Make build work under WSL (Windows services for Linux)

[tobiaswaldvogel]

In order to avoid using a VM under Windows for building LibreElec, I figured out that actually
only a few changes are required to make it work with WSL (Windows services for Linux).
Tested with Debian running on WSL

• fakeroot: Use tcp instead of ipc as it is still not implemented in WSL
• openssl: Clear execstack bit on libcrypto after host build when running on WSL
• checkdeps: Add execstack to dependencies if WSL is detected (Checking for "Microsoft" in /proc/version)

[MilhouseVH]

How about adding an is_wsl() function in config/functions, just in case the check ever needs to change and we can then change it in one place?

is_wsl() {
  grep -q  Microsoft /proc/version 2>/dev/null
}

then use:

+  if is_wsl; then

However as it's only used in two places it's kind of not a big deal, but I would suggest simplifying the check by replacing:

+  WSL=$(grep Microsoft /proc/version)
+  if [ ! -z "$WSL" ]; then

with:

+  if grep -q  Microsoft /proc/version 2>/dev/null; then

Of course this assumes that grep in WSL functions the way it does in every other GNU/Linux...

[MilhouseVH]

Also, what does uname -a, uname -s, and uname -o give under WSL?

[MilhouseVH]

It looks like uname under WSL is pretty useless:

microsoft/WSL#1090
https://stackoverflow.com/questions/38859145/detect-ubuntu-on-windows-vs-native-ubuntu-from-bash-script

in which case grepping /proc/version is probably the best we can do for now. Placing the check in a simple is_wsl() function would make it easier to update in future should Microsoft start returning sensible results in uname, or there's a better solution.

[tobiaswaldvogel]

Thanks for your thoughts.
I agree that it would be better to introduce a function is_wsl() as it might be necessary to change the detection method in future or that more fixes might be required. I also had thought in something like this but didn't know which would be a good place to put it.

On my computer uname -a gives
"Linux DESKTOP-3IVI4ER 4.4.0-43-Microsoft #1-Microsoft Wed Dec 31 14:42:53 PST 2014 x86_64 GNU/Linux"
but according to the link you provided it doesn't seem reliable, so I will stick with grepping /proc/version then.

I will rework it next week and present a new pull request.

[CvH]

just as info

cvh@DESKTOP$ uname -r
4.4.0-43-Microsoft
cvh@DESKTOP$ uname -a
Linux DESKTOP-E3FAQC7 4.4.0-43-Microsoft #1-Microsoft Wed Dec 31 14:42:53 PST 2014 x86_64 x86_64 x86_64 GNU/Linux
cvh@DESKTOP$ uname -s
Linux
cvh@DESKTOP$ uname -o
GNU/Linux

[MilhouseVH]

Thanks @CvH. In which case this should suffice as the function:

is_wsl() {
  [[ $(uname -r) =~ Microsoft ]] && return 0 || return 1
}