Rust now integrated into bcachefs binary

Rust is now required for building the bcachefs tool, and rust code is
now fully integrated with the C codebase - meaning it is possible to
call back and forth.

The mount helper is now a subcommand, 'mount.bcachefs' is now a small
shell wrapper that invokes 'bcachefs mount'.

This will make it easier to start rewriting other subcommands in rust,
and eventually the whole command line interface.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 99 insertions, 0 deletions

diff --git a/rust-src/src/cmd_mount.rs b/rust-src/src/cmd_mount.rs
new file mode 100644
index 00000000..7748b199
--- /dev/null
+++ b/rust-src/src/cmd_mount.rs
@@ -0,0 +1,99 @@
+use bch_bindgen::{error, info};
+use clap::Parser;
+use colored::Colorize;
+use atty::Stream;
+use uuid::Uuid;
+use crate::filesystem;
+use crate::key;
+use crate::key::KeyLoc;
+
+fn parse_fstab_uuid(uuid_raw: &str) -> Result<Uuid, uuid::Error> {
+    let mut uuid = String::from(uuid_raw);
+    if uuid.starts_with("UUID=") {
+        uuid = uuid.replacen("UUID=", "", 1);
+    }
+    return Uuid::parse_str(&uuid);
+}
+
+fn stdout_isatty() -> &'static str {
+    if atty::is(Stream::Stdout) {
+        "true"
+    } else {
+        "false"
+    }
+}
+
+/// Mount a bcachefs filesystem by its UUID.
+#[derive(Parser, Debug)]
+#[command(author, version, about, long_about = None)]
+pub struct Cli {
+    /// Where the password would be loaded from.
+    ///
+    /// Possible values are:
+    /// "fail" - don't ask for password, fail if filesystem is encrypted;
+    /// "wait" - wait for password to become available before mounting;
+    /// "ask" -  prompt the user for password;
+    #[arg(short, long, default_value = "", verbatim_doc_comment)]
+    pub key_location: KeyLoc,
+
+    /// External UUID of the bcachefs filesystem
+    ///
+    /// Accepts the UUID as is or as fstab style UUID=<UUID>
+    #[arg(value_parser = parse_fstab_uuid)]
+    pub uuid: uuid::Uuid,
+
+    /// Where the filesystem should be mounted. If not set, then the filesystem
+    /// won't actually be mounted. But all steps preceeding mounting the
+    /// filesystem (e.g. asking for passphrase) will still be performed.
+    pub mountpoint: Option<std::path::PathBuf>,
+
+    /// Mount options
+    #[arg(short, default_value = "")]
+    pub options: String,
+
+    /// Force color on/off. Default: autodetect tty
+    #[arg(short, long, action = clap::ArgAction::Set, default_value=stdout_isatty())]
+    pub colorize: bool,
+
+    #[arg(short = 'v', long, action = clap::ArgAction::Count)]
+    pub verbose: u8,
+}
+
+pub fn cmd_mount_inner(opt: Cli) -> anyhow::Result<()> {
+    unsafe {
+        libc::setvbuf(filesystem::stdout, std::ptr::null_mut(), libc::_IONBF, 0);
+    }
+
+    let fss = filesystem::probe_filesystems()?;
+    let fs = fss
+        .get(&opt.uuid)
+        .ok_or_else(|| anyhow::anyhow!("filesystem was not found"))?;
+
+    info!("found filesystem {}", fs);
+    if fs.encrypted() {
+        let key = opt
+            .key_location
+            .0
+            .ok_or_else(|| anyhow::anyhow!("no keyoption specified for locked filesystem"))?;
+
+        key::prepare_key(&fs, key)?;
+    }
+
+    let mountpoint = opt
+        .mountpoint
+        .ok_or_else(|| anyhow::anyhow!("mountpoint option was not specified"))?;
+
+    fs.mount(&mountpoint, &opt.options)?;
+
+    Ok(())
+}
+
+#[no_mangle]
+pub extern "C" fn cmd_mount() {
+    let opt = Cli::parse();
+    bch_bindgen::log::set_verbose_level(opt.verbose + bch_bindgen::log::ERROR);
+    colored::control::set_override(opt.colorize);
+    if let Err(e) = cmd_mount_inner(opt) {
+        error!("Fatal error: {}", e);
+    }
+}