dd: fix output issues (#3610)

src/uu/dd/src/dd.rs

@@ -346,15 +346,6 @@ where
         })
     }
 
-    /// Print the read/write statistics.
-    fn print_stats<R: Read>(&self, i: &Input<R>, prog_update: &ProgUpdate) {
-        match i.print_level {
-            Some(StatusLevel::None) => {}
-            Some(StatusLevel::Noxfer) => prog_update.print_io_lines(),
-            Some(StatusLevel::Progress) | None => prog_update.print_transfer_stats(),
-        }
-    }
-
     /// Flush the output to disk, if configured to do so.
     fn sync(&mut self) -> std::io::Result<()> {
         if self.cflags.fsync {
@@ -404,15 +395,17 @@ where
 
         // Start a thread that reports transfer progress.
         //
-        // When `status=progress` is given on the command-line, the
-        // `dd` program reports its progress every second or so. We
+        // The `dd` program reports its progress after every block is written,
+        // at most every 1 second, and only if `status=progress` is given on
+        // the command-line or a SIGUSR1 signal is received. We
         // perform this reporting in a new thread so as not to take
         // any CPU time away from the actual reading and writing of
         // data. We send a `ProgUpdate` from the transmitter `prog_tx`
         // to the receives `rx`, and the receiver prints the transfer
         // information.
         let (prog_tx, rx) = mpsc::channel();
-        thread::spawn(gen_prog_updater(rx, i.print_level));
+        let output_thread = thread::spawn(gen_prog_updater(rx, i.print_level));
+        let mut progress_as_secs = 0;
 
         // Create a common buffer with a capacity of the block size.
         // This is the max size needed.
@@ -437,7 +430,7 @@ where
             }
             let wstat_update = self.write_blocks(&buf)?;
 
-            // Update the read/write stats and inform the progress thread.
+            // Update the read/write stats and inform the progress thread once per second.
             //
             // If the receiver is disconnected, `send()` returns an
             // error. Since it is just reporting progress and is not
@@ -445,16 +438,23 @@ where
             // error.
             rstat += rstat_update;
             wstat += wstat_update;
-            let prog_update = ProgUpdate::new(rstat, wstat, start.elapsed());
-            prog_tx.send(prog_update).unwrap_or(());
+            let prog_update = ProgUpdate::new(rstat, wstat, start.elapsed(), false);
+            if prog_update.duration.as_secs() >= progress_as_secs {
+                progress_as_secs = prog_update.duration.as_secs() + 1;
+                prog_tx.send(prog_update).unwrap_or(());
+            }
         }
 
         // Flush the output, if configured to do so.
         self.sync()?;
 
         // Print the final read/write statistics.
-        let prog_update = ProgUpdate::new(rstat, wstat, start.elapsed());
-        self.print_stats(&i, &prog_update);
+        let prog_update = ProgUpdate::new(rstat, wstat, start.elapsed(), true);
+        prog_tx.send(prog_update).unwrap_or(());
+        // Wait for the output thread to finish
+        output_thread
+            .join()
+            .expect("Failed to join with the output thread.");
         Ok(())
     }
 }

src/uu/dd/src/progress.rs

@@ -44,15 +44,26 @@ pub(crate) struct ProgUpdate {
 
     /// The time period over which the reads and writes were measured.
     pub(crate) duration: Duration,
+
+    /// The status of the write.
+    ///
+    /// True if the write is completed, false if still in-progress.
+    pub(crate) complete: bool,
 }
 
 impl ProgUpdate {
     /// Instantiate this struct.
-    pub(crate) fn new(read_stat: ReadStat, write_stat: WriteStat, duration: Duration) -> Self {
+    pub(crate) fn new(
+        read_stat: ReadStat,
+        write_stat: WriteStat,
+        duration: Duration,
+        complete: bool,
+    ) -> Self {
         Self {
             read_stat,
             write_stat,
             duration,
+            complete,
         }
     }
 
@@ -175,7 +186,8 @@ impl ProgUpdate {
     /// This is a convenience method that calls
     /// [`ProgUpdate::write_io_lines`] and
     /// [`ProgUpdate::write_prog_line`] in that order. The information
-    /// is written to `w`.
+    /// is written to `w`. It optionally begins by writing a new line,
+    /// intended to handle the case of an existing progress line.
     ///
     /// # Examples
     ///
@@ -190,7 +202,7 @@ impl ProgUpdate {
     ///     duration: Duration::new(1, 0), // one second
     /// };
     /// let mut cursor = Cursor::new(vec![]);
-    /// prog_update.write_transfer_stats(&mut cursor).unwrap();
+    /// prog_update.write_transfer_stats(&mut cursor, false).unwrap();
     /// let mut iter = cursor.get_ref().split(|v| *v == b'\n');
     /// assert_eq!(iter.next().unwrap(), b"0+0 records in");
     /// assert_eq!(iter.next().unwrap(), b"0+0 records out");
@@ -198,7 +210,10 @@ impl ProgUpdate {
     /// assert_eq!(iter.next().unwrap(), b"");
     /// assert!(iter.next().is_none());
     /// ```
-    fn write_transfer_stats(&self, w: &mut impl Write) -> std::io::Result<()> {
+    fn write_transfer_stats(&self, w: &mut impl Write, new_line: bool) -> std::io::Result<()> {
+        if new_line {
+            writeln!(w)?;
+        }
         self.write_io_lines(w)?;
         let rewrite = false;
         self.write_prog_line(w, rewrite)?;
@@ -225,9 +240,22 @@ impl ProgUpdate {
     /// Write all summary statistics.
     ///
     /// See [`ProgUpdate::write_transfer_stats`] for more information.
-    pub(crate) fn print_transfer_stats(&self) {
+    pub(crate) fn print_transfer_stats(&self, new_line: bool) {
         let mut stderr = std::io::stderr();
-        self.write_transfer_stats(&mut stderr).unwrap();
+        self.write_transfer_stats(&mut stderr, new_line).unwrap();
+    }
+
+    /// Write all the final statistics.
+    pub(crate) fn print_final_stats(
+        &self,
+        print_level: Option<StatusLevel>,
+        progress_printed: bool,
+    ) {
+        match print_level {
+            Some(StatusLevel::None) => {}
+            Some(StatusLevel::Noxfer) => self.print_io_lines(),
+            Some(StatusLevel::Progress) | None => self.print_transfer_stats(progress_printed),
+        }
     }
 }
 
@@ -380,9 +408,16 @@ pub(crate) fn gen_prog_updater(
     print_level: Option<StatusLevel>,
 ) -> impl Fn() {
     move || {
+        let mut progress_printed = false;
         while let Ok(update) = rx.recv() {
+            // Print the final read/write statistics.
+            if update.complete {
+                update.print_final_stats(print_level, progress_printed);
+                return;
+            }
             if Some(StatusLevel::Progress) == print_level {
                 update.reprint_prog_line();
+                progress_printed = true;
             }
         }
     }
@@ -427,19 +462,29 @@ pub(crate) fn gen_prog_updater(
             }
         });
 
-        let mut progress_as_secs = 0;
+        // Holds the state of whether we have printed the current progress.
+        // This is needed so that we know whether or not to print a newline
+        // character before outputting non-progress data.
+        let mut progress_printed = false;
         while let Ok(update) = rx.recv() {
-            // (Re)print status line if progress is requested.
-            if Some(StatusLevel::Progress) == print_level
-                && update.duration.as_secs() >= progress_as_secs
-            {
-                update.reprint_prog_line();
-                progress_as_secs = update.duration.as_secs() + 1;
+            // Print the final read/write statistics.
+            if update.complete {
+                update.print_final_stats(print_level, progress_printed);
+                return;
+            }
+            // (Re)print status line if progress is requested.
+            if Some(StatusLevel::Progress) == print_level && !update.complete {
+                update.reprint_prog_line();
+                progress_printed = true;
+            }
+            // Handle signals and set the signal to un-seen.
+            // This will print a maximum of 1 time per second, even though it
+            // should be printing on every SIGUSR1.
+            if let SIGUSR1_USIZE = sigval.swap(0, Ordering::Relaxed) {
+                update.print_transfer_stats(progress_printed);
+                // Reset the progress printed, since print_transfer_stats always prints a newline.
+                progress_printed = false;
             }
-            // Handle signals
-            if let SIGUSR1_USIZE = sigval.load(Ordering::Relaxed) {
-                update.print_transfer_stats();
-            };
         }
     }
 }
@@ -460,6 +505,7 @@ mod tests {
                 ..Default::default()
             },
             duration: Duration::new(1, 0), // one second
+            complete: false,
         }
     }
 
@@ -484,10 +530,12 @@ mod tests {
         let read_stat = ReadStat::new(1, 2, 3);
         let write_stat = WriteStat::new(4, 5, 6);
         let duration = Duration::new(789, 0);
+        let complete = false;
         let prog_update = ProgUpdate {
             read_stat,
             write_stat,
             duration,
+            complete,
         };
 
         let mut cursor = Cursor::new(vec![]);
@@ -500,7 +548,13 @@ mod tests {
 
     #[test]
     fn test_prog_update_write_prog_line() {
-        let prog_update = prog_update_write(0);
+        let prog_update = ProgUpdate {
+            read_stat: Default::default(),
+            write_stat: Default::default(),
+            duration: Duration::new(1, 0), // one second
+            complete: false,
+        };
+
         let mut cursor = Cursor::new(vec![]);
         let rewrite = false;
         prog_update.write_prog_line(&mut cursor, rewrite).unwrap();
@@ -551,9 +605,12 @@ mod tests {
             read_stat: Default::default(),
             write_stat: Default::default(),
             duration: Duration::new(1, 0), // one second
+            complete: false,
         };
         let mut cursor = Cursor::new(vec![]);
-        prog_update.write_transfer_stats(&mut cursor).unwrap();
+        prog_update
+            .write_transfer_stats(&mut cursor, false)
+            .unwrap();
         let mut iter = cursor.get_ref().split(|v| *v == b'\n');
         assert_eq!(iter.next().unwrap(), b"0+0 records in");
         assert_eq!(iter.next().unwrap(), b"0+0 records out");
@@ -561,4 +618,26 @@ mod tests {
         assert_eq!(iter.next().unwrap(), b"");
         assert!(iter.next().is_none());
     }
+
+    #[test]
+    fn write_final_transfer_stats() {
+        // Tests the formatting of the final statistics written after a progress line.
+        let prog_update = ProgUpdate {
+            read_stat: Default::default(),
+            write_stat: Default::default(),
+            duration: Duration::new(1, 0), // one second
+            complete: false,
+        };
+        let mut cursor = Cursor::new(vec![]);
+        let rewrite = true;
+        prog_update.write_prog_line(&mut cursor, rewrite).unwrap();
+        prog_update.write_transfer_stats(&mut cursor, true).unwrap();
+        let mut iter = cursor.get_ref().split(|v| *v == b'\n');
+        assert_eq!(iter.next().unwrap(), b"\r0 bytes copied, 1.0 s, 0 B/s");
+        assert_eq!(iter.next().unwrap(), b"0+0 records in");
+        assert_eq!(iter.next().unwrap(), b"0+0 records out");
+        assert_eq!(iter.next().unwrap(), b"0 bytes copied, 1.0 s, 0 B/s");
+        assert_eq!(iter.next().unwrap(), b"");
+        assert!(iter.next().is_none());
+    }
 }