com.google.common.io.TempFileCreator Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* Copyright (C) 2007 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.common.io;
import static com.google.common.base.StandardSystemProperty.JAVA_IO_TMPDIR;
import static com.google.common.base.StandardSystemProperty.USER_NAME;
import static java.nio.file.attribute.AclEntryFlag.DIRECTORY_INHERIT;
import static java.nio.file.attribute.AclEntryFlag.FILE_INHERIT;
import static java.nio.file.attribute.AclEntryType.ALLOW;
import static java.nio.file.attribute.PosixFilePermissions.asFileAttribute;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.collect.ImmutableList;
import com.google.j2objc.annotations.J2ObjCIncompatible;
import java.io.File;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Paths;
import java.nio.file.attribute.AclEntry;
import java.nio.file.attribute.AclEntryPermission;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.PosixFilePermissions;
import java.nio.file.attribute.UserPrincipal;
import java.util.EnumSet;
import java.util.Set;
/**
* Creates temporary files and directories whose permissions are restricted to the current user or,
* in the case of Android, the current app. If that is not possible (as is the case under the very
* old Android Ice Cream Sandwich release), then this class throws an exception instead of creating
* a file or directory that would be more accessible.
*/
@J2ktIncompatible
@GwtIncompatible
@J2ObjCIncompatible
@ElementTypesAreNonnullByDefault
abstract class TempFileCreator {
static final TempFileCreator INSTANCE = pickSecureCreator();
/**
* @throws IllegalStateException if the directory could not be created (to implement the contract
* of {@link Files#createTempDir()}, such as if the system does not support creating temporary
* directories securely
*/
abstract File createTempDir();
abstract File createTempFile(String prefix) throws IOException;
private static TempFileCreator pickSecureCreator() {
try {
Class.forName("java.nio.file.Path");
return new JavaNioCreator();
} catch (ClassNotFoundException runningUnderAndroid) {
// Try another way.
}
try {
int version = (int) Class.forName("android.os.Build$VERSION").getField("SDK_INT").get(null);
int jellyBean =
(int) Class.forName("android.os.Build$VERSION_CODES").getField("JELLY_BEAN").get(null);
/*
* I assume that this check can't fail because JELLY_BEAN will be present only if we're
* running under Jelly Bean or higher. But it seems safest to check.
*/
if (version < jellyBean) {
return new ThrowingCreator();
}
// Don't merge these catch() blocks, let alone use ReflectiveOperationException directly:
// b/65343391
} catch (NoSuchFieldException e) {
// The JELLY_BEAN field doesn't exist because we're running on a version before Jelly Bean :)
return new ThrowingCreator();
} catch (ClassNotFoundException e) {
// Should be impossible, but we want to return *something* so that class init succeeds.
return new ThrowingCreator();
} catch (IllegalAccessException e) {
// ditto
return new ThrowingCreator();
}
// Android isolates apps' temporary directories since Jelly Bean:
// https://github.com/google/guava/issues/4011#issuecomment-770020802
// So we can create files there with any permissions and still get security from the isolation.
return new JavaIoCreator();
}
@IgnoreJRERequirement // used only when Path is available
private static final class JavaNioCreator extends TempFileCreator {
@Override
File createTempDir() {
try {
return java.nio.file.Files.createTempDirectory(
Paths.get(JAVA_IO_TMPDIR.value()), /* prefix= */ null, directoryPermissions.get())
.toFile();
} catch (IOException e) {
throw new IllegalStateException("Failed to create directory", e);
}
}
@Override
File createTempFile(String prefix) throws IOException {
return java.nio.file.Files.createTempFile(
Paths.get(JAVA_IO_TMPDIR.value()),
/* prefix= */ prefix,
/* suffix= */ null,
filePermissions.get())
.toFile();
}
@IgnoreJRERequirement // see enclosing class (whose annotation Animal Sniffer ignores here...)
private interface PermissionSupplier {
FileAttribute get() throws IOException;
}
private static final PermissionSupplier filePermissions;
private static final PermissionSupplier directoryPermissions;
static {
Set views = FileSystems.getDefault().supportedFileAttributeViews();
if (views.contains("posix")) {
filePermissions = () -> asFileAttribute(PosixFilePermissions.fromString("rw-------"));
directoryPermissions = () -> asFileAttribute(PosixFilePermissions.fromString("rwx------"));
} else if (views.contains("acl")) {
filePermissions = directoryPermissions = userPermissions();
} else {
filePermissions =
directoryPermissions =
() -> {
throw new IOException("unrecognized FileSystem type " + FileSystems.getDefault());
};
}
}
private static PermissionSupplier userPermissions() {
try {
UserPrincipal user =
FileSystems.getDefault()
.getUserPrincipalLookupService()
.lookupPrincipalByName(USER_NAME.value());
ImmutableList acl =
ImmutableList.of(
AclEntry.newBuilder()
.setType(ALLOW)
.setPrincipal(user)
.setPermissions(EnumSet.allOf(AclEntryPermission.class))
.setFlags(DIRECTORY_INHERIT, FILE_INHERIT)
.build());
FileAttribute> attribute =
new FileAttribute>() {
@Override
public String name() {
return "acl:acl";
}
@Override
public ImmutableList value() {
return acl;
}
};
return () -> attribute;
} catch (IOException e) {
// We throw a new exception each time so that the stack trace is right.
return () -> {
throw new IOException("Could not find user", e);
};
}
}
}
private static final class JavaIoCreator extends TempFileCreator {
@Override
File createTempDir() {
File baseDir = new File(JAVA_IO_TMPDIR.value());
@SuppressWarnings("GoodTime") // reading system time without TimeSource
String baseName = System.currentTimeMillis() + "-";
for (int counter = 0; counter < TEMP_DIR_ATTEMPTS; counter++) {
File tempDir = new File(baseDir, baseName + counter);
if (tempDir.mkdir()) {
return tempDir;
}
}
throw new IllegalStateException(
"Failed to create directory within "
+ TEMP_DIR_ATTEMPTS
+ " attempts (tried "
+ baseName
+ "0 to "
+ baseName
+ (TEMP_DIR_ATTEMPTS - 1)
+ ')');
}
@Override
File createTempFile(String prefix) throws IOException {
return File.createTempFile(
/* prefix= */ prefix,
/* suffix= */ null,
/* directory= */ null /* defaults to java.io.tmpdir */);
}
/** Maximum loop count when creating temp directories. */
private static final int TEMP_DIR_ATTEMPTS = 10000;
}
private static final class ThrowingCreator extends TempFileCreator {
private static final String MESSAGE =
"Guava cannot securely create temporary files or directories under SDK versions before"
+ " Jelly Bean. You can create one yourself, either in the insecure default directory"
+ " or in a more secure directory, such as context.getCacheDir(). For more information,"
+ " see the Javadoc for Files.createTempDir().";
@Override
File createTempDir() {
throw new IllegalStateException(MESSAGE);
}
@Override
File createTempFile(String prefix) throws IOException {
throw new IOException(MESSAGE);
}
}
private TempFileCreator() {}
}