/*
* Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* - Neither the name of the Git Development Community nor the
* names of its contributors may be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.spearce.jgit.util;
import java.io.File;
import java.security.AccessController;
import java.security.PrivilegedAction;
/** Abstraction to support various file system operations not in Java. */
public abstract class FS {
/** The implementation selected for this operating system and JRE. */
public static final FS INSTANCE;
static {
if (FS_Win32.detect()) {
if (FS_Win32_Cygwin.detect())
INSTANCE = new FS_Win32_Cygwin();
else
INSTANCE = new FS_Win32();
} else if (FS_POSIX_Java6.detect())
INSTANCE = new FS_POSIX_Java6();
else
INSTANCE = new FS_POSIX_Java5();
}
/**
* Does this operating system and JRE support the execute flag on files?
*
* @return true if this implementation can provide reasonably accurate
* executable bit information; false otherwise.
*/
public abstract boolean supportsExecute();
/**
* Determine if the file is executable (or not).
* <p>
* Not all platforms and JREs support executable flags on files. If the
* feature is unsupported this method will always return false.
*
* @param f
* abstract path to test.
* @return true if the file is believed to be executable by the user.
*/
public abstract boolean canExecute(File f);
/**
* Set a file to be executable by the user.
* <p>
* Not all platforms and JREs support executable flags on files. If the
* feature is unsupported this method will always return false and no
* changes will be made to the file specified.
*
* @param f
* path to modify the executable status of.
* @param canExec
* true to enable execution; false to disable it.
* @return true if the change succeeded; false otherwise.
*/
public abstract boolean setExecute(File f, boolean canExec);
/**
* Resolve this file to its actual path name that the JRE can use.
* <p>
* This method can be relatively expensive. Computing a translation may
* require forking an external process per path name translated. Callers
* should try to minimize the number of translations necessary by caching
* the results.
* <p>
* Not all platforms and JREs require path name translation. Currently only
* Cygwin on Win32 require translation for Cygwin based paths.
*
* @param dir
* directory relative to which the path name is.
* @param name
* path name to translate.
* @return the translated path. <code>new File(dir,name)</code> if this
* platform does not require path name translation.
*/
public static File resolve(final File dir, final String name) {
return INSTANCE.resolveImpl(dir, name);
}
/**
* Resolve this file to its actual path name that the JRE can use.
* <p>
* This method can be relatively expensive. Computing a translation may
* require forking an external process per path name translated. Callers
* should try to minimize the number of translations necessary by caching
* the results.
* <p>
* Not all platforms and JREs require path name translation. Currently only
* Cygwin on Win32 require translation for Cygwin based paths.
*
* @param dir
* directory relative to which the path name is.
* @param name
* path name to translate.
* @return the translated path. <code>new File(dir,name)</code> if this
* platform does not require path name translation.
*/
protected File resolveImpl(final File dir, final String name) {
final File abspn = new File(name);
if (abspn.isAbsolute())
return abspn;
return new File(dir, name);
}
/**
* Determine the user's home directory (location where preferences are).
* <p>
* This method can be expensive on the first invocation if path name
* translation is required. Subsequent invocations return a cached result.
* <p>
* Not all platforms and JREs require path name translation. Currently only
* Cygwin on Win32 requires translation of the Cygwin HOME directory.
*
* @return the user's home directory; null if the user does not have one.
*/
public static File userHome() {
return USER_HOME.home;
}
private static class USER_HOME {
static final File home = INSTANCE.userHomeImpl();
}
/**
* Determine the user's home directory (location where preferences are).
*
* @return the user's home directory; null if the user does not have one.
*/
protected File userHomeImpl() {
final String home = AccessController
.doPrivileged(new PrivilegedAction<String>() {
public String run() {
return System.getProperty("user.home");
}
});
if (home == null || home.length() == 0)
return null;
return new File(home).getAbsoluteFile();
}
}