getgrent_r(3)              Library Functions Manual              getgrent_r(3)

<?><?><?>
       getgrent_r, fgetgrent_r - <?><?><?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?> <?><?> <?><?><?><?><?> <?><?><?><?><?>
       (<?><?><?><?><?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?>)

LIBRARY
       Standard C library (libc, -lc)

<?><?><?><?><?><?><?><?><?>
       #include <grp.h>

       int getgrent_r(struct group *restrict gbuf,
                      char buf[restrict .buflen], size_t buflen,
                      struct group **restrict gbufp);
       int fgetgrent_r(FILE *restrict stream, struct group *restrict gbuf,
                      char buf[restrict .buflen], size_t buflen,
                      struct group **restrict gbufp);

   <?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?>
   <?><?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?> <?><?><?> glibc
   (<?><?>. feature_test_macros(7)):

       getgrent_r():
           _GNU_SOURCE

       fgetgrent_r():
           <?><?><?><?><?><?><?> <?> glibc 2.19:
               _DEFAULT_SOURCE
           glibc 2.19 <?> <?><?><?><?><?><?>:
               _SVID_SOURCE

<?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?> getgrent_r() <?> fgetgrent_r()
       <?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?> getgrent(3) <?> fgetgrent(3).
       <?><?><?><?><?><?> <?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?> <?><?><?><?><?><?> <?><?> <?><?><?><?><?><?>,
       <?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?> setgrent(3).
       <?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?> <?><?><?><?><?><?>
       <?><?> stream.

       <?><?><?><?><?><?><?><?><?> group <?><?><?><?><?><?><?><?><?><?> <?>
       <grp.h> <?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?>:

           struct group {
               char   *gr_name;        /* <?><?><?> <?><?><?><?><?><?> */
               char   *gr_passwd;      /* <?><?><?><?><?><?> <?><?><?><?><?><?> */
               gid_t   gr_gid;         /* ID <?><?><?><?><?><?> */
               char  **gr_mem;         /* <?><?><?><?><?><?>, <?><?><?><?><?><?><?><?><?><?>
                                          <?><?><?><?> <?><?><?><?><?><?> <?><?><?><?><?><?>, <?><?><?><?><?><?><?><?><?><?><?><?><?><?> NULL */
           };

       <?><?><?><?><?><?><?><?><?> <?> <?><?><?><?><?> <?><?><?><?>
       <?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?> <?> group(5).

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

<?><?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?>
       <?><?><?> <?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?><?>
       <?><?><?> <?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?><?> 0 <?>
       *gbufp <?><?><?><?><?><?><?><?><?> <?><?> struct group. <?><?><?>
       <?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?> <?><?><?><?><?><?> <?> *gbufp <?><?><?><?><?>
       NULL.

<?><?><?><?><?><?>
       ENOENT <?><?><?><?><?><?> <?><?><?><?><?><?><?> <?><?><?>.

       ERANGE <?><?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?> <?>
              <?><?><?><?><?><?>. <?><?><?><?><?><?><?><?><?><?> <?><?><?>
              <?><?><?> <?> <?><?><?><?><?><?><?> <?><?><?><?><?><?><?>.

<?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?> <?> attributes(7).

       +----------------------------+----------------------------------------------------------+--------------------------+
       |<?><?><?><?><?><?><?><?><?> | <?><?><?><?><?><?><?>                                    | <?><?><?><?><?><?><?><?> |
       +----------------------------+----------------------------------------------------------+--------------------------+
       |getgrent_r()                | <?><?><?><?><?><?><?><?><?><?><?><?> <?> <?><?><?><?><?> | MT-Unsafe race:grent     |
       |                            |                                                          | locale                   |
       +----------------------------+----------------------------------------------------------+--------------------------+
       |fgetgrent_r()               | <?><?><?><?><?><?><?><?><?><?><?><?> <?> <?><?><?><?><?> | MT-Safe                  |
       +----------------------------+----------------------------------------------------------+--------------------------+
       In the above table, grent in race:grent signifies that if any of the
       functions setgrent(3), getgrent(3), endgrent(3), or getgrent_r() are
       used in parallel in different threads of a program, then data races
       could occur.

<?><?><?><?><?><?>
       Other systems use the prototype

           struct group *getgrent_r(struct group *grp, char *buf,
                                    int buflen);

       <?><?><?>, <?><?><?><?><?>,

           int getgrent_r(struct group *grp, char *buf, int buflen,
                          FILE **gr_fp);

<?><?><?><?><?><?><?><?><?>
       GNU.

<?><?><?><?><?><?><?>
       These functions are done in a style resembling the POSIX version of
       functions like getpwnam_r(3).

<?><?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?> getgrent_r() <?><?> <?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?><?><?><?><?><?><?>, <?><?><?> <?><?><?>
       <?><?><?> <?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?>
       <?><?><?><?><?><?><?> <?><?><?><?><?><?> <?> <?><?><?><?><?><?> <?>
       <?><?><?><?><?><?><?> <?><?><?><?><?><?>.

<?><?><?><?><?><?><?>
       #define _GNU_SOURCE
       #include <grp.h>
       #include <stdint.h>
       #include <stdio.h>
       #include <stdlib.h>
       #define BUFLEN 4096

       int
       main(void)
       {
           struct group grp;
           struct group *grpp;
           char buf[BUFLEN];
           int i;

           setgrent();
           while (1) {
               i = getgrent_r(&grp, buf, sizeof(buf), &grpp);
               if (i)
                   break;
               printf("%s (%jd):", grpp->gr_name, (intmax_t) grpp->gr_gid);
               for (size_t j = 0; ; j++) {
                   if (grpp->gr_mem[j] == NULL)
                       break;
                   printf(" %s", grpp->gr_mem[j]);
               }
               printf("\n");
           }
           endgrent();
           exit(EXIT_SUCCESS);
       }

<?><?>. <?><?><?><?><?>
       fgetgrent(3), getgrent(3), getgrgid(3), getgrnam(3), putgrent(3),
       group(5)

<?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?> <?><?><?><?><?><?><?> <?><?><?><?>
       <?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?><?><?> <?><?><?>
       <?><?><?><?><?><?> Azamat Hackimov <azamat.hackimov@gmail.com>, Dmitry
       Bolkhovskikh <d20052005@yandex.ru>, Vladislav
       <ivladislavefimov@gmail.com>, Yuri Kozlov <yuray@komyakino.ru> <?>
       <?><?><?><?> <?><?><?><?><?><?> <pavia00@gmail.com>

       <?><?><?><?> <?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?><?><?><?><?>;
       <?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?> GNU
       <?><?><?><?><?><?> 3 <https://www.gnu.org/licenses/gpl-3.0.html>
       <?><?><?> <?><?><?><?><?> <?><?><?><?><?><?><?>, <?><?><?><?><?>
       <?><?><?><?><?><?> <?><?> <?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?>. <?><?> <?><?>
       <?><?><?><?><?> <?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?><?><?><?><?><?><?><?>.

       <?><?><?><?> <?><?> <?><?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?>
       <?> <?><?><?><?><?><?><?><?> <?><?><?><?> <?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?><?><?><?><?>, <?><?><?><?><?><?><?><?><?><?>,
       <?><?><?><?><?><?><?><?><?> <?><?><?><?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?> <?><?> <man-pages-ru-talks@lists.sourceforge.net>.

Linux man-pages 6.06  31 <?><?><?><?><?><?><?> 2023 <?>.         getgrent_r(3)