Import android_logger-0.8.6

Change-Id: Ib4e241a1fe892d4e5712014c1c3b89748f1b3e77

1 files changed, 408 insertions, 0 deletions

diff --git a/src/lib.rs b/src/lib.rs
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+++ b/src/lib.rs
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+// Copyright 2016 The android_logger Developers
+//
+// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
+// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
+// http://opensource.org/licenses/MIT>, at your option. This file may not be
+// copied, modified, or distributed except according to those terms.
+
+//! A logger which writes to android output.
+//!
+//! ## Example
+//!
+//! ```
+//! #[macro_use] extern crate log;
+//! extern crate android_logger;
+//!
+//! use log::Level;
+//! use android_logger::Config;
+//!
+//! /// Android code may not have obvious "main", this is just an example.
+//! fn main() {
+//!     android_logger::init_once(
+//!         Config::default().with_min_level(Level::Trace),
+//!     );
+//!
+//!     debug!("this is a debug {}", "message");
+//!     error!("this is printed by default");
+//! }
+//! ```
+//!
+//! ## Example with module path filter
+//!
+//! It is possible to limit log messages to output from a specific crate,
+//! and override the logcat tag name (by default, the crate name is used):
+//!
+//! ```
+//! #[macro_use] extern crate log;
+//! extern crate android_logger;
+//!
+//! use log::Level;
+//! use android_logger::{Config,FilterBuilder};
+//!
+//! fn main() {
+//!     android_logger::init_once(
+//!         Config::default()
+//!             .with_min_level(Level::Trace)
+//!             .with_tag("mytag")
+//!             .with_filter(FilterBuilder::new().parse("debug,hello::crate=trace").build()),
+//!     );
+//!
+//!     // ..
+//! }
+//! ```
+
+#[cfg(target_os = "android")]
+extern crate android_log_sys as log_ffi;
+#[macro_use]
+extern crate lazy_static;
+#[macro_use]
+extern crate log;
+
+extern crate env_logger;
+
+use std::sync::RwLock;
+
+#[cfg(target_os = "android")]
+use log_ffi::LogPriority;
+use log::{Level, Log, Metadata, Record};
+use std::ffi::{CStr, CString};
+use std::mem;
+use std::fmt;
+use std::ptr;
+
+pub use env_logger::filter::{Filter, Builder as FilterBuilder};
+
+/// Output log to android system.
+#[cfg(target_os = "android")]
+fn android_log(prio: log_ffi::LogPriority, tag: &CStr, msg: &CStr) {
+    unsafe {
+        log_ffi::__android_log_write(
+            prio as log_ffi::c_int,
+            tag.as_ptr() as *const log_ffi::c_char,
+            msg.as_ptr() as *const log_ffi::c_char,
+        )
+    };
+}
+
+/// Dummy output placeholder for tests.
+#[cfg(not(target_os = "android"))]
+fn android_log(_priority: Level, _tag: &CStr, _msg: &CStr) {}
+
+/// Underlying android logger backend
+pub struct AndroidLogger {
+    config: RwLock<Config>,
+}
+
+impl AndroidLogger {
+    /// Create new logger instance from config
+    pub fn new(config: Config) -> AndroidLogger {
+        AndroidLogger {
+            config: RwLock::new(config),
+        }
+    }
+}
+
+lazy_static! {
+   static ref ANDROID_LOGGER: AndroidLogger = AndroidLogger::default();
+}
+
+const LOGGING_TAG_MAX_LEN: usize = 23;
+const LOGGING_MSG_MAX_LEN: usize = 4000;
+
+impl Default for AndroidLogger {
+    /// Create a new logger with default config
+    fn default() -> AndroidLogger {
+        AndroidLogger {
+            config: RwLock::new(Config::default()),
+        }
+    }
+}
+
+impl Log for AndroidLogger {
+    fn enabled(&self, _: &Metadata) -> bool {
+        true
+    }
+
+    fn log(&self, record: &Record) {
+        let config = self.config
+            .read()
+            .expect("failed to acquire android_log filter lock for read");
+
+        if !config.filter_matches(record) {
+            return;
+        }
+
+        // tag must not exceed LOGGING_TAG_MAX_LEN
+        let mut tag_bytes: [u8; LOGGING_TAG_MAX_LEN + 1] = unsafe { mem::uninitialized() };
+
+        let module_path = record.module_path().unwrap_or_default().to_owned();
+
+        // If no tag was specified, use module name
+        let custom_tag = &config.tag;
+        let tag = custom_tag.as_ref().map(|s| s.as_bytes()).unwrap_or(module_path.as_bytes());
+
+        // truncate the tag here to fit into LOGGING_TAG_MAX_LEN
+        self.fill_tag_bytes(&mut tag_bytes, tag);
+        // use stack array as C string
+        let tag: &CStr = unsafe { CStr::from_ptr(mem::transmute(tag_bytes.as_ptr())) };
+
+        // message must not exceed LOGGING_MSG_MAX_LEN
+        // therefore split log message into multiple log calls
+        let mut writer = PlatformLogWriter::new(record.level(), tag);
+
+        // If a custom tag is used, add the module path to the message.
+        // Use PlatformLogWriter to output chunks if they exceed max size.
+        let _ = if custom_tag.is_some() {
+            fmt::write(&mut writer, format_args!("{}: {}", module_path, *record.args()))
+        } else {
+            fmt::write(&mut writer, *record.args())
+        };
+
+        // output the remaining message (this would usually be the most common case)
+        writer.flush();
+    }
+
+    fn flush(&self) {}
+}
+
+impl AndroidLogger {
+    fn fill_tag_bytes(&self, array: &mut [u8], tag: &[u8]) {
+        if tag.len() > LOGGING_TAG_MAX_LEN {
+            for (input, output) in tag.iter()
+                .take(LOGGING_TAG_MAX_LEN - 2)
+                .chain(b"..\0".iter())
+                .zip(array.iter_mut())
+            {
+                *output = *input;
+            }
+        } else {
+            for (input, output) in tag.iter()
+                .chain(b"\0".iter())
+                .zip(array.iter_mut())
+            {
+                *output = *input;
+            }
+        }
+    }
+}
+
+/// Filter for android logger.
+pub struct Config {
+    log_level: Option<Level>,
+    filter: Option<env_logger::filter::Filter>,
+    tag: Option<CString>,
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Config {
+            log_level: None,
+            filter: None,
+            tag: None,
+        }
+    }
+}
+
+impl Config {
+    /// Change the minimum log level.
+    ///
+    /// All values above the set level are logged. For example, if
+    /// `Warn` is set, the `Error` is logged too, but `Info` isn't.
+    pub fn with_min_level(mut self, level: Level) -> Self {
+        self.log_level = Some(level);
+        self
+    }
+
+    fn filter_matches(&self, record: &Record) -> bool {
+        if let Some(ref filter) = self.filter {
+            filter.matches(&record)
+        } else {
+            true
+        }
+    }
+
+    pub fn with_filter(mut self, filter: env_logger::filter::Filter) -> Self {
+        self.filter = Some(filter);
+        self
+    }
+
+    pub fn with_tag<S: Into<Vec<u8>>>(mut self, tag: S) -> Self {
+        self.tag = Some(CString::new(tag).expect("Can't convert tag to CString"));
+        self
+    }
+}
+
+struct PlatformLogWriter<'a> {
+    #[cfg(target_os = "android")] priority: LogPriority,
+    #[cfg(not(target_os = "android"))] priority: Level,
+    len: usize,
+    last_newline_index: usize,
+    tag: &'a CStr,
+    buffer: [u8; LOGGING_MSG_MAX_LEN + 1],
+}
+
+impl<'a> PlatformLogWriter<'a> {
+    #[cfg(target_os = "android")]
+    pub fn new(level: Level, tag: &CStr) -> PlatformLogWriter {
+        PlatformLogWriter {
+            priority: match level {
+                Level::Warn => LogPriority::WARN,
+                Level::Info => LogPriority::INFO,
+                Level::Debug => LogPriority::DEBUG,
+                Level::Error => LogPriority::ERROR,
+                Level::Trace => LogPriority::VERBOSE,
+            },
+            len: 0,
+            last_newline_index: 0,
+            tag,
+            buffer: unsafe { mem::uninitialized() },
+        }
+    }
+
+    #[cfg(not(target_os = "android"))]
+    pub fn new(level: Level, tag: &CStr) -> PlatformLogWriter {
+        PlatformLogWriter {
+            priority: level,
+            len: 0,
+            last_newline_index: 0,
+            tag,
+            buffer: unsafe { mem::uninitialized() },
+        }
+    }
+
+    /// Flush some bytes to android logger.
+    ///
+    /// If there is a newline, flush up to it.
+    /// If ther was no newline, flush all.
+    ///
+    /// Not guaranteed to flush everything.
+    fn temporal_flush(&mut self) {
+        let total_len = self.len;
+
+        if total_len == 0 {
+            return;
+        }
+
+        if self.last_newline_index > 0 {
+            let copy_from_index = self.last_newline_index;
+            let remaining_chunk_len = total_len - copy_from_index;
+
+            self.output_specified_len(copy_from_index);
+            self.copy_bytes_to_start(copy_from_index, remaining_chunk_len);
+            self.len = remaining_chunk_len;
+        } else {
+            self.output_specified_len(total_len);
+            self.len = 0;
+        }
+        self.last_newline_index = 0;
+    }
+
+    /// Flush everything remaining to android logger.
+    fn flush(&mut self) {
+        let total_len = self.len;
+
+        if total_len == 0 {
+            return;
+        }
+
+        self.output_specified_len(total_len);
+        self.len = 0;
+        self.last_newline_index = 0;
+    }
+
+    /// Output buffer up until the \0 which will be placed at `len` position.
+    fn output_specified_len(&mut self, len: usize) {
+        let mut last_byte: u8 = b'\0';
+        mem::swap(&mut last_byte, unsafe {
+            self.buffer.get_unchecked_mut(len)
+        });
+
+        let msg: &CStr = unsafe { CStr::from_ptr(mem::transmute(self.buffer.as_ptr())) };
+        android_log(self.priority, self.tag, msg);
+
+        *unsafe { self.buffer.get_unchecked_mut(len) } = last_byte;
+    }
+
+    /// Copy `len` bytes from `index` position to starting position.
+    fn copy_bytes_to_start(&mut self, index: usize, len: usize) {
+        let src = unsafe { self.buffer.as_ptr().offset(index as isize) };
+        let dst = self.buffer.as_mut_ptr();
+        unsafe { ptr::copy(src, dst, len) };
+    }
+}
+
+impl<'a> fmt::Write for PlatformLogWriter<'a> {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        let mut incomming_bytes = s.as_bytes();
+
+        while !incomming_bytes.is_empty() {
+            let len = self.len;
+
+            // write everything possible to buffer and mark last \n
+            let new_len = len + incomming_bytes.len();
+            let last_newline = self.buffer[len..LOGGING_MSG_MAX_LEN]
+                .iter_mut()
+                .zip(incomming_bytes)
+                .enumerate()
+                .fold(None, |acc, (i, (output, input))| {
+                    *output = *input;
+                    if *input == b'\n' {
+                        Some(i)
+                    } else {
+                        acc
+                    }
+                });
+
+            // update last \n index
+            if let Some(newline) = last_newline {
+                self.last_newline_index = len + newline;
+            }
+
+            // calculate how many bytes were written
+            let written_len = if new_len <= LOGGING_MSG_MAX_LEN {
+                // if the len was not exceeded
+                self.len = new_len;
+                new_len - len // written len
+            } else {
+                // if new length was exceeded
+                self.len = LOGGING_MSG_MAX_LEN;
+                self.temporal_flush();
+
+                LOGGING_MSG_MAX_LEN - len // written len
+            };
+
+            incomming_bytes = &incomming_bytes[written_len..];
+        }
+
+        Ok(())
+    }
+}
+
+/// Send a log record to Android logging backend.
+///
+/// This action does not require initialization. However, without initialization it
+/// will use the default filter, which allows all logs.
+pub fn log(record: &Record) {
+    ANDROID_LOGGER.log(record)
+}
+
+/// Initializes the global logger with an android logger.
+///
+/// This can be called many times, but will only initialize logging once,
+/// and will not replace any other previously initialized logger.
+///
+/// It is ok to call this at the activity creation, and it will be
+/// repeatedly called on every lifecycle restart (i.e. screen rotation).
+pub fn init_once(config: Config) {
+    if let Err(err) = log::set_logger(&*ANDROID_LOGGER) {
+        debug!("android_logger: log::set_logger failed: {}", err);
+    } else {
+        if let Some(level) = config.log_level {
+            log::set_max_level(level.to_level_filter());
+        }
+        *ANDROID_LOGGER
+            .config
+            .write()
+            .expect("failed to acquire android_log filter lock for write") = config;
+    }
+}