[PATCH 1/6] selftests/nolibc: reduce syscalls during space padding

From: "Thomas Weißschuh" <linux@weissschuh.net>
To: Willy Tarreau <w@1wt.eu>, Shuah Khan <shuah@kernel.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>
Cc: linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-riscv@lists.infradead.org,
	"Thomas Weißschuh" <linux@weissschuh.net>
Subject: [PATCH 1/6] selftests/nolibc: reduce syscalls during space padding
Date: Mon, 17 Apr 2023 18:01:31 +0200	[thread overview]
Message-ID: <20230408-nolibc-stackprotector-archs-v1-1-271f5c859c71@weissschuh.net> (raw)
In-Reply-To: <20230408-nolibc-stackprotector-archs-v1-0-271f5c859c71@weissschuh.net>

Previously each space character used for alignment during test execution
was written in a single write() call.
This would make the output from strace fairly unreadable.
Coalesce all spaces into a single call to write().

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 tools/testing/selftests/nolibc/nolibc-test.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 68e22617651c..35f203556a0c 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -108,19 +108,26 @@ const char *errorname(int err)
 	}
 }
 
+static void putcharn(char c, size_t n)
+{
+	char buf[64];
+
+	memset(buf, c, n);
+	buf[n] = '\0';
+	fputs(buf, stdout);
+}
+
 static int pad_spc(int llen, int cnt, const char *fmt, ...)
 {
 	va_list args;
-	int len;
 	int ret;
 
-	for (len = 0; len < cnt - llen; len++)
-		putchar(' ');
+	putcharn(' ', cnt - llen);
 
 	va_start(args, fmt);
 	ret = vfprintf(stdout, fmt, args);
 	va_end(args);
-	return ret < 0 ? ret : ret + len;
+	return ret < 0 ? ret : ret + cnt - llen;
 }
 
 /* The tests below are intended to be used by the macroes, which evaluate

-- 
2.40.0

