fgetpwent_r

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



NAME
       getpwent_r, fgetpwent_r - get passwd file entry reentrantly

SYNOPSIS
       #define _GNU_SOURCE
       #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);

DESCRIPTION
       The  functions  getpwent_r()  and fgetpwent_r() are the reentrant ver-
       sions 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 given as parameter.

       The passwd structure is defined in <pwd.h> as follows:

	      struct passwd {
		    char    *pw_name;	   /* user name */
		    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 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.

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

       int main() {
	     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();
	     return 0;
       }

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

	   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.

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



GNU				  2003-11-15			GETPWENT_R(3)