From: "Fabian Grünbichler" <f.gruenbichler@proxmox.com>
To: Proxmox Backup Server development discussion
<pbs-devel@lists.proxmox.com>
Subject: Re: [pbs-devel] [PATCH proxmox v2] tools: Add tempfile() helper function
Date: Thu, 13 Aug 2020 09:43:07 +0200 [thread overview]
Message-ID: <1597303267.ccruwq5t2k.astroid@nora.none> (raw)
In-Reply-To: <20200812143421.8899-1-m.limbeck@proxmox.com>
On August 12, 2020 4:34 pm, Mira Limbeck wrote:
> 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>
> ---
> proxmox/src/tools/fs.rs | 25 ++++++++++++++++++++++++-
> 1 file changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/proxmox/src/tools/fs.rs b/proxmox/src/tools/fs.rs
> index b1a95b5..b3072db 100644
> --- a/proxmox/src/tools/fs.rs
> +++ b/proxmox/src/tools/fs.rs
> @@ -3,6 +3,7 @@
> use std::ffi::CStr;
> use std::fs::{File, OpenOptions};
> use std::io::{self, BufRead, BufReader, Write};
> +use std::os::unix::fs::OpenOptionsExt;
> use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
> use std::path::Path;
> use std::time::Duration;
> @@ -11,7 +12,7 @@ use anyhow::{bail, format_err, Error};
> 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 +519,25 @@ pub fn open_file_locked<P: AsRef<Path>>(path: P, timeout: Duration) -> Result<Fi
> Err(err) => bail!("Unable to acquire lock {:?} - {}", path, err),
> }
> }
> +
> +/// 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> {
> + match std::fs::OpenOptions::new()
> + .write(true)
> + .read(true)
> + .custom_flags(libc::O_TMPFILE)
> + .open("/tmp")
> + {
> + Ok(file) => return Ok(file),
> + Err(err) => {
> + eprintln!(
> + "Error creating tempfile: '{}', trying mkstemp() instead",
> + err
> + );
print this once, cache result, always use fallback until restart if
needed?
also, can we decide based on the error if we even want/can
fallback? e.g., /tmp might have strange permissions? the man page states
that open should return EISDIR in case O_TMPFILE is not supported..
> + let (fd, path) = mkstemp("/tmp/proxmox-tmpfile_XXXXXX")?;
I'd still like this to be in a sub-directory (owned by 'backup'), even
if it should be unproblematic..
> + unlink(path.as_path())?;
> + let file = unsafe { File::from_raw_fd(fd) };
> + Ok(file)
> + }
> + }
> +}
> --
> 2.20.1
>
>
>
> _______________________________________________
> pbs-devel mailing list
> pbs-devel@lists.proxmox.com
> https://lists.proxmox.com/cgi-bin/mailman/listinfo/pbs-devel
>
>
>
prev parent reply other threads:[~2020-08-13 7:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-12 14:34 Mira Limbeck
2020-08-12 14:34 ` [pbs-devel] [PATCH proxmox-backup v2] Replace all occurences of open() with O_TMPFILE Mira Limbeck
2020-08-13 7:43 ` Fabian Grünbichler [this message]
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