Bug#973620: bash: overflow on integer variables greater than 9223372036854775807

[Chet Ramey]

On 4/15/24 7:59 AM, Gioele Barabucci wrote:

Control: found -1 5.2.21-2
Control: tags -1 upstream
X-Debbugs-CC: bug-b...@gnu.org

On Mon, 2 Nov 2020 16:46:14 +0100 Antonio <antde...@gmail.com> wrote:

Dear Maintainer,
recently while I was running some tests, I ran into this strange overflow:


n+=1; done

0 -> 9223372036854775800
1 -> 9223372036854775801
2 -> 9223372036854775802
3 -> 9223372036854775803
4 -> 9223372036854775804
5 -> 9223372036854775805
6 -> 9223372036854775806
7 -> 9223372036854775807
8 -> -9223372036854775808
9 -> -9223372036854775807
10 -> -9223372036854775806
11 -> -9223372036854775805
12 -> -9223372036854775804
13 -> -9223372036854775803
14 -> -9223372036854775802

The integer handled by bash is obviously very large, but I believe
that in the event of an overflow it would be better to reset the
variable and issue an error flow warning, rather than remain silent.

$ declare -i n=9223372036854775800; for((i=0; i<15; ++i)); do echo "$i -> $n";

Hi. Thanks for the report. As documented, bash integer arithmetic doesn't
check for overflow (it never has). Adding such checks is a low-priority
item.

Chet

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    c...@case.edu    http://tiswww.cwru.edu/~chet/

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