GETPWENT_R(3)                                       Linux Programmer's Manual                                      GETPWENT_R(3)



NAME
       getpwent_r, fgetpwent_r - get passwd file entry reentrantly

SYNOPSIS
       #include <pwd.h>

       int getpwent_r(struct passwd *pwbuf, char *buf,
                      size_t buflen, struct passwd **pwbufp);

       int fgetpwent_r(FILE *fp, struct passwd *pwbuf, char *buf,
                       size_t buflen, struct passwd **pwbufp);

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

       getpwent_r(), _BSD_SOURCE || _SVID_SOURCE
       fgetpwent_r(): _SVID_SOURCE

DESCRIPTION
       The  functions  getpwent_r()  and  fgetpwent_r()  are the reentrant versions of getpwent(3) and fgetpwent(3).  The former
       reads the next passwd entry from the stream initialized by setpwent(3).  The latter reads the next passwd entry from  the
       stream fp.

       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;     /* real name */
               char    *pw_dir;       /* home directory */
               char    *pw_shell;     /* shell program */
           };

       The  nonreentrant  functions  return  a pointer to static storage, where this static storage contains further pointers to
       user name, password, gecos field, home directory and shell.  The reentrant functions described here return all of that in
       caller-provided  buffers.  First of all there is the buffer pwbuf that can hold a struct passwd.  And next the buffer buf
       of size buflen that can hold additional strings.  The result of these functions, the struct passwd read from the  stream,
       is stored in the provided buffer *pwbuf, and a pointer to this struct passwd is returned in *pwbufp.

RETURN VALUE
       On  success, these functions return 0 and *pwbufp is a pointer to the struct passwd.  On error, these functions return an
       error value and *pwbufp is NULL.

ERRORS
       ENOENT No more entries.

       ERANGE Insufficient buffer space supplied.  Try again with larger buffer.

CONFORMING TO
       These functions are GNU extensions, done in a style resembling the POSIX version of functions like getpwnam_r(3).   Other
       systems use prototype

           struct passwd *
           getpwent_r(struct passwd *pwd, char *buf, int buflen);

       or, better,

           int
           getpwent_r(struct passwd *pwd, char *buf, int buflen,
                      FILE **pw_fp);

NOTES
       The  function  getpwent_r()  is  not  really  reentrant since it shares the reading position in the stream with all other
       threads.

EXAMPLE
       #define _GNU_SOURCE
       #include <pwd.h>
       #include <stdio.h>
       #define BUFLEN 4096

       int
       main(void)
       {
           struct passwd pw, *pwp;
           char buf[BUFLEN];
           int i;

           setpwent();
           while (1) {
               i = getpwent_r(&pw, buf, BUFLEN, &pwp);
               if (i)
                   break;
               printf("%s (%d)\tHOME %s\tSHELL %s\n", pwp->pw_name,
                      pwp->pw_uid, pwp->pw_dir, pwp->pw_shell);
           }
           endpwent();
           exit(EXIT_SUCCESS);
       }

SEE ALSO
       fgetpwent(3), getpw(3), getpwent(3), getpwnam(3), getpwuid(3), putpwent(3), passwd(5)

COLOPHON
       This page is part of release 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                                                        2007-07-26                                              GETPWENT_R(3)