feat(mmap): ensure the file is readable

Signed-off-by: Anhad Singh <andypythonappdeveloper@gmail.com>

Author: Andy-Python-Programmer

src/aero_kernel/src/fs/file_table.rs

@@ -65,8 +65,10 @@ impl FileHandle {
 
     #[inline]
     pub fn is_readable(&self) -> bool {
-        self.flags()
-            .intersects(OpenFlags::O_RDONLY | OpenFlags::O_RDWR)
+        // FIXME: switch to Linux ABI for fcntl. mlibc defines O_RDONLY as 0 so, we have to infer
+        // the read-only flag.
+        let flags = self.flags();
+        flags.contains(OpenFlags::O_RDWR) || !flags.contains(OpenFlags::O_WRONLY)
     }
 
     pub fn flags(&self) -> OpenFlags {

src/aero_kernel/src/userland/vm.rs

@@ -1410,7 +1410,7 @@ impl Vm {
                 }
 
                 if !file.is_readable() {
-                    // return None; // EACCES
+                    return None; // EACCES
                 }
 
                 // TODO: * check if the filsystem is noexec mounted and remove the MAY_EXEC flag.
@@ -1419,7 +1419,7 @@ impl Vm {
 
             (MMapFlags::MAP_PRIVATE, Some(file)) => {
                 if !file.is_readable() {
-                    // return None; // EACCES
+                    return None; // EACCES
                 }
 
                 // TODO: * check if the filsystem is noexec mounted and remove the MAY_EXEC flag.