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

NAME
       getpwentr, fgetpwentr - get passwd file entry reentrantly

SYNOPSIS
       #include 

       int getpwentr(struct passwd *pwbuf, char *buf,
                      sizet buflen, struct passwd **pwbufp);

       int fgetpwentr(FILE *fp, struct passwd *pwbuf, char *buf,
                       sizet buflen, struct passwd **pwbufp);

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

       getpwentr(), BSDSOURCE || SVIDSOURCE
       fgetpwentr(): SVIDSOURCE

DESCRIPTION
       The functions getpwentr() and fgetpwentr() 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  as follows:

           struct passwd {
               char    *pwname;      /* username */
               char    *pwpasswd;    /* user password */
               uidt    pwuid;       /* user ID */
               gidt    pwgid;       /* group ID */
               char    *pwgecos;     /* user information */
               char    *pwdir;       /* home directory */
               char    *pwshell;     /* shell program */
           };

       For more information about the fields of this structure, see passwd(5).

       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  buf‐
              fer.

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

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

       or, better,

           int
           getpwentr(struct passwd *pwd, char *buf, int buflen,
                      FILE **pwfp);

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

EXAMPLE
       #define GNUSOURCE
       #include 
       #include 
       #define BUFLEN 4096

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

           setpwent();
           while (1) {
               i = getpwentr(&pw, buf, BUFLEN, &pwp);
               if (i)
                   break;
               printf("%s (%d)\tHOME %s\tSHELL %s\n", pwp->pwname,
                      pwp->pwuid, pwp->pwdir, pwp->pwshell);
           }
           endpwent();
           exit(EXITSUCCESS);
       }

SEE ALSO
       fgetpwent(3), getpw(3), getpwent(3),  getpwnam(3),  getpwuid(3),  putp‐
       went(3), passwd(5)

COLOPHON
       This  page  is  part of release 3.53 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                               2010-10-21                     GETPWENTR(3)