convert main() from C to Rust

This moves the main() function from C to Rust. It also updates the name
of the Rust package from "bcachefs-rust" to "bcachefs-tools".

Signed-off-by: Thomas Bertschinger <tahbertschinger@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

6 files changed, 118 insertions, 53 deletions

diff --git a/rust-src/src/bcachefs.rs b/rust-src/src/bcachefs.rs
new file mode 100644
index 00000000..3d7af3d4
--- /dev/null
+++ b/rust-src/src/bcachefs.rs
@@ -0,0 +1,107 @@
+use std::ffi::CString;
+
+use bcachefs::cmd_completions::cmd_completions;
+use bcachefs::cmd_list::cmd_list;
+use bcachefs::cmd_mount::cmd_mount;
+use bcachefs::logger::SimpleLogger;
+use bch_bindgen::c;
+
+fn handle_c_command(args: Vec<String>, symlink_cmd: Option<&str>) -> i32 {
+    let mut argv: Vec<_> = args.clone();
+
+    let cmd = match symlink_cmd {
+        Some(s) => s.to_string(),
+        None => argv.remove(1),
+    };
+
+    let argc: i32 = argv.len().try_into().unwrap();
+
+    let argv: Vec<_> = argv
+        .iter()
+        .map(|s| CString::new(s.as_str()).unwrap())
+        .collect();
+    let argv: Vec<_> = argv.iter().map(|s| s.as_ptr()).collect();
+    let argv = argv.as_ptr() as *mut *mut i8;
+
+    // The C functions will mutate argv. It shouldn't be used after this block.
+    unsafe {
+        match cmd.as_str() {
+            "--help" => {
+                c::bcachefs_usage();
+                0
+            },
+            "data" => c::data_cmds(argc, argv),
+            "device" => c::device_cmds(argc, argv),
+            "dump" => c::cmd_dump(argc, argv),
+            "format" => c::cmd_format(argc, argv),
+            "fs" => c::fs_cmds(argc, argv),
+            "fsck" => c::cmd_fsck(argc, argv),
+            "list_journal" => c::cmd_list_journal(argc, argv),
+            "kill_btree_node" => c::cmd_kill_btree_node(argc, argv),
+            "migrate" => c::cmd_migrate(argc, argv),
+            "migrate-superblock" => c::cmd_migrate_superblock(argc, argv),
+            "mkfs" => c::cmd_format(argc, argv),
+            "remove-passphrase" => c::cmd_remove_passphrase(argc, argv),
+            "reset-counters" => c::cmd_reset_counters(argc, argv),
+            "set-option" => c::cmd_set_option(argc, argv),
+            "set-passphrase" => c::cmd_set_passphrase(argc, argv),
+            "setattr" => c::cmd_setattr(argc, argv),
+            "show-super" => c::cmd_show_super(argc, argv),
+            "subvolume" => c::subvolume_cmds(argc, argv),
+            "unlock" => c::cmd_unlock(argc, argv),
+            "version" => c::cmd_version(argc, argv),
+
+            #[cfg(fuse)]
+            "fusemount" => c::cmd_fusemount(argc, argv),
+
+            _ => {
+                println!("Unknown command {}", cmd);
+                c::bcachefs_usage();
+                1
+            }
+        }
+    }
+}
+
+fn main() {
+    let args: Vec<String> = std::env::args().collect();
+
+    let symlink_cmd: Option<&str> = if args[0].contains("mkfs") {
+        Some("mkfs")
+    } else if args[0].contains("fsck") {
+        Some("fsck")
+    } else if args[0].contains("mount.fuse") {
+        Some("fusemount")
+    } else if args[0].contains("mount") {
+        Some("mount")
+    } else {
+        None
+    };
+
+    if symlink_cmd.is_none() && args.len() < 2 {
+        println!("missing command");
+        unsafe { c::bcachefs_usage() };
+        std::process::exit(1);
+    }
+
+    unsafe { c::raid_init() };
+
+    log::set_boxed_logger(Box::new(SimpleLogger)).unwrap();
+    log::set_max_level(log::LevelFilter::Warn);
+
+    let cmd = match symlink_cmd {
+        Some(s) => s,
+        None => args[1].as_str(),
+    };
+
+    let ret = match cmd {
+        "completions" => cmd_completions(args[1..].to_vec()),
+        "list" => cmd_list(args[1..].to_vec()),
+        "mount" => cmd_mount(args, symlink_cmd),
+        _ => handle_c_command(args, symlink_cmd),
+    };
+
+    if ret != 0 {
+        std::process::exit(1);
+    }
+}
diff --git a/rust-src/src/cmd_completions.rs b/rust-src/src/cmd_completions.rs
index 3e839fe8..53cdd643 100644
--- a/rust-src/src/cmd_completions.rs
+++ b/rust-src/src/cmd_completions.rs
@@ -1,6 +1,5 @@
 use clap::{Command, CommandFactory, Parser};
 use clap_complete::{generate, Generator, Shell};
-use std::ffi::{c_int, OsStr};
 use std::io;
 
 /// Generate shell completions
@@ -13,7 +12,7 @@ fn print_completions<G: Generator>(gen: G, cmd: &mut Command) {
     generate(gen, cmd, cmd.get_name().to_string(), &mut io::stdout());
 }
 
-pub fn cmd_completions(argv: Vec<&OsStr>) -> c_int {
+pub fn cmd_completions(argv: Vec<String>) -> i32 {
     let cli = Cli::parse_from(argv);
     print_completions(cli.shell, &mut super::Cli::command());
     0
diff --git a/rust-src/src/cmd_list.rs b/rust-src/src/cmd_list.rs
index fa9c2f2f..cb352916 100644
--- a/rust-src/src/cmd_list.rs
+++ b/rust-src/src/cmd_list.rs
@@ -9,7 +9,6 @@ use bch_bindgen::btree::BtreeIter;
 use bch_bindgen::btree::BtreeNodeIter;
 use bch_bindgen::btree::BtreeIterFlags;
 use clap::{Parser};
-use std::ffi::{c_int, OsStr};
 
 fn list_keys(fs: &Fs, opt: Cli) -> anyhow::Result<()> {
     let trans = BtreeTrans::new(fs);
@@ -157,7 +156,7 @@ fn cmd_list_inner(opt: Cli) -> anyhow::Result<()> {
     }
 }
 
-pub fn cmd_list(argv: Vec<&OsStr>) -> c_int {
+pub fn cmd_list(argv: Vec<String>) -> i32 {
     let opt = Cli::parse_from(argv);
     colored::control::set_override(opt.colorize);
     if let Err(e) = cmd_list_inner(opt) {
diff --git a/rust-src/src/cmd_main.rs b/rust-src/src/cmd_main.rs
deleted file mode 100644
index baedc851..00000000
--- a/rust-src/src/cmd_main.rs
+++ /dev/null
@@ -1,34 +0,0 @@
-use log::{error, LevelFilter};
-use std::ffi::{CStr, c_int, c_char};
-use crate::transform_c_args;
-use crate::logger::SimpleLogger;
-use crate::cmd_completions::cmd_completions;
-use crate::cmd_list::cmd_list;
-use crate::cmd_mount::cmd_mount;
-
-#[no_mangle]
-pub extern "C" fn rust_main(argc: c_int, argv: *const *const c_char, cmd: *const c_char) -> c_int {
-    transform_c_args!(argv, argc, argv);
-
-    log::set_boxed_logger(Box::new(SimpleLogger)).unwrap();
-    log::set_max_level(LevelFilter::Warn);
-
-    let cmd: &CStr = unsafe { CStr::from_ptr(cmd) };
-    let cmd = match cmd.to_str() {
-        Ok(c) => c,
-        Err(e) => {
-            error!("could not parse command: {}", e);
-            return 1;
-        }
-    };
-
-    match cmd {
-        "completions" => cmd_completions(argv),
-        "list" => cmd_list(argv),
-        "mount" => cmd_mount(argv),
-        _ => {
-            error!("unknown command: {}", cmd);
-            1
-        }
-    }
-}
diff --git a/rust-src/src/cmd_mount.rs b/rust-src/src/cmd_mount.rs
index eccfe6d0..b120c91e 100644
--- a/rust-src/src/cmd_mount.rs
+++ b/rust-src/src/cmd_mount.rs
@@ -6,7 +6,7 @@ use uuid::Uuid;
 use std::path::PathBuf;
 use crate::key;
 use crate::key::KeyLocation;
-use std::ffi::{CString, c_int, c_char, c_void, OsStr};
+use std::ffi::{CString, c_char, c_void};
 use std::os::unix::ffi::OsStrExt;
 
 fn mount_inner(
@@ -223,7 +223,14 @@ fn cmd_mount_inner(opt: Cli) -> anyhow::Result<()> {
     Ok(())
 }
 
-pub fn cmd_mount(argv: Vec<&OsStr>) -> c_int {
+pub fn cmd_mount(mut argv: Vec<String>, symlink_cmd: Option<&str>) -> i32 {
+    // If the bcachefs tool is being called as "bcachefs mount dev ..." (as opposed to via a
+    // symlink like "/usr/sbin/mount.bcachefs dev ...", then we need to pop the 0th argument
+    // ("bcachefs") since the CLI parser here expects the device at position 1.
+    if symlink_cmd.is_none() {
+        argv.remove(0);
+    }
+
     let opt = Cli::parse_from(argv);
 
     // @TODO : more granular log levels via mount option
diff --git a/rust-src/src/lib.rs b/rust-src/src/lib.rs
index 026cca49..f8b508dc 100644
--- a/rust-src/src/lib.rs
+++ b/rust-src/src/lib.rs
@@ -2,7 +2,6 @@ use clap::Subcommand;
 
 pub mod key;
 pub mod logger;
-pub mod cmd_main;
 pub mod cmd_mount;
 pub mod cmd_list;
 pub mod cmd_completions;
@@ -32,18 +31,6 @@ macro_rules! c_str {
     };
 }
 
-#[macro_export]
-macro_rules! transform_c_args {
-    ($var:ident, $argc:expr, $argv:expr) => {
-        // TODO: `OsStr::from_bytes` only exists on *nix
-        use ::std::os::unix::ffi::OsStrExt;
-        let $var: Vec<_> = (0..$argc)
-        .map(|i| unsafe { ::std::ffi::CStr::from_ptr(*$argv.add(i as usize)) })
-        .map(|i| ::std::ffi::OsStr::from_bytes(i.to_bytes()))
-        .collect();
-    };
-}
-
 #[derive(Debug)]
 struct ErrnoError(errno::Errno);
 impl std::fmt::Display for ErrnoError {