We cannot use fputs(3) in passthrough() because the stdout stream

might be in stdio wide orientation due to prior formatting of an
unformatted manual in man -aTutf8 mode.  So for now, use fflush(3)
followed by unbuffered write(2) instead.  Fixes output corruption
on glibc discovered on Linux while testing a diff to fix a loosely
related bug reported by <jmates at ee dot washington dot edu>.

I detest the concept of stdio stream orientation.  One day, i will
rewrite term_ascii.c to always use narrow streams, even in UTF-8
output mode.  But that's too much work for today.

1 files changed, 15 insertions, 5 deletions

diff --git a/main.c b/main.c
index 02aa1968..30ef3d6f 100644
--- a/main.c
+++ b/main.c
@@ -1,4 +1,4 @@
-/*	$Id: main.c,v 1.276 2016/09/18 15:22:08 schwarze Exp $ */
+/*	$Id: main.c,v 1.277 2016/09/18 15:47:45 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2012, 2014-2016 Ingo Schwarze <schwarze@openbsd.org>
@@ -820,11 +820,17 @@ passthrough(const char *file, int fd, int synopsis_only)
 	const char	*syscall;
 	char		*line, *cp;
 	size_t		 linesz;
+	ssize_t		 len, written;
 	int		 print;
 
 	line = NULL;
 	linesz = 0;
 
+	if (fflush(stdout) == EOF) {
+		syscall = "fflush";
+		goto fail;
+	}
+
 	if ((stream = fdopen(fd, "r")) == NULL) {
 		close(fd);
 		syscall = "fdopen";
@@ -832,14 +838,16 @@ passthrough(const char *file, int fd, int synopsis_only)
 	}
 
 	print = 0;
-	while (getline(&line, &linesz, stream) != -1) {
+	while ((len = getline(&line, &linesz, stream)) != -1) {
 		cp = line;
 		if (synopsis_only) {
 			if (print) {
 				if ( ! isspace((unsigned char)*cp))
 					goto done;
-				while (isspace((unsigned char)*cp))
+				while (isspace((unsigned char)*cp)) {
 					cp++;
+					len--;
+				}
 			} else {
 				if (strcmp(cp, synb) == 0 ||
 				    strcmp(cp, synr) == 0)
@@ -847,9 +855,11 @@ passthrough(const char *file, int fd, int synopsis_only)
 				continue;
 			}
 		}
-		if (fputs(cp, stdout)) {
+		for (; len > 0; len -= written) {
+			if ((written = write(STDOUT_FILENO, cp, len)) != -1)
+				continue;
 			fclose(stream);
-			syscall = "fputs";
+			syscall = "write";
 			goto fail;
 		}
 	}