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