Fix for WindowsApps permission denied with run_command().

[alchitry]

I've been integrating Yosys into an application (Alchitry Labs) and it fails to run on Windows when installed to WindowsApps. The original error was reported here.

I found that my program could run yosys but when yosys would start yosys-abc it would simply return Access is denied.

After two days of pulling my hair out, I discovered that using CreateProcessA() instead of popen() or system() makes it work. I don't know exactly what the difference is but Windows must be passing something along that doesn't happen otherwise.

This is a Windows only problem and a Windows only solution so a lot was added in an #ifdef block. I couldn't find a way to make it work using the more standard functions.

[alchitry]

I improved the handling for when process_line is null to be more like system(). I also only redirect stdout not stderr.

system() uses a shell to launch the process while CreateProcess() does not. Using the shell is likely causing the problems but it means that stuff like redirection doesn't work with CreateProcess(). The launch of yosys-abc uses 2>&1 so it might be more accurate to also redirect stderr. It could be conditionally redirected if the command ends with this.

I don't know enough about how this is used elsewhere to make a good decision on how this should be handled.

[alchitry]

I updated the code so it only uses the new function when needed. This preserves the shell behavior everywhere else.

[whitequark]

The launch of yosys-abc uses 2>&1 so it might be more accurate to also redirect stderr. It could be conditionally redirected if the command ends with this.

Without the use of a shell, wouldn't this argument (however the redirection is done) be passed to yosys-abc itself, causing issues?

Using the shell is likely causing the problems

Can you please confirm that running cmd.exe via CreateProcess is also causing the error you're observing?

[whitequark]

I found that my program could run yosys but when yosys would start yosys-abc it would simply return Access is denied.

Are you aware that you can link abc into the main Yosys executable, avoiding the use of popen entirely? On reflection, I think this might be the better way to go to solve this issue.

[alchitry]

That would likely fix it. Can it be done using the oss-cad-suite-build? I'm using this to build the tools for windows/linux/mac.

Using cmd.exe to launch the program via CreateProcess gives the access denied error.

In my latest code change I remove the redirection argument if present before running the command.

[whitequark]

Can it be done using the oss-cad-suite-build?

Sorry, I'm not familiar with oss-cad-suite-build. I maintain YoWASP tool builds and that's been my primary deployment target since 2020.

In order to enable linking in abc you need to set in yosys/Makefile.conf the following:

LINK_ABC := 1

[alchitry]

I believe I was able to add this by adding echo 'LINK_ABC := 1' >> Makefile.conf as line 11 of yosys.sh but this lead to a build error.

/usr/lib/gcc/x86_64-w64-mingw32/13.2.1/../../../../x86_64-w64-mingw32/bin/ld: yosys-libabc.a(sclLiberty.o): in function `Scl_LibertyGlobMatch':
/work/_builds/windows-x64/yosys/yosys/abc/src/map/scl/sclLiberty.c:86: undefined reference to `__imp_PathMatchSpecA'
collect2: error: ld returned 1 exit status
make: *** [Makefile:718: yosys.exe] Error 1

This lead me to line 86 of sclLiberty.c which conveniently had the comment of // if the compiler complains, add "-lshlwapi"

Adding -lshlwapi to LIBS in the makefile did the trick. I need to figure out a cleaner way to only add it to Windows builds but it's a good start.

EDIT: Adding the following two lines to the yosys.sh file got it to compile for windows with ABC linked. This solves my problem without modification to yosys.

	echo 'LINK_ABC := 1' >> Makefile.conf
	echo 'LIBS := -lshlwapi' >> Makefile.conf

[whitequark]

Adding -lshlwapi to LIBS in the makefile did the trick. I need to figure out a cleaner way to only add it to Windows builds but it's a good start.

That should probably be done as a part of the main Yosys makefile.