STRERROR

NAME

strerror, strerror_r - return string describing error code

SYNOPSIS

#include <string.h>

char *strerror(int errnum);


int strerror_r(int errnum, char *buf, size_t n);

DESCRIPTION

The strerror() function returns a string describing the error code passed in the argument errnum, possibly using the LC_MESSAGES part of the current locale to select the appropriate language. This string must not be modified by the application, but may be modified by a subsequent call to perror() or strerror(). No library function will modify this string.

The strerror_r() function is similar to strerror(), but is thread safe. It returns the string in the user-supplied buffer buf of length n.

RETURN VALUE

The strerror() function returns the appropriate error description string, or an unknown error message if the error code is unknown. The value of errno is not changed for a successful call, and is set to a nonzero value upon error. The strerror_r() function returns 0 on success and -1 on failure, setting errno.

ERRORS

EINVAL: The value of errnum is not a valid error number.
ERANGE: Insufficient storage was supplied to contain the error description string.

CONFORMING TO

SVID 3, POSIX, BSD 4.3, ISO/IEC 9899:1990 (C89).
strerror_r() with prototype as given above is specified by SUSv3, and was in use under Digital Unix and HP Unix. An incompatible function, with prototype

char *strerror_r(int errnum, char *buf, size_t n);

is a GNU extension used by glibc (since 2.0), and must be regarded as obsolete in view of SUSv3. The GNU version may, but need not, use the user-supplied buffer. If it does, the result may be truncated in case the supplied buffer is too small. The result is always NUL-terminated.