commit a72478870ae66b7ac1e73b1d22b578cd31852f33
from: David Arroyo <david@aqwari.net>
via: Dan Cross <crossd@gmail.com>
date: Sun Jan 31 16:52:08 2021 UTC

9p: parse lines in rdwr command

Use bio(3) to read at most one line of input per iteration, even
if there is more than one line available in the input buffer. This
makes it easier to interact with line-oriented ctl files like that of
factotum(4) from shell scripts, without the need to control when
and how much data is flushed to a pipe.

commit - 36cd4c58c1346375b98f517fb8568be5bb47618d
commit + a72478870ae66b7ac1e73b1d22b578cd31852f33
blob - 75511a1947480ad5cb0c2c0a626749e683fe5ea6
blob + a5b97f85f0223de4a9f162325f63f92bc9671d67
--- src/cmd/9p.c
+++ src/cmd/9p.c
@@ -302,8 +302,10 @@ void
 xrdwr(int argc, char **argv)
 {
 	char buf[4096];
+	char *p;
 	int n;
 	CFid *fid;
+	Biobuf *b;
 
 	ARGBEGIN{
 	default:
@@ -313,6 +315,8 @@ xrdwr(int argc, char **argv)
 	if(argc != 1)
 		usage();
 
+	if((b = Bfdopen(0, OREAD)) == nil)
+		sysfatal("out of memory");
 	fid = xopen(argv[0], ORDWR);
 	for(;;){
 		fsseek(fid, 0, 0);
@@ -322,15 +326,15 @@ xrdwr(int argc, char **argv)
 			if(write(1, buf, n) < 0 || write(1, "\n", 1) < 0)
 				sysfatal("write error: %r");
 		}
-		n = read(0, buf, sizeof buf);
-		if(n <= 0)
+		if((p = Brdstr(b, '\n', 1)) == nil)
 			break;
-		if(buf[n-1] == '\n')
-			n--;
-		if(fswrite(fid, buf, n) != n)
+		n = strlen(p);
+		if(fswrite(fid, p, n) != n)
 			fprint(2, "write: %r\n");
+		free(p);
 	}
 	fsclose(fid);
+	Bterm(b);
 	threadexitsall(0);
 }