getpwuid


SYNOPSIS
       #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


       The return value may point to a static area, and may be overwritten  by
       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  maximum  number (OPEN_MAX) of files was open already in the
              calling process.

       ENFILE The maximum number of files was open already in the system.

       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
   Multithreading (see pthreads(7))
       The getpwnam() and getpwuid() functions are not thread-safe.

       The getpwnam_r() and getpwuid_r() functions are thread-safe.

CONFORMING TO
       SVr4, 4.3BSD, POSIX.1-2001.  The pw_gecos field  is  not  specified  in
       POSIX, but is present on most implementations.

NOTES
       The  formulation given above under "RETURN VALUE" is from POSIX.1-2001.
       It does not call "not found" an error, and hence does not specify  what
       value errno might have in this situation.  But that makes it impossible
       to recognize errors.  One might argue that  according  to  POSIX  errno
       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);
           }

           printf("Name: %s; UID: %ld\n", pwd.pw_gecos, (long) pwd.pw_uid);
           exit(EXIT_SUCCESS);
       }

SEE ALSO
       endpwent(3),  fgetpwent(3),  getgrnam(3), getpw(3), getpwent(3), getsp-
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