Remove the flags argument handling in fchmodat syscall

The flags argument of fchmodat syscall is handled by the wrapper
function in libc already, so Occlum does not need to accept this argument.

src/libos/src/fs/file_ops/chmod.rs

@@ -55,27 +55,14 @@ impl FileMode {
     }
 }
 
-bitflags! {
+pub fn do_fchmodat(fs_path: &FsPath, mode: FileMode) -> Result<()> {
-    pub struct ChmodFlags: i32 {
+    debug!("fchmodat: fs_path: {:?}, mode: {:#o}", fs_path, mode);
-        const AT_SYMLINK_NOFOLLOW = 0x100;
-    }
-}
-
-pub fn do_fchmodat(fs_path: &FsPath, mode: FileMode, flags: ChmodFlags) -> Result<()> {
-    debug!(
-        "fchmodat: fs_path: {:?}, mode: {:#o}, flags: {:?}",
-        fs_path, mode, flags
-    );
 
     let inode = {
         let path = fs_path.to_abs_path()?;
         let current = current!();
         let fs = current.fs().lock().unwrap();
-        if flags.contains(ChmodFlags::AT_SYMLINK_NOFOLLOW) {
+        fs.lookup_inode(&path)?
-            fs.lookup_inode_no_follow(&path)?
-        } else {
-            fs.lookup_inode(&path)?
-        }
     };
     let mut info = inode.metadata()?;
     info.mode = mode.bits();

src/libos/src/fs/file_ops/mod.rs

@@ -3,7 +3,7 @@ use super::*;
 use process::Process;
 
 pub use self::access::{do_faccessat, AccessibilityCheckFlags, AccessibilityCheckMode};
-pub use self::chmod::{do_fchmod, do_fchmodat, ChmodFlags, FileMode};
+pub use self::chmod::{do_fchmod, do_fchmodat, FileMode};
 pub use self::chown::{do_fchown, do_fchownat, ChownFlags};
 pub use self::close::do_close;
 pub use self::dirent::{do_getdents, do_getdents64};

src/libos/src/fs/syscalls.rs

@@ -1,8 +1,8 @@
 use super::event_file::EventCreationFlags;
 use super::file_ops;
 use super::file_ops::{
-    AccessibilityCheckFlags, AccessibilityCheckMode, ChmodFlags, ChownFlags, FcntlCmd, FsPath,
+    AccessibilityCheckFlags, AccessibilityCheckMode, ChownFlags, FcntlCmd, FsPath, LinkFlags,
-    LinkFlags, StatFlags, UnlinkFlags, AT_FDCWD,
+    StatFlags, UnlinkFlags, AT_FDCWD,
 };
 use super::fs_ops;
 use super::*;
@@ -433,7 +433,7 @@ pub fn do_symlinkat(target: *const i8, new_dirfd: i32, link_path: *const i8) ->
 }
 
 pub fn do_chmod(path: *const i8, mode: u16) -> Result<isize> {
-    self::do_fchmodat(AT_FDCWD, path, mode, 0)
+    self::do_fchmodat(AT_FDCWD, path, mode)
 }
 
 pub fn do_fchmod(fd: FileDesc, mode: u16) -> Result<isize> {
@@ -442,14 +442,13 @@ pub fn do_fchmod(fd: FileDesc, mode: u16) -> Result<isize> {
     Ok(0)
 }
 
-pub fn do_fchmodat(dirfd: i32, path: *const i8, mode: u16, flags: i32) -> Result<isize> {
+pub fn do_fchmodat(dirfd: i32, path: *const i8, mode: u16) -> Result<isize> {
     let path = from_user::clone_cstring_safely(path)?
         .to_string_lossy()
         .into_owned();
     let mode = FileMode::from_bits_truncate(mode);
     let fs_path = FsPath::new(&path, dirfd, false)?;
-    let flags = ChmodFlags::from_bits(flags).ok_or_else(|| errno!(EINVAL, "invalid flags"))?;
+    file_ops::do_fchmodat(&fs_path, mode)?;
-    file_ops::do_fchmodat(&fs_path, mode, flags)?;
     Ok(0)
 }
 

src/libos/src/syscall/mod.rs

@@ -352,7 +352,7 @@ macro_rules! process_syscall_table_with_callback {
             (Linkat = 265) => do_linkat(olddirfd: i32, oldpath: *const i8, newdirfd: i32, newpath: *const i8, flags: i32),
             (Symlinkat = 266) => do_symlinkat(target: *const i8, new_dirfd: i32, link_path: *const i8),
             (Readlinkat = 267) => do_readlinkat(dirfd: i32, path: *const i8, buf: *mut u8, size: usize),
-            (Fchmodat = 268) => do_fchmodat(dirfd: i32, path: *const i8, mode: u16, flags: i32),
+            (Fchmodat = 268) => do_fchmodat(dirfd: i32, path: *const i8, mode: u16),
             (Faccessat = 269) => do_faccessat(dirfd: i32, path: *const i8, mode: u32, flags: u32),
             (Pselect6 = 270) => handle_unsupported(),
             (Ppoll = 271) => handle_unsupported(),