Rust: Converting Vec<String> into a C-style 'char**' array to be used in libc library calls, such as in libc::execvp()

Cargo.toml

# Build by running `cargo make`
# or `cargo build`.
#
# Run by `cargo run`.

[package]
name = "experiment"
version = "0.1.0"
edition = "2018"

[dependencies]
libc = "0.2.55"

[[bin]]
name = "main"
path = "main.rs"

main.rs

mod utils {
  use libc::c_char;
  use std::ffi::CString;

  /// Consumes a `Vec<String>` and saves some helper data, so it can provide
  /// the `*const *const c_char` (`argv`) and `*const c_char` (`argv[0]`)
  /// when the user needs them i. e. for [`libc::execvp()`] library call.
  pub struct Argv {
    argv:     Vec<CString>,
    argv_ptr: Vec<*const c_char>,
  }

  impl Argv {
    /// Creates a new `Argv` structure.
    pub fn new(args: Vec<String>) -> Self {
      let argv: Vec<_> = args
        .iter()
        .map(|arg| CString::new(arg.as_str()).unwrap())
        .collect();
      let mut argv_ptr: Vec<_> = argv.iter().map(|arg| arg.as_ptr()).collect();
      argv_ptr.push(std::ptr::null());
      Self { argv, argv_ptr }
    }

    /// Returns the C language's `argv` (`*const *const c_char`).
    pub fn get_argv(&self) -> *const *const c_char { self.argv_ptr.as_ptr() }

    /// Returns the C language's `argv[0]` (`*const c_char`).
    pub fn get_argv0(&self) -> *const c_char { self.argv_ptr[0] }

    /// Gets total length of the `argv` array (including the last null pointer).
    pub fn get_len(&self) -> usize { self.argv_ptr.len() }
  }
}

fn main() {
  let args = vec!["ls".to_string(), "-l".to_string(), "-h".to_string()];
  let argv = utils::Argv::new(args.clone());
  unsafe {
    libc::execvp(argv.get_argv0(), argv.get_argv());
  }
}