/****************************************************************************
* Copyright (C) 2013 ecsec GmbH.
* All rights reserved.
* Contact: ecsec GmbH (info@ecsec.de)
*
* This file is part of the Open eCard App.
*
* GNU General Public License Usage
* This file may be used under the terms of the GNU General Public
* License version 3.0 as published by the Free Software Foundation
* and appearing in the file LICENSE.GPL included in the packaging of
* this file. Please review the following information to ensure the
* GNU General Public License version 3.0 requirements will be met:
* http://www.gnu.org/copyleft/gpl.html.
*
* Other Usage
* Alternatively, this file may be used in accordance with the terms
* and conditions contained in a signed written agreement between
* you and ecsec GmbH.
*
***************************************************************************/
package org.openecard.common.util;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Helper class to find shared object (.so) libraries in linux systems.
* The algorithm to find the objects is the same as used in the dynamic loader ld. There is one exception to this rule,
* the ELF variables DT_RPATH and DT_RUNPATH are not evaluated, because they are not available in java.
*
* @author Tobias Wich <tobias.wich@ecsec.de>
*/
public class LinuxLibraryFinder {
private static final Logger logger = LoggerFactory.getLogger(LinuxLibraryFinder.class);
/**
* Gets a file object pointing to the library which has been searched.
* On success, the file points to first file found which is readable and thus can be used.
* <p>The algorithm to find the library can be found in the ld.so(8) manpage and is as follows:
* <ol>
* <li>Check paths in {@code LD_LIBRARY_PATH} environment variable.</li>
* <li>Check for library in {@code /etc/ld.so.cache} by executing {@code ldconfig -p} and searching the output.</li>
* <li>Check the base library paths {@code /lib} and {@code /usr/lib} or {@code /lib64} and {@code /usr/lib64}
* depending on the architecture.</li>
* </ol>
* </p>
* @param name Name of the library, such as pcsclite.
* @param version Version suffix such as 1, 1.0 or null if no suffix is desired.
* @return The file object to the library.
*/
@Nonnull
public static File getLibraryPath(@Nonnull String name, @Nullable String version) throws FileNotFoundException {
// add version only if it has a meaningful value
version = version == null ? "" : version;
version = version.isEmpty() ? "" : ("." + version);
String libname = System.mapLibraryName(name) + version;
File result;
// LD_LIBRARY_PATH
result = findInEnv(libname, System.getenv("LD_LIBRARY_PATH"));
if (result != null) {
return result;
}
// ld.so.cache
result = findInLdCache(libname);
if (result != null) {
return result;
}
// base lib paths
result = findInBaseLibPaths(libname);
if (result != null) {
return result;
}
throw new FileNotFoundException("Library " + libname + " not found on your system.");
}
@Nullable
private static File findInEnv(@Nonnull String libname, @Nullable String env) {
if (env != null) {
for (String path : env.split(":")) {
// append lib to path and see if it exists
String result = path + "/" + libname;
File test = new File(result.trim());
if (test.canRead()) {
return test;
}
}
}
// nothing found
return null;
}
@Nullable
private static File findInLdCache(@Nonnull String libname) {
String ldconfExec = findProgramFile("ldconfig") + " -p";
Process p = null;
try {
p = Runtime.getRuntime().exec(ldconfExec);
InputStream cacheData = p.getInputStream();
BufferedReader cacheDataReader = new BufferedReader(new InputStreamReader(cacheData));
String next;
while ((next = cacheDataReader.readLine()) != null) {
if (next.endsWith(libname)) {
// extract library path from entry
// the line can look like this:
// libpcsclite.so.1 (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libpcsclite.so.1
int endIdx = next.lastIndexOf("=>");
if (endIdx != -1) {
String result = next.substring(endIdx + 2);
File test = new File(result.trim());
if (test.canRead()) {
return test;
}
}
}
}
} catch (IOException ex) {
logger.debug("Library {} not found in ld.so.cache.", libname);
} finally {
if (p != null) {
try {
p.getInputStream().close();
} catch (IOException ex) {
// dafuq?!?
}
try {
p.getOutputStream().close();
} catch (IOException ex) {
// dafuq?!?
}
try {
p.getErrorStream().close();
} catch (IOException ex) {
// dafuq?!?
}
}
}
return null;
}
@Nonnull
private static String findProgramFile(@Nonnull String name) {
String path = System.getenv().get("PATH");
path = path == null ? "" : path;
path = "/sbin:/usr/sbin:" + path;
// loop through entries and find program
for (String entry : path.split(":")) {
String fname = entry + "/" + name;
File f = new File(fname);
if (f.canExecute()) {
return fname;
}
}
// nothing found, maybe the file is in the same path
return name;
}
@Nullable
private static File findInBaseLibPaths(@Nonnull String libname) {
String archSuffix = "64".equals(System.getProperty("sun.arch.data.model")) ? "64" : "";
String[] basePaths = {"/lib" + archSuffix, "/usr/lib" + archSuffix};
// look for lib in those paths
for (String path : basePaths) {
String fname = path + "/" + libname;
File test = new File(fname);
if (test.canRead()) {
return test;
}
}
return null;
}
}