mirror of https://github.com/mkerrisk/man-pages
163 lines
4.6 KiB
Groff
163 lines
4.6 KiB
Groff
.\" Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.\" <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.TH GETNETENT_R 3 2015-07-23 "GNU" "Linux Programmer's Manual"
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.SH NAME
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getnetent_r, getnetbyname_r, getnetbyaddr_r \- get
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network entry (reentrant)
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.SH SYNOPSIS
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.nf
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.B #include <netdb.h>
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.sp
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.BI "int getnetent_r(struct netent *" result_buf ", char *" buf ,
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.BI " size_t " buflen ", struct netent **" result ,
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.BI " int *" h_errnop );
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.sp
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.BI "int getnetbyname_r(const char *" name ,
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.BI " struct netent *" result_buf ", char *" buf ,
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.BI " size_t " buflen ", struct netent **" result ,
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.BI " int *" h_errnop );
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.sp
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.BI "int getnetbyaddr_r(uint32_t " net ", int " type ,
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.BI " struct netent *" result_buf ", char *" buf ,
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.BI " size_t " buflen ", struct netent **" result ,
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.BI " int *" h_errnop );
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.sp
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.fi
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.ad l
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.in
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.sp
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.BR getnetent_r (),
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.BR getnetbyname_r (),
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.BR getnetbyaddr_r ():
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.RS 4
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_BSD_SOURCE || _SVID_SOURCE
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.RE
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.ad b
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.SH DESCRIPTION
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The
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.BR getnetent_r (),
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.BR getnetbyname_r (),
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and
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.BR getnetbyaddr_r ()
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functions are the reentrant equivalents of, respectively,
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.BR getnetent (3),
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.BR getnetbyname (3),
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and
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.BR getnetbynumber (3).
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They differ in the way that the
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.I netent
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structure is returned,
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and in the function calling signature and return value.
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This manual page describes just the differences from
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the nonreentrant functions.
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Instead of returning a pointer to a statically allocated
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.I netent
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structure as the function result,
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these functions copy the structure into the location pointed to by
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.IR result_buf .
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The
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.I buf
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array is used to store the string fields pointed to by the returned
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.I netent
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structure.
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(The nonreentrant functions allocate these strings in static storage.)
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The size of this array is specified in
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.IR buflen .
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If
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.I buf
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is too small, the call fails with the error
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.BR ERANGE ,
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and the caller must try again with a larger buffer.
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(A buffer of length 1024 bytes should be sufficient for most applications.)
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.\" I can find no information on the required/recommended buffer size;
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.\" the nonreentrant functions use a 1024 byte buffer -- mtk.
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If the function call successfully obtains a network record, then
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.I *result
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is set pointing to
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.IR result_buf ;
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otherwise,
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.I *result
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is set to NULL.
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The buffer pointed to by
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.I h_errnop
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is used to return the value that would be stored in the global variable
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.I h_errno
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by the nonreentrant versions of these functions.
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.\" getnetent.3 doesn't document any use of h_errno, but nevertheless
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.\" the nonreentrant functions no seem to set h_errno.
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.SH RETURN VALUE
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On success, these functions return 0.
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On error, they return one of the positive error numbers listed in ERRORS.
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On error, record not found
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.RB ( getnetbyname_r (),
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.BR getnetbyaddr_r ()),
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or end of input
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.RB ( getnetent_r ())
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.I result
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is set to NULL.
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.SH ERRORS
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.TP
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.B ENOENT
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.RB ( getnetent_r ())
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No more records in database.
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.TP
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.B ERANGE
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.I buf
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is too small.
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Try again with a larger buffer
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(and increased
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.IR buflen ).
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.TS
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allbox;
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lbw17 lb lb
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l l l.
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Interface Attribute Value
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T{
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.BR getnetent_r (),
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.BR getnetbyname_r (),
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.BR getnetbyaddr_r ()
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T} Thread safety MT-Safe locale
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.TE
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.SH CONFORMING TO
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These functions are GNU extensions.
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Functions with similar names exist on some other systems,
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though typically with different calling signatures.
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.SH SEE ALSO
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.BR getnetent (3),
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.BR networks (5)
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