Enable default-initializing liblog_rust to write to logcat on Android am: 28e0c72e03 am: 1af5e04469 am: 6e31631e59 am: 5be91b79c0 am: a5c0b79fcb

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/log/+/2717613

Change-Id: I1c3b3cc10dcf044e64005b5cbb12306db7c05dfb
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

4 files changed, 151 insertions, 0 deletions

diff --git a/Android.bp b/Android.bp
index e6ff3cf..81c9175 100644
--- a/Android.bp
+++ b/Android.bp
@@ -60,6 +60,18 @@ rust_library {
     product_available: true,
     vendor_available: true,
     min_sdk_version: "29",
+    target: {
+      android: {
+        cfgs: ["default_log_impl"],
+        rustlibs: [
+          "libandroid_log_sys",
+          "libonce_cell",
+        ],
+        shared_libs: [
+          "liblog",
+        ],
+      }
+    }
 }
 
 rust_library_rlib {
diff --git a/patches/0001-Enable-default-initializing-liblog_rust-to-write-to-.patch b/patches/0001-Enable-default-initializing-liblog_rust-to-write-to-.patch
new file mode 100644
index 0000000..0c8c38a
--- /dev/null
+++ b/patches/0001-Enable-default-initializing-liblog_rust-to-write-to-.patch
@@ -0,0 +1,115 @@
+From cd85e49c438e3aa9dbe2989f91e5ad7d3f4816de Mon Sep 17 00:00:00 2001
+From: Marcin Radomski <dextero@google.com>
+Date: Thu, 17 Aug 2023 16:11:56 +0000
+Subject: [PATCH] Enable default-initializing liblog_rust to write to logcat on
+ Android
+
+Add default_log_impl cfg that, when enabled, makes `liblog_rust` use
+`android_logger` instead of `NopLogger` by default.
+
+This makes it possible to embed android_logger as mod inside liblog_rust
+crate, so that AndroidLogger can be used as default logger instead of a
+NopLogger.
+
+Changing that default prevents dropping logs when the logger is
+uninitialized. This can happen by accident when an application doesn't
+intialize the logger in all linker namespaces it pulls libraries from.
+See discussion at b/294216366#comment7.
+
+Bug: 275290559
+Test: compile test app from aosp/2717614
+Test: run it on a Cuttlefish device
+Test: observe logcat logs on all level from FFI call
+Test: observe all logs on non-FFI call without initializing the logger
+Test: observe set log filter applying only to non-FFI call
+Change-Id: I04dd334c66e5a2be8cfb19e87be3afb9146e5aa6
+---
+ Android.bp            | 12 ++++++++++++
+ src/android_logger.rs |  1 +
+ src/lib.rs            | 23 +++++++++++++++++++++++
+ 3 files changed, 36 insertions(+)
+ create mode 120000 src/android_logger.rs
+
+diff --git a/Android.bp b/Android.bp
+index e6ff3cf..81c9175 100644
+--- a/Android.bp
++++ b/Android.bp
+@@ -60,6 +60,18 @@ rust_library {
+     product_available: true,
+     vendor_available: true,
+     min_sdk_version: "29",
++    target: {
++      android: {
++        cfgs: ["default_log_impl"],
++        rustlibs: [
++          "libandroid_log_sys",
++          "libonce_cell",
++        ],
++        shared_libs: [
++          "liblog",
++        ],
++      }
++    }
+ }
+ 
+ rust_library_rlib {
+diff --git a/src/android_logger.rs b/src/android_logger.rs
+new file mode 120000
+index 0000000..84b8625
+--- /dev/null
++++ b/src/android_logger.rs
+@@ -0,0 +1 @@
++../../android_logger/src/lib.rs
+\ No newline at end of file
+diff --git a/src/lib.rs b/src/lib.rs
+index 4ead826..8eb1c50 100644
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -344,6 +344,11 @@ mod serde;
+ #[cfg(feature = "kv_unstable")]

+ pub mod kv;

+ 

++#[cfg(default_log_impl)]

++extern crate once_cell;

++#[cfg(default_log_impl)]

++mod android_logger;

++

+ #[cfg(has_atomics)]

+ use std::sync::atomic::{AtomicUsize, Ordering};

+ 

+@@ -405,7 +410,10 @@ const UNINITIALIZED: usize = 0;
+ const INITIALIZING: usize = 1;

+ const INITIALIZED: usize = 2;

+ 

++#[cfg(not(default_log_impl))]

+ static MAX_LOG_LEVEL_FILTER: AtomicUsize = AtomicUsize::new(0);

++#[cfg(default_log_impl)]

++static MAX_LOG_LEVEL_FILTER: AtomicUsize = AtomicUsize::new(5);

+ 

+ static LOG_LEVEL_NAMES: [&str; 6] = ["OFF", "ERROR", "WARN", "INFO", "DEBUG", "TRACE"];

+ 

+@@ -1572,6 +1580,21 @@ impl error::Error for ParseLevelError {}
+ /// If a logger has not been set, a no-op implementation is returned.

+ pub fn logger() -> &'static dyn Log {

+     if STATE.load(Ordering::SeqCst) != INITIALIZED {

++        #[cfg(default_log_impl)]

++        {

++            // On Android, default to logging to logcat if not explicitly initialized. This

++            // prevents logs from being dropped by default, which may happen unexpectedly in case

++            // of using libraries from multiple linker namespaces and failing to initialize the

++            // logger in each namespace. See b/294216366#comment7.

++            use android_logger::{AndroidLogger, Config};

++            use std::sync::OnceLock;

++            static ANDROID_LOGGER: OnceLock<AndroidLogger> = OnceLock::new();

++            return

++                ANDROID_LOGGER.get_or_init(|| {

++                    // Pass all logs down to liblog - it does its own filtering.

++                    AndroidLogger::new(Config::default().with_max_level(LevelFilter::Trace))

++                });

++        }

+         static NOP: NopLogger = NopLogger;

+         &NOP

+     } else {

+-- 
+2.42.0.rc1.204.g551eb34607-goog
+
diff --git a/src/android_logger.rs b/src/android_logger.rs
new file mode 120000
index 0000000..84b8625
--- /dev/null
+++ b/src/android_logger.rs
@@ -0,0 +1 @@
+../../android_logger/src/lib.rs
\ No newline at end of file
diff --git a/src/lib.rs b/src/lib.rs
index 4ead826..8eb1c50 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -344,6 +344,11 @@ mod serde;
 #[cfg(feature = "kv_unstable")]

 pub mod kv;

 

+#[cfg(default_log_impl)]

+extern crate once_cell;

+#[cfg(default_log_impl)]

+mod android_logger;

+

 #[cfg(has_atomics)]

 use std::sync::atomic::{AtomicUsize, Ordering};

 

@@ -405,7 +410,10 @@ const UNINITIALIZED: usize = 0;
 const INITIALIZING: usize = 1;

 const INITIALIZED: usize = 2;

 

+#[cfg(not(default_log_impl))]

 static MAX_LOG_LEVEL_FILTER: AtomicUsize = AtomicUsize::new(0);

+#[cfg(default_log_impl)]

+static MAX_LOG_LEVEL_FILTER: AtomicUsize = AtomicUsize::new(5);

 

 static LOG_LEVEL_NAMES: [&str; 6] = ["OFF", "ERROR", "WARN", "INFO", "DEBUG", "TRACE"];

 

@@ -1572,6 +1580,21 @@ impl error::Error for ParseLevelError {}
 /// If a logger has not been set, a no-op implementation is returned.

 pub fn logger() -> &'static dyn Log {

     if STATE.load(Ordering::SeqCst) != INITIALIZED {

+        #[cfg(default_log_impl)]

+        {

+            // On Android, default to logging to logcat if not explicitly initialized. This

+            // prevents logs from being dropped by default, which may happen unexpectedly in case

+            // of using libraries from multiple linker namespaces and failing to initialize the

+            // logger in each namespace. See b/294216366#comment7.

+            use android_logger::{AndroidLogger, Config};

+            use std::sync::OnceLock;

+            static ANDROID_LOGGER: OnceLock<AndroidLogger> = OnceLock::new();

+            return

+                ANDROID_LOGGER.get_or_init(|| {

+                    // Pass all logs down to liblog - it does its own filtering.

+                    AndroidLogger::new(Config::default().with_max_level(LevelFilter::Trace))

+                });

+        }

         static NOP: NopLogger = NopLogger;

         &NOP

     } else {