src/pxar/fuse.rs: cleanup callback interface and store decoder within session context

Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
This commit is contained in:
Christian Ebner 2019-08-13 15:37:46 +02:00 committed by Dietmar Maurer
parent 7750b7f2b7
commit 742e64ea0b

View File

@ -4,23 +4,47 @@
use std::ffi::{OsStr, CString};
use std::fs::File;
use std::io::BufReader;
use std::os::unix::ffi::OsStrExt;
use std::path::Path;
use std::sync::Mutex;
use libc;
use libc::{c_int, c_void, c_char, size_t};
use failure::*;
use super::decoder::Decoder;
/// Node ID of the root inode
/// This is the only one whose ID is not equal to the offset in the file.
/// This is ok since offset 1 is part of the entry header and will therefore
/// not occur again, but remapping to the correct offset of 0 is required.
const FUSE_ROOT_ID: u64 = 1;
fn decoder_callback(path: &Path) -> Result<(), Error> {
println!("{:#?}", path);
Ok(())
}
/// FFI types for easier readability
type Request = *mut c_void;
type MutPtr = *mut c_void;
type ConstPtr = *const c_void;
type StrPtr = *const c_char;
#[link(name = "fuse3")]
extern "C" {
fn fuse_session_new(args: *const FuseArgs, oprs: *const Operations, size: size_t, op: *const c_void) -> *mut c_void;
fn fuse_set_signal_handlers(session: *const c_void) -> c_int;
fn fuse_remove_signal_handlers(session: *const c_void);
fn fuse_session_new(args: *const FuseArgs, oprs: *const Operations, size: size_t, op: ConstPtr) -> MutPtr;
fn fuse_set_signal_handlers(session: ConstPtr) -> c_int;
fn fuse_remove_signal_handlers(session: ConstPtr);
fn fuse_daemonize(foreground: c_int) -> c_int;
fn fuse_session_mount(session: *const c_void, mountpoint: *const c_char) -> c_int;
fn fuse_session_unmount(session: *const c_void);
fn fuse_session_loop(session: *const c_void) -> c_int;
fn fuse_session_destroy(session: *const c_void);
fn fuse_session_mount(session: ConstPtr, mountpoint: StrPtr) -> c_int;
fn fuse_session_unmount(session: ConstPtr);
fn fuse_session_loop(session: ConstPtr) -> c_int;
fn fuse_session_destroy(session: ConstPtr);
fn fuse_reply_attr(req: Request, attr: *const libc::stat, timeout: f64) -> c_int;
fn fuse_reply_err(req: Request, errno: c_int) -> c_int;
fn fuse_req_userdata(req: Request) -> MutPtr;
}
/// Command line arguments passed to fuse.
@ -28,24 +52,67 @@ extern "C" {
#[derive(Debug)]
struct FuseArgs {
argc: c_int,
argv: *const *const c_char,
argv: *const StrPtr,
allocated: c_int,
}
/// `Session` stores a pointer to the session context and is used to mount the
/// archive to the given mountpoint.
#[derive(Debug)]
pub struct Session {
ptr: *mut c_void,
archive: File,
ptr: MutPtr,
verbose: bool,
}
/// `Operations` defines the callback function table of supported operations.
#[repr(C)]
#[derive(Default)]
struct Operations {
init: extern fn(userdata: *mut c_void) -> *mut c_void,
destroy: extern fn(userdata: *mut c_void) -> *mut c_void,
// The order in which the functions are listed matters, as the offset in the
// struct defines what function the fuse driver uses.
// It should therefore not be altered!
init: Option<extern fn(userdata: MutPtr)>,
destroy: Option<extern fn(userdata: MutPtr)>,
lookup: Option<extern fn(req: Request, parent: u64, name: StrPtr)>,
forget: Option<extern fn(req: Request, inode: u64, nlookup: u64)>,
getattr: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr)>,
setattr: Option<extern fn(req: Request, inode: u64, attr: MutPtr, to_set: c_int, fileinfo: MutPtr)>,
readlink: Option<extern fn(req: Request, inode: u64)>,
mknod: Option<extern fn(req: Request, parent: u64, name: StrPtr, mode: c_int, rdev: c_int)>,
mkdir: Option<extern fn(req: Request, parent: u64, name: StrPtr, mode: c_int)>,
unlink: Option<extern fn(req: Request, parent: u64, name: StrPtr)>,
rmdir: Option<extern fn(req: Request, parent: u64, name: StrPtr)>,
symlink: Option<extern fn(req: Request, link: StrPtr, parent: u64, name: StrPtr)>,
rename: Option<extern fn(req: Request, parent: u64, name: StrPtr, newparent: u64, newname: StrPtr, flags: c_int)>,
link: Option<extern fn(req: Request, inode: u64, newparent: u64, newname: StrPtr)>,
open: Option<extern fn(req: Request, indoe: u64, fileinfo: MutPtr)>,
read: Option<extern fn(req: Request, inode: u64, size: size_t, offset: c_int, fileinfo: MutPtr)>,
write: Option<extern fn(req: Request, inode: u64, buffer: StrPtr, size: size_t, offset: c_void, fileinfo: MutPtr)>,
flush: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr)>,
release: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr)>,
fsync: Option<extern fn(req: Request, inode: u64, datasync: c_int, fileinfo: MutPtr)>,
opendir: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr)>,
readdir: Option<extern fn(req: Request, inode: u64, size: size_t, offset: c_int, fileinfo: MutPtr)>,
releasedir: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr)>,
fsyncdir: Option<extern fn(req: Request, inode: u64, datasync: c_int, fileinfo: MutPtr)>,
statfs: Option<extern fn(req: Request, inode: u64)>,
setxattr: Option<extern fn(req: Request, inode: u64, name: StrPtr, value: StrPtr, size: size_t, flags: c_int)>,
getxattr: Option<extern fn(req: Request, inode: u64, name: StrPtr, size: size_t)>,
listxattr: Option<extern fn(req: Request, inode: u64, size: size_t)>,
removexattr: Option<extern fn(req: Request, inode: u64, name: StrPtr)>,
access: Option<extern fn(req: Request, inode: u64, mask: i32)>,
create: Option<extern fn(req: Request, parent: u64, name: StrPtr, mode: c_int, fileinfo: MutPtr)>,
getlk: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr, lock: MutPtr)>,
setlk: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr, lock: MutPtr, sleep: c_int)>,
bmap: Option<extern fn(req: Request, inode: u64, blocksize: size_t, idx: u64)>,
ioctl: Option<extern fn(req: Request, inode: u64, cmd: c_int, arg: MutPtr, fileinfo: MutPtr, flags: c_int, in_buf: ConstPtr, in_bufsz: size_t, out_bufsz: size_t)>,
poll: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr, pollhandle: MutPtr)>,
write_buf: Option<extern fn(req: Request, inode: u64, bufv: MutPtr, offset: c_int, fileinfo: MutPtr)>,
retrieve_reply: Option<extern fn(req: Request, cookie: ConstPtr, inode: u64, offset: c_int, bufv: MutPtr)>,
forget_multi: Option<extern fn(req: Request, count: size_t, forgets: MutPtr)>,
flock: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr, op: c_int)>,
fallocate: Option<extern fn(req: Request, inode: u64, mode: c_int, offset: c_int, length: c_int, fileinfo: MutPtr)>,
readdirplus: Option<extern fn(req: Request, inode: u64, size: size_t, offset: c_int, fileinfo: MutPtr)>,
copy_file_range: Option<extern fn(req: Request, ino_in: u64, off_in: c_int, fi_in: MutPtr, ino_out: u64, off_out: c_int, fi_out: MutPtr, len: size_t, flags: c_int)>,
}
impl Session {
@ -72,16 +139,30 @@ impl Session {
};
// Register the callback funcitons for the session
let oprs = Operations {
init: init,
destroy: destroy,
};
let mut oprs = Operations::default();
oprs.init = Some(init);
oprs.destroy = Some(destroy);
oprs.lookup = Some(lookup);
oprs.getattr = Some(getattr);
oprs.open = Some(open);
oprs.read = Some(read);
oprs.opendir = Some(opendir);
oprs.readdir = Some(readdir);
// By storing the decoder as userdata of the session, each request may
// access it.
let reader = BufReader::new(file);
let decoder = Decoder::new(reader, decoder_callback as fn(&Path) -> Result<(), Error>)?;
let session_decoder = Box::new(Mutex::new(decoder));
let session_ptr = unsafe { fuse_session_new(
&args as *const FuseArgs,
&oprs as *const Operations,
std::mem::size_of::<Operations>(),
std::ptr::null()
// Ownership of session_decoder is passed to the session here.
// It has to be reclaimed before dropping the session to free
// the decoder and close the underlying file. This is done inside
// the destroy callback function.
Box::into_raw(session_decoder) as ConstPtr
)};
if session_ptr.is_null() {
@ -94,7 +175,6 @@ impl Session {
Ok(Self {
ptr: session_ptr,
archive: file,
verbose: verbose,
})
}
@ -147,13 +227,84 @@ impl Drop for Session {
}
}
/// Callback functions for fuse kernel driver.
extern "C" fn init(_userdata: *mut c_void) -> *mut c_void {
println!("Init callback");
return std::ptr::null_mut();
/// Creates a context providing an exclusive mutable reference to the decoder.
///
/// Each callback function needing access to the decoder can easily get an
/// exclusive handle by running the code inside this context.
/// Responses with error code can easily be generated by returning with the
/// error code.
fn run_in_context<F: FnOnce(&mut Decoder<BufReader<File>, fn(&Path) -> Result<(), Error>>) -> Result<(), i32>>(req: Request, code: F) {
let ptr = unsafe { fuse_req_userdata(req) as *mut Mutex<Decoder<BufReader<File>, fn(&Path) -> Result<(), Error>>> };
let boxed_decoder = unsafe { Box::from_raw(ptr) };
let result = boxed_decoder.lock()
.map(|mut decoder| code(&mut decoder))
.unwrap_or(Err(libc::ENOENT));
if let Err(err) = result {
unsafe { let _res = fuse_reply_err(req, err); }
}
// Release ownership of boxed decoder, do not drop it.
let _ = Box::into_raw(boxed_decoder);
}
extern "C" fn destroy(_userdata: *mut c_void) -> *mut c_void {
println!("Destroy callback");
return std::ptr::null_mut();
/// Callback functions for fuse kernel driver.
extern "C" fn init(_decoder: MutPtr) {
// Notting to do here for now
}
/// Cleanup the userdata created while creating the session, which is the decoder
extern "C" fn destroy(decoder: MutPtr) {
// Get ownership of the decoder and drop it when Box goes out of scope.
unsafe { Box::from_raw(decoder); }
}
extern "C" fn lookup(req: Request, _parent: u64, _name: StrPtr) {
run_in_context(req, |decoder| {
// code goes here
Err(libc::ENOENT)
});
}
extern "C" fn getattr(req: Request, _inode: u64, _fileinfo: MutPtr) {
run_in_context(req, |decoder| {
// code goes here
Err(libc::ENOENT)
});
}
extern "C" fn open(req: Request, _inode: u64, _fileinfo: MutPtr) {
run_in_context(req, |decoder| {
// code goes here
Err(libc::ENOENT)
});
}
extern "C" fn read(req: Request, _inode: u64, _size: size_t, _offset: c_int, _fileinfo: MutPtr) {
run_in_context(req, |decoder| {
// code goes here
Err(libc::ENOENT)
});
}
extern "C" fn opendir(req: Request, _inode: u64, _fileinfo: MutPtr) {
run_in_context(req, |decoder| {
// code goes here
Err(libc::ENOENT)
});
}
extern "C" fn readdir(req: Request, _inode: u64, _size: size_t, _offset: c_int, _fileinfo: MutPtr) {
run_in_context(req, |decoder| {
// code goes here
Err(libc::ENOENT)
});
}