tools: add helpful vector and read operations

After importing the I/O ops trait via:
    use crate::tools::io::ops::*;

Instead of:
    let mut buffer = vec![0u8; 65536];
    file.read_exact(&mut buffer)?;
use:
    let buffer = file.read_exact_allocated(65536)?;

After importing the vector helpers via:
    use crate::tools::vec::{self, ops::*};

For a buffer which *could* be uninitialized but you prefer
zero-initialization anyway for security reasons, instead of:
    let mut buffer = vec![0u8; len];
use:
    let mut buffer = vec::undefined(len);
which zero-initializes, but, if the `valgrind` feature flag
is enabled, marks the vector as having undefined contents,
so reading from it will cause valgrind errors.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

src/tools.rs

@@ -37,6 +37,8 @@ pub mod read;
 pub mod write;
 pub mod acl;
 pub mod xattr;
+pub mod vec;
+pub mod io;
 
 mod process_locker;
 pub use process_locker::*;