trusty (3) getpwnam_r.3posix.gz

NAME

       getpwnam, getpwnam_r - search user database for a name

SYNOPSIS

       #include <pwd.h>

       struct passwd *getpwnam(const char *name);

       int getpwnam_r(const char *name, struct passwd *pwd, char *buffer,
              size_t bufsize, struct passwd **result);

DESCRIPTION

       The getpwnam() function shall search the user database for an entry with a matching name.

       The  getpwnam()  function  need  not be reentrant. A function that is not required to be reentrant is not
       required to be thread-safe.

       Applications wishing to check for error situations should set errno to 0 before  calling  getpwnam().  If
       getpwnam() returns a null pointer and errno is non-zero, an error occurred.

       The getpwnam_r() function shall update the passwd structure pointed to by pwd and store a pointer to that
       structure at the location pointed to by result. The structure  shall  contain  an  entry  from  the  user
       database  with a matching name. Storage referenced by the structure is allocated from the memory provided
       with the buffer parameter, which is bufsize bytes in size. The maximum size needed for this buffer can be
       determined  with  the {_SC_GETPW_R_SIZE_MAX} sysconf() parameter. A NULL pointer shall be returned at the
       location pointed to by result on error or if the requested entry is not found.

RETURN VALUE

       The getpwnam() function shall return a pointer to a struct  passwd  with  the  structure  as  defined  in
       <pwd.h>  with  a  matching entry if found. A null pointer shall be returned if the requested entry is not
       found, or an error occurs. On error, errno shall be set to indicate the error.

       The return value may point to a static area which is overwritten by  a  subsequent  call  to  getpwent(),
       getpwnam(), or getpwuid().

       If  successful, the getpwnam_r() function shall return zero; otherwise, an error number shall be returned
       to indicate the error.

ERRORS

       The getpwnam() and getpwnam_r() functions may fail if:

       EIO    An I/O error has occurred.

       EINTR  A signal was caught during getpwnam().

       EMFILE {OPEN_MAX} file descriptors are currently open in the calling process.

       ENFILE The maximum allowable number of files is currently open in the system.

       The getpwnam_r() function may fail if:

       ERANGE Insufficient storage was supplied via buffer and bufsize to contain the data to be  referenced  by
              the resulting passwd structure.

       The following sections are informative.

EXAMPLES

   Getting an Entry for the Login Name
       The  following  example  uses  the getlogin() function to return the name of the user who logged in; this
       information is passed to the getpwnam() function to get the user database entry for that user.

              #include <sys/types.h>
              #include <pwd.h>
              #include <unistd.h>
              #include <stdio.h>
              #include <stdlib.h>
              ...
              char *lgn;
              struct passwd *pw;
              ...
              if ((lgn = getlogin()) == NULL || (pw = getpwnam(lgn)) == NULL) {
                  fprintf(stderr, "Get of user information failed.\n"); exit(1);
              }
              ...

APPLICATION USAGE

       Three names associated with the current process can be determined: getpwuid( geteuid()) returns the  name
       associated  with  the  effective  user ID of the process; getlogin() returns the name associated with the
       current login activity; and getpwuid( getuid()) returns the name associated with the real user ID of  the
       process.

       The getpwnam_r() function is thread-safe and returns values in a user-supplied buffer instead of possibly
       using a static data area that may be overwritten by each call.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       getpwuid() , the Base Definitions volume of IEEE Std 1003.1-2001, <limits.h>, <pwd.h>, <sys/types.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,
       Inc  and  The  Open Group. In the event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .