Add new mount api syscall for linux (#752)

* Add new mount api syscall for linux_raw

* Add new mount api syscall for libc of linux

* Add new mount api syscall for linux

src/backend/libc/fs/syscalls.rs

@@ -2103,6 +2103,231 @@ pub(crate) fn unmount(target: &CStr, flags: super::types::UnmountFlags) -> io::R
     unsafe { ret(c::umount2(target.as_ptr(), bitflags_bits!(flags))) }
 }
 
+#[cfg(linux_kernel)]
+pub(crate) fn fsopen(fs_name: &CStr, flags: super::types::FsOpenFlags) -> io::Result<OwnedFd> {
+    syscall! {
+        fn fsopen(
+            fs_name: *const c::c_char,
+            flags: c::c_uint
+        ) via SYS_fsopen -> c::c_int
+    }
+    unsafe { ret_owned_fd(fsopen(c_str(fs_name), flags.bits())) }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fsmount(
+    fs_fd: BorrowedFd<'_>,
+    flags: super::types::FsMountFlags,
+    attr_flags: super::types::MountAttrFlags,
+) -> io::Result<()> {
+    syscall! {
+        fn fsmount(
+            fs_fd: c::c_int,
+            flags: c::c_uint,
+            attr_flags: c::c_uint
+        ) via SYS_fsmount -> c::c_int
+    }
+    unsafe { ret(fsmount(borrowed_fd(fs_fd), flags.bits(), attr_flags.bits())) }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn move_mount(
+    from_dfd: BorrowedFd<'_>,
+    from_pathname: &CStr,
+    to_dfd: BorrowedFd<'_>,
+    to_pathname: &CStr,
+    flags: super::types::MoveMountFlags,
+) -> io::Result<()> {
+    syscall! {
+        fn move_mount(
+            from_dfd: c::c_int,
+            from_pathname: *const c::c_char,
+            to_dfd: c::c_int,
+            to_pathname: *const c::c_char,
+            flags: c::c_uint
+        ) via SYS_move_mount -> c::c_int
+    }
+    unsafe {
+        ret(move_mount(
+            borrowed_fd(from_dfd),
+            c_str(from_pathname),
+            borrowed_fd(to_dfd),
+            c_str(to_pathname),
+            flags.bits(),
+        ))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn open_tree(
+    dfd: BorrowedFd<'_>,
+    filename: &CStr,
+    flags: super::types::OpenTreeFlags,
+) -> io::Result<OwnedFd> {
+    syscall! {
+        fn open_tree(
+            dfd: c::c_int,
+            filename: *const c::c_char,
+            flags: c::c_uint
+        ) via SYS_open_tree -> c::c_int
+    }
+
+    unsafe { ret_owned_fd(open_tree(borrowed_fd(dfd), c_str(filename), flags.bits())) }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fspick(
+    dfd: BorrowedFd<'_>,
+    path: &CStr,
+    flags: super::types::FsPickFlags,
+) -> io::Result<OwnedFd> {
+    syscall! {
+        fn fspick(
+            dfd: c::c_int,
+            path: *const c::c_char,
+            flags: c::c_uint
+        ) via SYS_fspick -> c::c_int
+    }
+
+    unsafe { ret_owned_fd(fspick(borrowed_fd(dfd), c_str(path), flags.bits())) }
+}
+
+#[cfg(linux_kernel)]
+syscall! {
+    fn fsconfig(
+        fs_fd: c::c_int,
+        cmd: c::c_uint,
+        key: *const c::c_char,
+        val: *const c::c_char,
+        aux: c::c_int
+    ) via SYS_fsconfig -> c::c_int
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fsconfig_set_flag(fs_fd: BorrowedFd<'_>, key: &CStr) -> io::Result<()> {
+    unsafe {
+        ret(fsconfig(
+            borrowed_fd(fs_fd),
+            super::types::FsConfigCmd::SetFlag as _,
+            c_str(key),
+            null(),
+            0,
+        ))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fsconfig_set_string(
+    fs_fd: BorrowedFd<'_>,
+    key: &CStr,
+    value: &CStr,
+) -> io::Result<()> {
+    unsafe {
+        ret(fsconfig(
+            borrowed_fd(fs_fd),
+            super::types::FsConfigCmd::SetString as _,
+            c_str(key),
+            c_str(value),
+            0,
+        ))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fsconfig_set_binary(
+    fs_fd: BorrowedFd<'_>,
+    key: &CStr,
+    value: &[u8],
+) -> io::Result<()> {
+    unsafe {
+        ret(fsconfig(
+            borrowed_fd(fs_fd),
+            super::types::FsConfigCmd::SetBinary as _,
+            c_str(key),
+            value.as_ptr().cast(),
+            value.len().try_into().map_err(|_| io::Errno::OVERFLOW)?,
+        ))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fsconfig_set_fd(
+    fs_fd: BorrowedFd<'_>,
+    key: &CStr,
+    fd: BorrowedFd<'_>,
+) -> io::Result<()> {
+    unsafe {
+        ret(fsconfig(
+            borrowed_fd(fs_fd),
+            super::types::FsConfigCmd::SetFd as _,
+            c_str(key),
+            null(),
+            borrowed_fd(fd),
+        ))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fsconfig_set_path(
+    fs_fd: BorrowedFd<'_>,
+    key: &CStr,
+    path: &CStr,
+    fd: BorrowedFd<'_>,
+) -> io::Result<()> {
+    unsafe {
+        ret(fsconfig(
+            borrowed_fd(fs_fd),
+            super::types::FsConfigCmd::SetPath as _,
+            c_str(key),
+            c_str(path),
+            borrowed_fd(fd),
+        ))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fsconfig_set_path_empty(
+    fs_fd: BorrowedFd<'_>,
+    key: &CStr,
+    fd: BorrowedFd<'_>,
+) -> io::Result<()> {
+    unsafe {
+        ret(fsconfig(
+            borrowed_fd(fs_fd),
+            super::types::FsConfigCmd::SetPathEmpty as _,
+            c_str(key),
+            c_str(cstr!("")),
+            borrowed_fd(fd),
+        ))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fsconfig_create(fs_fd: BorrowedFd<'_>) -> io::Result<()> {
+    unsafe {
+        ret(fsconfig(
+            borrowed_fd(fs_fd),
+            super::types::FsConfigCmd::Create as _,
+            null(),
+            null(),
+            0,
+        ))
+    }
+}
+
+#[cfg(linux_kernel)]
+pub(crate) fn fsconfig_reconfigure(fs_fd: BorrowedFd<'_>) -> io::Result<()> {
+    unsafe {
+        ret(fsconfig(
+            borrowed_fd(fs_fd),
+            super::types::FsConfigCmd::Reconfigure as _,
+            null(),
+            null(),
+            0,
+        ))
+    }
+}
+
 #[cfg(any(apple, linux_kernel))]
 pub(crate) fn getxattr(path: &CStr, name: &CStr, value: &mut [u8]) -> io::Result<usize> {
     let value_ptr = value.as_mut_ptr();