System property to extract binaries to a different folder (#891)

Skiko extracts binaries to `~/.skiko` by default, but it is not always
possible. This PR adds a way to override the folder where to extract
binaries:
```
System.setProperty("skiko.data.path", File(System.getProperty("java.io.tmpdir")).resolve(".skiko").toString())
```

Fixes #885

The case seems rare - we only have a crash in tests reported. If we have
reports from real users, we have to change the default `~/.skiko` to
something else.

## Testing 1 (manual)
1. Run
```
import org.jetbrains.skia.Bitmap
import java.io.File

fun main() {
    val path = File(System.getProperty("java.io.tmpdir")).resolve(".skiko").toString()
    println(path)
    System.setProperty("skiko.data.path", path)
    Bitmap() // loads the library
}
```
2. See that `path` is created
## Testing 2 (manual)
The default way works:
```
import org.jetbrains.skia.Bitmap

fun main() {
    Bitmap() // loads the library
}
```

skiko/src/awtMain/kotlin/org/jetbrains/skiko/RenderExceptionsHandler.kt

@@ -12,7 +12,7 @@ internal class RenderExceptionsHandler {
         fun throwException(message: String) {
             if (output == null) {
                 output = File(
-                    "${Library.cacheRoot}/skiko-render-exception-${ProcessHandle.current().pid()}.log"
+                    "${SkikoProperties.dataPath}/skiko-render-exception-${ProcessHandle.current().pid()}.log"
                 )
             }
             val exception = RenderException(message)

skiko/src/awtTest/kotlin/org/jetbrains/skiko/SeveralClassloadersTest.kt

@@ -71,31 +71,21 @@ private fun newInstance(loader: ClassLoader, fqName: String, vararg args: Any):
 class SeveralClassloadersTest {
     @Test
     fun `load skiko in several classloaders (with skiko path)`()  {
-        check(skikoLibraryPath != null)
+        check(SkikoProperties.libraryPath != null)
         doTest()
     }
 
     @Test
     fun `load skiko in several classloaders (without skiko path)`()  {
-        val oldValue = skikoLibraryPath!!
-        skikoLibraryPath = null
+        val oldValue = SkikoProperties.libraryPath!!
+        SkikoProperties.libraryPath = null
         try {
             doTest()
         } finally {
-            skikoLibraryPath = oldValue
+            SkikoProperties.libraryPath = oldValue
         }
     }
 
-    private var skikoLibraryPath: String?
-        get() = System.getProperty(Library.SKIKO_LIBRARY_PATH_PROPERTY)
-        set(value) {
-            if (value != null) {
-                System.setProperty(Library.SKIKO_LIBRARY_PATH_PROPERTY, value)
-            } else {
-                System.clearProperty(Library.SKIKO_LIBRARY_PATH_PROPERTY)
-            }
-        }
-
     private fun doTest() {
         val threaded = false
         val jar = System.getProperty("skiko.jar.path")

skiko/src/jvmMain/kotlin/org/jetbrains/skiko/Library.kt

@@ -7,9 +7,6 @@ import java.nio.file.StandardCopyOption
 import java.util.concurrent.atomic.AtomicBoolean
 
 object Library {
-    internal const val SKIKO_LIBRARY_PATH_PROPERTY = "skiko.library.path"
-    internal val cacheRoot = "${System.getProperty("user.home")}/.skiko/"
-    private val skikoLibraryPath = System.getProperty(SKIKO_LIBRARY_PATH_PROPERTY)
     private var copyDir: File? = null
 
     // A native library cannot be loaded in several classloaders, so we have to clone
@@ -80,6 +77,7 @@ object Library {
         }
 
         // First try: system property is set.
+        val skikoLibraryPath = SkikoProperties.libraryPath
         if (skikoLibraryPath != null) {
             val library = File(File(skikoLibraryPath), platformName)
             loadLibraryOrCopy(library)
@@ -107,17 +105,17 @@ object Library {
         )
         val hash = hashResourceStream.use { it.bufferedReader().readLine() }
 
-        val cacheDir = File(File(cacheRoot), hash)
-        cacheDir.mkdirs()
-        val library = unpackIfNeeded(cacheDir, platformName, false)
+        val dataDir = File(File(SkikoProperties.dataPath), hash)
+        dataDir.mkdirs()
+        val library = unpackIfNeeded(dataDir, platformName, false)
         loadLibraryOrCopy(library)
         if (icu != null) {
             if (copyDir != null) {
                 // We made a duplicate to resolve classloader conflicts.
                 unpackIfNeeded(copyDir!!, icu, true)
             } else {
                 // Normal path where Skiko is loaded only once.
-                unpackIfNeeded(cacheDir, icu, false)
+                unpackIfNeeded(dataDir, icu, false)
             }
         }
     }

skiko/src/jvmMain/kotlin/org/jetbrains/skiko/SkikoProperties.kt

@@ -8,6 +8,30 @@ import java.lang.System.getProperty
  * Global Skiko properties, which are read from system JDK variables orr from environment variables
  */
 object SkikoProperties {
+    /**
+     * Path where the Skiko binaries (dll/so/dylib, depending on OS) are placed.
+     *
+     * If defined, SKiko doesn't extract binaries from `jar` files to external folder.
+     *
+     * If null (default), it extracts them to `libraryCachePath`
+     */
+    var libraryPath: String?
+        get() = getProperty("skiko.library.path")
+        internal set(value) {
+            if (value != null) {
+                System.setProperty("skiko.library.path", value)
+            } else {
+                System.clearProperty("skiko.library.path")
+            }
+        }
+
+    /**
+     * The path where to store data files.
+     *
+     * It is used for extracting the Skiko binaries (if `libraryPath` isn't null) and logging.
+     */
+    val dataPath: String get() = getProperty("skiko.data.path") ?: "${getProperty("user.home")}/.skiko/"
+
     val vsyncEnabled: Boolean get() = getProperty("skiko.vsync.enabled")?.toBoolean() ?: true
 
     /**