Merge pull request #1826 from zyuiop/feat/fs-syscalls

feat: implement `cwd`, `umask`, `access`, `faccessat`, `ftruncate`, `fchmod`, `truncate`

Author: mkroening

src/errno.rs

@@ -751,6 +751,12 @@ impl ToErrno for isize {
 	}
 }
 
+impl ToErrno for Errno {
+	fn to_errno(&self) -> Option<i32> {
+		Some(i32::from(*self))
+	}
+}
+
 impl ToErrno for u8 {}
 impl ToErrno for u16 {}
 impl ToErrno for u32 {}

src/fd/mod.rs

@@ -69,6 +69,52 @@ bitflags! {
 	}
 }
 
+bitflags! {
+	/// Options for checking file permissions or existence
+	#[derive(Debug, Copy, Clone, Default, Eq, PartialEq)]
+	pub struct AccessOption: i32 {
+		/// Test for read permission
+		const R_OK = 4;
+		/// Test for write permission
+		const W_OK = 2;
+		/// Test for execution permission
+		const X_OK = 1;
+		/// Test for existence
+		const F_OK = 0;
+	}
+}
+
+impl AccessOption {
+	/// Verifies if the current access options are all valid for the provided file access permissions
+	pub fn can_access(&self, access_permissions: AccessPermission) -> bool {
+		if self.contains(AccessOption::R_OK)
+			&& !access_permissions.contains(AccessPermission::S_IRUSR)
+			&& !access_permissions.contains(AccessPermission::S_IRGRP)
+			&& !access_permissions.contains(AccessPermission::S_IROTH)
+		{
+			return false;
+		}
+
+		if self.contains(AccessOption::W_OK)
+			&& !access_permissions.contains(AccessPermission::S_IWUSR)
+			&& !access_permissions.contains(AccessPermission::S_IWGRP)
+			&& !access_permissions.contains(AccessPermission::S_IWOTH)
+		{
+			return false;
+		}
+
+		if self.contains(AccessOption::X_OK)
+			&& !access_permissions.contains(AccessPermission::S_IXUSR)
+			&& !access_permissions.contains(AccessPermission::S_IXGRP)
+			&& !access_permissions.contains(AccessPermission::S_IXOTH)
+		{
+			return false;
+		}
+
+		true
+	}
+}
+
 bitflags! {
 	/// File status flags.
 	#[derive(Debug, Copy, Clone, Default)]
@@ -268,6 +314,16 @@ pub(crate) trait ObjectInterface: Sync + Send + core::fmt::Debug {
 		Err(Errno::Nosys)
 	}
 
+	/// Truncates the file
+	async fn truncate(&self, _size: usize) -> io::Result<()> {
+		Err(Errno::Nosys)
+	}
+
+	/// Changes access permissions to the file
+	async fn chmod(&self, _access_permission: AccessPermission) -> io::Result<()> {
+		Err(Errno::Nosys)
+	}
+
 	/// `isatty` returns `true` for a terminal device
 	async fn isatty(&self) -> io::Result<bool> {
 		Ok(false)
@@ -290,6 +346,12 @@ pub(crate) fn lseek(fd: FileDescriptor, offset: isize, whence: SeekWhence) -> io
 	block_on(obj.lseek(offset, whence), None)
 }
 
+pub(crate) fn chmod(fd: FileDescriptor, mode: AccessPermission) -> io::Result<()> {
+	let obj = get_object(fd)?;
+
+	block_on(obj.chmod(mode), None)
+}
+
 pub(crate) fn write(fd: FileDescriptor, buf: &[u8]) -> io::Result<usize> {
 	let obj = get_object(fd)?;
 
@@ -300,6 +362,11 @@ pub(crate) fn write(fd: FileDescriptor, buf: &[u8]) -> io::Result<usize> {
 	block_on(obj.write(buf), None)
 }
 
+pub(crate) fn truncate(fd: FileDescriptor, length: usize) -> io::Result<()> {
+	let obj = get_object(fd)?;
+	block_on(obj.truncate(length), None)
+}
+
 async fn poll_fds(fds: &mut [PollFd]) -> io::Result<u64> {
 	future::poll_fn(|cx| {
 		let mut counter: u64 = 0;

src/fs/fuse.rs

@@ -24,6 +24,7 @@ use crate::drivers::virtio::virtqueue::error::VirtqError;
 use crate::errno::Errno;
 use crate::executor::block_on;
 use crate::fd::PollEvent;
+use crate::fs::fuse::ops::SetAttrValidFields;
 use crate::fs::{
 	self, AccessPermission, DirectoryEntry, FileAttr, NodeKind, ObjectInterface, OpenOption,
 	SeekWhence, VfsNode,
@@ -63,11 +64,12 @@ pub(crate) mod ops {
 	use alloc::boxed::Box;
 	use alloc::ffi::CString;
 
+	use fuse_abi::linux;
 	use fuse_abi::linux::*;
 
 	use super::Cmd;
 	use crate::fd::PollEvent;
-	use crate::fs::SeekWhence;
+	use crate::fs::{FileAttr, SeekWhence};
 
 	#[repr(C)]
 	#[derive(Debug, Default, Copy, Clone, Hash, PartialEq, Eq)]
@@ -270,6 +272,76 @@ pub(crate) mod ops {
 		}
 	}
 
+	#[derive(Debug)]
+	pub(crate) struct Setattr;
+
+	impl Op for Setattr {
+		const OP_CODE: fuse_opcode = fuse_opcode::FUSE_SETATTR;
+		type InStruct = fuse_setattr_in;
+		type InPayload = ();
+		type OutStruct = fuse_attr_out;
+		type OutPayload = ();
+	}
+
+	bitflags! {
+		#[derive(Debug, Copy, Clone, Default)]
+		pub struct SetAttrValidFields: u32 {
+			const FATTR_MODE = linux::FATTR_MODE;
+			const FATTR_UID = linux::FATTR_UID;
+			const FATTR_GID = linux::FATTR_GID;
+			const FATTR_SIZE = linux::FATTR_SIZE;
+			const FATTR_ATIME = linux::FATTR_ATIME;
+			const FATTR_MTIME = linux::FATTR_MTIME;
+			const FATTR_FH = linux::FATTR_FH;
+			const FATTR_ATIME_NOW = linux::FATTR_ATIME_NOW;
+			const FATTR_MTIME_NOW = linux::FATTR_MTIME_NOW;
+			const FATTR_LOCKOWNER = linux::FATTR_LOCKOWNER;
+			const FATTR_CTIME = linux::FATTR_CTIME;
+			const FATTR_KILL_SUIDGID = linux::FATTR_KILL_SUIDGID;
+		}
+	}
+
+	impl Setattr {
+		pub(crate) fn create(
+			nid: u64,
+			fh: u64,
+			attr: FileAttr,
+			valid_attr: SetAttrValidFields,
+		) -> (Cmd<Self>, u32) {
+			let cmd = Cmd::new(
+				nid,
+				fuse_setattr_in {
+					valid: valid_attr
+						.difference(
+							// Remove unsupported attributes
+							SetAttrValidFields::FATTR_LOCKOWNER,
+						)
+						.bits(),
+					padding: 0,
+					fh,
+
+					// Fuse attributes mapping: https://github.com/libfuse/libfuse/blob/fc1c8da0cf8a18d222cb1feed0057ba44ea4d18f/lib/fuse_lowlevel.c#L105
+					size: attr.st_size as u64,
+					atime: attr.st_atim.tv_sec as u64,
+					atimensec: attr.st_atim.tv_nsec as u32,
+					mtime: attr.st_ctim.tv_sec as u64,
+					mtimensec: attr.st_ctim.tv_nsec as u32,
+					ctime: attr.st_ctim.tv_sec as u64,
+					ctimensec: attr.st_ctim.tv_nsec as u32,
+					mode: attr.st_mode.bits(),
+					unused4: 0,
+					uid: attr.st_uid,
+					gid: attr.st_gid,
+					unused5: 0,
+
+					lock_owner: 0, // unsupported
+				},
+			);
+
+			(cmd, 0)
+		}
+	}
+
 	#[derive(Debug)]
 	pub(crate) struct Readlink;
 
@@ -758,6 +830,23 @@ impl FuseFileHandleInner {
 			Err(Errno::Io)
 		}
 	}
+
+	fn set_attr(&mut self, attr: FileAttr, valid: SetAttrValidFields) -> io::Result<FileAttr> {
+		debug!("FUSE setattr");
+		if let (Some(nid), Some(fh)) = (self.fuse_nid, self.fuse_fh) {
+			let (cmd, rsp_payload_len) = ops::Setattr::create(nid, fh, attr, valid);
+			let rsp = get_filesystem_driver()
+				.ok_or(Errno::Nosys)?
+				.lock()
+				.send_command(cmd, rsp_payload_len)?;
+			if rsp.headers.out_header.error < 0 {
+				return Err(Errno::Io);
+			}
+			Ok(rsp.headers.op_header.attr.into())
+		} else {
+			Err(Errno::Io)
+		}
+	}
 }
 
 impl Drop for FuseFileHandleInner {
@@ -804,6 +893,32 @@ impl ObjectInterface for FuseFileHandle {
 	async fn fstat(&self) -> io::Result<FileAttr> {
 		self.0.lock().await.fstat()
 	}
+
+	async fn truncate(&self, size: usize) -> io::Result<()> {
+		let attr = FileAttr {
+			st_size: size.try_into().unwrap(),
+			..FileAttr::default()
+		};
+
+		self.0
+			.lock()
+			.await
+			.set_attr(attr, SetAttrValidFields::FATTR_SIZE)
+			.map(|_| ())
+	}
+
+	async fn chmod(&self, access_permission: AccessPermission) -> io::Result<()> {
+		let attr = FileAttr {
+			st_mode: access_permission,
+			..FileAttr::default()
+		};
+
+		self.0
+			.lock()
+			.await
+			.set_attr(attr, SetAttrValidFields::FATTR_MODE)
+			.map(|_| ())
+	}
 }
 
 impl Clone for FuseFileHandle {

src/fs/mem.rs

@@ -256,6 +256,19 @@ impl ObjectInterface for RamFileInterface {
 		let guard = self.inner.read().await;
 		Ok(guard.attr)
 	}
+
+	async fn truncate(&self, size: usize) -> io::Result<()> {
+		let mut guard = self.inner.write().await;
+		guard.data.resize(size, 0);
+		guard.attr.st_size = size as i64;
+		Ok(())
+	}
+
+	async fn chmod(&self, access_permission: AccessPermission) -> io::Result<()> {
+		let mut guard = self.inner.write().await;
+		guard.attr.st_mode = access_permission;
+		Ok(())
+	}
 }
 
 impl RamFileInterface {