[PATCH] fix display overlap between remote and local progress

It is possible for the remote summary line to be displayed over the 
local progress display line, and therefore that local progress gets 
bumped to the next line.  However, if the progress line is long enough, 
it might not be entirely overwritten by the remote summary line.  This 
creates a messed up display such as:

	remote: Total 310 (delta 160), reused 178 (delta 112)iB/s
	Receiving objects: 100% (310/310), 379.98 KiB | 136 KiB/s, done.

So we have to clear the screen line before displaying the remote message 
to make sure the local progress is not visible anymore on the first 
line.

Yet some Git versions on the remote side might be sending updates to the 
same line and terminate it with \r, and a separate packet with a single 
\n might be sent later when the progress display is done.  This means 
the screen line must *not* be cleared in that case.

Since the sideband code already has to figure out line breaks in the 
received packet to properly prepend the "remote:" prefix, we can easily 
determine if the remote line about to be displayed is empty.  Only when 
it is not then a proper suffix is inserted before the \r or \n to clear 
the end of the screen line.

Also some magic constants related to the prefix length have been 
replaced with a variable, making it similar to the suffix length 
handling.  Since gcc is smart enough to detect that the variable is 
constant there is no impact on the generated code.

Signed-off-by: Nicolas Pitre <redacted>
---

diff --git a/sideband.c b/sideband.c
index ab8a1e9..66385ad 100644
--- a/sideband.c
+++ b/sideband.c

@@ -11,13 +11,19 @@
  * stream, aka "verbose").  A message over band #3 is a signal that
  * the remote died unexpectedly.  A flush() concludes the stream.
  */
+
+#define PREFIX "remote:"
+#define SUFFIX "\e[K"  /* change to "        " if ANSI sequences don't work */ 
+
 int recv_sideband(const char *me, int in_stream, int out, int err)
 {
-	char buf[7 + LARGE_PACKET_MAX + 1];
-	strcpy(buf, "remote:");
+	unsigned pf = strlen(PREFIX);
+	unsigned sf = strlen(SUFFIX);
+	char buf[pf + LARGE_PACKET_MAX + sf + 1];
+	memcpy(buf, PREFIX, pf);
 	while (1) {
 		int band, len;
-		len = packet_read_line(in_stream, buf+7, LARGE_PACKET_MAX);
+		len = packet_read_line(in_stream, buf + pf, LARGE_PACKET_MAX);
 		if (len == 0)
 			break;
 		if (len < 1) {

@@ -25,35 +31,52 @@ int recv_sideband(const char *me, int in_stream, int out, int err)
 			safe_write(err, buf, len);
 			return SIDEBAND_PROTOCOL_ERROR;
 		}
-		band = buf[7] & 0xff;
+		band = buf[pf] & 0xff;
 		len--;
 		switch (band) {
 		case 3:
-			buf[7] = ' ';
-			buf[8+len] = '\n';
-			safe_write(err, buf, 8+len+1);
+			buf[pf] = ' ';
+			buf[pf+1+len] = '\n';
+			safe_write(err, buf, pf+1+len+1);
 			return SIDEBAND_REMOTE_ERROR;
 		case 2:
-			buf[7] = ' ';
-			len += 8;
+			buf[pf] = ' ';
+			len += pf+1;
 			while (1) {
-				int brk = 8;
+				int brk = pf+1;
+
+				/* Break the buffer into separate lines. */
 				while (brk < len) {
 					brk++;
 					if (buf[brk-1] == '\n' ||
 					    buf[brk-1] == '\r')
 						break;
 				}
-				safe_write(err, buf, brk);
+
+				/*
+				 * Let's insert a suffix to clear the end
+				 * of the screen line, but only if current
+				 * line data actually contains something.
+				 */
+				if (brk > pf+1 + 1) {
+					char save[sf];
+					memcpy(save, buf + brk, sf);
+					buf[brk + sf - 1] = buf[brk - 1];
+					memcpy(buf + brk - 1, SUFFIX, sf);
+					safe_write(err, buf, brk + sf);
+					memcpy(buf + brk, save, sf);
+				} else
+					safe_write(err, buf, brk);
+
 				if (brk < len) {
-					memmove(buf + 8, buf + brk, len - brk);
-					len = len - brk + 8;
+					memmove(buf + pf+1, buf + brk, len - brk);
+					len = len - brk + pf+1;
 				} else
 					break;
 			}
 			continue;
 		case 1:
-			safe_write(out, buf+8, len);
+			safe_write(out, buf + pf+1, len);
 			continue;
 		default:
 			len = sprintf(buf,

Hi,

On Sun, 4 Nov 2007, Nicolas Pitre wrote:

+#define SUFFIX "\e[K"  /* change to "        " if ANSI sequences don't work */ 

I am almost certain (without even testing) that cmd.exe has problems with 
that.  It does not even understand colorisation.

My vote is to let it be for the moment, and us msysGit people will 
probably add something like NO_ANSI_TERM=YesPlease later.

Ciao,
Dscho

On Sun, 4 Nov 2007, Johannes Schindelin wrote:

Hi,

On Sun, 4 Nov 2007, Nicolas Pitre wrote:

quoted

+#define SUFFIX "\e[K"  /* change to "        " if ANSI sequences don't work */ 

I am almost certain (without even testing) that cmd.exe has problems with 
that.  It does not even understand colorisation.

That's what I was expecting.  This is why I suggested an alternative in 
the comment.


Nicolas

(This is about ANSI clear-eol sequence introduced to sideline.c in commit
 ebe8fa738dcf6911fe520adce0cfa0cb26dee5e2)

quoted

Johannes Schindelin [off-list ref] wrote:

Hi,

On Sun, 4 Nov 2007, Nicolas Pitre wrote:

quoted

+#define SUFFIX "\e[K"  /* change to "        " if ANSI sequences don't work */ 

I am almost certain (without even testing) that cmd.exe has problems with 
that.  It does not even understand colorisation.

My vote is to let it be for the moment, and us msysGit people will 
probably add something like NO_ANSI_TERM=YesPlease later.

Hi,

We are using script(1) to record the workflow and troubleshoot problems.
script utility records all control codes as well (actually everything
that passes via pseudoterminal it creates.

We managed to get git quiet on most control codes with color.ui=false
and pager set to nothing, but we still get ESC [ K codes from the
remote output (we are using gerrit and it generates some). 

While I can live with git progress output lines in the log, it's
quite annoying to edit those ANSI sequences out of the script.
One has to remember to set TERM=dumb before invoking _some_ git
operations.

Is there any better solution possible?

//Marcin