getutxent.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2010 Ed Schouten <ed@FreeBSD.org>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include "namespace.h"
  33 #include <sys/endian.h>
  34 #include <sys/param.h>
  35 #include <sys/stat.h>
  36 #include <errno.h>
  37 #include <stdio.h>
  38 #include <string.h>
  39 #include <utmpx.h>
  40 #include "utxdb.h"
  41 #include "un-namespace.h"
  42
  43 #ifdef __NO_TLS
  44 static FILE *uf = NULL;
  45 static int udb;
  46 #else
  47 static _Thread_local FILE *uf = NULL;
  48 static _Thread_local int udb;
  49 #endif
  50
  51 int
  52 setutxdb(int db, const char *file)
  53 {
  54         struct stat sb;
  55
  56         switch (db) {
  57         case UTXDB_ACTIVE:
  58                 if (file == NULL)
  59                         file = _PATH_UTX_ACTIVE;
  60                 break;
  61         case UTXDB_LASTLOGIN:
  62                 if (file == NULL)
  63                         file = _PATH_UTX_LASTLOGIN;
  64                 break;
  65         case UTXDB_LOG:
  66                 if (file == NULL)
  67                         file = _PATH_UTX_LOG;
  68                 break;
  69         default:
  70                 errno = EINVAL;
  71                 return (-1);
  72         }
  73
  74         if (uf != NULL)
  75                 fclose(uf);
  76         uf = fopen(file, "re");
  77         if (uf == NULL)
  78                 return (-1);
  79
  80         if (db != UTXDB_LOG) {
  81                 /* Safety check: never use broken files. */
  82                 if (_fstat(fileno(uf), &sb) != -1 &&
  83                     sb.st_size % sizeof(struct futx) != 0) {
  84                         fclose(uf);
  85                         uf = NULL;
  86                         errno = EFTYPE;
  87                         return (-1);
  88                 }
  89                 /* Prevent reading of partial records. */
  90                 (void)setvbuf(uf, NULL, _IOFBF,
  91                     rounddown(BUFSIZ, sizeof(struct futx)));
  92         }
  93
  94         udb = db;
  95         return (0);
  96 }
  97
  98 void
  99 setutxent(void)
 100 {
 101
 102         setutxdb(UTXDB_ACTIVE, NULL);
 103 }
 104
 105 void
 106 endutxent(void)
 107 {
 108
 109         if (uf != NULL) {
 110                 fclose(uf);
 111                 uf = NULL;
 112         }
 113 }
 114
 115 static int
 116 getfutxent(struct futx *fu)
 117 {
 118
 119         if (uf == NULL)
 120                 setutxent();
 121         if (uf == NULL)
 122                 return (-1);
 123
 124         if (udb == UTXDB_LOG) {
 125                 uint16_t len;
 126
 127 retry:
 128                 if (fread(&len, sizeof(len), 1, uf) != 1)
 129                         return (-1);
 130                 len = be16toh(len);
 131                 if (len == 0) {
 132                         /*
 133                          * XXX: Though zero-size records are valid in theory,
 134                          * they can never occur in practice. Zero-size records
 135                          * indicate file corruption. Seek one byte forward, to
 136                          * see if we can find a record there.
 137                          */
 138                         ungetc('\0', uf);
 139                         goto retry;
 140                 }
 141                 if (len > sizeof *fu) {
 142                         /* Forward compatibility. */
 143                         if (fread(fu, sizeof(*fu), 1, uf) != 1)
 144                                 return (-1);
 145                         fseek(uf, len - sizeof(*fu), SEEK_CUR);
 146                 } else {
 147                         /* Partial record. */
 148                         memset(fu, 0, sizeof(*fu));
 149                         if (fread(fu, len, 1, uf) != 1)
 150                                 return (-1);
 151                 }
 152         } else {
 153                 if (fread(fu, sizeof(*fu), 1, uf) != 1)
 154                         return (-1);
 155         }
 156         return (0);
 157 }
 158
 159 struct utmpx *
 160 getutxent(void)
 161 {
 162         struct futx fu;
 163
 164         if (getfutxent(&fu) != 0)
 165                 return (NULL);
 166         return (futx_to_utx(&fu));
 167 }
 168
 169 struct utmpx *
 170 getutxid(const struct utmpx *id)
 171 {
 172         struct futx fu;
 173
 174         for (;;) {
 175                 if (getfutxent(&fu) != 0)
 176                         return (NULL);
 177
 178                 switch (fu.fu_type) {
 179                 case USER_PROCESS:
 180                 case INIT_PROCESS:
 181                 case LOGIN_PROCESS:
 182                 case DEAD_PROCESS:
 183                         switch (id->ut_type) {
 184                         case USER_PROCESS:
 185                         case INIT_PROCESS:
 186                         case LOGIN_PROCESS:
 187                         case DEAD_PROCESS:
 188                                 if (memcmp(fu.fu_id, id->ut_id,
 189                                     MIN(sizeof(fu.fu_id), sizeof(id->ut_id))) ==
 190                                     0)
 191                                         goto found;
 192                         }
 193                         break;
 194                 default:
 195                         if (fu.fu_type == id->ut_type)
 196                                 goto found;
 197                         break;
 198                 }
 199         }
 200
 201 found:
 202         return (futx_to_utx(&fu));
 203 }
 204
 205 struct utmpx *
 206 getutxline(const struct utmpx *line)
 207 {
 208         struct futx fu;
 209
 210         for (;;) {
 211                 if (getfutxent(&fu) != 0)
 212                         return (NULL);
 213
 214                 switch (fu.fu_type) {
 215                 case USER_PROCESS:
 216                 case LOGIN_PROCESS:
 217                         if (strncmp(fu.fu_line, line->ut_line,
 218                             MIN(sizeof(fu.fu_line), sizeof(line->ut_line))) ==
 219                             0)
 220                                 goto found;
 221                         break;
 222                 }
 223         }
 224
 225 found:
 226         return (futx_to_utx(&fu));
 227 }
 228
 229 struct utmpx *
 230 getutxuser(const char *user)
 231 {
 232         struct futx fu;
 233
 234         for (;;) {
 235                 if (getfutxent(&fu) != 0)
 236                         return (NULL);
 237
 238                 switch (fu.fu_type) {
 239                 case USER_PROCESS:
 240                         if (strncmp(fu.fu_user, user, sizeof(fu.fu_user)) == 0)
 241                                 goto found;
 242                         break;
 243                 }
 244         }
 245
 246 found:
 247         return (futx_to_utx(&fu));
 248 }