From ed09380b0bac10179dd69f4a4d4581e6c9e050b7 Mon Sep 17 00:00:00 2001
From: Marcin Radomski <dextero@google.com>
Date: Thu, 20 Mar 2025 13:58:18 +0000
Subject: [PATCH] Enable embedding android_logger in liblog_rust

Update of the patch file from aosp/2717316 compatible with
android_logger 0.15.0.

Replace crate:: imports with relative ones.

Also, add default_log_impl cfg that, when enabled:
* Removes the dependency on env_filter,
* Imports all log crate symbols from current crate.

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: I3f1bd7a34ebc8ead779ac028c66ac6c1e752fbe7
---
 src/arrays.rs              |  2 +-
 src/config.rs              | 16 +++++++++++++++-
 src/id.rs                  |  3 +++
 src/lib.rs                 | 14 ++++++++++++--
 src/platform_log_writer.rs | 10 ++++++++--
 5 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/src/arrays.rs b/src/arrays.rs
index f67b8e58..94625a7a 100644
--- a/src/arrays.rs
+++ b/src/arrays.rs
@@ -1,4 +1,4 @@
-use crate::LOGGING_TAG_MAX_LEN;
+use super::LOGGING_TAG_MAX_LEN;
 use std::ffi::CStr;
 use std::mem::MaybeUninit;
 
diff --git a/src/config.rs b/src/config.rs
index bd14f585..a8b8ce0b 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1,4 +1,18 @@
-use crate::{FormatFn, LogId};
+#[cfg(default_log_impl)]
+use {
+    crate as log,
+    super::log_ffi,
+};
+#[cfg(default_log_impl)]
+mod env_filter {
+    #[derive(Debug)]
+    pub struct Filter;
+    impl Filter {
+        pub fn matches(&self, _: &crate::Record) -> bool { true }
+    }
+}
+
+use super::{FormatFn, LogId};
 use log::{Level, LevelFilter, Record};
 use std::ffi::CString;
 use std::fmt;
diff --git a/src/id.rs b/src/id.rs
index 0b6597bb..77c2b850 100644
--- a/src/id.rs
+++ b/src/id.rs
@@ -1,3 +1,6 @@
+#[cfg(default_log_impl)]
+use super::log_ffi;
+
 /// Possible identifiers of a specific buffer of Android logging system for
 /// logging a message.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
diff --git a/src/lib.rs b/src/lib.rs
index 9597ae8e..0b324b69 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -63,6 +63,9 @@
 //! )
 //! ```
 
+#[cfg(default_log_impl)]
+use crate as log;
+
 #[cfg(target_os = "android")]
 extern crate android_log_sys as log_ffi;
 
@@ -72,9 +75,10 @@ use std::fmt;
 use std::mem::MaybeUninit;
 use std::sync::OnceLock;
 
-use crate::arrays::{fill_tag_bytes, uninit_array};
-use crate::platform_log_writer::PlatformLogWriter;
+use self::arrays::{fill_tag_bytes, uninit_array};
+use self::platform_log_writer::PlatformLogWriter;
 pub use config::Config;
+#[cfg(not(default_log_impl))]
 pub use env_filter::{Builder as FilterBuilder, Filter};
 pub use id::LogId;
 
@@ -236,4 +240,10 @@ pub fn init_once(config: Config) {
     } else if let Some(level) = log_level {
         log::set_max_level(level);
     }
+    // On Android, log crate is patched to default to LevelFilter::Trace rather than Off. Preserve
+    // the existing "android_logger default level is Off" behavior by explicitly setting the level.
+    #[cfg(target_os = "android")]
+    if log_level.is_none() {
+        log::set_max_level(log::LevelFilter::Off);
+    }
 }
diff --git a/src/platform_log_writer.rs b/src/platform_log_writer.rs
index 2a7b53a8..6a3da829 100644
--- a/src/platform_log_writer.rs
+++ b/src/platform_log_writer.rs
@@ -1,5 +1,11 @@
-use crate::arrays::slice_assume_init_ref;
-use crate::{LOGGING_MSG_MAX_LEN, LogId, android_log, uninit_array};
+#[cfg(default_log_impl)]
+use {
+    crate as log,
+    super::log_ffi,
+};
+
+use super::arrays::slice_assume_init_ref;
+use super::{LOGGING_MSG_MAX_LEN, LogId, android_log, uninit_array};
 use log::Level;
 #[cfg(target_os = "android")]
 use log_ffi::LogPriority;
-- 
2.49.0.rc1.451.g8f38331e32-goog