.\" Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.TH GETNETENT_R 3  2009-02-21 "GNU" "Linux Programmer's Manual"
.SH NAME
getnetent_r, getnetbyname_r, getnetbyaddr_r \- get
network entry (reentrant)
.SH SYNOPSIS
.nf
.B #include <netdb.h>
.sp
.BI "int getnetent_r(struct netent *" result_buf ", char *" buf ,
.BI "                size_t " buflen ", struct netent **" result ,
.BI "                int *" h_errnop );
.sp
.BI "int getnetbyname_r(const char *" name ,
.BI "                struct netent *" result_buf ", char *" buf ,
.BI "                size_t " buflen ", struct netent **" result ,
.BI "                int *" h_errnop );
.sp
.BI "int getnetbyaddr_r(uint32_t " net ", int " type ,
.BI "                struct netent *" result_buf ", char *" buf ,
.BI "                size_t " buflen ", struct netent **" result ,
.BI "                int *" h_errnop );
.sp
.fi
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.ad l
.in
.sp
.BR getnetent_r (),
.BR getnetbyname_r (),
.BR getnetbyaddr_r ():
_BSD_SOURCE || _SVID_SOURCE
.ad b
.SH DESCRIPTION
The
.BR getnetent_r (),
.BR getnetbyname_r (),
and
.BR getnetbyaddr_r ()
functions are the reentrant equivalents of, respectively,
.BR getnetent (3),
.BR getnetbyname (3),
and
.BR getnetbynumber (3).
They differ in the way that the
.I netent
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
.I netent
structure as the function result,
these functions copy the structure into the location pointed to by
.IR result_buf .

The
.I buf
array is used to store the string fields pointed to by the returned
.I netent
structure.
(The non-reentrant functions allocate these strings in static storage.)
The size of this array is specified in
.IR buflen .
If
.I buf
is too small, the call fails with the error
.BR ERANGE ,
and the caller must try again with a larger buffer.
(A buffer of length 1024 bytes should be sufficient for most applications.)
.\" I can find no information on the required/recommended buffer size;
.\" the non-reentrant functions use a 1024 byte buffer -- mtk.

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

The buffer pointed to by
.I h_errnop
is used to return the value that would be stored in the global variable
.I h_errno
by the non-reentrant versions of these functions.
.\" getnetent.3 doesn't document any use of h_errno, but nevertheless
.\" the non-reentrant functions no seem to set h_errno.
.SH "RETURN VALUE"
On success, these functions return 0.
On error, a positive error number is returned.

On error, record not found
.RB ( getnetbyname_r (),
.BR getnetbyaddr_r ()),
or end of input
.RB ( getnetent_r ())
.I result
is set to NULL.
.SH ERRORS
.TP
.B ENOENT
.RB ( getnetent_r ())
No more records in database.
.TP
.B ERANGE
.I buf
is too small.
Try again with a larger buffer
(and increased
.IR buflen ).
.SH "CONFORMING TO"
These functions are GNU extensions.
Functions with similar names exist on some other systems,
though typically with different calling signatures.
.SH "SEE ALSO"
.BR getnetent (3),
.BR networks (5)
.SH COLOPHON
This page is part of release 3.22 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
