feat/fix: change a few system calls and add stub values

Cargo.toml

@@ -79,6 +79,12 @@ mman = []
 ## [hermit-c]: https://github.com/hermit-os/hermit-c
 newlib = []
 
+## Enable stubbing result values for some system calls.
+##
+## For some system calls related to system options in which Hermit does not implement all possible options,
+## return 0 (success) instead of an error when the option is unknown ; or return a convincing fake value.
+syscall-fake-values = []
+
 #! ### Platform Features
 
 ## Enables [Uhyve] support.

src/fs/mem.rs

@@ -8,6 +8,8 @@ use alloc::sync::Arc;
 use alloc::vec::Vec;
 use core::marker::PhantomData;
 use core::mem::MaybeUninit;
+#[cfg(feature = "syscall-fake-values")]
+use core::sync::atomic::{AtomicU64, Ordering};
 use core::{mem, ptr};
 
 use align_address::Align;
@@ -36,6 +38,9 @@ impl RomFileInner {
 	}
 }
 
+#[cfg(feature = "syscall-fake-values")]
+static VFS_INO_NUM: AtomicU64 = AtomicU64::new(10_000);
+
 pub struct RomFileInterface {
 	/// Position within the file
 	pos: Mutex<usize>,
@@ -306,6 +311,8 @@ impl RomFile {
 			st_atim: t,
 			st_mtim: t,
 			st_ctim: t,
+			#[cfg(feature = "syscall-fake-values")]
+			st_ino: VFS_INO_NUM.fetch_add(1, Ordering::AcqRel),
 			..Default::default()
 		};
 
@@ -361,6 +368,12 @@ impl RamFile {
 			st_atim: t,
 			st_mtim: t,
 			st_ctim: t,
+			#[cfg(feature = "syscall-fake-values")]
+			st_nlink: 1,
+			#[cfg(feature = "syscall-fake-values")]
+			st_blksize: 4096,
+			#[cfg(feature = "syscall-fake-values")]
+			st_ino: VFS_INO_NUM.fetch_add(1, Ordering::AcqRel),
 			..Default::default()
 		};
 
@@ -614,15 +627,17 @@ impl VfsNode for MemDirectory {
 		block_on(
 			async {
 				let (component, rest) = path.split_once("/").unwrap_or((path, ""));
+				let inner = self.inner.read().await;
+				let node = inner.get(component).ok_or(Errno::Badf)?;
 
 				if !rest.is_empty() {
-					let inner = self.inner.read().await;
-					let directory = inner.get(component).ok_or(Errno::Badf)?;
-					return directory.traverse_lstat(rest);
+					if node.get_kind() == NodeKind::File {
+						Err(Errno::Notdir)?;
+					}
+
+					return node.traverse_lstat(rest);
 				}
 
-				let inner = self.inner.read().await;
-				let node = inner.get(component).ok_or(Errno::Badf)?;
 				node.get_file_attributes()
 			},
 			None,
@@ -633,15 +648,17 @@ impl VfsNode for MemDirectory {
 		block_on(
 			async {
 				let (component, rest) = path.split_once("/").unwrap_or((path, ""));
+				let inner = self.inner.read().await;
+				let node = inner.get(component).ok_or(Errno::Badf)?;
 
 				if !rest.is_empty() {
-					let inner = self.inner.read().await;
-					let directory = inner.get(component).ok_or(Errno::Badf)?;
-					return directory.traverse_stat(rest);
+					if node.get_kind() == NodeKind::File {
+						Err(Errno::Notdir)?;
+					}
+
+					return node.traverse_stat(rest);
 				}
 
-				let inner = self.inner.read().await;
-				let node = inner.get(component).ok_or(Errno::Badf)?;
 				node.get_file_attributes()
 			},
 			None,

src/syscalls/mod.rs

@@ -482,10 +482,6 @@ pub unsafe extern "C" fn sys_access(name: *const c_char, flags: i32) -> i32 {
 		return -i32::from(Errno::Inval);
 	};
 
-	if access_option.contains(AccessOption::F_OK) && access_option != AccessOption::F_OK {
-		return -i32::from(Errno::Inval);
-	}
-
 	let Ok(name) = unsafe { CStr::from_ptr(name) }.to_str() else {
 		return -i32::from(Errno::Inval);
 	};
@@ -684,13 +680,17 @@ pub unsafe extern "C" fn sys_ioctl(fd: RawFd, cmd: i32, argp: *mut core::ffi::c_
 #[hermit_macro::system(errno)]
 #[unsafe(no_mangle)]
 pub extern "C" fn sys_fcntl(fd: i32, cmd: i32, arg: i32) -> i32 {
+	const F_GETFD: i32 = 1;
 	const F_SETFD: i32 = 2;
 	const F_GETFL: i32 = 3;
 	const F_SETFL: i32 = 4;
 	const FD_CLOEXEC: i32 = 1;
 
 	if cmd == F_SETFD && arg == FD_CLOEXEC {
 		0
+	} else if cmd == F_GETFD {
+		// Only the FD_CLOEXEC flag is defined, and it has no effect in hermit, so always return 0
+		0
 	} else if cmd == F_GETFL {
 		let obj = get_object(fd);
 		obj.map_or_else(
@@ -717,6 +717,9 @@ pub extern "C" fn sys_fcntl(fd: i32, cmd: i32, arg: i32) -> i32 {
 				.map_or_else(|e| -i32::from(e), |()| 0)
 			},
 		)
+	} else if cfg!(feature = "syscall-fake-values") {
+		warn!("[syscall-fake-values] Unknown fcntl flag {cmd} {arg}, returning 0");
+		0
 	} else {
 		-i32::from(Errno::Inval)
 	}