1 files changed, 133 insertions, 0 deletions
diff --git a/src/lib/lib.rs b/src/lib/lib.rs
new file mode 100644
index 0000000..3557335
--- /dev/null
+++ b/src/lib/lib.rs
@@ -0,0 +1,133 @@
+use crate::CopyError::{FileOpenError, IoctlError};
+use jni::descriptors::Desc;
+use jni::objects::{JClass, JString};
+use jni::strings::JNIString;
+use jni::sys::jstring;
+use jni::JNIEnv;
+use log::debug;
+use nix::libc::{ioctl, FICLONE};
+use std::fmt::{Formatter, Write};
+use std::fs::OpenOptions;
+use std::os::fd::AsRawFd;
+use std::{fmt, io};
+
+fn throw<S: Into<JNIString>>(env: &mut JNIEnv, msg: S) {
+    throw_new(env, "java/lang/RuntimeException", msg);
+}
+
+fn throw_new<'a, 'b, S: Into<JNIString>, T: Desc<'a, JClass<'b>>>(
+    env: &mut JNIEnv<'a>,
+    ex: T,
+    msg: S,
+) {
+    if let Err(why) = env.throw_new(ex, msg) {
+        env.fatal_error(format!("failed to throw new exception: {why}"));
+    }
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_keuin_kbackupfabric_util_cow_FileCowCopier_init<'local>(
+    _env: JNIEnv<'local>, _class: JClass<'local>) {
+    env_logger::init();
+    debug!("kbackup-cow init");
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_keuin_kbackupfabric_util_cow_FileCowCopier_getVersion<'local>(
+    env: JNIEnv<'local>,
+    _class: JClass<'local>,
+) -> jstring {
+    match env.new_string(option_env!("CARGO_PKG_VERSION").unwrap_or("unknown")) {
+        Ok(s) => s.into_raw(),
+        Err(why) => env.fatal_error(format!("failed to create String: {why}")),
+    }
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_keuin_kbackupfabric_util_cow_FileCowCopier_copy<'local>(
+    mut env: JNIEnv<'local>,
+    _class: JClass<'local>,
+    dst: JString<'local>,
+    src: JString<'local>,
+) {
+    unsafe {
+        let src = match env.get_string_unchecked(&src) {
+            Ok(s) => s,
+            Err(why) => {
+                throw_new(
+                    &mut env,
+                    "java/lang/IllegalArgumentException",
+                    format!("invalid src: {why}"),
+                );
+                return;
+            }
+        };
+        let dst = match env.get_string_unchecked(&dst) {
+            Ok(s) => s,
+            Err(why) => {
+                throw_new(
+                    &mut env,
+                    "java/lang/IllegalArgumentException",
+                    format!("invalid dst: {why}"),
+                );
+                return;
+            }
+        };
+        match copy(dst.into(), src.into()) {
+            Ok(_) => {}
+            Err(why) => {
+                throw_new(&mut env, "java/io/IOException", format!("{}", why));
+            }
+        };
+    }
+}
+
+enum CopyError {
+    IoctlError(io::Error),
+    FileOpenError(String, io::Error),
+}
+
+impl fmt::Display for CopyError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        match &self {
+            IoctlError(why) => {
+                write!(f, "ioctl error: {why}")
+            }
+            FileOpenError(path, why) => {
+                write!(f, "error opening file `{path}`: {why}")
+            }
+        }
+    }
+}
+
+fn copy(dst: String, src: String) -> Result<(), CopyError> {
+    debug!("copy src: {src}, dst: {dst}");
+    let f_src = match OpenOptions::new().read(true).open(&src) {
+        Ok(f) => f,
+        Err(why) => {
+            return Err(FileOpenError(src.clone(), why));
+        }
+    };
+    let f_dst = match OpenOptions::new()
+        .read(true)
+        .write(true)
+        .create(true)
+        .open(&dst)
+    {
+        Ok(f) => f,
+        Err(why) => {
+            return Err(FileOpenError(dst.clone(), why));
+        }
+    };
+    unsafe {
+        let fd_dst = f_dst.as_raw_fd();
+        let fd_src = f_src.as_raw_fd();
+        debug!("fd_src: {fd_src}, fd_dst: {fd_dst}");
+        if ioctl(fd_dst, FICLONE, fd_src) != 0 {
+            let err = io::Error::last_os_error();
+            debug!("ioctl failed: {:?}", err);
+            return Err(IoctlError(err));
+        }
+    }
+    Ok(())
+}