Update log crate and create shim method(s) between git2's tracing and log

Cargo.toml

@@ -19,7 +19,7 @@ edition = "2018"
 url = "2.0"
 bitflags = "2.1.0"
 libc = "0.2"
-log = "0.4.8"
+log = "0.4.22"
 libgit2-sys = { path = "libgit2-sys", version = "0.17.0" }
 
 [target."cfg(all(unix, not(target_os = \"macos\")))".dependencies]

src/lib.rs

@@ -136,7 +136,7 @@ pub use crate::status::{StatusEntry, StatusIter, StatusOptions, StatusShow, Stat
 pub use crate::submodule::{Submodule, SubmoduleUpdateOptions};
 pub use crate::tag::Tag;
 pub use crate::time::{IndexTime, Time};
-pub use crate::tracing::{trace_set, TraceLevel};
+pub use crate::tracing::{trace_set, trace_shim_log_crate, TraceLevel};
 pub use crate::transaction::Transaction;
 pub use crate::tree::{Tree, TreeEntry, TreeIter, TreeWalkMode, TreeWalkResult};
 pub use crate::treebuilder::TreeBuilder;

src/tracing.rs

@@ -1,6 +1,7 @@
 use std::sync::atomic::{AtomicUsize, Ordering};
 
 use libc::c_char;
+use log::RecordBuilder;
 
 use crate::{panic, raw, util::Binding};
 
@@ -57,14 +58,36 @@ impl Binding for TraceLevel {
     }
 }
 
+impl TraceLevel {
+    /// Attempt to convert this [TraceLevel] to a [log::LevelFilter].
+    ///
+    /// This function is not public to avoid having a public dependency on [`log`].
+    ///
+    /// This is done trivially with two exceptions:
+    /// - [TraceLevel::None] goes to [None]
+    /// - [TraceLevel::Fatal] goes to [log::Level::Error].
+    const fn as_log_level(self) -> Option<log::Level> {
+        use log::Level;
+
+        match self {
+            Self::None => None,
+            Self::Fatal | Self::Error => Some(Level::Error),
+            Self::Warn => Some(Level::Warn),
+            Self::Info => Some(Level::Info),
+            Self::Debug => Some(Level::Debug),
+            Self::Trace => Some(Level::Trace),
+        }
+    }
+}
+
 //TODO: pass raw &[u8] and leave conversion to consumer (breaking API)
 /// Callback type used to pass tracing events to the subscriber.
 /// see `trace_set` to register a subscriber.
 pub type TracingCb = fn(TraceLevel, &str);
 
 static CALLBACK: AtomicUsize = AtomicUsize::new(0);
 
-///
+/// Set the tracing callback.
 pub fn trace_set(level: TraceLevel, cb: TracingCb) -> bool {
     CALLBACK.store(cb as usize, Ordering::SeqCst);
 
@@ -75,6 +98,27 @@ pub fn trace_set(level: TraceLevel, cb: TracingCb) -> bool {
     return true;
 }
 
+/// Passes [trace_set] a shim function to pass tracing info to the [log] crate.
+pub fn trace_shim_log_crate() {
+    // Use `trace` to get all tracing events -- let the user configure filtering
+    // through the `log` crate.
+    trace_set(TraceLevel::Trace, |level, msg| {
+        // Convert the trace level to a log level.
+        let log_level = level
+            .as_log_level()
+            .expect("libgit2 should not produce tracing events with level=None");
+
+        // Build a record to pass to the logger.
+        let mut record_builder = RecordBuilder::new();
+
+        // Set the target and level.
+        record_builder.target("libgit2").level(log_level);
+
+        // Log the trace event to the global logger.
+        log::logger().log(&record_builder.args(format_args!("{}", msg)).build());
+    });
+}
+
 extern "C" fn tracing_cb_c(level: raw::git_trace_level_t, msg: *const c_char) {
     let cb = CALLBACK.load(Ordering::SeqCst);
     panic::wrap(|| unsafe {