procps/library/pwcache.c

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/*
* pwcache.c - memory cache passwd file handling
*
* Copyright © 2011-2023 Jim Warner <james.warner@comcast.net>
* Copyright © 2015-2023 Craig Small <csmall@dropbear.xyz>
* Copyright © 2002 Albert Cahalan
*
* Older version:
* Copyright © 1992-1998 Michael K. Johnson <johnsonm@redhat.com>
* Note: most likely none of his code remains
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
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#include <stdio.h>
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#include <string.h>
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#include <sys/types.h>
#include <stdlib.h>
#include <pwd.h>
#include <grp.h>
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#include "pwcache.h"
#include "procps-private.h"
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// might as well fill cache lines... else we waste memory anyway
#define HASHSIZE 64 /* power of 2 */
#define HASH(x) ((x) & (HASHSIZE - 1))
static char ERRname[] = "?";
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static __thread struct pwbuf {
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struct pwbuf *next;
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uid_t uid;
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char name[P_G_SZ];
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} *pwhash[HASHSIZE];
char *pwcache_get_user(uid_t uid) {
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struct pwbuf **p;
struct passwd *pw;
p = &pwhash[HASH(uid)];
while (*p) {
if ((*p)->uid == uid)
return((*p)->name);
p = &(*p)->next;
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}
if (!(*p = (struct pwbuf *)malloc(sizeof(struct pwbuf))))
return ERRname;
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(*p)->uid = uid;
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pw = getpwuid(uid);
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if(!pw || strlen(pw->pw_name) >= P_G_SZ)
sprintf((*p)->name, "%u", uid);
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else
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strcpy((*p)->name, pw->pw_name);
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(*p)->next = NULL;
return((*p)->name);
}
static __thread struct grpbuf {
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struct grpbuf *next;
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gid_t gid;
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char name[P_G_SZ];
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} *grphash[HASHSIZE];
char *pwcache_get_group(gid_t gid) {
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struct grpbuf **g;
struct group *gr;
g = &grphash[HASH(gid)];
while (*g) {
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if ((*g)->gid == gid)
return((*g)->name);
g = &(*g)->next;
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}
if (!(*g = (struct grpbuf *)malloc(sizeof(struct grpbuf))))
return ERRname;;
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(*g)->gid = gid;
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gr = getgrgid(gid);
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if (!gr || strlen(gr->gr_name) >= P_G_SZ)
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sprintf((*g)->name, "%u", gid);
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else
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strcpy((*g)->name, gr->gr_name);
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(*g)->next = NULL;
return((*g)->name);
}