[pbs-devel] [PATCH] fix #2882: correctly parse optional fields from mountinfo
Stefan Reiter
s.reiter at proxmox.com
Mon Jul 27 17:30:43 CEST 2020
Sorry, this is for the "proxmox" crate obviously, my clever patch script
stripped the entire name as the prefix -.-
On 7/27/20 5:28 PM, Stefan Reiter wrote:
> As per the linux kernel documentation[0], the "optional fields" (called
> "tags" in our parser) are not comma-separated, but are a variable number
> (0 or more) of space-separated fields, always followed by a dash to mark
> the end.
>
> Fix the /proc/<pid>/mountinfo parser to correctly parse these and add
> test cases (l3 is the line that produced the original warning from the
> bug report).
>
> [0] https://www.kernel.org/doc/html/latest/filesystems/proc.html#proc-pid-mountinfo-information-about-mounts
>
> Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
> ---
>
> I still think the way we parse here (with the fixed next()'s) is kind of weird,
> but I don't have a better idea and the rest of the "mountinfo" format looks
> pretty set in stone, so I suppose it's fine.
>
> proxmox/src/sys/linux/procfs/mountinfo.rs | 53 ++++++++++++++++++-----
> 1 file changed, 42 insertions(+), 11 deletions(-)
>
> diff --git a/proxmox/src/sys/linux/procfs/mountinfo.rs b/proxmox/src/sys/linux/procfs/mountinfo.rs
> index 55f74c2..b57f132 100644
> --- a/proxmox/src/sys/linux/procfs/mountinfo.rs
> +++ b/proxmox/src/sys/linux/procfs/mountinfo.rs
> @@ -135,17 +135,18 @@ impl Entry {
> root: OsStr::from_bytes(next()?).to_owned().into(),
> mount_point: OsStr::from_bytes(next()?).to_owned().into(),
> mount_options: OsStr::from_bytes(next()?).to_owned(),
> - tags: next()?.split(|b| *b == b',').try_fold(
> - Vec::new(),
> - |mut acc, tag| -> Result<_, Error> {
> - acc.push(Tag::parse(tag)?);
> - Ok(acc)
> - },
> - )?,
> - fs_type: std::str::from_utf8({
> - next()?;
> - next()?
> - })?
> + tags: {
> + let mut tags = Vec::new();
> + loop {
> + let tval = next()?;
> + if tval == b"-" {
> + break;
> + }
> + tags.push(Tag::parse(tval)?);
> + }
> + tags
> + },
> + fs_type: std::str::from_utf8(next()?)?
> .to_string(),
> mount_source: next().map(|src| match src {
> b"none" => None,
> @@ -350,6 +351,36 @@ fn test_entry() {
> "rw,fd=26,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=27726"
> );
>
> + // test different tag configurations
> + let l3: &[u8] =
> + b"225 224 0:46 / /proc rw,nosuid,nodev,noexec,relatime - proc proc rw";
> + let entry = Entry::parse(l3).expect("failed to parse third mountinfo test entry");
> + assert_eq!(entry.tags, &[]);
> +
> + let l4: &[u8] =
> + b"48 32 0:43 / /sys/fs/cgroup/blkio rw,nosuid,nodev,noexec,relatime \
> + shared:5 master:7 propagate_from:2 unbindable \
> + - cgroup cgroup rw,blkio";
> + let entry = Entry::parse(l4).expect("failed to parse fourth mountinfo test entry");
> + assert_eq!(entry.tags, &[
> + Tag {
> + tag: OsString::from("shared"),
> + value: Some(OsString::from("5")),
> + },
> + Tag {
> + tag: OsString::from("master"),
> + value: Some(OsString::from("7")),
> + },
> + Tag {
> + tag: OsString::from("propagate_from"),
> + value: Some(OsString::from("2")),
> + },
> + Tag {
> + tag: OsString::from("unbindable"),
> + value: None,
> + },
> + ]);
> +
> let mount_info = [l1, l2].join(&b"\n"[..]);
> MountInfo::parse(&mount_info).expect("failed to parse mount info file");
> }
>
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