From 7921064ae2156293bb5d5e1a32bc4b5fabc45926 Mon Sep 17 00:00:00 2001
From: Moritz Gmeiner <moritz@gmeiner.net>
Date: Tue, 29 Jul 2025 20:34:35 +0200
Subject: [PATCH] moved short name str into separate buffer

---
 fat-bits/src/dir.rs | 106 ++++++++++++++++++++++++++++++++------------
 1 file changed, 78 insertions(+), 28 deletions(-)

diff --git a/fat-bits/src/dir.rs b/fat-bits/src/dir.rs
index bc8e7a4..be69a54 100644
--- a/fat-bits/src/dir.rs
+++ b/fat-bits/src/dir.rs
@@ -64,24 +64,30 @@ pub struct DirEntry {
 
     file_size: u32,
 
+    // buffer for holding short name str representation
+    // initial dot if hidden (1)
+    // stem (8)
+    // dot (1)
+    // extension (3)
+    short_name: [u8; 13],
     long_name: Option<String>,
 }
 
 impl Display for DirEntry {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let mut name = self.name_string().unwrap_or_else(|| "<unknown>".to_owned());
+        let name = self.name_str().unwrap_or("<unknown>");
 
-        if self.attr.contains(Attr::Directory) {
-            name.push('/');
-        }
+        // add slash to end of dir_names
+        let dir_slash = if self.is_dir() { "/" } else { " " };
 
         write!(
             f,
-            "{}    {}",
+            "{}    {}{}",
             self.attr,
             // self.create_time().format("%a %b %d %H:%M:%S%.3f %Y"),
             // self.write_time().format("%a %b %d %H:%M:%S%.3f %Y"),
             name,
+            dir_slash,
         )?;
 
         Ok(())
@@ -92,7 +98,7 @@ impl DirEntry {
     pub fn load(bytes: &[u8]) -> anyhow::Result<DirEntry> {
         assert_eq!(bytes.len(), 32);
 
-        let name = bytes[..11].try_into().unwrap();
+        let name: [u8; 11] = bytes[..11].try_into().unwrap();
         let attr = Attr::from_bits_truncate(bytes[11]);
 
         let create_time_tenths = bytes[13];
@@ -130,6 +136,32 @@ impl DirEntry {
             )
         }
 
+        let mut short_name = [0; 13];
+
+        let mut short_name_iter = short_name.iter_mut();
+
+        if attr.contains(Attr::Hidden) {
+            // if hidden: lead with '.'
+            *short_name_iter.next().unwrap() = b'.';
+        }
+
+        if name[0] != 0 && name[0] != 0xe5 {
+            // dir_entry is not free
+
+            for c in name[..8].iter().filter(|&x| x != &0x20) {
+                *short_name_iter.next().unwrap() = *c;
+            }
+
+            if &name[8..] != &[0x20, 0x20, 0x20] {
+                // if extension is not empty: add dot and extension
+                *short_name_iter.next().unwrap() = b'.';
+
+                for c in name[8..].iter().filter(|&x| x != &0x20) {
+                    *short_name_iter.next().unwrap() = *c;
+                }
+            }
+        }
+
         Ok(DirEntry {
             name,
             attr,
@@ -141,6 +173,7 @@ impl DirEntry {
             write_time,
             write_date,
             file_size,
+            short_name,
             long_name: None,
         })
     }
@@ -216,29 +249,19 @@ impl DirEntry {
         std::str::from_utf8(self.extension()).ok()
     }
 
-    pub fn name_string(&self) -> Option<String> {
-        if let Some(long_filename) = self.long_name() {
-            return Some(long_filename.to_owned());
+    fn short_name(&self) -> &[u8] {
+        &self.short_name
+    }
+
+    fn short_name_str(&self) -> Option<&str> {
+        let mut short_name = self.short_name();
+
+        // remove trailing zeros
+        while short_name.last() == Some(&0) {
+            short_name = &short_name[..short_name.len() - 1];
         }
 
-        let name = std::str::from_utf8(&self.name[..8]).ok()?.trim_ascii_end();
-        let ext = std::str::from_utf8(&self.name[8..]).ok()?.trim_ascii_end();
-
-        let mut s = String::new();
-
-        if self.attr.contains(Attr::Hidden) {
-            s.push('.');
-        }
-
-        s += name;
-
-        if !ext.is_empty() {
-            s.push('.');
-
-            s += ext;
-        }
-
-        Some(s)
+        std::str::from_utf8(short_name).ok()
     }
 
     pub fn long_name(&self) -> Option<&str> {
@@ -249,6 +272,33 @@ impl DirEntry {
         self.long_name = Some(long_name);
     }
 
+    pub fn name_str(&self) -> Option<&str> {
+        if let Some(long_filename) = self.long_name() {
+            return Some(long_filename);
+        }
+
+        self.short_name_str()
+
+        // let name = std::str::from_utf8(&self.name[..8]).ok()?.trim_ascii_end();
+        // let ext = std::str::from_utf8(&self.name[8..]).ok()?.trim_ascii_end();
+
+        // let mut s = String::new();
+
+        // if self.attr.contains(Attr::Hidden) {
+        //     s.push('.');
+        // }
+
+        // s += name;
+
+        // if !ext.is_empty() {
+        //     s.push('.');
+
+        //     s += ext;
+        // }
+
+        // Some(s)
+    }
+
     pub fn attr(&self) -> Attr {
         self.attr
     }
@@ -540,7 +590,7 @@ impl<R: Read> DirIter<R> {
             .map_err(|e| {
                 anyhow::anyhow!(
                     "failed to get long filename for {}: {}",
-                    dir_entry.name_string().as_deref().unwrap_or("<invalid>"),
+                    dir_entry.name_str().as_deref().unwrap_or("<invalid>"),
                     e
                 )
             })? {