Re: [pbs-devel] [PATCH proxmox v3 2/3] proxmox-sys: add FileSystemInformation struct and helper

[Wolfgang Bumiller <w.bumiller@proxmox.com>]

minor nit...

On Fri, Dec 17, 2021 at 09:09:53AM +0100, Dominik Csapak wrote:
> code mostly copied from proxmox-backups 'disk_usage'
> 
> Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
> ---
>  proxmox-sys/src/fs/mod.rs | 39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/proxmox-sys/src/fs/mod.rs b/proxmox-sys/src/fs/mod.rs
> index 9fe333b..f8a7744 100644
> --- a/proxmox-sys/src/fs/mod.rs
> +++ b/proxmox-sys/src/fs/mod.rs
> @@ -102,3 +102,42 @@ impl CreateOptions {
>      */
>  }
>  
> +/// Information about a mounted file system from statfs64 syscall
> +pub struct FileSystemInformation {
> +    /// total bytes available
> +    pub total: u64,
> +    /// bytes used
> +    pub used: u64,
> +    /// bytes available to an unprivileged user
> +    pub available: u64,
> +    /// total number of inodes
> +    pub total_inodes: u64,
> +    /// free number of inodes
> +    pub free_inodes: u64,
> +    /// the type of the filesystem (see statfs64(2))
> +    pub fs_type: i64,
> +    /// the filesystem id
> +    pub fs_id: libc::fsid_t,
> +}
> +
> +/// Get file system information from path
> +pub fn fs_info(path: &std::path::Path) -> Result<FileSystemInformation, Error> {

If you use `NixPath` below anyway, may as well go all the way:

    pub fn fs_info<P: ?Sized + NixPath>(path: &P) -> nix::Result<FileSystemInformation> {

(note the error type change since that's the only kind of error
appearing in this function)

Otherwise, you could at least go the `std` way of `<P: AsRef<Path>>(path: P)`.

(We're already mixing these a bit, but `&Path` is the least convenient
way for callers to interact with)

> +    let mut stat: libc::statfs64 = unsafe { std::mem::zeroed() };
> +
> +    use nix::NixPath;
> +
> +    let res = path.with_nix_path(|cstr| unsafe { libc::statfs64(cstr.as_ptr(), &mut stat) })?;
> +    nix::errno::Errno::result(res)?;
> +
> +    let bsize = stat.f_bsize as u64;
> +
> +    Ok(FileSystemInformation {
> +        total: stat.f_blocks * bsize,
> +        used: (stat.f_blocks - stat.f_bfree) * bsize,
> +        available: stat.f_bavail * bsize,
> +        total_inodes: stat.f_files,
> +        free_inodes: stat.f_ffree,
> +        fs_type: stat.f_type,
> +        fs_id: stat.f_fsid,
> +    })
> +}
> -- 
> 2.30.2