rust_libretro/
logger.rs

1//! [`log::Log`] implementation using the libretro logging interface.
2use super::*;
3use env_logger::filter::{Builder as FilterBuilder, Filter};
4use log::{Level, Metadata, Record};
5use std::io::Write;
6
7pub struct RetroLogger {
8    callback: retro_log_callback,
9    filter: Filter,
10}
11
12impl RetroLogger {
13    pub fn new(callback: retro_log_callback) -> Self {
14        let mut builder = FilterBuilder::new();
15        let mut set_default_level = true;
16
17        if let Ok(s) = std::env::var("RUST_LOG") {
18            builder.parse(&s);
19
20            // We assume that the user passed a valid filter when the
21            // environment variable was not empty.
22            if !s.trim().is_empty() {
23                set_default_level = false;
24            }
25        }
26
27        // By default the env_logger filter defaults to the error level
28        // if no directives have been set.
29        if set_default_level {
30            builder.filter(None, log::LevelFilter::Trace);
31        }
32
33        let filter = builder.build();
34
35        Self { callback, filter }
36    }
37
38    fn get_retro_log_level(level: Level) -> retro_log_level {
39        match level {
40            Level::Error => retro_log_level::RETRO_LOG_ERROR,
41            Level::Warn => retro_log_level::RETRO_LOG_WARN,
42            Level::Info => retro_log_level::RETRO_LOG_INFO,
43            Level::Debug => retro_log_level::RETRO_LOG_DEBUG,
44            Level::Trace => retro_log_level::RETRO_LOG_DEBUG,
45        }
46    }
47}
48
49impl log::Log for RetroLogger {
50    fn enabled(&self, metadata: &Metadata) -> bool {
51        self.filter.enabled(metadata)
52    }
53
54    fn log(&self, record: &Record) {
55        if !self.filter.matches(record) {
56            return;
57        }
58
59        let target = if !record.target().is_empty() {
60            record.target()
61        } else {
62            record.module_path().unwrap_or_default()
63        };
64
65        if let Some(cb) = self.callback.log {
66            let mut args: Vec<u8> = Vec::new();
67
68            if writeln!(args, "{}\0", record.args()).is_ok() {
69                let level = Self::get_retro_log_level(record.level());
70                let target = CString::new(target).unwrap();
71
72                unsafe {
73                    let args = CString::from_vec_unchecked(args);
74
75                    // The callback works like `printf`
76                    (cb)(
77                        level,
78                        "[%s] %s\n\0".as_ptr() as *const c_char,
79                        target.as_ptr() as *const c_char,
80                        args.as_ptr() as *const c_char,
81                    )
82                }
83            }
84        } else {
85            let level = match record.level() {
86                Level::Debug => "DEBUG",
87                Level::Info => "INFO",
88                Level::Warn => "WARN",
89                Level::Error => "ERROR",
90                Level::Trace => "TRACE",
91            };
92
93            let stderr = std::io::stderr();
94            let mut stderr_lock = stderr.lock();
95
96            let _ = writeln!(
97                stderr_lock,
98                "[libretro {}] [{}] {}",
99                level,
100                target,
101                record.args()
102            );
103        }
104    }
105
106    fn flush(&self) {
107        // Do nothing
108    }
109}
rust_libretro/logger.rs

rust_libretro/
logger.rs
