1IPSEC_TTOUL(3) Library Functions Manual IPSEC_TTOUL(3)
2
6 ipsec ttoul, ultot - convert unsigned-long numbers to and from text
7
9 #include <freeswan.h>
10 const char *ttoul(const char *src, size_t srclen,
12 int base, unsigned long *n);
13 size_t ultot(unsigned long n, int format, char *dst,
14 size_t dstlen);
15
17 Ttoul converts a text-string number into a binary unsigned long value.
18 Ultot does the reverse conversion, back to a text version.
19 Numbers are specified in text as decimal (e.g. 123), octal with a
21 leading zero (e.g. 012, which has value 10), or hexadecimal with a
22 leading 0x (e.g. 0x1f, which has value 31) in either upper or lower
23 case.
24 The srclen parameter of ttoul specifies the length of the string
26 pointed to by src; it is an error for there to be anything else (e.g.,
27 a terminating NUL) within that length. As a convenience for cases
28 where an entire NUL-terminated string is to be converted, a srclen
29 value of 0 is taken to mean strlen(src).
30 The base parameter of ttoul can be 8, 10, or 16, in which case the num‐
32 ber supplied is assumed to be of that form (and in the case of 16, to
33 lack any 0x prefix). It can also be 0, in which case the number is
34 examined for a leading zero or a leading 0x to determine its base.
35 The dstlen parameter of ultot specifies the size of the dst parameter;
37 under no circumstances are more than dstlen bytes written to dst. A
38 result which will not fit is truncated. Dstlen can be zero, in which
39 case dst need not be valid and no result is written, but the return
40 value is unaffected; in all other cases, the (possibly truncated)
41 result is NUL-terminated. The freeswan.h header file defines a con‐
42 stant, ULTOT_BUF, which is the size of a buffer just large enough for
43 worst-case results.
44 The format parameter of ultot must be one of:
46 'o' octal conversion with leading 0
48 8 octal conversion with no leading 0
50 'd' decimal conversion
52 10 same as d
54 'x' hexadecimal conversion, including leading 0x
56 16 hexadecimal conversion with no leading 0x
58 17 like 16 except padded on left with 0s to eight digits (full
60 width of a 32-bit number)
61 Ttoul returns NULL for success and a pointer to a string-literal error
63 message for failure; see DIAGNOSTICS. Ultot returns 0 for a failure,
64 and otherwise returns the size of buffer which would be needed to
65 accommodate the full conversion result, including terminating NUL (it
66 is the caller's responsibility to check this against the size of the
67 provided buffer to determine whether truncation has occurred).
68
70 atol(3), strtoul(3)
71
73 Fatal errors in ttoul are: empty input; unknown base; non-digit charac‐
74 ter found; number too large for an unsigned long.
75 Fatal errors in ultot are: unknown format.
77
79 Written for the FreeS/WAN project by Henry Spencer.
80
82 Conversion of 0 with format o yields 00.
83 Ultot format 17 is a bit of a kludge.
85 The restriction of error reports to literal strings (so that callers
87 don't need to worry about freeing them or copying them) does limit the
88 precision of error reporting.
89 The error-reporting convention lends itself to slightly obscure code,
91 because many readers will not think of NULL as signifying success. A
92 good way to make it clearer is to write something like:
93 const char *error;
95 error = ttoul( /* ... */ );
97 if (error != NULL) {
98 /* something went wrong */
99 16 Aug 2000 IPSEC_TTOUL(3)