From: Mira Limbeck <m.limbeck@proxmox.com>
To: pbs-devel@lists.proxmox.com
Subject: [pbs-devel] [PATCH v3 proxmox] Add tempfile() helper function
Date: Thu, 13 Aug 2020 16:56:02 +0200 [thread overview]
Message-ID: <20200813145603.27999-1-m.limbeck@proxmox.com> (raw)
The tempfile() helper function tries to create a temporary file in /tmp
with the O_TMPFILE option. If that fails it falls back to using
mkstemp().
As O_TMPFILE was introduced in kernel 3.11 this fallback can help with
CentOS 7 and its 3.10 kernel as well as with WSL (Windows Subsystem for
Linux).
Signed-off-by: Mira Limbeck <m.limbeck@proxmox.com>
---
v3:
- O_TMPFILE support is tested on first run of tempfile()
- EISDIR is handled specifically to test for O_TMPFILE support
- AtomicBool is used as it provides a safe interface, but 'static mut'
could also be used
- mkstemp() now creates the tempfile in a subdirectory called
proxmox-backup-<UID>
proxmox/src/tools/fs.rs | 62 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 60 insertions(+), 2 deletions(-)
diff --git a/proxmox/src/tools/fs.rs b/proxmox/src/tools/fs.rs
index b1a95b5..0a12254 100644
--- a/proxmox/src/tools/fs.rs
+++ b/proxmox/src/tools/fs.rs
@@ -1,17 +1,20 @@
//! File related utilities such as `replace_file`.
use std::ffi::CStr;
-use std::fs::{File, OpenOptions};
+use std::fs::{DirBuilder, File, OpenOptions};
use std::io::{self, BufRead, BufReader, Write};
+use std::os::unix::fs::{DirBuilderExt, OpenOptionsExt};
use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
use std::path::Path;
+use std::sync::atomic::{AtomicBool, Ordering};
use std::time::Duration;
use anyhow::{bail, format_err, Error};
+use lazy_static::lazy_static;
use nix::errno::Errno;
use nix::fcntl::OFlag;
use nix::sys::stat;
-use nix::unistd::{self, Gid, Uid};
+use nix::unistd::{self, mkstemp, unlink, Gid, Uid};
use serde_json::Value;
use crate::sys::error::SysResult;
@@ -518,3 +521,58 @@ pub fn open_file_locked<P: AsRef<Path>>(path: P, timeout: Duration) -> Result<Fi
Err(err) => bail!("Unable to acquire lock {:?} - {}", path, err),
}
}
+
+static O_TMPFILE_SUPPORT: AtomicBool = AtomicBool::new(true);
+lazy_static! {
+ static ref MKSTEMP_PATH: String = {
+ use nix::unistd::geteuid;
+ let uid = geteuid();
+ format!("/tmp/proxmox-backup-{}", uid)
+ };
+ static ref MKSTEMP_FILE: String = {
+ format!("{}/tmpfile_XXXXXX", MKSTEMP_PATH.as_str())
+ };
+}
+
+/// Create a new tempfile by using O_TMPFILE with a fallback to mkstemp() if it fails (e.g. not supported).
+pub fn tempfile() -> Result<File, Error> {
+ if O_TMPFILE_SUPPORT.load(Ordering::Relaxed) {
+ match std::fs::OpenOptions::new()
+ .write(true)
+ .read(true)
+ .custom_flags(libc::O_TMPFILE)
+ .open("/tmp")
+ {
+ Ok(file) => return Ok(file),
+ Err(err) => {
+ let raw_os_error = match err.raw_os_error() {
+ Some(v) => v,
+ None => -1,
+ };
+ if raw_os_error == 21 {
+ O_TMPFILE_SUPPORT.store(false, Ordering::Relaxed);
+ eprintln!(
+ "Error creating tempfile: 'EISDIR', falling back to mkstemp() instead",
+ );
+ } else {
+ bail!("Error creating tempfile: '{}'", err);
+ }
+ }
+ }
+ }
+
+
+ match DirBuilder::new().recursive(true).mode(0o700).create(MKSTEMP_PATH.as_str()) {
+ Err(err) => {
+ if err.kind() != std::io::ErrorKind::AlreadyExists {
+ bail!("Error creating directory: '{}'", MKSTEMP_PATH.as_str());
+ }
+ // ignore EEXISTS
+ },
+ _ => {},
+ }
+ let (fd, path) = mkstemp(MKSTEMP_FILE.as_str())?;
+ unlink(path.as_path())?;
+ let file = unsafe { File::from_raw_fd(fd) };
+ Ok(file)
+}
--
2.20.1
next reply other threads:[~2020-08-13 14:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-13 14:56 Mira Limbeck [this message]
2020-08-13 14:56 ` [pbs-devel] [PATCH v3 proxmox-backup] Replace all occurences of open() with O_TMPFILE Mira Limbeck
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