linux-kernel - [PATCH v2 nolibc 19/53] selftests/nolibc: reduce syscalls during space padding

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Message-Id: <20230612204514.292087-19-paulmck@kernel.org>
Date:   Mon, 12 Jun 2023 13:44:40 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     gwml@...r.gnuweeb.org, kernel-team@...a.com, w@....eu,
        Thomas Weißschuh <linux@...ssschuh.net>,
        Willy Tarreau <w@....eu>,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: [PATCH v2 nolibc 19/53] selftests/nolibc: reduce syscalls during space padding

From: Thomas Weißschuh <linux@...ssschuh.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@...ssschuh.net>
Signed-off-by: Willy Tarreau <w@....eu>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 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 0e2ee513b273..d5d4dea63cd6 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -111,19 +111,26 @@ 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
-- 
2.40.1