don't show fallback ~ lines if not initial draw

Author: aaron-ang

src/uu/more/src/more.rs

@@ -336,7 +336,7 @@ fn more(
     }
 
     // Initial display
-    pager.draw(&mut stdout, None)?;
+    pager.draw(&mut stdout, true, None)?;
 
     // Reset multi-file settings after initial display
     if multiple_file {
@@ -446,7 +446,7 @@ fn process_events(pager: &mut Pager, stdout: &mut Stdout, options: &Options) ->
             _ => continue,
         }
         update_display(stdout, options)?;
-        pager.draw(stdout, wrong_key)?;
+        pager.draw(stdout, false, wrong_key)?;
     }
 }
 
@@ -532,7 +532,7 @@ impl<'a> Pager<'a> {
             lines_squeezed: 0,
         };
 
-        // Load initial content
+        // Start from the specified line
         pager.read_until_line(pager.upper_mark)?;
 
         // Handle pattern search if specified
@@ -549,24 +549,25 @@ impl<'a> Pager<'a> {
         Ok(pager)
     }
 
-    fn read_until_line(&mut self, line_num: usize) -> UResult<()> {
-        // Read until we reach the specified line number or EOF
+    fn read_until_line(&mut self, target_line: usize) -> UResult<()> {
+        // Check if already read enough lines
+        if self.lines.len() > target_line {
+            return Ok(());
+        }
+        // Read lines until we reach the target line or EOF
         let mut line = String::new();
-        while self.lines.len() <= line_num {
+        while self.lines.len() <= target_line {
             line.clear();
             let bytes_read = self.input.read_line(&mut line)?;
             if bytes_read == 0 {
                 self.eof_reached = true;
-                // Adjust upper mark to ensure content fills the screen
-                // without going beyond available lines
-                self.upper_mark = self.lines.len().saturating_sub(self.content_rows);
                 break;
             }
             // Track cumulative byte position
             let current_position =
                 self.cumulative_line_sizes.last().unwrap_or(&0) + bytes_read as u64;
             self.cumulative_line_sizes.push(current_position);
-            // Use mem::take to avoid unnecessary clone
+            // Store the line (using mem::take to avoid clone)
             self.lines.push(std::mem::take(&mut line));
         }
         Ok(())
@@ -637,14 +638,19 @@ impl<'a> Pager<'a> {
         };
     }
 
-    fn draw(&mut self, stdout: &mut Stdout, wrong_key: Option<char>) -> UResult<()> {
-        self.draw_lines(stdout)?;
+    fn draw(
+        &mut self,
+        stdout: &mut Stdout,
+        first_paint: bool,
+        wrong_key: Option<char>,
+    ) -> UResult<()> {
+        self.draw_lines(stdout, first_paint)?;
         self.draw_prompt(stdout, wrong_key);
         stdout.flush()?;
         Ok(())
     }
 
-    fn draw_lines(&mut self, stdout: &mut impl Write) -> UResult<()> {
+    fn draw_lines(&mut self, stdout: &mut impl Write, first_paint: bool) -> UResult<()> {
         // Clear current prompt line
         stdout.queue(Clear(ClearType::CurrentLine))?;
 
@@ -665,6 +671,10 @@ impl<'a> Pager<'a> {
                 index += 1;
                 continue;
             }
+            // Stop if we reach the end of the file and not in first paint
+            if !first_paint && index >= self.lines.len() {
+                break;
+            }
             // Display the line
             let line = self.lines.get(index).unwrap_or(&fallback);
             stdout.write_all(format!("\r{}", line).as_bytes())?;