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/* GNU variant of strerror_r. */
/*
FUNCTION
<<strerror_r>>---convert error number to string and copy to buffer
INDEX
strerror_r
SYNOPSIS
#include <string.h>
#ifdef _GNU_SOURCE
char *strerror_r(int <[errnum]>, char *<[buffer]>, size_t <[n]>);
#else
int strerror_r(int <[errnum]>, char *<[buffer]>, size_t <[n]>);
#endif
DESCRIPTION
<<strerror_r>> converts the error number <[errnum]> into a
string and copies the result into the supplied <[buffer]> for
a length up to <[n]>, including the NUL terminator. The value of
<[errnum]> is usually a copy of <<errno>>. If <<errnum>> is not a known
error number, the result is the empty string.
See <<strerror>> for how strings are mapped to <<errnum>>.
RETURNS
There are two variants: the GNU version always returns a NUL-terminated
string, which is <[buffer]> if all went well, but which is another
pointer if <[n]> was too small (leaving <[buffer]> untouched). If the
return is not <[buffer]>, your application must not modify that string.
The POSIX version returns 0 on success, <[EINVAL]> if <<errnum>> was not
recognized, and <[ERANGE]> if <[n]> was too small. The variant chosen
depends on macros that you define before inclusion of <<string.h>>.
PORTABILITY
<<strerror_r>> with a <[char *]> result is a GNU extension.
<<strerror_r>> with an <[int]> result is required by POSIX 2001.
This function is compliant only if <<_user_strerror>> is not provided,
or if it is thread-safe and uses separate storage according to whether
the second argument of that function is non-zero. For more details
on <<_user_strerror>>, see the <<strerror>> documentation.
POSIX states that the contents of <[buf]> are unspecified on error,
although this implementation guarantees a NUL-terminated string for
all except <[n]> of 0.
POSIX recommends that unknown <[errnum]> result in a message including
that value, however it is not a requirement and this implementation
provides only an empty string (unless you provide <<_user_strerror>>).
POSIX also recommends that unknown <[errnum]> fail with EINVAL even
when providing such a message, however it is not a requirement and
this implementation will return success if <<_user_strerror>> provided
a non-empty alternate string without assigning into its third argument.
<<strerror_r>> requires no supporting OS subroutines.
*/
#undef __STRICT_ANSI__
#define _GNU_SOURCE
#include <errno.h>
#include <string.h>
#undef strerror_r
/* For backwards-compatible linking, this must be the GNU signature;
see xpg_strerror_r.c for the POSIX version. */
char *
strerror_r (int errnum,
char *buffer,
size_t n)
{
char *error = _strerror_r (_REENT, errnum, 1, NULL);
if (strlen (error) >= n)
return error;
return strcpy (buffer, error);
}
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