mk: handle rc blocks in shell quote

this is so we cna handle:

foo = `{echo `{echo bar}}

thanks to erik and friedrich psiorz on 9fans for
bringing the issue up.

1 files changed, 5 insertions, 2 deletions

diff --git a/sys/src/cmd/mk/lex.c b/sys/src/cmd/mk/lex.c
index d942918f3..5c4bc99be 100644
--- a/sys/src/cmd/mk/lex.c
+++ b/sys/src/cmd/mk/lex.c
@@ -67,7 +67,7 @@ eof:
 static int
 bquote(Biobuf *bp, Bufblock *buf)
 {
-	int c, line, term;
+	int c, line, term, depth;
 	int start;
 
 	line = mkinline;
@@ -80,9 +80,12 @@ bquote(Biobuf *bp, Bufblock *buf)
 	} else
 		term = '`';		/* sh style */
 
+	depth = 1;
 	start = buf->current-buf->start;
 	for(;c > 0; c = nextrune(bp, 0)){
-		if(c == term){
+		if(c == '{' && term == '}')
+			depth++;
+		if(c == term && --depth == 0){
 			insert(buf, '\n');
 			insert(buf,0);
 			buf->current = buf->start+start;