lookup.subproj/getpwent.3

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  28 .\"     From: @(#)getpwent.3    8.2 (Berkeley) 12/11/93
  29 .\" $FreeBSD: src/lib/libc/gen/getpwent.3,v 1.30 2007/01/09 00:27:54 imp Exp $
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  31 .Dd October 26, 2011
  32 .Dt GETPWENT 3
  33 .Os
  34 .Sh NAME
  35 .Nm getpwent ,
  36 .\".Nm getpwent_r ,
  37 .Nm getpwnam ,
  38 .Nm getpwnam_r ,
  39 .Nm getpwuid ,
  40 .Nm getpwuid_r ,
  41 .Nm getpwuuid ,
  42 .Nm getpwuuid_r ,
  43 .Nm setpassent ,
  44 .Nm setpwent ,
  45 .Nm endpwent
  46 .Nd password database operations
  47 .Sh LIBRARY
  48 .Lb libc
  49 .Sh SYNOPSIS
  50 .In sys/types.h
  51 .In pwd.h
  52 .In uuid/uuid.h
  53 .Ft struct passwd *
  54 .Fn getpwent void
  55 .\".Ft int
  56 .\".Fn getpwent_r "struct passwd *pwd" "char *buffer" "size_t bufsize" "struct passwd **result"
  57 .Ft struct passwd *
  58 .Fn getpwnam "const char *login"
  59 .Ft int
  60 .Fn getpwnam_r "const char *name" "struct passwd *pwd" "char *buffer" "size_t bufsize" "struct passwd **result"
  61 .Ft struct passwd *
  62 .Fn getpwuid "uid_t uid"
  63 .Ft int
  64 .Fn getpwuid_r "uid_t uid" "struct passwd *pwd" "char *buffer" "size_t bufsize" "struct passwd **result"
  65 .Ft struct passwd *
  66 .Fn getpwuuid "uuid_t uuid"
  67 .Ft int
  68 .Fn getpwuuid_r "uuid_t uuid" "struct passwd *pwd" "char *buffer" "size_t bufsize" "struct passwd **result"
  69 .Ft int
  70 .Fn setpassent "int stayopen"
  71 .Ft void
  72 .Fn setpwent void
  73 .Ft void
  74 .Fn endpwent void
  75 .Sh DESCRIPTION
  76 These functions
  77 .\"operate on the password database file
  78 obtain information from
  79 .Xr opendirectoryd 8 ,
  80 including records in
  81 .Pa /etc/master.passwd
  82 which is described
  83 in
  84 .Xr master.passwd 5 .
  85 Each entry in the database is defined by the structure
  86 .Vt passwd
  87 found in the include
  88 file
  89 .In pwd.h :
  90 .Bd -literal -offset indent
  91 struct passwd {
  92         char    *pw_name;       /* user name */
  93         char    *pw_passwd;     /* encrypted password */
  94         uid_t   pw_uid;         /* user uid */
  95         gid_t   pw_gid;         /* user gid */
  96         time_t  pw_change;      /* password change time */
  97         char    *pw_class;      /* user access class */
  98         char    *pw_gecos;      /* Honeywell login info */
  99         char    *pw_dir;        /* home directory */
 100         char    *pw_shell;      /* default shell */
 101         time_t  pw_expire;      /* account expiration */
 102         int     pw_fields;      /* internal: fields filled in */
 103 };
 104 .Ed
 105 .Pp
 106 The functions
 107 .Fn getpwnam ,
 108 .Fn getpwuid ,
 109 and
 110 .Fn getpwuuid
 111 search the password database for the given login name, user uid, or user uuid
 112 respectively, always returning the first one encountered.
 113 .Pp
 114 Note that the password file
 115 .Pa /etc/master.passwd
 116 does not contain user UUIDs.
 117 The UUID for a user may be found using
 118 .Fn mbr_uid_to_uuid .
 119 .Pp
 120 On Mac OS X, these routines are thread-safe and return a pointer to a
 121 thread-specific data structure.  The contents of this data
 122 structure are automatically released by subsequent calls to
 123 any of these routines on the same thread, or when the thread exits.
 124 These routines are therefore unsuitable for use in libraries or frameworks,
 125 from where they may overwrite the per-thread data that the calling
 126 application expects to find as a result of its own calls to these
 127 routines. Library and framework code should use the alternative reentrant
 128 variants detailed below.
 129 .Pp
 130 The
 131 .Fn getpwent
 132 function
 133 sequentially reads the password database and is intended for programs
 134 that wish to process the complete list of users.
 135 .Pp
 136 The functions
 137 .Fn getpwnam_r ,
 138 .Fn getpwuid_r ,
 139 and
 140 .Fn getpwuuid_r
 141 are alternative versions of
 142 .Fn getpwnam ,
 143 .Fn getpwuid ,
 144 and
 145 .Fn getpwuuid
 146 respectively.
 147 They store the results of their search in the caller-provided
 148 .Fa pwd
 149 structure, which additionally contains pointers to strings that are
 150 stored in the caller-provided
 151 .Fa buffer
 152 of size
 153 .Fa bufsize .
 154 (The maximum required
 155 .Fa bufsize
 156 can be obtained by passing the _SC_GETPW_R_SIZE_MAX constant to the
 157 .Xr sysconf 3
 158 call. See example code below.) When these functions are successful, the
 159 .Fa pwd
 160 argument will be filled in, and a pointer to that argument will be
 161 stored in the caller-provided
 162 .Fa result .
 163 If an entry is not found or an error occurs,
 164 .Fa result
 165 will be set to
 166 .Dv NULL .
 167 .Pp
 168 The
 169 .Fn setpassent
 170 function
 171 accomplishes two purposes.
 172 First, it causes
 173 .Fn getpwent
 174 to ``rewind'' to the beginning of the database.
 175 Additionally, if
 176 .Fa stayopen
 177 is non-zero, file descriptors are left open, significantly speeding
 178 up subsequent accesses for all of the routines.
 179 (This latter functionality is unnecessary for
 180 .Fn getpwent
 181 as it does not close its file descriptors by default.)
 182 .Pp
 183 It is dangerous for long-running programs to keep the file descriptors
 184 open as the database will become out of date if it is updated while the
 185 program is running.
 186 .Pp
 187 The
 188 .Fn setpwent
 189 function
 190 is identical to
 191 .Fn setpassent
 192 with an argument of zero.
 193 .Pp
 194 The
 195 .Fn endpwent
 196 function
 197 closes any open files.
 198 .Pp
 199 .\"These routines have been written to ``shadow'' the password file, e.g.\&
 200 .\"allow only certain programs to have access to the encrypted password.
 201 .\"If the process which calls them has an effective uid of 0, the encrypted
 202 .\"password will be returned, otherwise, the password field of the returned
 203 .\"structure will point to the string
 204 These routines have been written to
 205 .Ql shadow
 206 the password of user records created on Mac OS X 10.3 or later,
 207 by returning a structure whose password field points to the string
 208 .Ql ******** .
 209 Legacy crypt passwords are still returned for user records created on
 210 earlier versions of Mac OS X whose
 211 .Xr opendirectoryd 8
 212 .Dt AuthenticationAuthority
 213 attribute contains the value
 214 .Ql ;basic; .
 215 .Pp
 216 Note that
 217 .Xr opendirectoryd 8
 218 allows user records from some sources which may not include all the component
 219 fields present in a passwd structure.
 220 Only the name, uid, and gid of a user record are required.
 221 Default values will be supplied as follows:
 222 .Bd -literal -offset indent
 223 pw_passwd = "*"
 224 pw_change = 0
 225 pw_class = ""
 226 pw_gecos = ""
 227 pw_dir = "/var/empty"
 228 pw_shell = "/usr/bin/false"
 229 pw_expire = 0
 230 .Ed
 231 .Sh RETURN VALUES
 232 The functions
 233 .Fn getpwent ,
 234 .Fn getpwnam ,
 235 .Fn getpwuid ,
 236 and
 237 .Fn getpwuuid
 238 return a valid pointer to a passwd structure on success
 239 or
 240 .Dv NULL
 241 if the entry is not found or if an error occurs.
 242 If an error does occur,
 243 .Va errno
 244 will be set.
 245 Note that programs must explicitly set
 246 .Va errno
 247 to zero before calling any of these functions if they need to
 248 distinguish between a non-existent entry and an error.
 249 The functions
 250 .Fn getpwnam_r ,
 251 .Fn getpwuid_r ,
 252 and
 253 .Fn getpwuuid_r
 254 return 0 if no error occurred, or an error number to indicate failure.
 255 It is not an error if a matching entry is not found.
 256 (Thus, if
 257 .Fa result
 258 is
 259 .Dv NULL
 260 and the return value is 0, no matching entry exists.)
 261 .Pp
 262 The
 263 .Fn setpassent
 264 function returns 0 on failure and 1 on success.
 265 The
 266 .Fn endpwent
 267 and
 268 .Fn setpwent
 269 functions
 270 have no return value.
 271 .Sh EXAMPLES
 272 To print the current user's home directory without depending on per-thread storage:
 273 .Bd -literal -offset indent
 274 #include <sys/types.h>
 275 #include <unistd.h>
 276 #include <stdlib.h>
 277 #include <stdio.h>
 278 #include <pwd.h>
 279
 280 int bufsize;
 281
 282 if ((bufsize = sysconf(_SC_GETPW_R_SIZE_MAX)) == -1)
 283     abort();
 284
 285 char buffer[bufsize];
 286 struct passwd pwd, *result = NULL;
 287 if (getpwuid_r(getuid(), &pwd, buffer, bufsize, &result) != 0 || !result)
 288     abort();
 289
 290 printf("%s\\n", pwd.pw_dir);
 291 .Ed
 292 .Sh FILES
 293 .Bl -tag -width /etc/master.passwd -compact
 294 .\".It Pa /etc/pwd.db
 295 .\"The insecure password database file
 296 .\".It Pa /etc/spwd.db
 297 The secure password database file
 298 .It Pa /etc/master.passwd
 299 The current password file
 300 .It Pa /etc/passwd
 301 A Version 7 format password file
 302 .El
 303 .\".Sh COMPATIBILITY
 304 .\"The historic function
 305 .\".Xr setpwfile 3 ,
 306 .\"which allowed the specification of alternate password databases,
 307 .\"has been deprecated and is no longer available.
 308 .Sh ERRORS
 309 These routines may fail for any of the errors specified in
 310 .Xr open 2 ,
 311 .Xr dbopen 3 ,
 312 .Xr socket 2 ,
 313 and
 314 .Xr connect 2 ,
 315 in addition to the following:
 316 .Bl -tag -width Er
 317 .It Bq Er ERANGE
 318 The buffer specified by the
 319 .Fa buffer
 320 and
 321 .Fa bufsize
 322 arguments was insufficiently sized to store the result.
 323 The caller should retry with a larger buffer.
 324 .El
 325 .Sh SEE ALSO
 326 .Xr getlogin 2 ,
 327 .Xr getgrent 3 ,
 328 .\".Xr nsswitch.conf 5 ,
 329 .Xr passwd 5 ,
 330 .\".Xr pwd_mkdb 8 ,
 331 .\".Xr vipw 8 ,
 332 .Xr mbr_uid_to_uuid 3,
 333 .Xr opendirectoryd 8 ,
 334 .Xr yp 8
 335 .Sh STANDARDS
 336 The
 337 .Fn getpwent ,
 338 .Fn getpwnam ,
 339 .Fn getpwnam_r ,
 340 .Fn getpwuid ,
 341 .Fn getpwuid_r ,
 342 .Fn setpwent ,
 343 and
 344 .Fn endpwent
 345 functions conform to
 346 .St -p1003.1-96 .
 347 .Sh HISTORY
 348 The
 349 .Fn getpwent ,
 350 .Fn getpwnam ,
 351 .Fn getpwuid ,
 352 .Fn setpwent ,
 353 and
 354 .Fn endpwent
 355 functions appeared in
 356 .At v7 .
 357 The
 358 .Fn setpassent
 359 function appeared in
 360 .Bx 4.3 Reno .
 361 The
 362 .\".Fn getpwent_r ,
 363 .\".Fn getpwnam_r ,
 364 .Fn getpwnam_r
 365 and
 366 .Fn getpwuid_r
 367 functions appeared in
 368 .Fx 5.1 .
 369 The functions
 370 .Fn getpwuuid
 371 and
 372 .Fn getpwuuid_r
 373 appeared in Mac OS X 10.8.
 374 .Sh BUGS
 375 The functions
 376 .Fn getpwent ,
 377 .Fn getpwnam ,
 378 .Fn getpwuid ,
 379 and
 380 .Fn getpwuuid ,
 381 .\"leave their results in an internal static object and return
 382 leave their results in an internal thread-specific memory and return
 383 a pointer to that object.
 384 Subsequent calls to
 385 the same function
 386 will modify the same object.
 387 .\".Pp
 388 .\"The functions
 389 .\".Fn getpwent ,
 390 .\".Fn getpwent_r ,
 391 .\".Fn endpwent ,
 392 .\".Fn setpassent ,
 393 .\"and
 394 .\".Fn setpwent
 395 .\"are fairly useless in a networked environment and should be
 396 .\"avoided, if possible.
 397 .\"The
 398 .\".Fn getpwent
 399 .\"and
 400 .\".Fn getpwent_r
 401 .\"functions
 402 .\"make no attempt to suppress duplicate information if multiple
 403 .\"sources are specified in
 404 .\".Xr nsswitch.conf 5 .