Bug#794876: manpages-dev: Should guide users away from deprecated sys_errlist more

2016-02-18 Thread Stéphane Aulery 
First commit of upstream to fix this bug:

Michael Kerrisk 
2016-02-08 15:23:13 (GMT)
88cc4cb6cc7d95f2389061d69a9692b7633b54e2

https://git.kernel.org/cgit/docs/man-pages/man-pages.git/commit/man3/perror.3?id=88cc4cb6cc7d95f2389061d69a9692b7633b54e2

-- 
Stéphane Aulery

Bug#794876: manpages-dev: Should guide users away from deprecated sys_errlist more

2015-08-08 Thread Michael Kerrisk (man-pages) 
On 08/07/2015 04:24 PM, Dale E. Martin wrote:
 Package: manpages-dev
 Version: 3.74-1
 Severity: wishlist
 Tags: patch
 
 Dear Maintainer,
 I recently caused a problem for myself when writing some C-code by making
 direct use of sys_errlist.  I did this after reading the manpage for
 perror. The code I wrote worked on Debian 7, but was not binary
 compatible with Debian 6, much to my surprise.  Replacing my use of
 sys_errlist with strerror fixed the problem.
 
 I have attached a suggested update to the perror (3) manpage.  It is meant
 as an example, I have no strong feelings about my actual text.

Hello Dale, 

Your submission would be much better to understand as a diff (preferably
against latest upstream), with an explanation of how your proposed
changes address the problem you encountered.

Thanks,

Michael

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/


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Bug#794876: manpages-dev: Should guide users away from deprecated sys_errlist more

2015-08-07 Thread Dale E. Martin 
Package: manpages-dev
Version: 3.74-1
Severity: wishlist
Tags: patch

Dear Maintainer,
I recently caused a problem for myself when writing some C-code by making
direct use of sys_errlist.  I did this after reading the manpage for
perror. The code I wrote worked on Debian 7, but was not binary
compatible with Debian 6, much to my surprise.  Replacing my use of
sys_errlist with strerror fixed the problem.

I have attached a suggested update to the perror (3) manpage.  It is meant
as an example, I have no strong feelings about my actual text.

-- System Information:
Debian Release: 8.1
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.16.0-4-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages manpages-dev depends on:
ii  manpages  3.74-1

manpages-dev recommends no packages.

Versions of packages manpages-dev suggests:
ii  konqueror [man-browser]  4:4.14.2-1
ii  man-db [man-browser] 2.7.0.2-5

-- no debconf information
.\ Copyright (c) 1994 Michael Haardt (mich...@moria.de), 1994-06-04
.\ Copyright (c) 1995 Michael Haardt
.\  (mich...@cantor.informatik.rwth-aachen.de), 1995-03-16
.\ Copyright (c) 1996 Andries Brouwer (a...@cwi.nl), 1996-01-13
.\
.\ %%%LICENSE_START(GPLv2+_DOC_FULL)
.\ This is free documentation; you can redistribute it and/or
.\ modify it under the terms of the GNU General Public License as
.\ published by the Free Software Foundation; either version 2 of
.\ the License, or (at your option) any later version.
.\
.\ The GNU General Public License's references to object code
.\ and executables are to be interpreted as the output of any
.\ document formatting or typesetting system, including
.\ intermediate and printed output.
.\
.\ This manual is distributed in the hope that it will be useful,
.\ but WITHOUT ANY WARRANTY; without even the implied warranty of
.\ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
.\ GNU General Public License for more details.
.\
.\ You should have received a copy of the GNU General Public
.\ License along with this manual; if not, see
.\ http://www.gnu.org/licenses/.
.\ %%%LICENSE_END
.\
.\ 1996-01-13 aeb: merged in some text contributed by Melvin Smith
.\   (msm...@falcon.mercer.peachnet.edu) and various other changes.
.\ Modified 1996-05-16 by Martin Schulze (j...@infodrom.north.de)
.\
.TH PERROR 3 2014-05-28  Linux Programmer's Manual
.SH NAME
perror \- print a system error message
.SH SYNOPSIS
.B #include stdio.h
.sp
.BI void perror(const char * s );
.sp
.B #include errno.h
.sp
.BI char * strerror(int errnum);
.br
.BI int  sys_nerr ;
.br
.BI int  errno ; /* Not really declared this way; see errno(3). */
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.IR sys_errlist ,
.IR sys_nerr :
_BSD_SOURCE
.SH DESCRIPTION
The routine
.BR perror ()
produces a message on the standard error output, describing the last
error encountered during a call to a system or library function.
First (if
.I s
is not NULL and
.I *s
is not a null byte (\(aq\\0\(aq)) the argument string
.I s
is printed, followed by a colon and a blank.
Then the message and a new-line.

To be of most use, the argument string should include the name
of the function that incurred the error.
The error number is taken from
the external variable
.IR errno ,
which is set when errors occur but not
cleared when successful calls are made.

To obtain the error message without the newline, call
.IR strerror
with the the argument
.I errno
.

Traditionally one would access the error string through
.IR sys_errlist []
indexed by
.I errno
.
The largest message number provided in the table is
.IR sys_nerr \-1.
Be careful when directly accessing this list because new error values
may not have been added to
.IR sys_errlist [].
The use of this method is nowadays deprecated and you should use
.IR strerror
.

When a system call fails, it usually returns \-1 and sets the
variable
.I errno
to a value describing what went wrong.
(These values can be found in
.IR errno.h .)
Many library functions do likewise.
The function
.BR perror ()
serves to translate this error code into human-readable form.
Note that
.I errno
is undefined after a successful library call:
this call may well change this variable, even though it succeeds,
for example because it internally used some other library function that failed.
Thus, if a failing call is not immediately followed by a call to
.BR perror (),
the value of
.I errno
should be saved.
.SH CONFORMING TO
The function
.BR perror ()
and the external
.I errno
(see
.BR errno (3))
conform to C89, C99, 4.3BSD, POSIX.1-2001.
The externals
.I sys_nerr
and
.I sys_errlist
conform to BSD.
.SH NOTES
The externals
.I sys_nerr
and
.I sys_errlist
are defined by glibc, but in
.IR stdio.h .
.\ and only when _BSD_SOURCE is defined.
.\