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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
use std::fs::File;
use std::io::Write;
use std::sync::RwLock;
#[cfg(target_os = "windows")]
use std::os::windows::io::FromRawHandle;
#[cfg(target_os = "windows")]
use std::ffi::c_void;
#[cfg(not(target_os = "windows"))]
use std::os::unix::io::FromRawFd;
use serde::Serialize;
/// An implementation of log::Log that writes log messages in JSON format to a
/// file descriptor/handle. The logging level is ignored in this implementation:
/// it is up to the receiver of these log messages (on the language binding
/// side) to filter the log messages based on their level.
/// The JSON payload of each message in an object with the following keys:
/// - `level` (string): One of the logging levels defined here:
/// - `message` (string): The logging message.
pub struct FdLogger {
pub file: RwLock<File>,
}
#[derive(Serialize)]
struct FdLoggingRecord {
level: String,
message: String,
target: String,
}
#[cfg(target_os = "windows")]
unsafe fn get_file_from_fd(fd: u64) -> File {
File::from_raw_handle(fd as *mut c_void)
}
#[cfg(not(target_os = "windows"))]
unsafe fn get_file_from_fd(fd: u64) -> File {
File::from_raw_fd(fd as i32)
}
impl FdLogger {
pub unsafe fn new(fd: u64) -> Self {
FdLogger {
file: RwLock::new(get_file_from_fd(fd)),
}
}
}
impl log::Log for FdLogger {
fn enabled(&self, _metadata: &log::Metadata) -> bool {
// This logger always emits logging messages of any level, and the
// language binding consuming these messages is responsible for
// filtering and routing them.
true
}
fn log(&self, record: &log::Record) {
// Normally, classes implementing the Log trait would filter based on
// the log level here. But in this case, we want to emit all log
// messages and let the logging system in the language binding filter
// and route them.
let payload = FdLoggingRecord {
level: record.level().to_string(),
message: record.args().to_string(),
target: record.target().to_string(),
};
let _ = writeln!(
self.file.write().unwrap(),
"{}",
serde_json::to_string(&payload).unwrap()
);
}
fn flush(&self) {
let _ = self.file.write().unwrap().flush();
}
}