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Diffstat (limited to 'src/lib.rs')
-rw-r--r-- | src/lib.rs | 408 |
1 files changed, 408 insertions, 0 deletions
diff --git a/src/lib.rs b/src/lib.rs new file mode 100644 index 0000000..ade6b8a --- /dev/null +++ b/src/lib.rs @@ -0,0 +1,408 @@ +// 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; + } +} |