strerror

strerror, strerror_r - return string describing error number

#include <string.h>
 I char *strerror(int  errnum );
 I char *strerror_r(int  errnum , char * buf , size_t  buflen );
                        /* GNU-specific strerror_r() */
 #define _XOPEN_SOURCE 600
#include <string.h>
 I int strerror_r(int  errnum , char * buf , size_t  buflen );
                        /* XSI-compliant strerror_r() */

The R 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(3) or R strerror (). No library function will modify this string. The R strerror_r () function is similar to R strerror (), but is thread safe. This function is available in two versions: an XSI-compliant version specified in POSIX.1-2001, and a GNU-specific version (available since glibc 2.0). If _XOPEN_SOURCE is defined with the value 600, then the XSI-compliant version is provided, otherwise the GNU-specific version is provided. The XSI-compliant R strerror_r () is preferred for portable applications. It returns the error string in the user-supplied buffer buf of length R buflen . The GNU-specific R strerror_r () returns a pointer to a string containing the error message. This may be either a pointer to a string that the function stores in R buf , or a pointer to some (immutable) static string (in which case buf is unused). If the function stores a string in R buf , then at most buflen bytes are stored (the string may be truncated if buflen is too small) and the string always includes a terminating null byte.

The R strerror () and R strerror_r () functions return the appropriate error description string, or an "Unknown error nnn" message if the error number is unknown. The XSI-compliant R strerror_r () function returns 0 on success; on error, -1 is returned and errno is set to indicate the error.

EINVAL

ERANGE

R strerror () is specified by POSIX.1-2001, C89, C99. R strerror_r () is specified by POSIX.1-2001. The GNU-specific R strerror_r () function is a non-standard extension. POSIX.1-2001 permits R strerror () to set errno if the call encounters an error, but does not specify what value should be returned as the function result in the event of an error. On some systems, R strerror () returns NULL if the error number is unknown. On other systems, R strerror () returns a string something like "Error nnn occurred" and sets errno to EINVAL if the error number is unknown.

err(3), errno(3), error(3), perror(3), strsignal(3), feature_test_macros(7)