The OpenNET Project / Index page

[ новости /+++ | форум | wiki | теги | ]

Интерактивная система просмотра системных руководств (man-ов)

 ТемаНаборКатегория 
 
 [Cписок руководств | Печать]

getservent_r (3)
  • >> getservent_r (3) ( Linux man: Библиотечные вызовы )
  •  

    NAME

    getservent_r, getservbyname_r, getservbyport_r - get
    service entry (reentrant)
     
    

    SYNOPSIS

    #include <netdb.h>
    
    int getservent_r(struct servent *result_buf, char *buf,
                    size_t buflen, struct servent **result);
    
    int getservbyname_r(const char *name, const char *proto,
                    struct servent *result_buf, char *buf,
                    size_t buflen, struct servent **result);
    
    int getservbyport_r(int port, const char *proto,
                    struct servent *result_buf, char *buf,
                    size_t buflen, struct servent **result);
    
    
    Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

    getservent_r(), getservbyname_r(), getservbyport_r(): _BSD_SOURCE || _SVID_SOURCE  

    DESCRIPTION

    The getservent_r(), getservbyname_r(), and getservbyport_r() functions are the reentrant equivalents of, respectively, getservent(3), getservbyname(3), and getservbyport(3). They differ in the way that the servent structure is returned, and in the function calling signature and return value. This manual page describes just the differences from the non-reentrant functions.

    Instead of returning a pointer to a statically allocated servent structure as the function result, these functions copy the structure into the location pointed to by result_buf.

    The buf array is used to store the string fields pointed to by the returned servent structure. (The non-reentrant functions allocate these strings in static storage.) The size of this array is specified in buflen. 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 length 1024 bytes should be sufficient for most applications.)

    If the function call successfully obtains a service record, then *result is set pointing to result_buf; otherwise, *result is set to NULL.  

    RETURN VALUE

    On success, these functions return 0. On error, a positive error number is returned.

    On error, record not found (getservbyname_r(), getservbyport_r()), or end of input (getservent_r()) result is set to NULL.  

    ERRORS

    ENOENT
    (getservent_r()) No more records in database.
    ERANGE
    buf is too small. Try again with a larger buffer (and increased buflen).
     

    CONFORMING TO

    These functions are GNU extensions. Functions with similar names exist on some other systems, though typically with different calling signatures.  

    EXAMPLE

    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 buflen; 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)  (buflen=87)
    s_name=echo; s_proto=tcp; s_port=7; aliases=
    $ ./a.out 77777 tcp
    getservbyport_r() returned: 0 (success)  (buflen=1024)
    Call failed/record not found
    
     

    Program source

    #define _GNU_SOURCE
    #include <ctype.h>
    #include <netdb.h>
    #include <stdlib.h>
    #include <stdio.h>
    #include <errno.h>
    #include <string.h>
    
    #define MAX_BUF 10000
    
    int
    main(int argc, char *argv[])
    {
        int buflen, erange_cnt, port, s;
        struct servent result_buf;
        struct servent *result;
        char buf[MAX_BUF];
        char *protop;
        char **p;
    
        if (argc < 3) {
            printf("Usage: %s port-num proto-name [buflen]\n", argv[0]);
            exit(EXIT_FAILURE);
        }
    
        port = htons(atoi(argv[1]));
        protop = (strcmp(argv[2], "null") == 0 ||
                  strcmp(argv[2], "NULL") == 0) ?  NULL : argv[2];
    
        buflen = 1024;
        if (argc > 3)
            buflen = atoi(argv[3]);
    
        if (buflen > 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, buflen, &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 */
    
                buflen++;
    
                if (buflen > MAX_BUF) {
                    printf("Exceeded buffer limit (%d)\n", MAX_BUF);
                    exit(EXIT_FAILURE);
                }
            }
        } while (s == ERANGE);
    
        printf("getservbyport_r() returned: %s  (buflen=%d)\n",
                (s == 0) ? "0 (success)" : (s == ENOENT) ? "ENOENT" :
                strerror(s), buflen);
    
        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 (p = result_buf.s_aliases; *p != NULL; p++)
            printf("%s ", *p);
        printf("\n");
    
        exit(EXIT_SUCCESS);
    }
    
     

    SEE ALSO

    getservent(3), services(5)  

    COLOPHON

    This page is part of release 3.14 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/.


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    RETURN VALUE
    ERRORS
    CONFORMING TO
    EXAMPLE
    Program source
    SEE ALSO
    COLOPHON


    Поиск по тексту MAN-ов: 




    Спонсоры:
    Inferno Solutions
    Ideco
    Hosting by Hoster.ru
    Хостинг:

    Закладки на сайте
    Проследить за страницей
    Created 1996-2021 by Maxim Chirkov
    Добавить, Поддержать, Вебмастеру