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This patch is based on the upstream commit described below, adapted for use
in the Debian package by Peter Michael Green.
commit 3037b5d110e035ff60c6f7b6fd5440aa56091b4e
Author: Daniel Estévez <daniel@destevez.net>
Date: Fri Apr 28 10:03:04 2023 +0200
call memfd_create as syscall instead of through libc
In order to support glibc < 2.27, we call memfd_create() through
syscall() instead of as a libc function, since memfd_create() was
added in glibc 2.27.
Index: libsystemd/src/logging.rs
===================================================================
--- libsystemd.orig/src/logging.rs
+++ libsystemd/src/logging.rs
@@ -1,12 +1,13 @@
use crate::errors::SdError;
use libc::{dev_t, ino_t};
use nix::fcntl::*;
-use nix::sys::memfd::memfd_create;
+use nix::errno::Errno;
use nix::sys::memfd::MemFdCreateFlag;
use nix::sys::socket::{sendmsg, ControlMessage, MsgFlags, UnixAddr};
use once_cell::sync::OnceCell;
use std::collections::HashMap;
-use std::ffi::{CString, OsStr};
+use std::ffi::{CStr, CString, OsStr};
+use std::os::unix::prelude::RawFd;
use std::fs::File;
use std::io::Write;
use std::os::unix::io::AsRawFd;
@@ -185,6 +186,27 @@ pub fn journal_print(priority: Priority,
journal_send(priority, msg, map.iter())
}
+// Implementation of memfd_create() using a syscall instead of calling the libc
+// function.
+//
+// The memfd_create() function is only available in glibc >= 2.27 (and other
+// libc implementations). To support older versions of glibc, we perform a raw
+// syscall (this will fail in Linux < 3.17, where the syscall was not
+// available).
+//
+// nix::sys::memfd::memfd_create chooses at compile time between calling libc
+// and performing a syscall, since platforms such as Android and uclibc don't
+// have memfd_create() in libc. Here we always use the syscall.
+fn memfd_create(name: &CStr, flags: MemFdCreateFlag) -> Result<File, Errno> {
+ unsafe {
+ let res = libc::syscall(libc::SYS_memfd_create, name.as_ptr(), flags.bits());
+ Errno::result(res).map(|r| {
+ // SAFETY: `memfd_create` just returned this FD, so we own it now.
+ File::from_raw_fd(r as RawFd)
+ })
+ }
+}
+
/// Send an overlarge payload to systemd-journald socket.
///
/// This is a slow-path for sending a large payload that could not otherwise fit
@@ -193,11 +215,9 @@ pub fn journal_print(priority: Priority,
fn send_memfd_payload(sock: &UnixDatagram, data: &[u8]) -> Result<usize, SdError> {
let memfd = {
let fdname = &CString::new("libsystemd-rs-logging").map_err(|e| e.to_string())?;
- let tmpfd =
+ let mut file =
memfd_create(fdname, MemFdCreateFlag::MFD_ALLOW_SEALING).map_err(|e| e.to_string())?;
- // SAFETY: `memfd_create` just returned this FD.
- let mut file = unsafe { File::from_raw_fd(tmpfd) };
file.write_all(data).map_err(|e| e.to_string())?;
file
};
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