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
Dietmar Maurer
parent
7750b7f2b7
commit
742e64ea0b
203
src/pxar/fuse.rs
203
src/pxar/fuse.rs
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@ -4,23 +4,47 @@
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use std::ffi::{OsStr, CString};
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use std::fs::File;
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use std::io::BufReader;
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use std::os::unix::ffi::OsStrExt;
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use std::path::Path;
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use std::sync::Mutex;
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use libc;
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use libc::{c_int, c_void, c_char, size_t};
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use failure::*;
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use super::decoder::Decoder;
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/// Node ID of the root inode
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/// This is the only one whose ID is not equal to the offset in the file.
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/// This is ok since offset 1 is part of the entry header and will therefore
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/// not occur again, but remapping to the correct offset of 0 is required.
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const FUSE_ROOT_ID: u64 = 1;
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fn decoder_callback(path: &Path) -> Result<(), Error> {
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println!("{:#?}", path);
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Ok(())
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}
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/// FFI types for easier readability
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type Request = *mut c_void;
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type MutPtr = *mut c_void;
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type ConstPtr = *const c_void;
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type StrPtr = *const c_char;
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#[link(name = "fuse3")]
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extern "C" {
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fn fuse_session_new(args: *const FuseArgs, oprs: *const Operations, size: size_t, op: *const c_void) -> *mut c_void;
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fn fuse_set_signal_handlers(session: *const c_void) -> c_int;
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fn fuse_remove_signal_handlers(session: *const c_void);
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fn fuse_session_new(args: *const FuseArgs, oprs: *const Operations, size: size_t, op: ConstPtr) -> MutPtr;
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fn fuse_set_signal_handlers(session: ConstPtr) -> c_int;
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fn fuse_remove_signal_handlers(session: ConstPtr);
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fn fuse_daemonize(foreground: c_int) -> c_int;
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fn fuse_session_mount(session: *const c_void, mountpoint: *const c_char) -> c_int;
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fn fuse_session_unmount(session: *const c_void);
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fn fuse_session_loop(session: *const c_void) -> c_int;
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fn fuse_session_destroy(session: *const c_void);
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fn fuse_session_mount(session: ConstPtr, mountpoint: StrPtr) -> c_int;
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fn fuse_session_unmount(session: ConstPtr);
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fn fuse_session_loop(session: ConstPtr) -> c_int;
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fn fuse_session_destroy(session: ConstPtr);
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fn fuse_reply_attr(req: Request, attr: *const libc::stat, timeout: f64) -> c_int;
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fn fuse_reply_err(req: Request, errno: c_int) -> c_int;
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fn fuse_req_userdata(req: Request) -> MutPtr;
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}
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/// Command line arguments passed to fuse.
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@ -28,24 +52,67 @@ extern "C" {
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#[derive(Debug)]
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struct FuseArgs {
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argc: c_int,
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argv: *const *const c_char,
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argv: *const StrPtr,
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allocated: c_int,
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}
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/// `Session` stores a pointer to the session context and is used to mount the
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/// archive to the given mountpoint.
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#[derive(Debug)]
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pub struct Session {
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ptr: *mut c_void,
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archive: File,
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ptr: MutPtr,
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verbose: bool,
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}
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/// `Operations` defines the callback function table of supported operations.
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#[repr(C)]
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#[derive(Default)]
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struct Operations {
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init: extern fn(userdata: *mut c_void) -> *mut c_void,
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destroy: extern fn(userdata: *mut c_void) -> *mut c_void,
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// The order in which the functions are listed matters, as the offset in the
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// struct defines what function the fuse driver uses.
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// It should therefore not be altered!
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init: Option<extern fn(userdata: MutPtr)>,
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destroy: Option<extern fn(userdata: MutPtr)>,
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lookup: Option<extern fn(req: Request, parent: u64, name: StrPtr)>,
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forget: Option<extern fn(req: Request, inode: u64, nlookup: u64)>,
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getattr: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr)>,
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setattr: Option<extern fn(req: Request, inode: u64, attr: MutPtr, to_set: c_int, fileinfo: MutPtr)>,
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readlink: Option<extern fn(req: Request, inode: u64)>,
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mknod: Option<extern fn(req: Request, parent: u64, name: StrPtr, mode: c_int, rdev: c_int)>,
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mkdir: Option<extern fn(req: Request, parent: u64, name: StrPtr, mode: c_int)>,
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unlink: Option<extern fn(req: Request, parent: u64, name: StrPtr)>,
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rmdir: Option<extern fn(req: Request, parent: u64, name: StrPtr)>,
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symlink: Option<extern fn(req: Request, link: StrPtr, parent: u64, name: StrPtr)>,
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rename: Option<extern fn(req: Request, parent: u64, name: StrPtr, newparent: u64, newname: StrPtr, flags: c_int)>,
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link: Option<extern fn(req: Request, inode: u64, newparent: u64, newname: StrPtr)>,
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open: Option<extern fn(req: Request, indoe: u64, fileinfo: MutPtr)>,
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read: Option<extern fn(req: Request, inode: u64, size: size_t, offset: c_int, fileinfo: MutPtr)>,
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write: Option<extern fn(req: Request, inode: u64, buffer: StrPtr, size: size_t, offset: c_void, fileinfo: MutPtr)>,
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flush: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr)>,
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release: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr)>,
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fsync: Option<extern fn(req: Request, inode: u64, datasync: c_int, fileinfo: MutPtr)>,
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opendir: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr)>,
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readdir: Option<extern fn(req: Request, inode: u64, size: size_t, offset: c_int, fileinfo: MutPtr)>,
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releasedir: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr)>,
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fsyncdir: Option<extern fn(req: Request, inode: u64, datasync: c_int, fileinfo: MutPtr)>,
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statfs: Option<extern fn(req: Request, inode: u64)>,
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setxattr: Option<extern fn(req: Request, inode: u64, name: StrPtr, value: StrPtr, size: size_t, flags: c_int)>,
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getxattr: Option<extern fn(req: Request, inode: u64, name: StrPtr, size: size_t)>,
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listxattr: Option<extern fn(req: Request, inode: u64, size: size_t)>,
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removexattr: Option<extern fn(req: Request, inode: u64, name: StrPtr)>,
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access: Option<extern fn(req: Request, inode: u64, mask: i32)>,
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create: Option<extern fn(req: Request, parent: u64, name: StrPtr, mode: c_int, fileinfo: MutPtr)>,
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getlk: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr, lock: MutPtr)>,
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setlk: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr, lock: MutPtr, sleep: c_int)>,
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bmap: Option<extern fn(req: Request, inode: u64, blocksize: size_t, idx: u64)>,
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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)>,
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poll: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr, pollhandle: MutPtr)>,
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write_buf: Option<extern fn(req: Request, inode: u64, bufv: MutPtr, offset: c_int, fileinfo: MutPtr)>,
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retrieve_reply: Option<extern fn(req: Request, cookie: ConstPtr, inode: u64, offset: c_int, bufv: MutPtr)>,
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forget_multi: Option<extern fn(req: Request, count: size_t, forgets: MutPtr)>,
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flock: Option<extern fn(req: Request, inode: u64, fileinfo: MutPtr, op: c_int)>,
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fallocate: Option<extern fn(req: Request, inode: u64, mode: c_int, offset: c_int, length: c_int, fileinfo: MutPtr)>,
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readdirplus: Option<extern fn(req: Request, inode: u64, size: size_t, offset: c_int, fileinfo: MutPtr)>,
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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)>,
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}
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impl Session {
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@ -72,16 +139,30 @@ impl Session {
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};
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// Register the callback funcitons for the session
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let oprs = Operations {
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init: init,
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destroy: destroy,
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};
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let mut oprs = Operations::default();
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oprs.init = Some(init);
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oprs.destroy = Some(destroy);
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oprs.lookup = Some(lookup);
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oprs.getattr = Some(getattr);
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oprs.open = Some(open);
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oprs.read = Some(read);
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oprs.opendir = Some(opendir);
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oprs.readdir = Some(readdir);
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// By storing the decoder as userdata of the session, each request may
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// access it.
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let reader = BufReader::new(file);
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let decoder = Decoder::new(reader, decoder_callback as fn(&Path) -> Result<(), Error>)?;
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let session_decoder = Box::new(Mutex::new(decoder));
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let session_ptr = unsafe { fuse_session_new(
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&args as *const FuseArgs,
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&oprs as *const Operations,
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std::mem::size_of::<Operations>(),
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std::ptr::null()
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// Ownership of session_decoder is passed to the session here.
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// It has to be reclaimed before dropping the session to free
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// the decoder and close the underlying file. This is done inside
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// the destroy callback function.
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Box::into_raw(session_decoder) as ConstPtr
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)};
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if session_ptr.is_null() {
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@ -94,7 +175,6 @@ impl Session {
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Ok(Self {
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ptr: session_ptr,
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archive: file,
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verbose: verbose,
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})
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}
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@ -147,13 +227,84 @@ impl Drop for Session {
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}
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}
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/// Callback functions for fuse kernel driver.
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extern "C" fn init(_userdata: *mut c_void) -> *mut c_void {
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println!("Init callback");
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return std::ptr::null_mut();
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/// Creates a context providing an exclusive mutable reference to the decoder.
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///
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/// Each callback function needing access to the decoder can easily get an
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/// exclusive handle by running the code inside this context.
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/// Responses with error code can easily be generated by returning with the
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/// error code.
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fn run_in_context<F: FnOnce(&mut Decoder<BufReader<File>, fn(&Path) -> Result<(), Error>>) -> Result<(), i32>>(req: Request, code: F) {
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let ptr = unsafe { fuse_req_userdata(req) as *mut Mutex<Decoder<BufReader<File>, fn(&Path) -> Result<(), Error>>> };
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let boxed_decoder = unsafe { Box::from_raw(ptr) };
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let result = boxed_decoder.lock()
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.map(|mut decoder| code(&mut decoder))
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.unwrap_or(Err(libc::ENOENT));
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if let Err(err) = result {
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unsafe { let _res = fuse_reply_err(req, err); }
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}
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// Release ownership of boxed decoder, do not drop it.
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let _ = Box::into_raw(boxed_decoder);
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}
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extern "C" fn destroy(_userdata: *mut c_void) -> *mut c_void {
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println!("Destroy callback");
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return std::ptr::null_mut();
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/// Callback functions for fuse kernel driver.
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extern "C" fn init(_decoder: MutPtr) {
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// Notting to do here for now
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}
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/// Cleanup the userdata created while creating the session, which is the decoder
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extern "C" fn destroy(decoder: MutPtr) {
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// Get ownership of the decoder and drop it when Box goes out of scope.
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unsafe { Box::from_raw(decoder); }
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}
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extern "C" fn lookup(req: Request, _parent: u64, _name: StrPtr) {
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run_in_context(req, |decoder| {
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// code goes here
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Err(libc::ENOENT)
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});
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}
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extern "C" fn getattr(req: Request, _inode: u64, _fileinfo: MutPtr) {
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run_in_context(req, |decoder| {
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// code goes here
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Err(libc::ENOENT)
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});
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}
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extern "C" fn open(req: Request, _inode: u64, _fileinfo: MutPtr) {
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run_in_context(req, |decoder| {
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// code goes here
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Err(libc::ENOENT)
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});
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}
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extern "C" fn read(req: Request, _inode: u64, _size: size_t, _offset: c_int, _fileinfo: MutPtr) {
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run_in_context(req, |decoder| {
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// code goes here
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Err(libc::ENOENT)
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});
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}
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extern "C" fn opendir(req: Request, _inode: u64, _fileinfo: MutPtr) {
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run_in_context(req, |decoder| {
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// code goes here
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Err(libc::ENOENT)
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});
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}
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extern "C" fn readdir(req: Request, _inode: u64, _size: size_t, _offset: c_int, _fileinfo: MutPtr) {
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run_in_context(req, |decoder| {
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// code goes here
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Err(libc::ENOENT)
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});
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}
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