.\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
-.\" and Copyright (C) 2005, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2005, 2014 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
+.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
.\"
.\" References consulted:
.\" Linux libc source code
.\" 2005-12-13, mtk, Substantial rewrite of strerror_r() description
.\" Addition of extra material on portability and standards.
.\"
-.TH STRERROR 3 2012-04-22 "" "Linux Programmer's Manual"
+.TH STRERROR 3 2017-09-15 "" "Linux Programmer's Manual"
.SH NAME
-strerror, strerror_r \- return string describing error number
+strerror, strerror_r, strerror_l \- return string describing error number
.SH SYNOPSIS
.nf
.B #include <string.h>
-.sp
+.PP
.BI "char *strerror(int " errnum );
-.sp
+.PP
.BI "int strerror_r(int " errnum ", char *" buf ", size_t " buflen );
/* XSI-compliant */
-.sp
+.PP
.BI "char *strerror_r(int " errnum ", char *" buf ", size_t " buflen );
/* GNU-specific */
+.PP
+.BI "char *strerror_l(int " errnum ", locale_t " locale );
.fi
-.sp
+.PP
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
-.sp
-The XSI-compliant version of
-.BR strerror_r ()
-is provided if:
+.ad l
+.PP
+.BR strerror_r ():
+.RS 4
+The XSI-compliant version is provided if:
.br
-(_POSIX_C_SOURCE\ >=\ 200112L || _XOPEN_SOURCE\ >=\ 600) && !\ _GNU_SOURCE
+(_POSIX_C_SOURCE\ >=\ 200112L) && ! \ _GNU_SOURCE
.br
Otherwise, the GNU-specific version is provided.
+.RE
+.ad
.SH DESCRIPTION
The
.BR strerror ()
.I errnum
is
.BR EINVAL ,
-the returned description will "Invalid argument".)
+the returned description will be "Invalid argument".)
This string must not be modified by the application, but may be
modified by a subsequent call to
-.BR strerror ().
-No library function, including
+.BR strerror ()
+or
+.BR strerror_l ().
+No other library function, including
.BR perror (3),
will modify this string.
-
+.\"
+.SS strerror_r()
The
.BR strerror_r ()
function is similar to
otherwise the GNU-specific version is provided.
If no feature test macros are explicitly defined,
then (since glibc 2.4)
-.B _POSIX_SOURCE
+.B _POSIX_C_SOURCE
is defined by default with the value
200112L, so that the XSI-compliant version of
.BR strerror_r ()
is provided by default.
-
+.PP
The XSI-compliant
.BR strerror_r ()
is preferred for portable applications.
.I buf
of length
.IR buflen .
-
+.PP
The GNU-specific
.BR strerror_r ()
returns a pointer to a string containing the error message.
is too small and
.I errnum
is unknown).
-The string always includes a terminating null byte.
+The string always includes a terminating null byte (\(aq\\0\(aq).
+.\"
+.SS strerror_l()
+.BR strerror_l ()
+is like
+.BR strerror (),
+but maps
+.I errnum
+to a locale-dependent error message in the locale specified by
+.IR locale .
+The behavior of
+.BR strerror_l ()
+is undefined if
+.I locale
+is the special locale object
+.BR LC_GLOBAL_LOCALE
+or is not a valid locale object handle.
.SH RETURN VALUE
The
-.BR strerror ()
+.BR strerror (),
+.BR strerror_l (),
and the GNU-specific
.BR strerror_r ()
functions return
the appropriate error description string,
or an "Unknown error nnn" message if the error number is unknown.
-
+.PP
+The XSI-compliant
+.BR strerror_r ()
+function returns 0 on success.
+On error,
+a (positive) error number is returned (since glibc 2.13),
+or \-1 is returned and
+.I errno
+is set to indicate the error (glibc versions before 2.13).
+.PP
POSIX.1-2001 and POSIX.1-2008 require that a successful call to
.BR strerror ()
+or
+.BR strerror_l ()
shall leave
.I errno
unchanged, and note that,
and then check
.I errno
after the call.
-
-The XSI-compliant
-.BR strerror_r ()
-function returns 0 on success.
-On error,
-a (positive) error number is returned (since glibc 2.13),
-or \-1 is returned and
-.I errno
-is set to indicate the error (glibc versions before 2.13).
.SH ERRORS
.TP
.B EINVAL
.TP
.B ERANGE
Insufficient storage was supplied to contain the error description string.
+.SH VERSIONS
+The
+.BR strerror_l ()
+function first appeared in glibc 2.6.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbw14 lb lb
+l l l.
+Interface Attribute Value
+T{
+.BR strerror ()
+T} Thread safety MT-Unsafe race:strerror
+T{
+.BR strerror_r (),
+.br
+.BR strerror_l ()
+T} Thread safety MT-Safe
+.TE
.SH CONFORMING TO
.BR strerror ()
-is specified by POSIX.1-2001, C89, C99.
+is specified by POSIX.1-2001, POSIX.1-2008, C89, and C99.
.BR strerror_r ()
-is specified by POSIX.1-2001.
-
+is specified by POSIX.1-2001 and POSIX.1-2008.
+.\" FIXME . for later review when Issue 8 is one day released...
+.\" A future POSIX.1 may remove strerror_r()
+.\" http://austingroupbugs.net/tag_view_page.php?tag_id=8
+.\" http://austingroupbugs.net/view.php?id=508
+.PP
+.BR strerror_l ()
+is specified in POSIX.1-2008.
+.PP
The GNU-specific
.BR strerror_r ()
function is a nonstandard extension.
-
+.PP
POSIX.1-2001 permits
.BR strerror ()
to set
.B EINVAL
if the error number is unknown.
C99 and POSIX.1-2008 require the return value to be non-NULL.
+.SH NOTES
+The GNU C Library uses a buffer of 1024 characters for
+.BR strerror ().
+This buffer size therefore should be sufficient to avoid an
+.B ERANGE
+error when calling
+.BR strerror_r ()
+and
+.BR strerror_l ().
.SH SEE ALSO
.BR err (3),
.BR errno (3),
.BR error (3),
.BR perror (3),
-.BR strsignal (3)
+.BR strsignal (3),
+.BR locale (7)
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