fat: Improve handling of longer filenames

This patch increases the size of the byte array to 12 bytes (so that the
'.' can be included for files that are named the full 8 + 3 bytes. If
the string presented is exactly 11 bytes then adjust it to correctly
included the '.' separator.

Fixes: #261
Signed-off-by: Jianyong Wu <[email protected]>

src/fat.rs

@@ -232,6 +232,17 @@ fn name_to_str(input: &str, output: &mut [u8]) {
             break;
         }
     }
+
+    // If name is exactly 11 characters long then ensure separator is correctly added
+    if (output[10] >= b'a' && output[10] <= b'z' || output[10] >= b'A' && output[10] <= b'Z')
+        && output[7] != b' '
+        && output[7] != b'.'
+    {
+        output[11] = output[10];
+        output[10] = output[9];
+        output[9] = output[8];
+        output[8] = b'.';
+    }
 }
 
 impl<'a> Read for Node<'a> {
@@ -403,9 +414,9 @@ impl<'a> Directory<'a> {
         }
     }
 
-    pub fn next_node(&mut self) -> Result<(Node, [u8; 11]), Error> {
+    pub fn next_node(&mut self) -> Result<(Node, [u8; 12]), Error> {
         let de = self.next_entry()?;
-        let mut name = [0_u8; 11];
+        let mut name = [0_u8; 12];
         name_to_str(core::str::from_utf8(&de.name).unwrap(), &mut name);
 
         match de.file_type {
@@ -1172,17 +1183,17 @@ mod tests {
 
     #[test]
     fn test_name_to_str() {
-        let mut s = [0_u8; 11];
+        let mut s = [0_u8; 12];
         super::name_to_str("X       ABC", &mut s);
         assert_eq!(crate::common::ascii_strip(&s), "X.ABC");
-        let mut s = [0_u8; 11];
+        let mut s = [0_u8; 12];
         super::name_to_str(".", &mut s);
         assert_eq!(crate::common::ascii_strip(&s), ".");
-        let mut s = [0_u8; 11];
+        let mut s = [0_u8; 12];
         super::name_to_str("..", &mut s);
         assert_eq!(crate::common::ascii_strip(&s), "..");
-        let mut s = [0_u8; 11];
+        let mut s = [0_u8; 12];
         super::name_to_str("ABCDEFGHIJK", &mut s);
-        assert_eq!(crate::common::ascii_strip(&s), "ABCDEFGHIJK");
+        assert_eq!(crate::common::ascii_strip(&s), "ABCDEFGH.IJK");
     }
 }