Re: seq: fix check for rounding error/truncation
On Mon, 12 Jun 2023 18:48:56 +0100, Stuart Henderson wrote: > Neither of these are really ideal, and mean that we still need gseq > for integers >= 1,000,000 > > $ seq 99 99 > 99 > $ seq 100 100 > 1e+06 > > $ gseq 105 105 > 105 That probably requires a separate code path specifically for integers. One thing at a time. - todd
Re: seq: fix check for rounding error/truncation
On 2023/06/12 11:20, Todd C. Miller wrote:
> We need to compare the printable version of the last value displayed,
> not the floating point representation. Otherwise, we may print the
> last value twice.
>
> Old:
>
> $ seq 105 105
> 1.05e+06
> 1.05e+06
>
> New:
>
> $ seq 105 105
> 1.05e+06
Neither of these are really ideal, and mean that we still need gseq
for integers >= 1,000,000
$ seq 99 99
99
$ seq 100 100
1e+06
$ gseq 105 105
105
> We really need seq regression tests. I have a few that I will
> commit after this is in.
>
> - todd
>
> Index: usr.bin/seq/seq.c
> ===
> RCS file: /cvs/src/usr.bin/seq/seq.c,v
> retrieving revision 1.6
> diff -u -p -u -r1.6 seq.c
> --- usr.bin/seq/seq.c 25 Feb 2022 16:00:39 - 1.6
> +++ usr.bin/seq/seq.c 12 Jun 2023 17:13:44 -
> @@ -89,13 +89,13 @@ main(int argc, char *argv[])
> double first = 1.0;
> double last = 0.0;
> double incr = 0.0;
> - double last_shown_value = 0.0;
> + double prev = 0.0;
> double cur, step;
> struct lconv *locale;
> char *fmt = NULL;
> const char *sep = "\n";
> const char *term = "\n";
> - char *cur_print, *last_print;
> + char *cur_print, *last_print, *prev_print;
> char pad = ZERO;
>
> if (pledge("stdio", NULL) == -1)
> @@ -181,29 +181,31 @@ main(int argc, char *argv[])
> if (cur != first)
> fputs(sep, stdout);
> printf(fmt, cur);
> - last_shown_value = cur;
> + prev = cur;
> }
>
> /*
>* Did we miss the last value of the range in the loop above?
>*
>* We might have, so check if the printable version of the last
> - * computed value ('cur') and desired 'last' value are equal. If they
> - * are equal after formatting truncation, but 'cur' and
> - * 'last_shown_value' are not equal, it means the exit condition of the
> - * loop held true due to a rounding error and we still need to print
> - * 'last'.
> + * computed value ('cur') and desired 'last' value are equal. If
> + * they are equal after formatting truncation, but 'cur' and 'prev'
> + * are different, it means the exit condition of the loop held true
> + * due to a rounding error and we still need to print 'last'.
>*/
> if (asprintf(&cur_print, fmt, cur) == -1 ||
> - asprintf(&last_print, fmt, last) == -1)
> + asprintf(&last_print, fmt, last) == -1 ||
> + asprintf(&prev_print, fmt, prev) == -1)
> err(1, "asprintf");
> - if (strcmp(cur_print, last_print) == 0 && cur != last_shown_value) {
> + if (strcmp(cur_print, last_print) == 0 &&
> + strcmp(cur_print, prev_print) != 0) {
> if (cur != first)
> fputs(sep, stdout);
> fputs(last_print, stdout);
> }
> free(cur_print);
> free(last_print);
> + free(prev_print);
>
> fputs(term, stdout);
>
>
Re: seq: fix check for rounding error/truncation
For context, see: https://chaos.social/@Gottox/110527807405964874 https://github.com/chimera-linux/chimerautils/commit/1ecc1e99d4a309631e846a868b5a422f996704ac
seq: fix check for rounding error/truncation
We need to compare the printable version of the last value displayed,
not the floating point representation. Otherwise, we may print the
last value twice.
Old:
$ seq 105 105
1.05e+06
1.05e+06
New:
$ seq 105 105
1.05e+06
We really need seq regression tests. I have a few that I will
commit after this is in.
- todd
Index: usr.bin/seq/seq.c
===
RCS file: /cvs/src/usr.bin/seq/seq.c,v
retrieving revision 1.6
diff -u -p -u -r1.6 seq.c
--- usr.bin/seq/seq.c 25 Feb 2022 16:00:39 - 1.6
+++ usr.bin/seq/seq.c 12 Jun 2023 17:13:44 -
@@ -89,13 +89,13 @@ main(int argc, char *argv[])
double first = 1.0;
double last = 0.0;
double incr = 0.0;
- double last_shown_value = 0.0;
+ double prev = 0.0;
double cur, step;
struct lconv *locale;
char *fmt = NULL;
const char *sep = "\n";
const char *term = "\n";
- char *cur_print, *last_print;
+ char *cur_print, *last_print, *prev_print;
char pad = ZERO;
if (pledge("stdio", NULL) == -1)
@@ -181,29 +181,31 @@ main(int argc, char *argv[])
if (cur != first)
fputs(sep, stdout);
printf(fmt, cur);
- last_shown_value = cur;
+ prev = cur;
}
/*
* Did we miss the last value of the range in the loop above?
*
* We might have, so check if the printable version of the last
-* computed value ('cur') and desired 'last' value are equal. If they
-* are equal after formatting truncation, but 'cur' and
-* 'last_shown_value' are not equal, it means the exit condition of the
-* loop held true due to a rounding error and we still need to print
-* 'last'.
+* computed value ('cur') and desired 'last' value are equal. If
+* they are equal after formatting truncation, but 'cur' and 'prev'
+* are different, it means the exit condition of the loop held true
+* due to a rounding error and we still need to print 'last'.
*/
if (asprintf(&cur_print, fmt, cur) == -1 ||
- asprintf(&last_print, fmt, last) == -1)
+ asprintf(&last_print, fmt, last) == -1 ||
+ asprintf(&prev_print, fmt, prev) == -1)
err(1, "asprintf");
- if (strcmp(cur_print, last_print) == 0 && cur != last_shown_value) {
+ if (strcmp(cur_print, last_print) == 0 &&
+ strcmp(cur_print, prev_print) != 0) {
if (cur != first)
fputs(sep, stdout);
fputs(last_print, stdout);
}
free(cur_print);
free(last_print);
+ free(prev_print);
fputs(term, stdout);
