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Fix unhandled UnsupportedOperationException in Fallocate #1008

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Fix unhandled UnsupportedOperationException in Fallocate #1008

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09298ee
Fix unhandled UnsupportedOperationException in Fallocate
torusrxxx Nov 21, 2024
cdc6b94
Merge branch 'hyphanet:next' into patch-2
torusrxxx Nov 30, 2024
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251 changes: 134 additions & 117 deletions src/freenet/support/io/Fallocate.java
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Original file line number Diff line number Diff line change
Expand Up @@ -19,121 +19,138 @@
*/
public final class Fallocate {

private static final boolean IS_LINUX = Platform.isLinux();
private static final boolean IS_POSIX = !Platform.isWindows() && !Platform.isMac() && !Platform.isOpenBSD();
private static final boolean IS_ANDROID = Platform.isAndroid();

private static final int FALLOC_FL_KEEP_SIZE = 0x01;

private final int fd;
private int mode;
private long offset;
private final long final_filesize;
private final FileChannel channel;

private Fallocate(FileChannel channel, int fd, long final_filesize) {
this.fd = fd;
this.final_filesize = final_filesize;
this.channel = channel;
}

public static Fallocate forChannel(FileChannel channel, long final_filesize) {
return new Fallocate(channel, getDescriptor(channel), final_filesize);
}

public static Fallocate forChannel(FileChannel channel, FileDescriptor fd, long final_filesize) {
return new Fallocate(channel, getDescriptor(fd), final_filesize);
}

public Fallocate fromOffset(long offset) {
if(offset < 0 || offset > final_filesize) throw new IllegalArgumentException();
this.offset = offset;
return this;
}

public Fallocate keepSize() {
requireLinux("fallocate keep size");
mode |= FALLOC_FL_KEEP_SIZE;
return this;
}

private void requireLinux(String feature) {
if (!IS_LINUX) {
throwUnsupported(feature);
}
}

private void throwUnsupported(String feature) {
throw new UnsupportedOperationException(feature + " is not supported on this file system");
}

public void execute() throws IOException {
int errno = 0;
boolean isUnsupported = false;
if (IS_LINUX) {
final int result = FallocateHolder.fallocate(fd, mode, offset, final_filesize-offset);
errno = result == 0 ? 0 : Native.getLastError();
} else if (IS_POSIX) {
errno = FallocateHolderPOSIX.posix_fallocate(fd, offset, final_filesize-offset);
} else {
isUnsupported = true;
}

if (isUnsupported || errno != 0) {
Logger.normal(this, "fallocate() failed; using legacy method; errno="+errno);
legacyFill(channel, final_filesize, offset);
}
}

private static class FallocateHolder {
static {
Native.register(FallocateHolder.class, Platform.C_LIBRARY_NAME);
}

private static native int fallocate(int fd, int mode, long offset, long length);
}

private static class FallocateHolderPOSIX {
static {
Native.register(FallocateHolderPOSIX.class, Platform.C_LIBRARY_NAME);
}

private static native int posix_fallocate(int fd, long offset, long length);
}

private static int getDescriptor(FileChannel channel) {
try {
// sun.nio.ch.FileChannelImpl declares private final java.io.FileDescriptor fd
final Field field = channel.getClass().getDeclaredField("fd");
field.setAccessible(true);
return getDescriptor((FileDescriptor) field.get(channel));
} catch (final Exception e) {
throw new UnsupportedOperationException("unsupported FileChannel implementation", e);
}
}

private static int getDescriptor(FileDescriptor descriptor) {
try {
// Oracle java.io.FileDescriptor declares private int fd
final Field field = descriptor.getClass().getDeclaredField(IS_ANDROID ? "descriptor" : "fd");
field.setAccessible(true);
return (int) field.get(descriptor);
} catch (final Exception e) {
throw new UnsupportedOperationException("unsupported FileDescriptor implementation", e);
}
}

private static void legacyFill(FileChannel fc, long newLength, long offset) throws IOException {
MersenneTwister mt = new MersenneTwister();
byte[] b = new byte[4096];
ByteBuffer bb = ByteBuffer.wrap(b);
while (offset < newLength) {
bb.rewind();
mt.nextBytes(b);
offset += fc.write(bb, offset);
if (offset % (1024 * 1024 * 1024L) == 0) {
mt = new MersenneTwister();
}
}
}
private static final boolean IS_LINUX = Platform.isLinux();
private static final boolean IS_POSIX = !Platform.isWindows() && !Platform.isMac() && !Platform.isOpenBSD();
private static final boolean IS_ANDROID = Platform.isAndroid();

private static final int FALLOC_FL_KEEP_SIZE = 0x01;

private final int fd;
private int mode;
private long offset;
private final long final_filesize;
private final FileChannel channel;

private Fallocate(FileChannel channel, int fd, long final_filesize) {
this.fd = fd;
this.final_filesize = final_filesize;
this.channel = channel;
}

public static Fallocate forChannel(FileChannel channel, long final_filesize) {
try {
return new Fallocate(channel, getDescriptor(channel), final_filesize);
} catch (final UnsupportedOperationException exception) {
return new Fallocate(channel, 0, final_filesize);
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It would be good to have a comment here that explains why 0 is the right file descriptor.

}
}

public static Fallocate forChannel(FileChannel channel, FileDescriptor fd, long final_filesize) {
try {
return new Fallocate(channel, getDescriptor(fd), final_filesize);
} catch (final UnsupportedOperationException exception) {
return new Fallocate(channel, 0, final_filesize);
}
}

public Fallocate fromOffset(long offset) throws IllegalArgumentException {
if(offset < 0 || offset > final_filesize) throw new IllegalArgumentException();
this.offset = offset;
return this;
}

public Fallocate keepSize() throws UnsupportedOperationException {
requireLinux("fallocate keep size");
mode |= FALLOC_FL_KEEP_SIZE;
return this;
}

private void requireLinux(String feature) throws UnsupportedOperationException {
if (!IS_LINUX) {
throwUnsupported(feature);
}
}

private void throwUnsupported(String feature) throws UnsupportedOperationException {
throw new UnsupportedOperationException(feature + " is not supported on this file system");
}

public void execute() throws IOException {
int errno = 0;
boolean isUnsupported = false;
if (fd != 0) {
if (IS_LINUX) {
final int result = FallocateHolder.fallocate(fd, mode, offset, final_filesize-offset);
errno = result == 0 ? 0 : Native.getLastError();
} else if (IS_POSIX) {
errno = FallocateHolderPOSIX.posix_fallocate(fd, offset, final_filesize-offset);
} else {
isUnsupported = true;
}
} else {
if (Platform.isWindows()) {
// On Windows, just write a byte at the end.
channel.write(ByteBuffer.allocate(1), final_filesize - 1);
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why is this safe?

} else {
isUnsupported = true;
}
}

if (isUnsupported || errno != 0) {
Logger.normal(this, "fallocate() failed; using legacy method; errno=" + errno);
legacyFill(channel, final_filesize, offset);
}
}

private static class FallocateHolder {
static {
Native.register(FallocateHolder.class, Platform.C_LIBRARY_NAME);
}

private static native int fallocate(int fd, int mode, long offset, long length);
}

private static class FallocateHolderPOSIX {
static {
Native.register(FallocateHolderPOSIX.class, Platform.C_LIBRARY_NAME);
}

private static native int posix_fallocate(int fd, long offset, long length);
}

private static int getDescriptor(FileChannel channel) throws UnsupportedOperationException {
try {
// sun.nio.ch.FileChannelImpl declares private final java.io.FileDescriptor fd
final Field field = channel.getClass().getDeclaredField("fd");
field.setAccessible(true);
return getDescriptor((FileDescriptor) field.get(channel));
} catch (final Exception e) {
throw new UnsupportedOperationException("unsupported FileChannel implementation", e);
}
}

private static int getDescriptor(FileDescriptor descriptor) throws UnsupportedOperationException {
try {
// Oracle java.io.FileDescriptor declares private int fd
final Field field = descriptor.getClass().getDeclaredField(IS_ANDROID ? "descriptor" : "fd");
field.setAccessible(true);
return (int) field.get(descriptor);
} catch (final Exception e) {
throw new UnsupportedOperationException("unsupported FileDescriptor implementation", e);
}
}

private static void legacyFill(FileChannel fc, long newLength, long offset) throws IOException {
MersenneTwister mt = new MersenneTwister();
byte[] b = new byte[4096];
ByteBuffer bb = ByteBuffer.wrap(b);
while (offset < newLength) {
bb.rewind();
mt.nextBytes(b);
offset += fc.write(bb, offset);
if (offset % (1024 * 1024 * 1024L) == 0) {
mt = new MersenneTwister();
}
}
}
}