tracing_journald/
memfd.rs

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1//! memfd helpers.
2
3use libc::*;
4use std::fs::File;
5use std::io::Error;
6use std::io::Result;
7use std::os::raw::c_uint;
8use std::os::unix::prelude::{FromRawFd, RawFd};
9
10fn create(flags: c_uint) -> Result<File> {
11    let fd = memfd_create_syscall(flags);
12    if fd < 0 {
13        Err(Error::last_os_error())
14    } else {
15        Ok(unsafe { File::from_raw_fd(fd as RawFd) })
16    }
17}
18
19/// Make the `memfd_create` syscall ourself instead of going through `libc`;
20/// `memfd_create` isn't supported on `glibc<2.27` so this allows us to
21/// support old-but-still-used distros like Ubuntu Xenial, Debian Stretch,
22/// RHEL 7, etc.
23///
24/// See: https://github.com/tokio-rs/tracing/issues/1879
25fn memfd_create_syscall(flags: c_uint) -> c_int {
26    unsafe {
27        syscall(
28            SYS_memfd_create,
29            "tracing-journald\0".as_ptr() as *const c_char,
30            flags,
31        ) as c_int
32    }
33}
34
35pub fn create_sealable() -> Result<File> {
36    create(MFD_ALLOW_SEALING | MFD_CLOEXEC)
37}
38
39pub fn seal_fully(fd: RawFd) -> Result<()> {
40    let all_seals = F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE | F_SEAL_SEAL;
41    let result = unsafe { fcntl(fd, F_ADD_SEALS, all_seals) };
42    if result < 0 {
43        Err(Error::last_os_error())
44    } else {
45        Ok(())
46    }
47}
tracing_journald/memfd.rs

tracing_journald/
memfd.rs
