From 34f3df213c0141d904dbe69ff6cf16bc3cfae28c Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Wed, 29 Jul 2015 05:19:24 +0200
Subject: ratrace: avoid blank line prints, make writer the parent

when there where multiple syscalls returning out of order,
it would print blank lines between the exits. avoid this
by remembering if the last char written was a newline and
conditionally insert newline on out of order return.

sometimes, ratrace would return before all messages have
been printed. make the writer process the parent so ratrace
wont exit until all readers are finished avoiding the
problem.
---
 sys/src/cmd/ratrace.c | 41 ++++++++++++++++++++++++++---------------
 1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/sys/src/cmd/ratrace.c b/sys/src/cmd/ratrace.c
index f44f702e7..95c50933c 100644
--- a/sys/src/cmd/ratrace.c
+++ b/sys/src/cmd/ratrace.c
@@ -9,7 +9,7 @@ enum {
 Channel *out;
 Channel *quit;
 Channel *forkc;
-int nread = 0;
+int readers = 1;
 
 typedef struct Msg Msg;
 struct Msg {
@@ -36,8 +36,10 @@ die(Reader *r)
 	snprint(s->buf, sizeof(s->buf), " = %r\n");
 	s->pid = r->pid;
 	sendp(quit, s);
-	close(r->tfd);
-	close(r->cfd);
+	if(r->tfd >= 0)
+		close(r->tfd);
+	if(r->cfd >= 0)
+		close(r->cfd);
 	threadexits(nil);
 }
 
@@ -105,13 +107,12 @@ reader(void *v)
 }
 
 void
-writer(void *arg)
+writer(int lastpid)
 {
-	int lastpid;
+	char lastc = -1;
 	Alt a[4];
 	Msg *s;
-
-	lastpid = (int)(uintptr)arg;
+	int n;
 
 	a[0].op = CHANRCV;
 	a[0].c = quit;
@@ -124,20 +125,29 @@ writer(void *arg)
 	a[2].v = nil;
 	a[3].op = CHANEND;
 
-	while(nread > 0){
+	while(readers > 0){
 		switch(alt(a)){
 		case 0:
-			nread--;
+			readers--;
 		case 1:
 			if(s->pid != lastpid){
 				lastpid = s->pid;
-				fprint(2, s->buf[1]=='='? "\n%d ...": "\n", lastpid);
+				if(lastc != '\n'){
+					lastc = '\n';
+					write(2, &lastc, 1);
+				}
+				if(s->buf[1] == '=')
+					fprint(2, "%d ...", lastpid);
+			}
+			n = strlen(s->buf);
+			if(n > 0){
+				write(2, s->buf, n);
+				lastc = s->buf[n-1];
 			}
-			write(2, s->buf, strlen(s->buf));
 			free(s);
 			break;
 		case 2:
-			nread++;
+			readers++;
 			break;
 		}
 	}
@@ -196,7 +206,8 @@ threadmain(int argc, char **argv)
 	out   = chancreate(sizeof(Msg*), 0);
 	quit  = chancreate(sizeof(Msg*), 0);
 	forkc = chancreate(sizeof(void*), 0);
-	nread++;
-	procrfork(writer, (void*)pid, Stacksize, 0);
-	reader((void*)pid);
+	procrfork(reader, (void*)pid, Stacksize, 0);
+
+	writer(pid);
+	threadexits(nil);
 }
-- 
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