Import libchromeos-rs am: 5cc8a92ff3 am: 674821bae2

Original change: https://android-review.googlesource.com/c/platform/external/libchromeos-rs/+/1530501

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I1d6537c6fac6f85365f8dabbb23dccd150992c37

1 files changed, 73 insertions, 0 deletions

diff --git a/src/syslog.rs b/src/syslog.rs
new file mode 100644
index 0000000..0a12ae2
--- /dev/null
+++ b/src/syslog.rs
@@ -0,0 +1,73 @@
+// Copyright 2018 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+use std::ffi::CStr;
+
+use log::{self, Level, LevelFilter, Metadata, Record, SetLoggerError};
+
+static LOGGER: SyslogLogger = SyslogLogger;
+
+struct SyslogLogger;
+
+impl log::Log for SyslogLogger {
+    fn enabled(&self, metadata: &Metadata) -> bool {
+        if cfg!(debug_assertions) {
+            metadata.level() <= Level::Debug
+        } else {
+            metadata.level() <= Level::Info
+        }
+    }
+
+    fn log(&self, record: &Record) {
+        if !self.enabled(&record.metadata()) {
+            return;
+        }
+
+        let level = match record.level() {
+            Level::Error => libc::LOG_ERR,
+            Level::Warn => libc::LOG_WARNING,
+            Level::Info => libc::LOG_INFO,
+            Level::Debug => libc::LOG_DEBUG,
+            Level::Trace => libc::LOG_DEBUG,
+        };
+
+        let msg = format!("{}\0", record.args());
+        let cmsg = if let Ok(m) = CStr::from_bytes_with_nul(msg.as_bytes()) {
+            m
+        } else {
+            // For now we just drop messages with interior nuls.
+            return;
+        };
+
+        // Safe because this doesn't modify any memory.  There's not much use
+        // in checking the return value because this _is_ the logging function
+        // so there's no way for us to tell anyone about the error.
+        unsafe {
+            libc::syslog(level, cmsg.as_ptr());
+        }
+    }
+    fn flush(&self) {}
+}
+
+/// Initializes the logger to send log messages to syslog.
+pub fn init(ident: &'static CStr) -> Result<(), SetLoggerError> {
+    // Safe because this only modifies libc's internal state and is safe to call
+    // multiple times.
+    unsafe {
+        libc::openlog(
+            ident.as_ptr(),
+            libc::LOG_NDELAY | libc::LOG_PID,
+            libc::LOG_USER,
+        )
+    };
+    log::set_logger(&LOGGER)?;
+    let level = if cfg!(debug_assertions) {
+        LevelFilter::Debug
+    } else {
+        LevelFilter::Info
+    };
+    log::set_max_level(level);
+
+    Ok(())
+}