updated method for choosing a free drive letter (fixes #2743)

[philwalk]

In order to shorten the native-image command line in Windows, it is necessary to find a free drive letter to be used as an alias for graalvm home.

The original approach can sometimes choose a drive letter that is not actually free (details below).

The new method queries the Windows registry to identify mounted Devices.

Command line to get a list of unavailable drive letters from the registry:

$ reg query 'HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices' | grep 'DosDevices' | sed -E -e 's#REG_BINARY.*##' \DosDevices\C: \DosDevices\D: \DosDevices\E: \DosDevices\F: \DosDevices\H: 

See #2743 for more details.

Because the failure is a function of the Windows hardware configuration, an automated regression test might be difficult.

The fix was verified manually. Here are the before-and-after manual sessions.

The original problem session, caused by choosing E: as a free drive letter:

# scala-cli --power package versionSort.sc --graal Invalid parameter - E: Error: os.SubprocessException: Result of cmdà: 1 For more details, please see 'C:\opt\ue\clisrc\.scala-build\stacktraces\1708383535-2865679820207472018.log'`

Here's the result with the changes (I: is now the chosen free drive letterrather thanE:`):

# ./mill -i scala --power package versionSort.sc --graal [587/863] runner[3.0.2].publishLocalNoFluff Publishing Artifact(org.virtuslab.scala-cli,runner_3,0.0.1-SNAPSHOT) to ivy repo C:\Users\philwalk\workspace\scala-cli-2743\out\repo\0.0.1-SNAPSHOT [643/863] test-runner[3.0.2].publishLocalNoFluff Publishing Artifact(org.virtuslab.scala-cli,test-runner_3,0.0.1-SNAPSHOT) to ivy repo C:\Users\philwalk\workspace\scala-cli-2743\out\repo\0.0.1-SNAPSHOT [705/863] runner[2.13.12].publishLocalNoFluff Publishing Artifact(org.virtuslab.scala-cli,runner_2.13,0.0.1-SNAPSHOT) to ivy repo C:\Users\philwalk\workspace\scala-cli-2743\out\repo\0.0.1-SNAPSHOT [728/863] test-runner[2.13.12].publishLocalNoFluff Publishing Artifact(org.virtuslab.scala-cli,test-runner_2.13,0.0.1-SNAPSHOT) to ivy repo C:\Users\philwalk\workspace\scala-cli-2743\out\repo\0.0.1-SNAPSHOT [790/863] runner[2.12.18].publishLocalNoFluff Publishing Artifact(org.virtuslab.scala-cli,runner_2.12,0.0.1-SNAPSHOT) to ivy repo C:\Users\philwalk\workspace\scala-cli-2743\out\repo\0.0.1-SNAPSHOT [852/863] test-runner[2.12.18].publishLocalNoFluff Publishing Artifact(org.virtuslab.scala-cli,test-runner_2.12,0.0.1-SNAPSHOT) to ivy repo C:\Users\philwalk\workspace\scala-cli-2743\out\repo\0.0.1-SNAPSHOT [862/863] cli.run Starting compilation server Compiling project (Scala 3.3.1, JVM (17)) Compiled project (Scala 3.3.1, JVM (17)) C:\Users\philwalk\workspace\scala-cli-2743>chcp 437 Active code page: 437 ********************************************************************** ** Visual Studio 2022 Developer Command Prompt v17.9.0 ** Copyright (c) 2022 Microsoft Corporation ********************************************************************** [vcvarsall.bat] Environment initialized for: 'x64' ======================================================================================================================== GraalVM Native Image: Generating 'versionSort' (executable)... ======================================================================================================================== [1/7] Initializing... (6.4s @ 0.23GB) Version info: 'GraalVM 22.3.1 Java 17 CE' Java version info: '17.0.6+10-jvmci-22.3-b13' C compiler: cl.exe (microsoft, x64, 19.39.33519) Garbage collector: Serial GC 1 user-specific feature(s) - com.oracle.svm.polyglot.scala.ScalaFeature [2/7] Performing analysis... [******] (9.5s @ 1.03GB) 3,061 (73.87%) of 4,144 classes reachable 3,559 (51.90%) of 6,858 fields reachable 13,352 (38.50%) of 34,685 methods reachable 29 classes, 42 fields, and 418 methods registered for reflection 62 classes, 53 fields, and 52 methods registered for JNI access 1 native library: version [3/7] Building universe... (1.2s @ 1.56GB) [4/7] Parsing methods... [*] (0.9s @ 0.73GB) [5/7] Inlining methods... [***] (0.6s @ 1.13GB) [6/7] Compiling methods... [***] (6.4s @ 2.20GB) [7/7] Creating image... (1.3s @ 2.59GB) 4.28MB (37.50%) for code area: 7,608 compilation units 6.95MB (60.88%) for image heap: 94,903 objects and 5 resources 189.36KB ( 1.62%) for other data 11.41MB in total ------------------------------------------------------------------------------------------------------------------------ Top 10 packages in code area: Top 10 object types in image heap: 667.18KB java.util 922.63KB byte[] for code metadata 336.15KB java.lang 906.34KB java.lang.String 266.91KB java.text 854.46KB byte[] for general heap data 218.85KB java.util.regex 736.92KB byte[] for java.lang.String 196.46KB java.util.concurrent 672.07KB java.lang.Class 149.11KB java.math 387.80KB java.util.HashMap$Node 128.83KB com.oracle.svm.core.code 239.14KB com.oracle.svm.core.hub.DynamicHubCompanion 120.51KB com.oracle.svm.core.genscavenge 167.58KB java.util.HashMap$Node[] 116.84KB java.lang.invoke 164.54KB java.lang.String[] 104.38KB java.util.logging 154.92KB java.util.concurrent.ConcurrentHashMap$Node 1.97MB for 122 more packages 1.45MB for 800 more object types ------------------------------------------------------------------------------------------------------------------------ 0.7s (2.4% of total time) in 17 GCs | Peak RSS: 3.18GB | CPU load: 6.33 ------------------------------------------------------------------------------------------------------------------------ Produced artifacts: C:\Users\philwalk\workspace\scala-cli-2743\versionSort.build_artifacts.txt (txt) C:\Users\philwalk\workspace\scala-cli-2743\versionSort.exe (executable) ======================================================================================================================== Finished generating 'versionSort' in 27.6s. Wrote C:\Users\philwalk\workspace\scala-cli-2743\versionSort.exe, run it with .\versionSort.exe [863/863] scala

[Gedochao]

LGTM