Allow clients to set a log callback.

cubeb-core/Cargo.toml

@@ -20,3 +20,6 @@ gecko-in-tree = ["cubeb-sys/gecko-in-tree"]
 [dependencies]
 bitflags = "1.2.0"
 cubeb-sys = { path = "../cubeb-sys", version = "0.14" }
+
+[build-dependencies]
+cc = "1.1.30"

cubeb-core/src/log.rs

@@ -3,7 +3,9 @@
 // This program is made available under an ISC-style license. See the
 // accompanying file LICENSE for details.
 
-use ffi;
+use std::ffi::{c_char, CStr};
+use std::sync::Mutex;
+use {ffi, Error, Result};
 
 /// Level (verbosity) of logging for a particular cubeb context.
 #[derive(PartialEq, Eq, Clone, Debug, Copy, PartialOrd, Ord)]
@@ -31,6 +33,44 @@ pub fn log_enabled() -> bool {
  unsafe { ffi::cubeb_log_get_level() != LogLevel::Disabled as _ }
 }
 
+static LOG_CALLBACK: Mutex<Option<fn(s: &CStr)>> = Mutex::new(None);
+
+extern "C" {
+ fn cubeb_write_log(fmt: *const c_char, ...);
+}
+
+/// # Safety
+///
+/// |s| must be null, or a pointer to a valid, nul-terminated, array of chars.
+pub unsafe extern "C" fn rust_write_formatted_msg(s: *const c_char) {
+ if s.is_null() {
+ // Do nothing if the pointer is null.
+ return;
+ }
+ if let Ok(guard) = LOG_CALLBACK.lock() {
+ if let Some(f) = *guard {
+ f(CStr::from_ptr(s));
+ }
+ // Do nothing if there is no callback.
+ }
+ // Silently fail if lock cannot be acquired.
+}
+
+pub fn set_logging(level: LogLevel, f: Option<fn(s: &CStr)>) -> Result<()> {
+ match LOG_CALLBACK.lock() {
+ Ok(mut guard) => {
+ *guard = f;
+ }
+ Err(_) => return Err(Error::error()),
+ }
+ unsafe {
+ call!(ffi::cubeb_set_log_callback(
+ level as u32,
+ Some(cubeb_write_log)
+ ))
+ }
+}
+
 #[cfg(test)]
 mod tests {
  use super::*;