src/basic/user-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <alloca.h>
   4 #include <errno.h>
   5 #include <fcntl.h>
   6 #include <grp.h>
   7 #include <pwd.h>
   8 #include <stddef.h>
   9 #include <stdint.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13 #include <sys/stat.h>
  14 #include <unistd.h>
  15 #include <utmp.h>
  16
  17 #include "alloc-util.h"
  18 #include "fd-util.h"
  19 #include "fileio.h"
  20 #include "format-util.h"
  21 #include "macro.h"
  22 #include "missing.h"
  23 #include "parse-util.h"
  24 #include "path-util.h"
  25 #include "string-util.h"
  26 #include "strv.h"
  27 #include "user-util.h"
  28 #include "utf8.h"
  29
  30 bool uid_is_valid(uid_t uid) {
  31
  32         /* Also see POSIX IEEE Std 1003.1-2008, 2016 Edition, 3.436. */
  33
  34         /* Some libc APIs use UID_INVALID as special placeholder */
  35         if (uid == (uid_t) UINT32_C(0xFFFFFFFF))
  36                 return false;
  37
  38         /* A long time ago UIDs where 16bit, hence explicitly avoid the 16bit -1 too */
  39         if (uid == (uid_t) UINT32_C(0xFFFF))
  40                 return false;
  41
  42         return true;
  43 }
  44
  45 int parse_uid(const char *s, uid_t *ret) {
  46         uint32_t uid = 0;
  47         int r;
  48
  49         assert(s);
  50
  51         assert_cc(sizeof(uid_t) == sizeof(uint32_t));
  52         r = safe_atou32(s, &uid);
  53         if (r < 0)
  54                 return r;
  55
  56         if (!uid_is_valid(uid))
  57                 return -ENXIO; /* we return ENXIO instead of EINVAL
  58                                 * here, to make it easy to distuingish
  59                                 * invalid numeric uids from invalid
  60                                 * strings. */
  61
  62         if (ret)
  63                 *ret = uid;
  64
  65         return 0;
  66 }
  67
  68 char* getlogname_malloc(void) {
  69         uid_t uid;
  70         struct stat st;
  71
  72         if (isatty(STDIN_FILENO) && fstat(STDIN_FILENO, &st) >= 0)
  73                 uid = st.st_uid;
  74         else
  75                 uid = getuid();
  76
  77         return uid_to_name(uid);
  78 }
  79
  80 char *getusername_malloc(void) {
  81         const char *e;
  82
  83         e = getenv("USER");
  84         if (e)
  85                 return strdup(e);
  86
  87         return uid_to_name(getuid());
  88 }
  89
  90 static inline bool is_nologin_shell(const char *shell) {
  91
  92         return PATH_IN_SET(shell,
  93                            /* 'nologin' is the friendliest way to disable logins for a user account. It prints a nice
  94                             * message and exits. Different distributions place the binary at different places though,
  95                             * hence let's list them all. */
  96                            "/bin/nologin",
  97                            "/sbin/nologin",
  98                            "/usr/bin/nologin",
  99                            "/usr/sbin/nologin",
 100                            /* 'true' and 'false' work too for the same purpose, but are less friendly as they don't do
 101                             * any message printing. Different distributions place the binary at various places but at
 102                             * least not in the 'sbin' directory. */
 103                            "/bin/false",
 104                            "/usr/bin/false",
 105                            "/bin/true",
 106                            "/usr/bin/true");
 107 }
 108
 109 static int synthesize_user_creds(
 110                 const char **username,
 111                 uid_t *uid, gid_t *gid,
 112                 const char **home,
 113                 const char **shell,
 114                 UserCredsFlags flags) {
 115
 116         /* We enforce some special rules for uid=0 and uid=65534: in order to avoid NSS lookups for root we hardcode
 117          * their user record data. */
 118
 119         if (STR_IN_SET(*username, "root", "0")) {
 120                 *username = "root";
 121
 122                 if (uid)
 123                         *uid = 0;
 124                 if (gid)
 125                         *gid = 0;
 126
 127                 if (home)
 128                         *home = "/root";
 129
 130                 if (shell)
 131                         *shell = "/bin/sh";
 132
 133                 return 0;
 134         }
 135
 136         if (synthesize_nobody() &&
 137             STR_IN_SET(*username, NOBODY_USER_NAME, "65534")) {
 138                 *username = NOBODY_USER_NAME;
 139
 140                 if (uid)
 141                         *uid = UID_NOBODY;
 142                 if (gid)
 143                         *gid = GID_NOBODY;
 144
 145                 if (home)
 146                         *home = FLAGS_SET(flags, USER_CREDS_CLEAN) ? NULL : "/";
 147
 148                 if (shell)
 149                         *shell = FLAGS_SET(flags, USER_CREDS_CLEAN) ? NULL : "/sbin/nologin";
 150
 151                 return 0;
 152         }
 153
 154         return -ENOMEDIUM;
 155 }
 156
 157 int get_user_creds(
 158                 const char **username,
 159                 uid_t *uid, gid_t *gid,
 160                 const char **home,
 161                 const char **shell,
 162                 UserCredsFlags flags) {
 163
 164         uid_t u = UID_INVALID;
 165         struct passwd *p;
 166         int r;
 167
 168         assert(username);
 169         assert(*username);
 170
 171         if (!FLAGS_SET(flags, USER_CREDS_PREFER_NSS) ||
 172             (!home && !shell)) {
 173
 174                 /* So here's the deal: normally, we'll try to synthesize all records we can synthesize, and override
 175                  * the user database with that. However, if the user specifies USER_CREDS_PREFER_NSS then the
 176                  * user database will override the synthetic records instead — except if the user is only interested in
 177                  * the UID and/or GID (but not the home directory, or the shell), in which case we'll always override
 178                  * the user database (i.e. the USER_CREDS_PREFER_NSS flag has no effect in this case). Why?
 179                  * Simply because there are valid usecase where the user might change the home directory or the shell
 180                  * of the relevant users, but changing the UID/GID mappings for them is something we explicitly don't
 181                  * support. */
 182
 183                 r = synthesize_user_creds(username, uid, gid, home, shell, flags);
 184                 if (r >= 0)
 185                         return 0;
 186                 if (r != -ENOMEDIUM) /* not a username we can synthesize */
 187                         return r;
 188         }
 189
 190         if (parse_uid(*username, &u) >= 0) {
 191                 errno = 0;
 192                 p = getpwuid(u);
 193
 194                 /* If there are multiple users with the same id, make sure to leave $USER to the configured value
 195                  * instead of the first occurrence in the database. However if the uid was configured by a numeric uid,
 196                  * then let's pick the real username from /etc/passwd. */
 197                 if (p)
 198                         *username = p->pw_name;
 199                 else if (FLAGS_SET(flags, USER_CREDS_ALLOW_MISSING) && !gid && !home && !shell) {
 200
 201                         /* If the specified user is a numeric UID and it isn't in the user database, and the caller
 202                          * passed USER_CREDS_ALLOW_MISSING and was only interested in the UID, then juts return that
 203                          * and don't complain. */
 204
 205                         if (uid)
 206                                 *uid = u;
 207
 208                         return 0;
 209                 }
 210         } else {
 211                 errno = 0;
 212                 p = getpwnam(*username);
 213         }
 214         if (!p) {
 215                 r = errno > 0 ? -errno : -ESRCH;
 216
 217                 /* If the user requested that we only synthesize as fallback, do so now */
 218                 if (FLAGS_SET(flags, USER_CREDS_PREFER_NSS)) {
 219                         if (synthesize_user_creds(username, uid, gid, home, shell, flags) >= 0)
 220                                 return 0;
 221                 }
 222
 223                 return r;
 224         }
 225
 226         if (uid) {
 227                 if (!uid_is_valid(p->pw_uid))
 228                         return -EBADMSG;
 229
 230                 *uid = p->pw_uid;
 231         }
 232
 233         if (gid) {
 234                 if (!gid_is_valid(p->pw_gid))
 235                         return -EBADMSG;
 236
 237                 *gid = p->pw_gid;
 238         }
 239
 240         if (home) {
 241                 if (FLAGS_SET(flags, USER_CREDS_CLEAN) && empty_or_root(p->pw_dir))
 242                         *home = NULL;
 243                 else
 244                         *home = p->pw_dir;
 245         }
 246
 247         if (shell) {
 248                 if (FLAGS_SET(flags, USER_CREDS_CLEAN) && (isempty(p->pw_shell) || is_nologin_shell(p->pw_shell)))
 249                         *shell = NULL;
 250                 else
 251                         *shell = p->pw_shell;
 252         }
 253
 254         return 0;
 255 }
 256
 257 int get_group_creds(const char **groupname, gid_t *gid, UserCredsFlags flags) {
 258         struct group *g;
 259         gid_t id;
 260
 261         assert(groupname);
 262
 263         /* We enforce some special rules for gid=0: in order to avoid NSS lookups for root we hardcode its data. */
 264
 265         if (STR_IN_SET(*groupname, "root", "0")) {
 266                 *groupname = "root";
 267
 268                 if (gid)
 269                         *gid = 0;
 270
 271                 return 0;
 272         }
 273
 274         if (synthesize_nobody() &&
 275             STR_IN_SET(*groupname, NOBODY_GROUP_NAME, "65534")) {
 276                 *groupname = NOBODY_GROUP_NAME;
 277
 278                 if (gid)
 279                         *gid = GID_NOBODY;
 280
 281                 return 0;
 282         }
 283
 284         if (parse_gid(*groupname, &id) >= 0) {
 285                 errno = 0;
 286                 g = getgrgid(id);
 287
 288                 if (g)
 289                         *groupname = g->gr_name;
 290                 else if (FLAGS_SET(flags, USER_CREDS_ALLOW_MISSING)) {
 291                         if (gid)
 292                                 *gid = id;
 293
 294                         return 0;
 295                 }
 296         } else {
 297                 errno = 0;
 298                 g = getgrnam(*groupname);
 299         }
 300
 301         if (!g)
 302                 return errno > 0 ? -errno : -ESRCH;
 303
 304         if (gid) {
 305                 if (!gid_is_valid(g->gr_gid))
 306                         return -EBADMSG;
 307
 308                 *gid = g->gr_gid;
 309         }
 310
 311         return 0;
 312 }
 313
 314 char* uid_to_name(uid_t uid) {
 315         char *ret;
 316         int r;
 317
 318         /* Shortcut things to avoid NSS lookups */
 319         if (uid == 0)
 320                 return strdup("root");
 321         if (synthesize_nobody() &&
 322             uid == UID_NOBODY)
 323                 return strdup(NOBODY_USER_NAME);
 324
 325         if (uid_is_valid(uid)) {
 326                 long bufsize;
 327
 328                 bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
 329                 if (bufsize <= 0)
 330                         bufsize = 4096;
 331
 332                 for (;;) {
 333                         struct passwd pwbuf, *pw = NULL;
 334                         _cleanup_free_ char *buf = NULL;
 335
 336                         buf = malloc(bufsize);
 337                         if (!buf)
 338                                 return NULL;
 339
 340                         r = getpwuid_r(uid, &pwbuf, buf, (size_t) bufsize, &pw);
 341                         if (r == 0 && pw)
 342                                 return strdup(pw->pw_name);
 343                         if (r != ERANGE)
 344                                 break;
 345
 346                         bufsize *= 2;
 347                 }
 348         }
 349
 350         if (asprintf(&ret, UID_FMT, uid) < 0)
 351                 return NULL;
 352
 353         return ret;
 354 }
 355
 356 char* gid_to_name(gid_t gid) {
 357         char *ret;
 358         int r;
 359
 360         if (gid == 0)
 361                 return strdup("root");
 362         if (synthesize_nobody() &&
 363             gid == GID_NOBODY)
 364                 return strdup(NOBODY_GROUP_NAME);
 365
 366         if (gid_is_valid(gid)) {
 367                 long bufsize;
 368
 369                 bufsize = sysconf(_SC_GETGR_R_SIZE_MAX);
 370                 if (bufsize <= 0)
 371                         bufsize = 4096;
 372
 373                 for (;;) {
 374                         struct group grbuf, *gr = NULL;
 375                         _cleanup_free_ char *buf = NULL;
 376
 377                         buf = malloc(bufsize);
 378                         if (!buf)
 379                                 return NULL;
 380
 381                         r = getgrgid_r(gid, &grbuf, buf, (size_t) bufsize, &gr);
 382                         if (r == 0 && gr)
 383                                 return strdup(gr->gr_name);
 384                         if (r != ERANGE)
 385                                 break;
 386
 387                         bufsize *= 2;
 388                 }
 389         }
 390
 391         if (asprintf(&ret, GID_FMT, gid) < 0)
 392                 return NULL;
 393
 394         return ret;
 395 }
 396
 397 int in_gid(gid_t gid) {
 398         long ngroups_max;
 399         gid_t *gids;
 400         int r, i;
 401
 402         if (getgid() == gid)
 403                 return 1;
 404
 405         if (getegid() == gid)
 406                 return 1;
 407
 408         if (!gid_is_valid(gid))
 409                 return -EINVAL;
 410
 411         ngroups_max = sysconf(_SC_NGROUPS_MAX);
 412         assert(ngroups_max > 0);
 413
 414         gids = newa(gid_t, ngroups_max);
 415
 416         r = getgroups(ngroups_max, gids);
 417         if (r < 0)
 418                 return -errno;
 419
 420         for (i = 0; i < r; i++)
 421                 if (gids[i] == gid)
 422                         return 1;
 423
 424         return 0;
 425 }
 426
 427 int in_group(const char *name) {
 428         int r;
 429         gid_t gid;
 430
 431         r = get_group_creds(&name, &gid, 0);
 432         if (r < 0)
 433                 return r;
 434
 435         return in_gid(gid);
 436 }
 437
 438 int get_home_dir(char **_h) {
 439         struct passwd *p;
 440         const char *e;
 441         char *h;
 442         uid_t u;
 443
 444         assert(_h);
 445
 446         /* Take the user specified one */
 447         e = secure_getenv("HOME");
 448         if (e && path_is_absolute(e)) {
 449                 h = strdup(e);
 450                 if (!h)
 451                         return -ENOMEM;
 452
 453                 *_h = h;
 454                 return 0;
 455         }
 456
 457         /* Hardcode home directory for root and nobody to avoid NSS */
 458         u = getuid();
 459         if (u == 0) {
 460                 h = strdup("/root");
 461                 if (!h)
 462                         return -ENOMEM;
 463
 464                 *_h = h;
 465                 return 0;
 466         }
 467         if (synthesize_nobody() &&
 468             u == UID_NOBODY) {
 469                 h = strdup("/");
 470                 if (!h)
 471                         return -ENOMEM;
 472
 473                 *_h = h;
 474                 return 0;
 475         }
 476
 477         /* Check the database... */
 478         errno = 0;
 479         p = getpwuid(u);
 480         if (!p)
 481                 return errno > 0 ? -errno : -ESRCH;
 482
 483         if (!path_is_absolute(p->pw_dir))
 484                 return -EINVAL;
 485
 486         h = strdup(p->pw_dir);
 487         if (!h)
 488                 return -ENOMEM;
 489
 490         *_h = h;
 491         return 0;
 492 }
 493
 494 int get_shell(char **_s) {
 495         struct passwd *p;
 496         const char *e;
 497         char *s;
 498         uid_t u;
 499
 500         assert(_s);
 501
 502         /* Take the user specified one */
 503         e = getenv("SHELL");
 504         if (e) {
 505                 s = strdup(e);
 506                 if (!s)
 507                         return -ENOMEM;
 508
 509                 *_s = s;
 510                 return 0;
 511         }
 512
 513         /* Hardcode shell for root and nobody to avoid NSS */
 514         u = getuid();
 515         if (u == 0) {
 516                 s = strdup("/bin/sh");
 517                 if (!s)
 518                         return -ENOMEM;
 519
 520                 *_s = s;
 521                 return 0;
 522         }
 523         if (synthesize_nobody() &&
 524             u == UID_NOBODY) {
 525                 s = strdup("/sbin/nologin");
 526                 if (!s)
 527                         return -ENOMEM;
 528
 529                 *_s = s;
 530                 return 0;
 531         }
 532
 533         /* Check the database... */
 534         errno = 0;
 535         p = getpwuid(u);
 536         if (!p)
 537                 return errno > 0 ? -errno : -ESRCH;
 538
 539         if (!path_is_absolute(p->pw_shell))
 540                 return -EINVAL;
 541
 542         s = strdup(p->pw_shell);
 543         if (!s)
 544                 return -ENOMEM;
 545
 546         *_s = s;
 547         return 0;
 548 }
 549
 550 int reset_uid_gid(void) {
 551         int r;
 552
 553         r = maybe_setgroups(0, NULL);
 554         if (r < 0)
 555                 return r;
 556
 557         if (setresgid(0, 0, 0) < 0)
 558                 return -errno;
 559
 560         if (setresuid(0, 0, 0) < 0)
 561                 return -errno;
 562
 563         return 0;
 564 }
 565
 566 int take_etc_passwd_lock(const char *root) {
 567
 568         struct flock flock = {
 569                 .l_type = F_WRLCK,
 570                 .l_whence = SEEK_SET,
 571                 .l_start = 0,
 572                 .l_len = 0,
 573         };
 574
 575         const char *path;
 576         int fd, r;
 577
 578         /* This is roughly the same as lckpwdf(), but not as awful. We
 579          * don't want to use alarm() and signals, hence we implement
 580          * our own trivial version of this.
 581          *
 582          * Note that shadow-utils also takes per-database locks in
 583          * addition to lckpwdf(). However, we don't given that they
 584          * are redundant as they invoke lckpwdf() first and keep
 585          * it during everything they do. The per-database locks are
 586          * awfully racy, and thus we just won't do them. */
 587
 588         if (root)
 589                 path = prefix_roota(root, ETC_PASSWD_LOCK_PATH);
 590         else
 591                 path = ETC_PASSWD_LOCK_PATH;
 592
 593         fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0600);
 594         if (fd < 0)
 595                 return log_debug_errno(errno, "Cannot open %s: %m", path);
 596
 597         r = fcntl(fd, F_SETLKW, &flock);
 598         if (r < 0) {
 599                 safe_close(fd);
 600                 return log_debug_errno(errno, "Locking %s failed: %m", path);
 601         }
 602
 603         return fd;
 604 }
 605
 606 bool valid_user_group_name(const char *u) {
 607         const char *i;
 608         long sz;
 609
 610         /* Checks if the specified name is a valid user/group name. Also see POSIX IEEE Std 1003.1-2008, 2016 Edition,
 611          * 3.437. We are a bit stricter here however. Specifically we deviate from POSIX rules:
 612          *
 613          * - We don't allow any dots (this would break chown syntax which permits dots as user/group name separator)
 614          * - We require that names fit into the appropriate utmp field
 615          * - We don't allow empty user names
 616          *
 617          * Note that other systems are even more restrictive, and don't permit underscores or uppercase characters.
 618          */
 619
 620         if (isempty(u))
 621                 return false;
 622
 623         if (!(u[0] >= 'a' && u[0] <= 'z') &&
 624             !(u[0] >= 'A' && u[0] <= 'Z') &&
 625             u[0] != '_')
 626                 return false;
 627
 628         for (i = u+1; *i; i++) {
 629                 if (!(*i >= 'a' && *i <= 'z') &&
 630                     !(*i >= 'A' && *i <= 'Z') &&
 631                     !(*i >= '0' && *i <= '9') &&
 632                     !IN_SET(*i, '_', '-'))
 633                         return false;
 634         }
 635
 636         sz = sysconf(_SC_LOGIN_NAME_MAX);
 637         assert_se(sz > 0);
 638
 639         if ((size_t) (i-u) > (size_t) sz)
 640                 return false;
 641
 642         if ((size_t) (i-u) > UT_NAMESIZE - 1)
 643                 return false;
 644
 645         return true;
 646 }
 647
 648 bool valid_user_group_name_or_id(const char *u) {
 649
 650         /* Similar as above, but is also fine with numeric UID/GID specifications, as long as they are in the right
 651          * range, and not the invalid user ids. */
 652
 653         if (isempty(u))
 654                 return false;
 655
 656         if (valid_user_group_name(u))
 657                 return true;
 658
 659         return parse_uid(u, NULL) >= 0;
 660 }
 661
 662 bool valid_gecos(const char *d) {
 663
 664         if (!d)
 665                 return false;
 666
 667         if (!utf8_is_valid(d))
 668                 return false;
 669
 670         if (string_has_cc(d, NULL))
 671                 return false;
 672
 673         /* Colons are used as field separators, and hence not OK */
 674         if (strchr(d, ':'))
 675                 return false;
 676
 677         return true;
 678 }
 679
 680 bool valid_home(const char *p) {
 681         /* Note that this function is also called by valid_shell(), any
 682          * changes must account for that. */
 683
 684         if (isempty(p))
 685                 return false;
 686
 687         if (!utf8_is_valid(p))
 688                 return false;
 689
 690         if (string_has_cc(p, NULL))
 691                 return false;
 692
 693         if (!path_is_absolute(p))
 694                 return false;
 695
 696         if (!path_is_normalized(p))
 697                 return false;
 698
 699         /* Colons are used as field separators, and hence not OK */
 700         if (strchr(p, ':'))
 701                 return false;
 702
 703         return true;
 704 }
 705
 706 int maybe_setgroups(size_t size, const gid_t *list) {
 707         int r;
 708
 709         /* Check if setgroups is allowed before we try to drop all the auxiliary groups */
 710         if (size == 0) { /* Dropping all aux groups? */
 711                 _cleanup_free_ char *setgroups_content = NULL;
 712                 bool can_setgroups;
 713
 714                 r = read_one_line_file("/proc/self/setgroups", &setgroups_content);
 715                 if (r == -ENOENT)
 716                         /* Old kernels don't have /proc/self/setgroups, so assume we can use setgroups */
 717                         can_setgroups = true;
 718                 else if (r < 0)
 719                         return r;
 720                 else
 721                         can_setgroups = streq(setgroups_content, "allow");
 722
 723                 if (!can_setgroups) {
 724                         log_debug("Skipping setgroups(), /proc/self/setgroups is set to 'deny'");
 725                         return 0;
 726                 }
 727         }
 728
 729         if (setgroups(size, list) < 0)
 730                 return -errno;
 731
 732         return 0;
 733 }
 734
 735 bool synthesize_nobody(void) {
 736
 737 #ifdef NOLEGACY
 738         return true;
 739 #else
 740         /* Returns true when we shall synthesize the "nobody" user (which we do by default). This can be turned off by
 741          * touching /etc/systemd/dont-synthesize-nobody in order to provide upgrade compatibility with legacy systems
 742          * that used the "nobody" user name and group name for other UIDs/GIDs than 65534.
 743          *
 744          * Note that we do not employ any kind of synchronization on the following caching variable. If the variable is
 745          * accessed in multi-threaded programs in the worst case it might happen that we initialize twice, but that
 746          * shouldn't matter as each initialization should come to the same result. */
 747         static int cache = -1;
 748
 749         if (cache < 0)
 750                 cache = access("/etc/systemd/dont-synthesize-nobody", F_OK) < 0;
 751
 752         return cache;
 753 #endif
 754 }
 755
 756 int putpwent_sane(const struct passwd *pw, FILE *stream) {
 757         assert(pw);
 758         assert(stream);
 759
 760         errno = 0;
 761         if (putpwent(pw, stream) != 0)
 762                 return errno > 0 ? -errno : -EIO;
 763
 764         return 0;
 765 }
 766
 767 int putspent_sane(const struct spwd *sp, FILE *stream) {
 768         assert(sp);
 769         assert(stream);
 770
 771         errno = 0;
 772         if (putspent(sp, stream) != 0)
 773                 return errno > 0 ? -errno : -EIO;
 774
 775         return 0;
 776 }
 777
 778 int putgrent_sane(const struct group *gr, FILE *stream) {
 779         assert(gr);
 780         assert(stream);
 781
 782         errno = 0;
 783         if (putgrent(gr, stream) != 0)
 784                 return errno > 0 ? -errno : -EIO;
 785
 786         return 0;
 787 }
 788
 789 #if ENABLE_GSHADOW
 790 int putsgent_sane(const struct sgrp *sg, FILE *stream) {
 791         assert(sg);
 792         assert(stream);
 793
 794         errno = 0;
 795         if (putsgent(sg, stream) != 0)
 796                 return errno > 0 ? -errno : -EIO;
 797
 798         return 0;
 799 }
 800 #endif
 801
 802 int fgetpwent_sane(FILE *stream, struct passwd **pw) {
 803         struct passwd *p;
 804
 805         assert(pw);
 806         assert(stream);
 807
 808         errno = 0;
 809         p = fgetpwent(stream);
 810         if (!p && errno != ENOENT)
 811                 return errno > 0 ? -errno : -EIO;
 812
 813         *pw = p;
 814         return !!p;
 815 }
 816
 817 int fgetspent_sane(FILE *stream, struct spwd **sp) {
 818         struct spwd *s;
 819
 820         assert(sp);
 821         assert(stream);
 822
 823         errno = 0;
 824         s = fgetspent(stream);
 825         if (!s && errno != ENOENT)
 826                 return errno > 0 ? -errno : -EIO;
 827
 828         *sp = s;
 829         return !!s;
 830 }
 831
 832 int fgetgrent_sane(FILE *stream, struct group **gr) {
 833         struct group *g;
 834
 835         assert(gr);
 836         assert(stream);
 837
 838         errno = 0;
 839         g = fgetgrent(stream);
 840         if (!g && errno != ENOENT)
 841                 return errno > 0 ? -errno : -EIO;
 842
 843         *gr = g;
 844         return !!g;
 845 }
 846
 847 #if ENABLE_GSHADOW
 848 int fgetsgent_sane(FILE *stream, struct sgrp **sg) {
 849         struct sgrp *s;
 850
 851         assert(sg);
 852         assert(stream);
 853
 854         errno = 0;
 855         s = fgetsgent(stream);
 856         if (!s && errno != ENOENT)
 857                 return errno > 0 ? -errno : -EIO;
 858
 859         *sg = s;
 860         return !!s;
 861 }
 862 #endif