git: e54db9a9ccd5 - main - seq: fix check for rounding error/truncation

[Ed Maste]

The branch main has been updated by emaste:

URL: 
https://cgit.FreeBSD.org/src/commit/?id=e54db9a9ccd588f650a2e57bf9d1cbbafc0e12eb

commit e54db9a9ccd588f650a2e57bf9d1cbbafc0e12eb
Author:     Ed Maste <ema...@freebsd.org>
AuthorDate: 2023-06-19 01:37:06 +0000
Commit:     Ed Maste <ema...@freebsd.org>
CommitDate: 2023-06-19 15:02:38 +0000

    seq: fix check for rounding error/truncation
    
    Based on OpenBSD 30f0fd29ba6c:
    > 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.
    
    PR:             271964
    Reported by:    Daniel Kolesa
    Reviewed by:    yuripv
    Obtained from:  OpenBSD
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D40601
---
 usr.bin/seq/seq.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/usr.bin/seq/seq.c b/usr.bin/seq/seq.c
index 85fca6e88792..3618a106ec9e 100644
--- a/usr.bin/seq/seq.c
+++ b/usr.bin/seq/seq.c
@@ -88,14 +88,14 @@ main(int argc, char *argv[])
 {
        const char *sep, *term;
        struct lconv *locale;
-       char pad, *fmt, *cur_print, *last_print;
-       double first, last, incr, last_shown_value, cur, step;
+       char pad, *fmt, *cur_print, *last_print, *prev_print;
+       double first, last, incr, prev, cur, step;
        int c, errflg, equalize;
 
        pad = ZERO;
        fmt = NULL;
        first = 1.0;
-       last = incr = last_shown_value = 0.0;
+       last = incr = prev = 0.0;
        c = errflg = equalize = 0;
        sep = "\n";
        term = NULL;
@@ -186,7 +186,7 @@ main(int argc, char *argv[])
            cur = first + incr * step++) {
                printf(fmt, cur);
                fputs(sep, stdout);
-               last_shown_value = cur;
+               prev = cur;
        }
 
        /*
@@ -194,10 +194,9 @@ main(int argc, char *argv[])
         *
         * 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'.
+        * are equal after formatting truncation, but 'cur' and 'prev' 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'.
         */
        if (asprintf(&cur_print, fmt, cur) < 0) {
                err(1, "asprintf");
@@ -205,12 +204,17 @@ main(int argc, char *argv[])
        if (asprintf(&last_print, fmt, last) < 0) {
                err(1, "asprintf");
        }
-       if (strcmp(cur_print, last_print) == 0 && cur != last_shown_value) {
+       if (asprintf(&prev_print, fmt, prev) < 0) {
+               err(1, "asprintf");
+       }
+       if (strcmp(cur_print, last_print) == 0 &&
+           strcmp(cur_print, prev_print) != 0) {
                fputs(last_print, stdout);
                fputs(sep, stdout);
        }
        free(cur_print);
        free(last_print);
+       free(prev_print);
 
        if (term != NULL)
                fputs(term, stdout);