NAME

       ipsec_atoul, ipsec_ultoa - convert unsigned-long numbers to and from ASCII

SYNOPSIS

       #include <freeswan.h>

       const char *atoul(const char * src, size_t srclen, int base, unsigned long * n);

       size_t ultoa(unsigned long n, int base, char * dst, size_t dstlen);

DESCRIPTION

       These functions are obsolete; see ipsec_ttoul(3) for their replacements.

       Atoul converts an ASCII number into a binary unsigned long value.  Ultoa does the reverse conversion,
       back to an ASCII version.

       Numbers are specified in ASCII as decimal (e.g.  123), octal with a leading zero (e.g.  012, which has
       value 10), or hexadecimal with a leading 0x (e.g.  0x1f, which has value 31) in either upper or lower
       case.

       The srclen parameter of atoul specifies the length of the ASCII string pointed to by src; it is an error
       for there to be anything else (e.g., a terminating NUL) within that length. As a convenience for cases
       where an entire NUL-terminated string is to be converted, a srclen value of 0 is taken to mean
       strlen(src).

       The base parameter of atoul can be 8, 10, or 16, in which case the number supplied is assumed to be of
       that form (and in the case of 16, to lack any 0x prefix). It can also be 0, in which case the number is
       examined for a leading zero or a leading 0x to determine its base, or 13 (halfway between 10 and 16),
       which has the same effect as 0 except that a non-hexadecimal number is considered decimal regardless of
       any leading zero.

       The dstlen parameter of ultoa specifies the size of the dst parameter; under no circumstances are more
       than dstlen bytes written to dst. A result which will not fit is truncated.  Dstlen can be zero, in which
       case dst need not be valid and no result is written, but the return value is unaffected; in all other
       cases, the (possibly truncated) result is NUL-terminated.

       The base parameter of ultoa must be 8, 10, or 16.

       Atoul returns NULL for success and a pointer to a string-literal error message for failure; see
       DIAGNOSTICS.  Ultoa returns the size of buffer which would be needed to accommodate the full conversion
       result, including terminating NUL; it is the caller´s responsibility to check this against the size of
       the provided buffer to determine whether truncation has occurred.

SEE ALSO

       atol(3), strtoul(3)

DIAGNOSTICS

       Fatal errors in atoul are: empty input; unknown base; non-digit character found; number too large for an
       unsigned long.

HISTORY

       Written for the FreeS/WAN project by Henry Spencer.

BUGS

       There is no provision for reporting an invalid base parameter given to ultoa.

       The restriction of error reports to literal strings (so that callers don´t need to worry about freeing
       them or copying them) does limit the precision of error reporting.

       The error-reporting convention lends itself to slightly obscure code, because many readers will not think
       of NULL as signifying success. A good way to make it clearer is to write something like:

           const char *error;

           error = atoul( /* ... */ );
           if (error != NULL) {
                   /* something went wrong */

11 June 2001                                       11/14/2008                                     IPSEC_ATOUL(3)