upas/marshal: handle nonexistent save folder correctly (thanks sirjofri)

When the save folder did not exist, and we could not create
it, we would handle up to one Biobuf worth of message, and
then fail, due to a failed tee. The sequence of events leading
up to this was:

	openfolder() -> error
	tee(0, fd, -1) -> wait for read
	write(0, data) ->
		write(fd, data) -> ok
		write(-1, data) -> error, tee terminates
	write(0, attachment) -> error

This change prevents us from writing to a closed fd, and
therefore from erroring out when sending.

We also warn the user.

1 files changed, 19 insertions, 10 deletions

diff --git a/sys/src/cmd/upas/marshal/marshal.c b/sys/src/cmd/upas/marshal/marshal.c
index 3e26d9dbf..893775b03 100644
--- a/sys/src/cmd/upas/marshal/marshal.c
+++ b/sys/src/cmd/upas/marshal/marshal.c
@@ -985,10 +985,12 @@ tee(int in, int out1, int out2)
 	int n;
 	char buf[8*1024];
 
-	while ((n = read(in, buf, sizeof buf)) > 0)
-		if (write(out1, buf, n) != n ||
-		    write(out2, buf, n) != n)
+	while ((n = read(in, buf, sizeof buf)) > 0){
+		if(out1 != -1 && write(out1, buf, n) != n)
 			break;
+		if(out2 != -1 && write(out2, buf, n) != n)
+			break;
+	}
 }
 
 /* print the unix from line */
@@ -1033,7 +1035,7 @@ int
 sendmail(Addr *to, Addr *cc, Addr *bcc, int *pid, char *rcvr)
 {
 	int ac, fd, pfd[2];
-	char **v, cmd[Pathlen];
+	char **v, *f, cmd[Pathlen];
 	Addr *a;
 	Biobuf *b;
 
@@ -1086,12 +1088,18 @@ sendmail(Addr *to, Addr *cc, Addr *bcc, int *pid, char *rcvr)
 			case 0:
 				close(pfd[0]);
 				/* BOTCH; "From " time gets changed */
-				b = openfolder(foldername(nil, user, rcvr), time(0));
-				fd = b? Bfildes(b): -1;
-				printunixfrom(fd);
-				tee(0, pfd[1], fd);
-				write(fd, "\n", 1);
-				closefolder(b);
+				f = foldername(nil, user, rcvr);
+				b = openfolder(f, time(0));
+				if(b != nil){
+					fd = Bfildes(b);
+					printunixfrom(fd);
+					tee(0, pfd[1], fd);
+					write(fd, "\n", 1);
+					closefolder(b);
+				}else{
+					fprint(2, "warning: open %s: %r", f);
+					tee(0, pfd[1], -1);
+				}
 				exits(0);
 			default:
 				close(pfd[1]);
@@ -1172,6 +1180,7 @@ waitforsubprocs(void)
 
 	err = nil;
 	while((w = wait()) != nil){
+		fprint(2, "%d: %s\n", w->pid, w->msg);
 		if(w->pid == pid || w->pid == pgppid)
 			if(w->msg[0] != 0)
 				err = estrdup(w->msg);