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use std::{borrow::Cow, ffi::CStr, io, os::raw::c_void, ptr};
use thiserror::Error;
use crate::{
sys::{JavaVMInitArgs, JavaVMOption},
JNIVersion,
};
use cfg_if::cfg_if;
mod char_encoding_generic;
#[cfg(windows)]
mod char_encoding_windows;
/// Errors that can occur when invoking a [`JavaVM`](super::vm::JavaVM) with the
/// [Invocation API](https://docs.oracle.com/en/java/javase/12/docs/specs/jni/invocation.html).
#[derive(Debug, Error)]
#[non_exhaustive]
pub enum JvmError {
/// [`InitArgsBuilder::option`] or [`InitArgsBuilder::try_option`] was used, but the supplied
/// string contains a U+0000 code point (except at the end).
///
/// This error is not raised if the string has a single U+0000 code point at the end.
///
/// [`InitArgsBuilder::option_encoded`] never raises this error.
#[error("internal null in option: {0}")]
NullOptString(String),
/// [`InitArgsBuilder::option`] or [`InitArgsBuilder::try_option`] was used, but the option
/// string is too long.
///
/// Currently, this error only occurs on Windows, where string length is limited to 1MB to
/// avoid overflow in [`WideCharToMultiByte`] (see [discussion]). String length is not
/// currently limited (other than by available memory) on other platforms.
///
/// [`InitArgsBuilder::option_encoded`] never raises this error, regardless of platform.
///
/// [discussion]: https://github.com/jni-rs/jni-rs/pull/414
/// [`WideCharToMultiByte`]: https://learn.microsoft.com/en-us/windows/win32/api/stringapiset/nf-stringapiset-widechartomultibyte
#[error("option is too long: {opt_string}")]
#[non_exhaustive]
OptStringTooLong {
/// The option string.
opt_string: String,
},
/// [`InitArgsBuilder::option`] or [`InitArgsBuilder::try_option`] was used, but the option
/// string is not representable in the platform default character encoding.
///
/// [`InitArgsBuilder::option_encoded`] never raises this error.
#[error(
"option {opt_string:?} is not representable in the platform default character encoding"
)]
#[non_exhaustive]
OptStringNotRepresentable {
/// The option string.
opt_string: String,
},
/// [`InitArgsBuilder::option`] or [`InitArgsBuilder::try_option`] was used, but the platform
/// reported an error converting it to its default character encoding.
///
/// [`InitArgsBuilder::option_encoded`] never raises this error.
#[error("couldn't convert option {opt_string:?} to the platform default character encoding: {error}")]
#[non_exhaustive]
OptStringTranscodeFailure {
/// The option string.
opt_string: String,
/// The error reported by the platform's character encoding conversion routine.
#[source]
error: io::Error,
},
}
impl JvmError {
/// Returns the JVM option that caused the error, if it was caused by one.
pub fn opt_string(&self) -> Option<&str> {
match self {
Self::NullOptString(opt_string) => Some(opt_string),
Self::OptStringTooLong { opt_string, .. } => Some(opt_string),
Self::OptStringNotRepresentable { opt_string, .. } => Some(opt_string),
Self::OptStringTranscodeFailure { opt_string, .. } => Some(opt_string),
}
.map(String::as_str)
}
#[cfg(all(test, windows))]
fn opt_string_mut(&mut self) -> Option<&mut String> {
match self {
Self::NullOptString(opt_string) => Some(opt_string),
Self::OptStringTooLong { opt_string, .. } => Some(opt_string),
Self::OptStringNotRepresentable { opt_string, .. } => Some(opt_string),
Self::OptStringTranscodeFailure { opt_string, .. } => Some(opt_string),
}
}
}
const SPECIAL_OPTIONS: &[&str] = &["vfprintf", "abort", "exit"];
const SPECIAL_OPTIONS_C: &[&CStr] = unsafe {
&[
CStr::from_bytes_with_nul_unchecked(b"vfprintf\0"),
CStr::from_bytes_with_nul_unchecked(b"abort\0"),
CStr::from_bytes_with_nul_unchecked(b"exit\0"),
]
};
/// Builder for JavaVM InitArgs.
///
/// *This API requires "invocation" feature to be enabled,
/// see ["Launching JVM from Rust"](struct.JavaVM.html#launching-jvm-from-rust).*
#[derive(Debug)]
pub struct InitArgsBuilder<'a> {
opts: Result<Vec<Cow<'a, CStr>>, JvmError>,
ignore_unrecognized: bool,
version: JNIVersion,
}
impl<'a> Default for InitArgsBuilder<'a> {
fn default() -> Self {
InitArgsBuilder {
opts: Ok(vec![]),
ignore_unrecognized: false,
version: JNIVersion::V8,
}
}
}
impl<'a> InitArgsBuilder<'a> {
/// Create a new default InitArgsBuilder
pub fn new() -> Self {
Default::default()
}
/// Adds a JVM option, such as `-Djavax.net.debug=all`.
///
/// See [the JNI specification][jni-options] for details on which options are accepted.
///
/// The `vfprintf`, `abort`, and `exit` options are unsupported at this time. Setting one of
/// these options has no effect.
///
/// The option must not contain any U+0000 code points except one at the end. A U+0000 code
/// point at the end is not required, but on platforms where UTF-8 is the default character
/// encoding, including one U+0000 code point at the end will make this method run slightly
/// faster.
///
/// # Errors
///
/// This method can fail if:
///
/// * `opt_string` contains a U+0000 code point before the end.
/// * `opt_string` cannot be represented in the platform default character encoding.
/// * the platform's character encoding conversion API reports some other error.
/// * `opt_string` is too long. (In the current implementation, the maximum allowed length is
/// 1048576 bytes on Windows. There is currently no limit on other platforms.)
///
/// Errors raised by this method are deferred. If an error occurs, it is returned from
/// [`InitArgsBuilder::build`] instead.
///
/// [jni-options]: https://docs.oracle.com/en/java/javase/11/docs/specs/jni/invocation.html#jni_createjavavm
pub fn option(mut self, opt_string: impl AsRef<str> + Into<Cow<'a, str>>) -> Self {
if let Err(error) = self.try_option(opt_string) {
self.opts = Err(error);
}
self
}
/// Adds a JVM option, such as `-Djavax.net.debug=all`. Returns an error immediately upon
/// failure.
///
/// This is an alternative to [`InitArgsBuilder::option`] that does not defer errors. See
/// below for details.
///
/// See [the JNI specification][jni-options] for details on which options are accepted.
///
/// The `vfprintf`, `abort`, and `exit` options are unsupported at this time. Setting one of
/// these options has no effect.
///
/// The option must not contain any U+0000 code points except one at the end. A U+0000 code
/// point at the end is not required, but on platforms where UTF-8 is the default character
/// encoding, including one U+0000 code point at the end will make this method run slightly
/// faster.
///
/// # Errors
///
/// This method can fail if:
///
/// * `opt_string` contains a U+0000 code point before the end.
/// * `opt_string` cannot be represented in the platform default character encoding.
/// * the platform's character encoding conversion API reports some other error.
/// * `opt_string` is too long. (In the current implementation, the maximum allowed length is
/// 1048576 bytes on Windows. There is currently no limit on other platforms.)
///
/// Unlike the `option` method, this one does not defer errors. If the `opt_string` cannot be
/// used, then this method returns `Err` and `self` is not changed. If there is already a
/// deferred error, however, then this method does nothing.
///
/// [jni-options]: https://docs.oracle.com/en/java/javase/11/docs/specs/jni/invocation.html#jni_createjavavm
pub fn try_option(&mut self, opt_string: impl Into<Cow<'a, str>>) -> Result<(), JvmError> {
let opt_string = opt_string.into();
// If there is already a deferred error, do nothing.
let opts = match &mut self.opts {
Ok(ok) => ok,
Err(_) => return Ok(()),
};
// If the option is the empty string, then skip everything else and pass a constant empty
// C string. This isn't just an optimization; Win32 `WideCharToMultiByte` will **fail** if
// passed an empty string, so we have to do this check first.
if matches!(opt_string.as_ref(), "" | "\0") {
opts.push(Cow::Borrowed(unsafe {
// Safety: This string not only is null-terminated without any interior null bytes,
// it's nothing but a null terminator.
CStr::from_bytes_with_nul_unchecked(b"\0")
}));
return Ok(());
}
// If this is one of the special options, do nothing.
else if SPECIAL_OPTIONS.contains(&&*opt_string) {
return Ok(());
}
let encoded: Cow<'a, CStr> = {
cfg_if! {
if #[cfg(windows)] {
char_encoding_windows::str_to_cstr_win32_default_codepage(opt_string)?
}
else {
// Assume UTF-8 on all other platforms.
char_encoding_generic::utf8_to_cstr(opt_string)?
}
}
};
opts.push(encoded);
Ok(())
}
/// Adds a JVM option, such as `-Djavax.net.debug=all`. The option must be a `CStr` encoded in
/// the platform default character encoding.
///
/// This is an alternative to [`InitArgsBuilder::option`] that does not do any encoding. This
/// method is not `unsafe` as it cannot cause undefined behavior, but the option will be
/// garbled (that is, become [mojibake](https://en.wikipedia.org/wiki/Mojibake)) if not
/// encoded correctly.
///
/// See [the JNI specification][jni-options] for details on which options are accepted.
///
/// The `vfprintf`, `abort`, and `exit` options are unsupported at this time. Setting one of
/// these options has no effect.
///
/// This method does not fail, and will neither return nor defer an error.
///
/// [jni-options]: https://docs.oracle.com/en/java/javase/11/docs/specs/jni/invocation.html#jni_createjavavm
pub fn option_encoded(mut self, opt_string: impl Into<Cow<'a, CStr>>) -> Self {
let opt_string = opt_string.into();
// If there is already a deferred error, do nothing.
let opts = match &mut self.opts {
Ok(ok) => ok,
Err(_) => return self,
};
// If this is one of the special options, do nothing.
if SPECIAL_OPTIONS_C.contains(&&*opt_string) {
return self;
}
// Add the option.
opts.push(opt_string);
self
}
/// Set JNI version for the init args
///
/// Default: V8
pub fn version(self, version: JNIVersion) -> Self {
let mut s = self;
s.version = version;
s
}
/// Set the `ignoreUnrecognized` init arg flag
///
/// If ignoreUnrecognized is true, JavaVM::new ignores all unrecognized option strings that
/// begin with "-X" or "_". If ignoreUnrecognized is false, JavaVM::new returns Err as soon as
/// it encounters any unrecognized option strings.
///
/// Default: `false`
pub fn ignore_unrecognized(self, ignore: bool) -> Self {
let mut s = self;
s.ignore_unrecognized = ignore;
s
}
/// Build the `InitArgs`
///
/// # Errors
///
/// If a call to [`InitArgsBuilder::option`] caused a deferred error, it is returned from this
/// method.
pub fn build(self) -> Result<InitArgs<'a>, JvmError> {
let opt_strings = self.opts?;
let opts: Vec<JavaVMOption> = opt_strings
.iter()
.map(|opt_string| JavaVMOption {
optionString: opt_string.as_ptr() as _,
extraInfo: ptr::null_mut(),
})
.collect();
Ok(InitArgs {
inner: JavaVMInitArgs {
version: self.version.into(),
ignoreUnrecognized: self.ignore_unrecognized as _,
options: opts.as_ptr() as _,
nOptions: opts.len() as _,
},
_opts: opts,
_opt_strings: opt_strings,
})
}
/// Returns collected options.
///
/// If a call to [`InitArgsBuilder::option`] caused a deferred error, then this method returns
/// a reference to that error.
pub fn options(&self) -> Result<&[Cow<'a, CStr>], &JvmError> {
self.opts.as_ref().map(Vec::as_slice)
}
}
/// JavaVM InitArgs.
///
/// *This API requires "invocation" feature to be enabled,
/// see ["Launching JVM from Rust"](struct.JavaVM.html#launching-jvm-from-rust).*
pub struct InitArgs<'a> {
inner: JavaVMInitArgs,
// `JavaVMOption` structures are stored here. The JVM accesses this `Vec`'s contents through a
// raw pointer.
_opts: Vec<JavaVMOption>,
// Option strings are stored here. This ensures that any that are owned aren't dropped before
// the JVM is finished with them.
_opt_strings: Vec<Cow<'a, CStr>>,
}
impl<'a> InitArgs<'a> {
pub(crate) fn inner_ptr(&self) -> *mut c_void {
&self.inner as *const _ as _
}
}