From b3e8b172354a23246314d34bbf847f2f2dc2ad6b Mon Sep 17 00:00:00 2001
From: FRIGN <dev@frign.de>
Date: Wed, 18 Mar 2015 22:58:42 +0100
Subject: [PATCH] Audit concat() in libutil

Be more pedantic about the error-checking, fread can also return
values > 0 even though there has been a read-error.
We want to write the last incoming data and then bail.
---
 libutil/concat.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/libutil/concat.c b/libutil/concat.c
index ef1e5b9..551b5b9 100644
--- a/libutil/concat.c
+++ b/libutil/concat.c
@@ -10,12 +10,13 @@ concat(FILE *fp1, const char *s1, FILE *fp2, const char *s2)
 	char buf[BUFSIZ];
 	size_t n;
 
-	while ((n = fread(buf, 1, sizeof(buf), fp1)) > 0) {
-		if (fwrite(buf, 1, n, fp2) != n)
-			eprintf("%s: write error:", s2);
-		if (feof(fp1))
+	while ((n = fread(buf, 1, sizeof(buf), fp1))) {
+		fwrite(buf, 1, n, fp2);
+		if (ferror(fp2))
+			eprintf("fwrite %s:", s2);
+		if (feof(fp1) || ferror(fp1))
 			break;
 	}
 	if (ferror(fp1))
-		eprintf("%s: read error:", s1);
+		eprintf("fread %s", s1);
 }