ProgramTools.java

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package org.gffs.application;
 
import java.io.File;
import java.io.IOException;
import java.net.URISyntaxException;
import java.net.URL;
 
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.gffs.filesystem.FileSystemHelper;
 
public class ProgramTools
{
  public static Log _logger = LogFactory.getLog(ProgramTools.class);
  
  public static String showLastFewOnStack(int howManyFrames)
  {
    StackTraceElement[] elements = Thread.currentThread().getStackTrace();
    StringBuilder toReturn = new StringBuilder();
    /*
     * don't start at the very first frame; we want to skip backwards to the direct caller of this function.
     */
    int startFrame = 3;
    int endFrame = Math.min(howManyFrames + 3, elements.length - 1);
    for (int i = startFrame; i < endFrame; i++) {
      if (toReturn.length() != 0) {
        toReturn.append("\n<= ");
      }
      toReturn.append(getStackFrame(i));
    }
    return toReturn.toString();
  }
 
  public static String getStackFrame(int which)
  {
    StackTraceElement[] elements = Thread.currentThread().getStackTrace();
    /* a little self-protection to avoid accessing missing parts of the array. */
    if (which >= elements.length)
      which = elements.length - 1;
    return elements[which].toString();
  }
 
  static public String getInstallationDirectory()
  {
    String appPath = null;
    // see if we can intuit our location from living in a jar.
    URL url = ProgramTools.class.getProtectionDomain().getCodeSource().getLocation();
    try {
      // get the app path but switch back slashes to forward ones.
      appPath = new File(url.toURI().getSchemeSpecificPart()).toString().replace('\\', '/');
    } catch (URISyntaxException e) {
      String msg = "failed to convert code source url to app path: " + url;
      _logger.error(msg);
      throw new RuntimeException(msg);
    }
    if (_logger.isTraceEnabled())
      _logger.trace("got source path as: " + appPath);
    if (appPath.endsWith(".jar")) {
      // we need to chop off the jar file part of the name.
      int lastSlash = appPath.lastIndexOf("/");
      // if (lastSlash < 0)
      // lastSlash = appPath.lastIndexOf("\\");
      if (lastSlash < 0) {
        String msg = "could not find a slash character in the path: " + appPath;
        _logger.error(msg);
        throw new RuntimeException(msg);
      }
      appPath = appPath.substring(0, lastSlash);
      if (_logger.isTraceEnabled())
        _logger.trace("truncated path since inside jar: " + appPath);
    }
    appPath = appPath.concat("/..");
 
    if (_logger.isTraceEnabled())
      _logger.trace("jar-intuited startup bundle path: " + appPath);
 
    File startupDir = new File(appPath);
    if (!startupDir.exists() || !startupDir.isDirectory()) {
      throw new RuntimeException(
        "the location where we believe the installation is running from does not actually exist as a directory.");
    }
 
    //hmmm: below may not be very general since it does osgi?  but it will work if people use a bundles dir.
    
    /*
     * make sure we can find our own bundles directory, which is a crucial thing for osgi. if we can't find it, then we really don't know
     * where home is.
     */
    File testingBundlesDir = new File(startupDir, "bundles");
    File testingExtDir = new File(startupDir, "ext");
    String lastStartupDirState = "not-equal"; // a string we should never see as a full path.
 
    while (!testingBundlesDir.exists() || !testingExtDir.exists()) {
      if (_logger.isDebugEnabled()) {
        if (_logger.isTraceEnabled())
          _logger.debug("failed to find bundles directory at '" + startupDir.getAbsolutePath() + "', popping up a level.");
      }
 
      if (lastStartupDirState.equals(FileSystemHelper.sanitizeFilename(startupDir.getAbsolutePath()))) {
        throw new RuntimeException(
          "caught the startup directory not changing, which means we have hit the root and failed to find our bundles and ext directories.");
      }
      // reset for next time.
      lastStartupDirState = FileSystemHelper.sanitizeFilename(startupDir.getAbsolutePath());
 
      // pop up a level, since we didn't find our bundles directory.
      startupDir = new File(startupDir, "..");
      testingBundlesDir = new File(startupDir, "bundles");
      testingExtDir = new File(startupDir, "ext");
 
      if (startupDir.getParent() == null) {
        throw new RuntimeException("failed to find the bundles and ext directories after hitting top of file system paths.");
      }
    }
 
    // we successfully found the bundles directory, even if we may have had to jump a few hoops.
    if (_logger.isTraceEnabled()) {
      _logger.debug("successfully found bundles directory under path: " + appPath);
    }
 
    // now resolve the path to an absolute location without relative components.
    try {
      appPath = FileSystemHelper.sanitizeFilename(startupDir.getCanonicalPath());
    } catch (IOException e) {
      _logger.error("could not open osgi directory: " + appPath);
    }
    if (_logger.isTraceEnabled())
      _logger.debug("startup path after resolution with File: " + appPath);
    return appPath;
  }
}