From 99a3d02370b6b526594ee73eb26d39e8d8ced8d3 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Marek=20Beh=C3=BAn?= <marek.behun@nic.cz>
Date: Fri, 24 Sep 2021 23:07:07 +0200
Subject: [PATCH] tools: kwboot: Check whether baudrate was set to requested
value
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The tcsetattr() function can return 0 even if baudrate was not changed.
Check whether baudrate was changed to requested value, and in case of
arbitrary baudrate, check whether the set value is within 3% tolerance.
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>
---
tools/kwboot.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/tools/kwboot.c b/tools/kwboot.c
index 7ccab2993f..d8b950787b 100644
--- a/tools/kwboot.c
+++ b/tools/kwboot.c
@@ -567,6 +567,13 @@ kwboot_tty_baudrate_to_speed(int baudrate)
}
}
+static int
+_is_within_tolerance(int value, int reference, int tolerance)
+{
+ return 100 * value >= reference * (100 - tolerance) &&
+ 100 * value <= reference * (100 + tolerance);
+}
+
static int
kwboot_tty_change_baudrate(int fd, int baudrate)
{
@@ -601,7 +608,32 @@ kwboot_tty_change_baudrate(int fd, int baudrate)
if (rc)
return rc;
+ rc = tcgetattr(fd, &tio);
+ if (rc)
+ return rc;
+
+ if (cfgetospeed(&tio) != speed || cfgetispeed(&tio) != speed)
+ goto baud_fail;
+
+#ifdef BOTHER
+ /*
+ * Check whether set baudrate is within 3% tolerance.
+ * If BOTHER is defined, Linux always fills out c_ospeed / c_ispeed
+ * with real values.
+ */
+ if (!_is_within_tolerance(tio.c_ospeed, baudrate, 3))
+ goto baud_fail;
+
+ if (!_is_within_tolerance(tio.c_ispeed, baudrate, 3))
+ goto baud_fail;
+#endif
+
return 0;
+
+baud_fail:
+ fprintf(stderr, "Could not set baudrate to requested value\n");
+ errno = EINVAL;
+ return -1;
}
static int
--
2.39.5