next = user_alist;
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user_alist = tail;
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return &tail->id.u;
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}
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tail->next = nouser_alist;
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nouser_alist = tail;
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return 0;
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}
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/* Use the same struct as for userids. */
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static struct userid *group_alist;
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static struct userid *nogroup_alist;
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/* Translate GID to a group name, with cache, or NULL if unresolved. */
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char *
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getgroup (gid_t gid)
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{
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register struct userid *tail;
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struct group *grent;
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for (tail = group_alist; tail; tail = tail->next)
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if (tail->id.g == gid)
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return tail->name;
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grent = getgrgid (gid);
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tail = xmalloc (sizeof *tail);
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tail->id.g = gid;
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tail->name = grent ? xstrdup (grent->gr_name) : NULL;
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/* Add to the head of the list, so most recently used is first. */
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tail->next = group_alist;
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group_alist = tail;
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return tail->name;
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}
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/* Translate GROUP to a GID, with cache.
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Return NULL if there is no such group.
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(We also cache which group names have no group entry,
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so we don't keep looking them up.) */
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gid_t *
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getgidbyname (const char *group)
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{
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register struct userid *tail;
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struct group *grent;
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for (tail = group_alist; tail; tail = tail->next)
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/* Avoid a function call for the most common case. */
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if (*tail->name == *group && !strcmp (tail->name, group))
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return &tail->id.g;
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for (tail = nogroup_alist; tail; tail = tail->next)
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/* Avoid a function call for the most common case. */
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if (*tail->name == *group && !strcmp (tail->name, group))
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return 0;
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grent = getgrnam (group);
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#ifdef __DJGPP__
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/* We need to pretend to belong to group GROUP, to make
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grp functions know about any arbitrary group name. */
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if (!grent && strspn (group, digits) < strlen (group))
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{
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setenv ("GROUP", group, 1);
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grent = getgrnam (group); /* now it will succeed */
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}
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#endif
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tail = xmalloc (sizeof *tail);
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tail->name = xstrdup (group);
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/* Add to the head of the list, so most recently used is first. */
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if (grent)
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{
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tail->id.g = grent->gr_gid;
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tail->next = group_alist;
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group_alist = tail;
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return &tail->id.g;
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}
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tail->next = nogroup_alist;
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nogroup_alist = tail;
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return 0;
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}
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