Update bug status of 2000/dlowe
This entry crashes in macOS. This MIGHT be related to the version of perl, both with MacPorts and Homebrew. See the bugs.md for many more details. The author gave an example command and output (well several) and one I tried (I did not try all) did not report correct output (some did). Again the bugs.md file has many more details. Format/typo fix README.md. With the exception of possibly fixing the bugs noted in bugs.md this should complete the review of 2000/dlowe.
This commit is contained in:
Cody Boone Ferguson committed
1 parent
7e0b9fa298
commit
c0a2eedb56
2 files changed
+262
-15
No files matched your search
@@ -1507,6 +1507,234 @@ There was no IOCCC in 1999.
|
||||
# 2000
|
||||
|
||||
|
||||
## 2000 dlowe
|
||||
|
||||
### STATUS: doesn't work with some platforms - please help us fix
|
||||
### Source code: [2000/dlowe/dlowe.c](2000/dlowe/dlowe.c)
|
||||
### Information: [2000/dlowe/README.md](2000/dlowe/README.md)
|
||||
|
||||
This **MIGHT** be better described as doesn't work with some versions of perl:
|
||||
the author states that in perl < 5.6.0 there is a bug with a core dump in what
|
||||
they said is in `Perl_sv_upgrade`. This does not exist in the code, seemingly,
|
||||
but it might be that this is impossible to fix without getting a perl upgrade.
|
||||
In any event the below details a problem. Another bug that happens in linux also
|
||||
is below.
|
||||
|
||||
In macOS this program crashes. A tip from Cody is that the code that crashes is:
|
||||
|
||||
```c
|
||||
perl_eval_sv
|
||||
(newSVpv("_:$_= <> ; defined or exit; @ARGV"
|
||||
"=split; __:$_= shift;defined or goto _; chomp "
|
||||
";(m*^\\x70oO" "\\x74$*i)?(pri" "nt \"$_ w\\x"
|
||||
"61s h\\145r\\x" "65!\\n\"):((m*" "^\\s\\*(-?\\d+"
|
||||
"(\\.\\d+)?)\\s" "\\*$*)?(push@SS ,$1):(&{chr(((o"
|
||||
"rd)%39)+3**4)x2 } )); goto __; sub ff { @SS= ("
|
||||
")} sub __{print \"stack empty\\" "n\"} sub ss{$#"
|
||||
"SS<0 and goto & __; print $SS[$" "#SS].\"\\n\"} "
|
||||
"sub SS{ $#SS<0 and goto &__ ; print pop @SS}"
|
||||
"sub _ { print \"divide by zer" "o\\n\"}sub ii{"
|
||||
"map{ print\"$_" "\\n\" } reverse @SS} sub AUTOLO"
|
||||
"AD { print\"un" "implemented\\n" "\"} sub gg{ $#"
|
||||
"SS<0 and goto &__;push@SS,$SS[ $#SS]} sub uu{ "
|
||||
"$#SS<1 and goto &__;$SS[ $#SS]+= $SS[$#SS-1];$SS"
|
||||
"[$#SS-1]=$SS[$" "#SS]-$SS[$#SS-" "1]; $SS[$#SS]-"
|
||||
"=$SS[$#SS-1]} ",0),0 );
|
||||
```
|
||||
|
||||
and in particular it appears that it is the perl itself. In other words if one
|
||||
changes it to be:
|
||||
|
||||
```c
|
||||
perl_eval_sv(newSVpv("",0),0);
|
||||
```
|
||||
|
||||
it will not crash. But of course it won't do anything either. So it's more
|
||||
specifically that the call to `newSVpv()` crashes the code but _INSIDE_
|
||||
(key point!) the call to `perl_eval_sv()` that does it. Given what the author
|
||||
stated and that the version of perl is < than 5.6.0 that might be exactly what
|
||||
is going on.
|
||||
|
||||
The example command above _should_ print:
|
||||
|
||||
```sh
|
||||
$ echo "13 14 15 16 17 + - * / p" | ./dlowe
|
||||
-0.0515873015873016
|
||||
```
|
||||
|
||||
and that's what it shows in linux.
|
||||
|
||||
Note that with different perl libraries in macOS (for instance from
|
||||
[Homebrew](https://brew.sh) and [MacPorts](https://www.macports.org) it will
|
||||
likely print different warnings when compiling. It was observed that with
|
||||
Homebrew it does not report any warnings but with MacPorts it results in a total
|
||||
of 92 warnings! Nonetheless neither works okay and both crash.
|
||||
|
||||
|
||||
### STATUS: known bug - please help us fix
|
||||
|
||||
The author gives an example command:
|
||||
|
||||
```sh
|
||||
echo "7 P 6 d P P 8 p" | ./dlowe | tr 876 tpo
|
||||
```
|
||||
|
||||
which should print out `poot` but it doesn't, not in linux and not in macOS.
|
||||
This might in part be because `./dlowe` will show not a number with `876` but
|
||||
rather
|
||||
|
||||
```sh
|
||||
$ echo "7 P 6 d P P 8 p" | ./dlowe
|
||||
7668
|
||||
```
|
||||
|
||||
In linux it doesn't crash but it doesn't print anything out either.
|
||||
|
||||
In macOS it crashes; it might appear to not crash in macOS but this is because
|
||||
of the pipeline. If you remove the `| tr 876 tpo` part of the command you will
|
||||
see that it does indeed crash!
|
||||
|
||||
Other commands do work, however, and give the appropriate output, such as:
|
||||
|
||||
```sh
|
||||
$ echo 1 2 + p | ./dlowe
|
||||
3
|
||||
```
|
||||
|
||||
so something is wrong with some commands/operators.
|
||||
|
||||
Another feature that does work in linux is:
|
||||
|
||||
```sh
|
||||
$ echo poot | ./dlowe
|
||||
poot was here!
|
||||
```
|
||||
|
||||
Can you help fix these problems?
|
||||
|
||||
Cody provided the C code that creates an unformatted perl script that will just
|
||||
print 'unimplemented' for operators but it seems to work in some other ways (see
|
||||
below for how to go further than unimplemented) which is the exact perl from the
|
||||
C program except that it has the `#!/usr/bin/env perl` and `use warnings;` as
|
||||
well. A note below might suggest that doing this creates incomplete perl.
|
||||
Anyway:
|
||||
|
||||
```c
|
||||
#include <stdio.h>
|
||||
int main(void)
|
||||
{
|
||||
printf("#!/usr/bin/env perl\nuse warnings;_:$_= <> ; defined or exit; @ARGV"
|
||||
"=split; __:$_= shift;defined or goto _; chomp "
|
||||
";(m*^\\x70oO" "\\x74$*i)?(pri" "nt \"$_ w\\x"
|
||||
"61s h\\145r\\x" "65!\\n\"):((m*" "^\\s\\*(-?\\d+"
|
||||
"(\\.\\d+)?)\\s" "\\*$*)?(push@SS ,$1):(&{chr(((o"
|
||||
"rd)%%39)+3**4)x2 } )); goto __; sub ff { @SS= ("
|
||||
")} sub __{print \"stack empty\\" "n\"} sub ss{$#"
|
||||
"SS<0 and goto & __; print $SS[$" "#SS].\"\\n\"} "
|
||||
"sub SS{ $#SS<0 and goto &__ ; print pop @SS}"
|
||||
"sub _ { print \"divide by zer" "o\\n\"}sub ii{"
|
||||
"map{ print\"$_" "\\n\" } reverse @SS} sub AUTOLO"
|
||||
"AD { print\"un" "implemented\\n" "\"} sub gg{ $#"
|
||||
"SS<0 and goto &__;push@SS,$SS[ $#SS]} sub uu{ "
|
||||
"$#SS<1 and goto &__;$SS[ $#SS]+= $SS[$#SS-1];$SS"
|
||||
"[$#SS-1]=$SS[$" "#SS]-$SS[$#SS-" "1]; $SS[$#SS]-"
|
||||
"=$SS[$#SS-1]}");
|
||||
}
|
||||
```
|
||||
|
||||
Compiling this you can generate:
|
||||
|
||||
|
||||
```perl
|
||||
#!/usr/bin/env perl
|
||||
use warnings;_:$_= <> ; defined or exit; @ARGV=split; __:$_= shift;defined or goto _; chomp ;(m*^\x70oO\x74$*i)?(print "$_ w\x61s h\145r\x65!\n"):((m*^\s\*(-?\d+(\.\d+)?)\s\*$*)?(push@SS ,$1):(&{chr(((ord)%39)+3**4)x2 } )); goto __; sub ff { @SS= ()} sub __{print "stack empty\n"} sub ss{$#SS<0 and goto & __; print $SS[$#SS]."\n"} sub SS{ $#SS<0 and goto &__ ; print pop @SS}sub _ { print "divide by zero\n"}sub ii{map{ print"$_\n" } reverse @SS} sub AUTOLOAD { print"unimplemented\n"} sub gg{ $#SS<0 and goto &__;push@SS,$SS[ $#SS]} sub uu{ $#SS<1 and goto &__;$SS[ $#SS]+= $SS[$#SS-1];$SS[$#SS-1]=$SS[$#SS]-$SS[$#SS-1]; $SS[$#SS]-=$SS[$#SS-1]}
|
||||
```
|
||||
|
||||
Here is example input/output:
|
||||
|
||||
```
|
||||
p
|
||||
stack empty
|
||||
5 p
|
||||
5
|
||||
5 + 5 p
|
||||
unimplemented
|
||||
5
|
||||
P
|
||||
5
|
||||
p
|
||||
5
|
||||
```
|
||||
|
||||
So you can see that if one uses operators it just shows 'unimplemented' (observe
|
||||
how this does not happen in the C program in linux!) but if one uses 'p' by
|
||||
itself it will print what's on the stack (for example).
|
||||
|
||||
To not get 'unimplemented' you can remove from the perl:
|
||||
|
||||
|
||||
```perl
|
||||
sub AUTOLOAD { print"unimplemented\n"}
|
||||
```
|
||||
|
||||
(Note that the author stated this was used for exception handling so another
|
||||
possibility is that the C code doesn't generate the correct perl and indeed even
|
||||
spaces is known to break the perl in at least one way, syntax errors, but maybe
|
||||
others too.)
|
||||
|
||||
Here is an example run of several operations in the perl script after removing
|
||||
that subroutine:
|
||||
|
||||
```sh
|
||||
$ echo 5 5 p | ./dlowe.pl
|
||||
5
|
||||
$ echo 5 5 + p | ./dlowe.pl
|
||||
5
|
||||
Undefined subroutine &main::UU called at ./pl.pl line 2, <> line 1.
|
||||
$ echo 5 5 * p | ./dlowe.pl
|
||||
5
|
||||
Undefined subroutine &main::ww called at ./pl.pl line 2, <> line 1.
|
||||
$ echo 5 5 - p | ./dlowe.pl
|
||||
5
|
||||
Undefined subroutine &main::WW called at ./pl.pl line 2, <> line 1.
|
||||
$ echo 5 5 / p | ./dlowe.pl
|
||||
5
|
||||
Undefined subroutine &main::YY called at ./pl.pl line 2, <> line 1.
|
||||
$ echo 5 P | ./dlowe.pl
|
||||
5$ echo p | ./dlowe.pl
|
||||
stack empty
|
||||
$ echo P | ./dlowe.pl
|
||||
stack empty
|
||||
```
|
||||
|
||||
Note the undefined subroutine error: that happens with commands that are not
|
||||
even in the program. Again the author used `AUTOLOAD` for exception handling so
|
||||
it seems likely that there is something missing (which the below shows as well).
|
||||
For instance inputting `D` followed by `XX`:
|
||||
|
||||
```
|
||||
Undefined subroutine &main::nn called at ./pl.pl line 2, <> line 6.
|
||||
Undefined subroutine &main::[[ called at ./pl.pl line 2, <> line 1.
|
||||
```
|
||||
|
||||
That means then that in linux despite the subroutines seemingly not existing it
|
||||
works in the code, at least in some cases.
|
||||
|
||||
As far as the unimplemented error goes: the author stated that it means there is
|
||||
invalid input. But as can be seen by the input I (Cody) gave the input is not
|
||||
actually incorrect. It is also curious to note that it ends up printing what's
|
||||
on the stack at that point:
|
||||
|
||||
```sh
|
||||
$ echo 5 5 + p | ./dlowe.pl
|
||||
unimplemented
|
||||
5
|
||||
```
|
||||
|
||||
which might (?) suggest that the `+` operator is unimplemented. Unfortunately it
|
||||
has been many years since I have used perl and I was never a guru either.
|
||||
|
||||
|
||||
## 2000 primenum
|
||||
|
||||
### STATUS: INABIAF - please **DO NOT** fix
|
||||
|
||||
Reference in new issue
Block a user