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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,87 @@ | ||
| /* | ||
| * Copyright 2023 ByteDance and/or its affiliates. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
|
||
| use std::ffi::CStr; | ||
| use std::fs::File; | ||
| use std::io::Write; | ||
| use std::os::fd::AsRawFd; | ||
| use std::os::unix::net::UnixDatagram; | ||
| use std::sync::OnceLock; | ||
|
|
||
| use anyhow::{anyhow, Context}; | ||
| use nix::fcntl::{fcntl, FcntlArg, SealFlag}; | ||
| use nix::sys::memfd::{memfd_create, MemFdCreateFlag}; | ||
| use nix::sys::socket::{sendmsg, ControlMessage, MsgFlags, UnixAddr}; | ||
|
|
||
| /// Default path of the systemd-journald `AF_UNIX` datagram socket. | ||
| static SD_JOURNAL_SOCK_PATH: &str = "/run/systemd/journal/socket"; | ||
| static SD_SOCK: OnceLock<UnixDatagram> = OnceLock::new(); | ||
|
|
||
| const MEM_FD_NAME: &CStr = unsafe { CStr::from_bytes_with_nul_unchecked(b"journal-logging\0") }; | ||
|
|
||
| #[allow(unused)] | ||
| pub(crate) fn journal_send(data: &[u8]) -> anyhow::Result<()> { | ||
| // TODO use thread local socket path | ||
| let sock = SD_SOCK.get_or_init(|| UnixDatagram::unbound().unwrap()); | ||
|
|
||
| if let Err(e) = sock.send_to(data, SD_JOURNAL_SOCK_PATH) { | ||
| if e.raw_os_error() == Some(nix::libc::EMSGSIZE) { | ||
| // fallback if size limit reached | ||
| send_memfd_payload(sock, data).context("sending with memfd failed") | ||
| } else { | ||
| Err(anyhow!("send_to failed: {e}")) | ||
| } | ||
| } else { | ||
| Ok(()) | ||
| } | ||
| } | ||
|
|
||
| /// Send an overlarge payload to systemd-journald socket. | ||
| /// | ||
| /// This is a slow-path for sending a large payload that could not otherwise fit | ||
| /// in a UNIX datagram. Payload is thus written to a memfd, which is sent as ancillary | ||
| /// data. | ||
| fn send_memfd_payload(sock: &UnixDatagram, data: &[u8]) -> anyhow::Result<()> { | ||
| let tmpfd = memfd_create(MEM_FD_NAME, MemFdCreateFlag::MFD_ALLOW_SEALING) | ||
| .map_err(|e| anyhow!("unable to create memfd: {e}"))?; | ||
|
|
||
| let mut mem_file = File::from(tmpfd); | ||
| mem_file | ||
| .write_all(data) | ||
| .map_err(|e| anyhow!("failed to write to memfd: {e}"))?; | ||
|
|
||
| // Seal the memfd, so that journald knows it can safely mmap/read it. | ||
| fcntl(mem_file.as_raw_fd(), FcntlArg::F_ADD_SEALS(SealFlag::all())) | ||
| .map_err(|e| anyhow!("unable to seal memfd: {e}"))?; | ||
|
|
||
| let fds = &[mem_file.as_raw_fd()]; | ||
| let ancillary = [ControlMessage::ScmRights(fds)]; | ||
| let path = UnixAddr::new(SD_JOURNAL_SOCK_PATH) | ||
| .map_err(|e| anyhow!("unable to create new unix address: {e}"))?; | ||
| sendmsg( | ||
| sock.as_raw_fd(), | ||
| &[], | ||
| &ancillary, | ||
| MsgFlags::empty(), | ||
| Some(&path), | ||
| ) | ||
| .map_err(|e| anyhow!("sendmsg failed: {e}"))?; | ||
|
|
||
| // Close our side of the memfd after we send it to systemd. | ||
| drop(mem_file); | ||
|
|
||
| Ok(()) | ||
| } |
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