svn commit: r211304 - head/lib/libutil
mdf at FreeBSD.org
mdf at FreeBSD.org
Sat Aug 14 14:45:31 UTC 2010
On Sat, Aug 14, 2010 at 2:34 PM, Dag-Erling Smorgrav <des at freebsd.org> wrote:
> Author: des
> Date: Sat Aug 14 14:34:36 2010
> New Revision: 211304
> URL: http://svn.freebsd.org/changeset/base/211304
>
> Log:
> Simplify expand_number() by combining the (unrolled) loop with the
> switch. Since expand_number() does not accept negative numbers, switch
> from int64_t to uint64_t; this makes it easier to check for overflow.
>
> MFC after: 3 weeks
>
> Modified:
> head/lib/libutil/expand_number.c
> head/lib/libutil/libutil.h
>
> Modified: head/lib/libutil/expand_number.c
> ==============================================================================
> --- head/lib/libutil/expand_number.c Sat Aug 14 14:18:02 2010 (r211303)
> +++ head/lib/libutil/expand_number.c Sat Aug 14 14:34:36 2010 (r211304)
> @@ -37,7 +37,7 @@ __FBSDID("$FreeBSD$");
>
> /*
> * Convert an expression of the following forms to a int64_t.
> - * 1) A positive decimal number.
> + * 1) A positive decimal number.
> * 2) A positive decimal number followed by a 'b' or 'B' (mult by 1).
> * 3) A positive decimal number followed by a 'k' or 'K' (mult by 1 << 10).
> * 4) A positive decimal number followed by a 'm' or 'M' (mult by 1 << 20).
> @@ -47,14 +47,12 @@ __FBSDID("$FreeBSD$");
> * 8) A positive decimal number followed by a 'e' or 'E' (mult by 1 << 60).
> */
> int
> -expand_number(const char *buf, int64_t *num)
> +expand_number(const char *buf, uint64_t *num)
> {
> - static const char unit[] = "bkmgtpe";
> - char *endptr, s;
> - int64_t number;
> - int i;
> + uint64_t number;
> + char *endptr;
>
> - number = strtoimax(buf, &endptr, 0);
> + number = strtoumax(buf, &endptr, 0);
>
> if (endptr == buf) {
> /* No valid digits. */
> @@ -68,15 +66,23 @@ expand_number(const char *buf, int64_t *
> return (0);
> }
>
> - s = tolower(*endptr);
> - switch (s) {
> - case 'b':
> - case 'k':
> - case 'm':
> - case 'g':
> - case 't':
> - case 'p':
> +#define SHIFT(n, b) \
> + do { if ((n << b) < n) goto overflow; n <<= b; } while (0)
I think it's possible for the number to overflow but also not shrink.
e.g. 0x12345678T.
Perhaps if (((n << b) >> b) != n) would be better.
Thanks,
matthew
> +
> + switch (tolower((unsigned char)*endptr)) {
> case 'e':
> + SHIFT(number, 10);
> + case 'p':
> + SHIFT(number, 10);
> + case 't':
> + SHIFT(number, 10);
> + case 'g':
> + SHIFT(number, 10);
> + case 'm':
> + SHIFT(number, 10);
> + case 'k':
> + SHIFT(number, 10);
> + case 'b':
> break;
> default:
> /* Unrecognized unit. */
> @@ -84,17 +90,11 @@ expand_number(const char *buf, int64_t *
> return (-1);
> }
>
> - for (i = 0; unit[i] != '\0'; i++) {
> - if (s == unit[i])
> - break;
> - if ((number < 0 && (number << 10) > number) ||
> - (number >= 0 && (number << 10) < number)) {
> - errno = ERANGE;
> - return (-1);
> - }
> - number <<= 10;
> - }
> -
> *num = number;
> return (0);
> +
> +overflow:
> + /* Overflow */
> + errno = ERANGE;
> + return (-1);
> }
>
> Modified: head/lib/libutil/libutil.h
> ==============================================================================
> --- head/lib/libutil/libutil.h Sat Aug 14 14:18:02 2010 (r211303)
> +++ head/lib/libutil/libutil.h Sat Aug 14 14:34:36 2010 (r211304)
> @@ -109,7 +109,7 @@ int forkpty(int *_amaster, char *_name,
> struct termios *_termp, struct winsize *_winp);
> int humanize_number(char *_buf, size_t _len, int64_t _number,
> const char *_suffix, int _scale, int _flags);
> -int expand_number(const char *_buf, int64_t *_num);
> +int expand_number(const char *_buf, uint64_t *_num);
> const char *uu_lockerr(int _uu_lockresult);
> int uu_lock(const char *_ttyname);
> int uu_unlock(const char *_ttyname);
>
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