| From 8d6bfc60f38d2b0c2d5f1cca55cef64b6f9b3f42 Mon Sep 17 00:00:00 2001 |
| From: Jiyong Park <jiyong@google.com> |
| Date: Sat, 26 Jun 2021 00:31:25 +0900 |
| Subject: [PATCH] Open /dev/kmsg in Android |
| |
| In Android, ordinary processes don't have privilege to open /dev/kmsg. |
| That has been done by letting init open it (via `file /dev/kmsg w`) and |
| share the file descriptor with the forked process. The file descriptor |
| number is passed via an environment variable. |
| |
| Implement the procedure. |
| |
| Bug: 189805435 |
| Test: m |
| Change-Id: I8e39c9bd506fdc9d37a7fb5cd2b14e7d4a5074b7 |
| --- |
| src/lib.rs | 22 ++++++++++++++++++++-- |
| 1 file changed, 20 insertions(+), 2 deletions(-) |
| |
| diff --git a/src/lib.rs b/src/lib.rs |
| index 157c43d..d87df22 100644 |
| --- a/src/lib.rs |
| +++ b/src/lib.rs |
| @@ -46,7 +46,7 @@ extern crate log; |
| extern crate libc; |
| |
| use std::fs::{OpenOptions, File}; |
| -use std::io::{Write, self}; |
| +use std::io::{Error, ErrorKind, Write, self}; |
| use std::sync::Mutex; |
| use std::env; |
| |
| @@ -75,10 +75,28 @@ impl KernelLog { |
| } |
| } |
| |
| + #[cfg(not(target_os = "android"))] |
| + fn open_kmsg() -> io::Result<File> { |
| + OpenOptions::new().write(true).open("/dev/kmsg") |
| + } |
| + |
| + #[cfg(target_os = "android")] |
| + fn open_kmsg() -> io::Result<File> { |
| + // In Android, a process normally doesn't have the permission to open /dev/kmsg. Instead it |
| + // is opened by init (via `file /dev/kmsg w` in the rc file) and the file descriptor is |
| + // shared when executing the process. The file descriptor number is passed via an |
| + // environment variable "ANDROID_FILE_<file_name>" where <file_name> is the path to the |
| + // file where non alpha-numeric characters are replaced with '_'. |
| + match env::var("ANDROID_FILE__dev_kmsg") { |
| + Ok(val) => OpenOptions::new().write(true).open(format!("/proc/self/fd/{}", val)), |
| + Err(e) => Err(Error::new(ErrorKind::Other, "ANDROID_FILE__dev_kmsg doesn't exist")), |
| + } |
| + } |
| + |
| /// Create new kernel logger with error level filter |
| pub fn with_level(filter: LevelFilter) -> io::Result<KernelLog> { |
| Ok(KernelLog { |
| - kmsg: Mutex::new(OpenOptions::new().write(true).open("/dev/kmsg")?), |
| + kmsg: Mutex::new(Self::open_kmsg()?), |
| maxlevel: filter |
| }) |
| } |
| -- |
| 2.32.0.93.g670b81a890-goog |
| |