Invalid multiplication (px * px) crashes

[mgreter]

This code produces a crash with current master:

div {
    $a: 1px;
    $b: 2px;
    foo: $a * $b;
}

The test suite does not include this case!
All other math operations work correctly!

[KittyGiraudel]

Actually Ruby Sass doesn't allow this calculation either.

2px*px isn't a valid CSS value.

[mgreter]

@hugogiraudel Thanks for the heads up. IMO this is still a valid report as it should not crash! Or could you not reproduce the crash @xzyfer ?

[xzyfer]

@mgreter you're correct. Sorry I got a bit overzealous

[xzyfer]

@mgreter I've had a look at this and after a clean recompile I can't reproduce the crash. It errors as expected with the following

2px*px is not a valid CSS value

[drewwells]

I'm reproducing this on sha 420d7fb

div {
    $a: 1px;
    $b: 2px;
    foo: $a * $b;
}

terminate called after throwing an instance of 'Sass::Sass_Error'
SIGABRT: abort
PC=0x7f6ce215f107
signal arrived during cgo execution

[xzyfer]

Interesting, I cannot produce this on that commit. I'm on OSX 10.9.5

$ cpp --version
Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin13.4.0
Thread model: posix

$ sassc --version
sassc: 3.0.2-14-g65d2
libsass: 3.1.0-beta.2-2-g420d
sass2scss: 1.0.3

$ (cd sassc; git rev-parse HEAD)
65d2bdbb48987acb1e68dd926ed23d4f19ccc271

$ (cd libsass; git rev-parse HEAD)
420d7fb4e578857150e15d80c966e5cac779d932

[drewwells]

I'm reproducing on OS X and linux:

Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin14.0.0
Thread model: posix

[xzyfer]

@drewwells can you please run the commands in my previous message and update the output in your comment.

[drewwells]

I'm running the following Sass. What command did you want me to try?

div {
    $a: 1px;
    $b: 2px;
    foo: $a * $b;
}

[xzyfer]

$ cpp --version
$ sassc --version
$ (cd sassc; git rev-parse HEAD)
$ (cd libsass; git rev-parse HEAD)

[drewwells]

Ahh, I'm not running Sassc I'm running my implementation of libsass.

-> % cpp --version
Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin14.0.0
Thread model: posix

-> % cd libsass; git rev-parse HEAD
420d7fb4e578857150e15d80c966e5cac779d932

[xzyfer]

Could you please produce a gdb backtrace. Instructions on how to do so are here https://unix.stackexchange.com/questions/132192/running-application-ends-with-segmentation-fault/132193#132193?newreg=429090a85808440692bd71de25468216

[drewwells]

I'm working through setting up gdb debugging on OS X. I'm not having much luck getting it to work with cgo (golang linker) though.

[drewwells]

Aha, this is why I'm having so much trouble: golang/go#5221

On linux,

rogram received signal SIGABRT, Aborted.
0x00007ffff7029107 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
56  ../nptl/sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0  0x00007ffff7029107 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1  0x00007ffff702a4e8 in __GI_abort () at abort.c:89
#2  0x00007ffff7b31b3d in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#3  0x00007ffff7b2fbb6 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#4  0x00007ffff7b2fc01 in std::terminate() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#5  0x00007ffff7b2fe19 in __cxa_throw () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#6  0x00000000007cf481 in Sass::error (msg="2px*px is not a valid CSS value", path="stdin", position=...) at error_handling.cpp:15
#7  0x0000000000767acf in Sass::Inspect::operator() (this=<optimized out>, n=0xd2ad80) at inspect.cpp:372
#8  0x0000000000760ebc in Sass::Inspect::operator() (this=0x210, dec=0x210) at inspect.cpp:94
#9  0x0000000000779c6f in fallback_impl (n=0xd2ae20, this=0x7fffffffea60) at output_nested.cpp:22
#10 fallback<Sass::Declaration*> (x=0xd2ae20, this=0x7fffffffea60) at output_nested.hpp:102
#11 Sass::Operation_CRTP<void, Sass::Output_Nested>::operator() (this=0x7fffffffea60, x=0xd2ae20) at operation.hpp:93
#12 0x0000000000778e78 in Sass::Output_Nested::operator() (this=0x7fffffffea60, r=<optimized out>) at output_nested.cpp:115
#13 0x00000000007774e9 in Sass::Output_Nested::operator() (this=0x210, this@entry=0x7fffffffea60, b=0x210, b@entry=0xd2a1b0) at output_nested.cpp:52
#14 0x00000000006f5837 in perform (op=0x7fffffffea60, this=0xd2a1b0) at ast.hpp:290
#15 Sass::Context::compile_block (this=this@entry=0xd08fd0, root=0xd2a1b0) at context.cpp:244
#16 0x00000000006eaf81 in sass_compiler_execute (compiler=0xd08fa0) at sass_context.cpp:549
#17 0x000000000044dc77 in _cgo_22273bb0d233_Cfunc_sass_compiler_execute (v=0xc208085998) at /go/src/github.com/wellington/wellington/context/context.go:52
#18 0x000000000048b3f5 in asmcgocall () at /usr/src/go/src/runtime/asm_amd64.s:665
#19 0x000000c208085950 in ?? ()
#20 0x0000000000000008 in ?? ()
#21 0x000000c20804cbc0 in ?? ()
#22 0x000000000044fd19 in runtime.cgocall_errno (fn=0x489d25 <runtime.rt0_go+293>, arg=0x0, ~r2=4758828) at /usr/src/go/src/runtime/cgocall.go:117
#23 0x0000000000480054 in runtime.mstart () at /usr/src/go/src/runtime/proc.c:836
#24 0x0000000000489d2c in runtime.rt0_go () at /usr/src/go/src/runtime/asm_amd64.s:106
#25 0x0000000000000001 in ?? ()
#26 0x00007fffffffeca8 in ?? ()
#27 0x0000000000000001 in ?? ()
#28 0x00007fffffffeca8 in ?? ()
#29 0x0000000000000000 in ?? ()

[xzyfer]

Thanks for that!

It looks like Libsass is returning the correct error

#6 0x00000000007cf481 in Sass::error (msg="2px*px is not a valid CSS value", path="stdin", position=...) at error_handling.cpp:15

Are you sure wellington is dealing with the Sass_Error objects correct?

Do you still get segfaults with this code?

@error("foo");

[drewwells]

Yep, @error parsing works great:

@error("foo");

Error: foo
         stdin:6

On Tue Dec 30 2014 at 6:52:35 PM Michael Mifsud notifications@github.com
wrote:

Thanks for that!

It looks like Libsass is returning the correct error

#6 #6 0x00000000007cf481 in
Sass::error (msg="2px*px is not a valid CSS value", path="stdin",
position=...) at error_handling.cpp:15

Are you sure wellington is dealing with the Sass_Error objects correct?

Do you still get segfaults with this code?

@error("foo");

—
Reply to this email directly or view it on GitHub
#789 (comment).

[mgreter]

Actually I also still get this crash with perl-libsass. Since everything else is working ok, I guess this is a real problem. And since I can reproduce it I might be able to find out what's the cause for this!
IMO it's not really a regression since it is pretty probable that it never worked anyway!

[xzyfer]

Interesting. Cool sounds like @mgreter is on the case. I've gotten about as far as I can with it. Thanks for all your help @drewwells

[mgreter]

This was a problem/bug with the C API. Should be fixed by #791!
I now also get the error message: 2px*px is not a valid CSS value!

[mgreter]

Btw. the different behaviour could be a system specfic one, since it boils down to an unhandled C++ exception in C code. For me it was previously crashing with the message terminate called after throwing an instance of 'Sass::Sass_Error' ...

@xzyfer please review and merge at your discretion 🍷

[drewwells]

working for me too, thanks @mgreter !

Error > stdin:9
2px*px is not a valid CSS value

[mgreter]

👍

[am11]

👍

@xzyfer, got your message on #libsass, with node-sass I tested with this:

require("node-sass").renderSync({data:"div {\
    $a: 1px;\
    $b: 2px;\
    foo: $a * $b;\
}"})

And it returned the error:

{
  "status": 1,
  "file": "stdin",
  "line": 1,
  "column": 27,
  "message": "2px*px is not a valid CSS value"
}

(no crash)

This happened before applying 6729b1a (it is pointing to 420d7fb).

[xzyfer]

Thanks @am11. Looks like @mgreter got to the bottom of it.