From 5773a8f22b400601ec82cc6b199b160a1d1cca22 Mon Sep 17 00:00:00 2001 From: sin Date: Thu, 13 Nov 2014 14:14:20 +0000 Subject: [PATCH] Implement concat() using read(2) and write(2) This forces the data to be read as soon as they are available and a simple cat(1) when stdin is referring to a tty works as expected. --- util/concat.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/util/concat.c b/util/concat.c index 939219d..a276fbb 100644 --- a/util/concat.c +++ b/util/concat.c @@ -1,5 +1,6 @@ /* See LICENSE file for copyright and license details. */ #include +#include #include "../text.h" #include "../util.h" @@ -8,14 +9,12 @@ void concat(FILE *fp1, const char *s1, FILE *fp2, const char *s2) { char buf[BUFSIZ]; - size_t n; + ssize_t n; - while ((n = fread(buf, 1, sizeof buf, fp1)) > 0) { - if (fwrite(buf, 1, n, fp2) != n) + while ((n = read(fileno(fp1), buf, sizeof buf)) > 0) { + if (write(fileno(fp2), buf, n) != n) eprintf("%s: write error:", s2); - if (feof(fp1)) - break; } - if (ferror(fp1)) + if (n < 0) eprintf("%s: read error:", s1); }