Increase detection probability of installed git, cygwin and potentially more

[markusschuh]

Category: Enhancement
Severity: Medium
Comments:

Changing files inside file system (outside app specific directories) during setup of an application is not less - or more - invasive than using the windows registry. It is only different. The registry has the advantage, that it is a common place with - at least on top level - well known structure. Of course it is up to devon-ide-tools, if uses registry or not for own configuration purposes. But besides that, the detection rate of external tools would be higher, if not only default paths would be checked, but instead also the related registry would be checked, that might contain the installation path.
With CMD batch methods the related coding is a bit more complex and hard to maintain, but it is doable:

FOR /F "tokens=2*" %%O IN ('REG.EXE QUERY "HKLM\Software\Cygwin\setup" /V "rootdir" 2^>NUL ^| FIND "REG_SZ"') DO set CYGWIN_ROOT_PATH=%%P
FOR /F "tokens=2*" %%O IN ('REG.EXE QUERY "HKLM\Software\GitForWindows" /V "InstallPath" 2^>NUL ^| FIND "REG_SZ"') DO set GIT_ROOT_PATH=%%P

If agreed, I'd propose a related change via pull request, which first checks those value and - if not exist or path empty - falls back to checks for some default paths as already realized.

N.B.: The read from registry would even more helpful, if it would also support the cases, when cygwin / git are installed without administrative access in some user-writable area on file system. But unfortunately this does not mean automatically that the above registry values could just be written from HKCU instead of HKLM. Newer cygwins seem to store some value there, but in a different syntax, that supports several cygwin in parallel. This makes using the registry more complex for that purpose
HKEY_CURRENT_USER\Software\Cygwin\installations
<some dyn 128 bit key in hex> REG_SZ ??\C:\tools\cygwin

Your environment - Windows 7/Windows 10, devon-ide-scripts-3.0.0-beta2

[markusschuh]

There is an even more "stable against system specific setups" version of the command, like: A "reg" or find in path before the windows system one. Or a "SystemRoot" containing spaces (if that works).

This command though needs another know workaround - windows CMD can't execute the sub-command, when it starts with a double quote (due to some historic compatibility - if I redetect the web reference, I'll add it here). The workaround: Start the command with an - otherwise useless - "call":

FOR /F "usebackq tokens=2*" %%O IN (`call "%SystemRoot%"\system32\reg.exe QUERY "HKLM\Software\Cygwin\setup" /V "rootdir" 2^>NUL ^| "%SystemRoot%\system32\find.exe" "REG_SZ"`) DO set CYGWIN_ROOT_PATH=%%P

[hohwille]

Wow! I am impressed by your great contributions and activities. I also very much appreaciate your insights and knowledge both in linux/mac/bash as well as in windows/cmd/registry.
Yes, It would be great to find the real installation path of git-bash and cygwin rahter than guessign and trying some of the most primenent candidates.
Can we do the same thing for git-bash as well? That is actually the recommended and major shell for devon-ide. Cygwin is only supported as kind of fallback. However, any improvement to find a bash in windows more reliable is most welcome.

[markusschuh]

Yes, already mentioned in my enhancement proposal. Here the "more stable against system specific setups" version:

for /F "usebackq tokens=2*" %%O in (`call "%SystemRoot%"\system32\reg.exe query "HKLM\Software\GitForWindows" /v "InstallPath" 2^>nul ^| "%SystemRoot%\system32\findstr.exe" REG_SZ`) do set GIT_ROOT_PATH=%%P
if exist "%GIT_ROOT_PATH%\git-bash.exe" ( echo git-bash.exe found )

For quick test on interactive CMD as usual the double percent (only needed in batch scripts) need to be replaced by single percent.

[hohwille]

@markusschuh thanks for your valuable input. This seems to work fine for arbitrary installations of git bash and I also adopted the same for cygwin what also seems to work fine.

Of course some testing for various setups (including a vanilla windows without git and cygwin) will still be helpful.

[hohwille]

PR #105 merged. Hence done.