getservent_r(3)            Library Functions Manual            getservent_r(3)

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       getservent_r, getservbyname_r, getservbyport_r -
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       <?><?><?><?><?> C (libc, -lc)

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       #include <netdb.h>

       int getservent_r(size_t size;
                        struct servent *restrict result_buf,
                        char buf[restrict size], size_t size,
                        struct servent **restrict result);
       int getservbyname_r(size_t size;
                        const char *restrict name,
                        const char *restrict proto,
                        struct servent *restrict result_buf,
                        char buf[restrict size], size_t size,
                        struct servent **restrict result);
       int getservbyport_r(size_t size;
                        int port,
                        const char *restrict proto,
                        struct servent *restrict result_buf,
                        char buf[restrict size], size_t size,
                        struct servent **restrict result);

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

       getservent_r(), getservbyname_r(), getservbyport_r():
           <?><?><?><?><?><?><?> <?> glibc 2.19:
               _DEFAULT_SOURCE
           <?> glibc 2.19 <?> <?><?><?><?><?><?>:
               _BSD_SOURCE || _SVID_SOURCE

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       <?><?><?><?><?><?><?> getservent_r(), getservbyname_r() <?>
       getservbyport_r() <?><?><?><?><?><?><?><?>
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       <?><?><?><?><?><?><?><?><?><?><?><?><?> getservent(3), getservbyname(3)
       <?> getservbyport(3), <?><?><?><?><?><?><?><?><?><?><?><?><?><?>.
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       <?><?><?><?><?><?><?><?><?> servent <?> <?><?><?><?><?><?><?><?>
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       result_buf.

       The buf array is used to store the string fields pointed to by the
       returned servent structure.  (The nonreentrant functions allocate these
       strings in static storage.)  The size of this array is specified in
       size.  If buf is too small, the call fails with the error ERANGE, and
       the caller must try again with a larger buffer.  (A buffer of size 1024
       bytes should be sufficient for most applications.)

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       *result <?><?><?><?><?><?><?><?><?><?><?><?><?><?><?> <?> NULL.

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       <?><?><?> <?><?><?><?><?><?>, <?><?><?><?><?><?><?><?><?><?>
       <?><?><?><?><?><?> (getservbyname_r(), getservbyport_r()) <?><?><?>
       <?><?><?><?><?> <?><?><?><?><?><?> (getservent_r())
       <?><?><?><?><?><?><?><?> result <?><?><?><?><?> NULL.

<?><?><?><?><?><?>
       ENOENT (getservent_r()) <?><?><?><?><?><?> <?><?><?>
              <?><?><?><?><?><?><?> <?> <?><?><?><?> <?><?><?><?><?><?>.

       ERANGE buf is too small.  Try again with a larger buffer (and increased
              size).

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       +----------------------------+----------------------------------------------------------+--------------------------+
       |<?><?><?><?><?><?><?><?><?> | <?><?><?><?><?><?><?>                                    | <?><?><?><?><?><?><?><?> |
       +----------------------------+----------------------------------------------------------+--------------------------+
       |getservent_r(),             | <?><?><?><?><?><?><?><?><?><?><?><?> <?> <?><?><?><?><?> | MT-Safe locale           |
       |getservbyname_r(),          |                                                          |                          |
       |getservbyport_r()           |                                                          |                          |
       +----------------------------+----------------------------------------------------------+--------------------------+
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       GNU.

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       The program below uses getservbyport_r()  to retrieve the service
       record for the port and protocol named in its first command-line
       argument.  If a third (integer) command-line argument is supplied, it
       is used as the initial value for size; if getservbyport_r()  fails with
       the error ERANGE, the program retries with larger buffer sizes.  The
       following shell session shows a couple of sample runs:

           $ ./a.out 7 tcp 1
           ERANGE! Retrying with larger buffer
           getservbyport_r() returned: 0 (success)  (size=87)
           s_name=echo; s_proto=tcp; s_port=7; aliases=
           $ ./a.out 77777 tcp
           getservbyport_r() returned: 0 (success)  (size=1024)
           Call failed/record not found

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       #define _GNU_SOURCE
       #include <ctype.h>
       #include <errno.h>
       #include <netdb.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <string.h>

       #define MAX_BUF 10000

       #define streq(...)  (strcmp(__VA_ARGS__) == 0)

       int
       main(int argc, char *argv[])
       {
           int size, erange_cnt, port, s;
           struct servent result_buf;
           struct servent *result;
           char buf[MAX_BUF];
           char *protop;

           if (argc < 3) {
               printf("Usage: %s port-num proto-name [size]\n", argv[0]);
               exit(EXIT_FAILURE);
           }

           port = htons(atoi(argv[1]));
           protop = (streq(argv[2], "null") ||
                     streq(argv[2], "NULL")) ?  NULL : argv[2];

           size = 1024;
           if (argc > 3)
               size = atoi(argv[3]);

           if (size > MAX_BUF) {
               printf("Exceeded buffer limit (%d)\n", MAX_BUF);
               exit(EXIT_FAILURE);
           }

           erange_cnt = 0;
           do {
               s = getservbyport_r(port, protop, &result_buf,
                                   buf, size, &result);
               if (s == ERANGE) {
                   if (erange_cnt == 0)
                       printf("ERANGE! Retrying with larger buffer\n");
                   erange_cnt++;

                   /* Increment a byte at a time so we can see exactly
                      what size buffer was required.  */

                   size++;

                   if (size > MAX_BUF) {
                       printf("Exceeded buffer limit (%d)\n", MAX_BUF);
                       exit(EXIT_FAILURE);
                   }
               }
           } while (s == ERANGE);

           printf("getservbyport_r() returned: %s  (size=%d)\n",
                  (s == 0) ? "0 (success)" : (s == ENOENT) ? "ENOENT" :
                  strerror(s), size);

           if (s != 0 || result == NULL) {
               printf("Call failed/record not found\n");
               exit(EXIT_FAILURE);
           }

           printf("s_name=%s; s_proto=%s; s_port=%d; aliases=",
                  result_buf.s_name, result_buf.s_proto,
                  ntohs(result_buf.s_port));
           for (char **p = result_buf.s_aliases; *p != NULL; p++)
               printf("%s ", *p);
           printf("\n");

           exit(EXIT_SUCCESS);
       }

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       getservent(3), services(5)

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

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       <?><?><?><?><?><?><?><?> GNU (GNU General Public License - GPL,
       <https://www.gnu.org/licenses/gpl-3.0.html> <?><?><?><?><?><?> 3
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       <debian-l10n-russian@lists.debian.org>.

Linux man-pages 6.18  22 <?><?><?><?><?><?><?> 2026 <?>.       getservent_r(3)