Introduce FSHealthCheck to run after a possibly-filesystem related error.

src/main/java/com/sheepit/client/Configuration.java

@@ -26,10 +26,12 @@ import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Calendar;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.ListIterator;
 
 import com.sheepit.client.hardware.cpu.CPU;
 import com.sheepit.client.hardware.gpu.GPUDevice;
@@ -330,6 +332,65 @@ import lombok.Data;
 		return files_local;
 	}
 	
+	/**
+	 * Runs through all SheepIt related directories and checks if files and folders are all readable, writeable
+	 * and in case of directories, checks if the contents can be listed and if usable space is enough.
+	 * Only logs instances where something was detected, otherwise is it will only print "FilesystemHealthCheck started"
+	 * @return an ArrayList of Strings containing all of the logs of the FSHealth check
+	 */
+	public ArrayList<String> filesystemHealthCheck() {
+		ArrayList<String> logs = new ArrayList<>();
+		String f = "FSHealth: ";
+		logs.add(f + "FilesystemHealthCheck started");
+		ArrayList<File> dirsToCheck = new ArrayList<>();
+		ArrayList<File> dirsChecked = new ArrayList<>();
+		dirsToCheck.add(workingDirectory.getAbsoluteFile());
+		if (sharedDownloadsDirectory != null && dirsToCheck.contains(sharedDownloadsDirectory.getAbsoluteFile()) == false) {
+			dirsToCheck.add(sharedDownloadsDirectory.getAbsoluteFile());
+		}
+		if (storageDirectory != null && dirsToCheck.contains(storageDirectory.getAbsoluteFile()) == false) {
+			dirsToCheck.add(storageDirectory.getAbsoluteFile());
+		}
+		ListIterator<File> dirs = dirsToCheck.listIterator();
+		while (dirs.hasNext()) {
+			File dir = dirs.next();
+			dirs.remove();
+			dirsChecked.add(dir);
+			File[] fileList = dir.listFiles();
+			if (fileList == null) {
+				logs.add(f + "File list of " + dir + " is null");
+			}
+			else {
+				for (File file : fileList) {
+					file = file.getAbsoluteFile();
+					//logs.add(f + file);
+					boolean canRead = file.canRead();
+					boolean canWrite = file.canWrite();
+					boolean isDir = file.isDirectory();
+					if (canRead == false) {
+						logs.add(f + "Can't read from " + file);
+					}
+					if (canWrite == false) {
+						logs.add(f + "Can't write to " + file);
+					}
+					if (canRead && canWrite && isDir) {
+						if (dirsChecked.contains(file)) {
+							logs.add(f + "Dir " + file + " already checked. Loop detected");
+						}
+						else {
+							dirs.add(file);
+						}
+						long usableSpace = file.getUsableSpace();
+						if (usableSpace < 512 * 1024) {
+							logs.add(f + "Usable space is " + usableSpace + " for " + file);
+						}
+					}
+				}
+			}
+		}
+		return logs;
+	}
+	
 	private static String getJarVersion() {
 		String versionPath = "/VERSION";
 		String version = "6.0.0";