getpwuid_r

       #include <sys/types.h>
       #include <pwd.h>

       struct passwd *getpwnam(const char *name);

       struct passwd *getpwuid(uid_t uid);

       int getpwnam_r(const char *name, struct passwd *pwd,
                      char *buf, size_t buflen, struct passwd **result);

       int getpwuid_r(uid_t uid, struct passwd *pwd,
                      char *buf, size_t buflen, struct passwd **result);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getpwnam_r(), getpwuid_r():
           _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _BSD_SOURCE ||
           _SVID_SOURCE || _POSIX_SOURCE

DESCRIPTION
       The getpwnam() function returns a pointer to a structure containing the
       broken-out  fields  of  the  record in the password database (e.g., the
       local password file /etc/passwd, NIS, and LDAP) that matches the  user-
       name name.

       The getpwuid() function returns a pointer to a structure containing the
       broken-out fields of the record in the password database  that  matches
       the user ID uid.

       The passwd structure is defined in <pwd.h> as follows:

           struct passwd {
               char   *pw_name;       /* username */
               char   *pw_passwd;     /* user password */
               uid_t   pw_uid;        /* user ID */
               gid_t   pw_gid;        /* group ID */
               char   *pw_gecos;      /* user information */
               char   *pw_dir;        /* home directory */
               char   *pw_shell;      /* shell program */
           };

       See passwd(5) for more information about these fields.

       The getpwnam_r() and getpwuid_r() functions obtain the same information
       as getpwnam() and getpwuid(), but store the retrieved passwd  structure
       in  the  space  pointed to by pwd.  The string fields pointed to by the
       members of the passwd structure are stored in the buffer  buf  of  size
       buflen.   A pointer to the result (in case of success) or NULL (in case
       no entry was found or an error occurred) is stored in *result.

       The call

           sysconf(_SC_GETPW_R_SIZE_MAX)

       subsequent  calls  to  getpwent(3), getpwnam(), or getpwuid().  (Do not
       pass the returned pointer to free(3).)

       On success, getpwnam_r() and getpwuid_r() return zero, and set  *result
       to  pwd.   If  no  matching  password record was found, these functions
       return 0 and store NULL in *result.  In case of error, an error  number
       is returned, and NULL is stored in *result.

ERRORS
       0 or ENOENT or ESRCH or EBADF or EPERM or ...
              The given name or uid was not found.

       EINTR  A signal was caught.

       EIO    I/O error.

       EMFILE The per-process limit on the number of open file descriptors has
              been reached.

       ENFILE The system-wide limit on the total number of open files has been
              reached.

       ENOMEM Insufficient memory to allocate passwd structure.

       ERANGE Insufficient buffer space supplied.

NOTE
       The user password database mostly refers to /etc/passwd.  However, with
       recent systems it also refers to network wide databases using NIS, LDAP
       and other local files as configured in /etc/nsswitch.conf.

FILES
       /etc/passwd
              local password database file

       /etc/nsswitch.conf
              System Databases and Name Service Switch configuration file

ATTRIBUTES
       For   an   explanation   of   the  terms  used  in  this  section,  see
       attributes(7).

       +--------------+---------------+-----------------------------+
       |Interface     | Attribute     | Value                       |
       +--------------+---------------+-----------------------------+
       |getpwnam()    | Thread safety | MT-Unsafe race:pwnam locale |
       +--------------+---------------+-----------------------------+
       |getpwuid()    | Thread safety | MT-Unsafe race:pwuid locale |
       +--------------+---------------+-----------------------------+
       |getpwnam_r(), | Thread safety | MT-Safe locale              |
       |getpwuid_r()  |               |                             |
       +--------------+---------------+-----------------------------+
CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.  The pw_gecos  field  is  not
       The pw_dir field contains the name of the initial working directory  of
       the user.  Login programs use the value of this field to initialize the
       HOME environment variable for the login  shell.   An  application  that
       wants  to  determine its user's home directory should inspect the value
       of HOME (rather than the value getpwuid(getuid())->pw_dir)  since  this
       allows the user to modify their notion of "the home directory" during a
       login session.  To determine the (initial) home  directory  of  another
       user, it is necessary to use getpwnam("username")->pw_dir or similar.

EXAMPLE
       The program below demonstrates the use of getpwnam_r() to find the full
       username and user ID for the username supplied as a command-line  argu-
       ment.

       #include <pwd.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <unistd.h>
       #include <errno.h>

       int
       main(int argc, char *argv[])
       {
           struct passwd pwd;
           struct passwd *result;
           char *buf;
           size_t bufsize;
           int s;

           if (argc != 2) {
               fprintf(stderr, "Usage: %s username\n", argv[0]);
               exit(EXIT_FAILURE);
           }

           bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
           if (bufsize == -1)          /* Value was indeterminate */
               bufsize = 16384;        /* Should be more than enough */

           buf = malloc(bufsize);
           if (buf == NULL) {
               perror("malloc");
               exit(EXIT_FAILURE);
           }

           s = getpwnam_r(argv[1], &pwd, buf, bufsize, &result);
           if (result == NULL) {
               if (s == 0)
                   printf("Not found\n");
               else {
                   errno = s;
                   perror("getpwnam_r");
               }
               exit(EXIT_FAILURE);
           }

       latest    version    of    this    page,    can     be     found     at
       http://www.kernel.org/doc/man-pages/.

GNU                               2015-12-28                       GETPWNAM(3)
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