getnetent_r(3)                                        Library Functions Manual                                       getnetent_r(3)

NAME
       getnetent_r, getnetbyname_r, getnetbyaddr_r - get network entry (reentrant)

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <netdb.h>

       int getnetent_r(struct netent *restrict result_buf,
                       char buf[restrict .buflen], size_t buflen,
                       struct netent **restrict result,
                       int *restrict h_errnop);
       int getnetbyname_r(const char *restrict name,
                       struct netent *restrict result_buf,
                       char buf[restrict .buflen], size_t buflen,
                       struct netent **restrict result,
                       int *restrict h_errnop);
       int getnetbyaddr_r(uint32_t net, int type,
                       struct netent *restrict result_buf,
                       char buf[restrict .buflen], size_t buflen,
                       struct netent **restrict result,
                       int *restrict h_errnop);

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

       getnetent_r(), getnetbyname_r(), getnetbyaddr_r():
           Since glibc 2.19:
               _DEFAULT_SOURCE
           glibc 2.19 and earlier:
               _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION
       The  getnetent_r(),  getnetbyname_r(), and getnetbyaddr_r() functions are the reentrant equivalents of, respectively, getne‐
       tent(3), getnetbyname(3), and getnetbynumber(3).  They differ in the way that the netent structure is returned, and  in  the
       function  calling  signature  and return value.  This manual page describes just the differences from the nonreentrant func‐
       tions.

       Instead of returning a pointer to a statically allocated netent 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 netent structure.  (The nonreentrant 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 network record, then *result is set pointing to result_buf;  otherwise,  *result
       is set to NULL.

       The  buffer  pointed  to  by h_errnop is used to return the value that would be stored in the global variable h_errno by the
       nonreentrant versions of these functions.

RETURN VALUE
       On success, these functions return 0.  On error, they return one of the positive error numbers listed in ERRORS.

       On error, record not found (getnetbyname_r(), getnetbyaddr_r()), or end of input (getnetent_r()) result is set to NULL.

ERRORS
       ENOENT (getnetent_r()) No more records in database.

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

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       ┌──────────────────────────────────────────────────────────────────────────────────────────┬───────────────┬────────────────┐
       │Interface                                                                                 │ Attribute     │ Value          │
       ├──────────────────────────────────────────────────────────────────────────────────────────┼───────────────┼────────────────┤
       │getnetent_r(), getnetbyname_r(), getnetbyaddr_r()                                         │ Thread safety │ MT-Safe locale │
       └──────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴────────────────┘

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

SEE ALSO
       getnetent(3), networks(5)

Linux man-pages 6.03                                         2023-02-05                                              getnetent_r(3)