From: Ralph Corderoy <ralph@inputplus.co.uk>
Date: Sat, 16 Sep 2017 21:58:11 +0000 (+0100)
Subject: mhlsbr.c: Don't read(2) from fileno(3) of stdout.
X-Git-Url: https://diplodocus.org/git/nmh/commitdiff_plain/6fd323cc02e4e90d24e30b8c78a88a55e749556f?ds=inline;hp=4d0110006d4e72f82fb597f170c7d9991f2ca0bf

mhlsbr.c: Don't read(2) from fileno(3) of stdout.

Remove the assumption that file descriptor 1 is readable.  It can be if
it, or where it was dup(2)'d from, was opened read/write, e.g. on
/dev/tty.  But it can easily be arranged with shell re-direction that it
isn't, and then the read(2) fails.  Pass 0, standard input's file
descriptor, instead.  Don't use fileno(stdin) as I can't think of a need
to support that being non-zero, but its use makes the reader think it
might.  Bug pre-dates git.
---

diff --git a/uip/mhlsbr.c b/uip/mhlsbr.c
index 9b7cdd49..83cef9a2 100644
--- a/uip/mhlsbr.c
+++ b/uip/mhlsbr.c
@@ -969,7 +969,7 @@ mhlfile (FILE *fp, char *mname, int ofilen, int ofilec)
 		    }
 		    fflush (stdout);
 		    buf[0] = 0;
-		    if (read (fileno (stdout), buf, sizeof(buf)) < 0) {
+		    if (read(0, buf, sizeof(buf)) < 0) {
 			advise ("stdout", "read");
 		    }
 		}
@@ -1524,7 +1524,7 @@ putch (char ch, unsigned long flags)
 		putchar ('\007');
 	    fflush (stdout);
 	    buf[0] = 0;
-	    if (read (fileno (stdout), buf, sizeof(buf)) < 0) {
+	    if (read(0, buf, sizeof(buf)) < 0) {
 		advise ("stdout", "read");
 	    }
 	    if (strchr(buf, '\n')) {