Add and use the camino library for UTF-8 paths

ostree hard requires UTF-8 paths (and really we should
never have any non-UTF-8 paths in the OS in general).  The
camino library has types that are both `Path` and `&str` and
has a convenient `try_into()` too to avoid us duplicating
the error handling.

Cargo.lock

@@ -1394,6 +1394,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "c_utf8",
+ "camino",
  "chrono",
  "clap",
  "curl",

Cargo.toml

@@ -27,6 +27,7 @@ rpm = "4"
 [dependencies]
 anyhow = "1.0.40"
 c_utf8 = "0.1.0"
+camino = "1.0.4"
 chrono = { version = "0.4.19", features = ["serde"] }
 clap = "2.33.3"
 curl = "0.4.36"

rust/src/composepost.rs

@@ -10,12 +10,14 @@ use crate::cxxrsutil::{CxxResult, FFIGObjectWrapper};
 use crate::passwd::PasswdDB;
 use crate::treefile::Treefile;
 use anyhow::{anyhow, bail, Context, Result};
+use camino::Utf8Path;
 use fn_error_context::context;
 use gio::CancellableExt;
 use nix::sys::stat::Mode;
 use openat_ext::OpenatDirExt;
 use rayon::prelude::*;
 use std::borrow::Cow;
+use std::convert::TryInto;
 use std::fmt::Write as FmtWrite;
 use std::fs::File;
 use std::io::{BufRead, BufReader, BufWriter, Seek, Write};
@@ -648,13 +650,8 @@ fn convert_path_to_tmpfiles_d_recurse(
         };
 
         let subpath = subpath?;
-        let full_path = {
-            let fname = subpath.file_name();
-            let path_name = fname
-                .to_str()
-                .ok_or_else(|| anyhow!("invalid non-UTF-8 path: {:?}", fname))?;
-            format!("{}/{}", &current_prefix, &path_name)
-        };
+        let fname: &Utf8Path = Path::new(subpath.file_name()).try_into()?;
+        let full_path = format!("{}/{}", &current_prefix, fname);
         let path_type = subpath.simple_type().unwrap_or(SimpleType::Other);
 
         // Workaround for nfs-utils in RHEL7:

rust/src/initramfs.rs

@@ -3,15 +3,18 @@
 
 use crate::cxxrsutil::*;
 use anyhow::{Context, Result};
+use camino::Utf8Path;
 use gio::prelude::*;
 use openat::SimpleType;
 use std::collections::BTreeSet;
 use std::collections::HashSet;
+use std::convert::TryInto;
 use std::fs;
 use std::io;
 use std::io::prelude::*;
 use std::os::unix::io::AsRawFd;
 use std::os::unix::io::IntoRawFd;
+use std::path::Path;
 use std::pin::Pin;
 use std::rc;
 use subprocess::Exec;
@@ -33,11 +36,7 @@ fn list_files_recurse<P: glib::IsA<gio::Cancellable>>(
         SimpleType::Dir => {
             for e in d.list_dir(path).context("readdir")? {
                 let e = e.context("readdir")?;
-                let name = e.file_name();
-                let name = match name.to_str() {
-                    Some(n) => n,
-                    None => anyhow::bail!("Invalid UTF-8 name {}", name.to_string_lossy()),
-                };
+                let name: &Utf8Path = Path::new(e.file_name()).try_into()?;
                 let subpath = format!("{}/{}", path, name);
                 list_files_recurse(&d, &subpath, filelist, cancellable)?;
             }