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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  non-reentrant  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  func-
       tions,  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 getpw-
       nam_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 3.22 of the Linux man-pages project.  A description of the project, and informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                               2007-07-26                     GETPWENT_R(3)