[PATCH libiio] iio-monitor: Set locale before parsing double values from sysfs

[PATCH libiio] iio-monitor: Set locale before parsing double values from sysfs

[Geert Uytterhoeven]

strtod() uses the current locale when parsing numbers, while all values
in sysfs use the "C" locale.  Hence the former may expect a comma as the
radix character, while the latter always uses a decimal point, leading
to the display of incorrect values.

Temporarily switch to the "C" locale before parsing double numbers to
fix this.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 examples/iio-monitor.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/examples/iio-monitor.c b/examples/iio-monitor.c
index 8b632187829869ae..558c0f33a36ef7b9 100644
--- a/examples/iio-monitor.c
+++ b/examples/iio-monitor.c
@@ -21,6 +21,7 @@
 #define _DEFAULT_SOURCE
 
 #include <cdk/cdk.h>
+#include <locale.h>
 #include <pthread.h>
 #include <stdbool.h>
 #include <unistd.h>
@@ -61,9 +62,13 @@ static bool is_valid_channel(struct iio_channel *chn)
 
 static double get_channel_value(struct iio_channel *chn)
 {
+	char *old_locale;
 	char buf[1024];
 	double val;
 
+	old_locale = strdup(setlocale(LC_NUMERIC, NULL));
+	setlocale(LC_NUMERIC, "C");
+
 	if (channel_has_attr(chn, "input")) {
 		iio_channel_attr_read(chn, "input", buf, sizeof(buf));
 		val = strtod(buf, NULL);
@@ -82,6 +87,9 @@ static double get_channel_value(struct iio_channel *chn)
 		}
 	}
 
+	setlocale(LC_NUMERIC, old_locale);
+	free(old_locale);
+
 	return val / 1000.0;
 }
 
-- 
1.9.1

Re: [PATCH libiio] iio-monitor: Set locale before parsing double values from sysfs

[Cercueil, Paul]

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Hi,
Le mercredi 21 décembre 2016 à 15:09 +0100, Geert Uytterhoeven a
écrit :
> strtod() uses the current locale when parsing numbers, while all
> values
> in sysfs use the "C" locale.  Hence the former may expect a comma as
> the
> radix character, while the latter always uses a decimal point,
> leading
> to the display of incorrect values.
> 
> Temporarily switch to the "C" locale before parsing double numbers to
> fix this.
> 
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> ---
>  examples/iio-monitor.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/examples/iio-monitor.c b/examples/iio-monitor.c
> index 8b632187829869ae..558c0f33a36ef7b9 100644
> --- a/examples/iio-monitor.c
> +++ b/examples/iio-monitor.c
> @@ -21,6 +21,7 @@
>  #define _DEFAULT_SOURCE
>  
>  #include <cdk/cdk.h>
> +#include <locale.h>
>  #include <pthread.h>
>  #include <stdbool.h>
>  #include <unistd.h>
> @@ -61,9 +62,13 @@ static bool is_valid_channel(struct iio_channel
> *chn)
>  
>  static double get_channel_value(struct iio_channel *chn)
>  {
> +	char *old_locale;
>  	char buf[1024];
>  	double val;
>  
> +	old_locale = strdup(setlocale(LC_NUMERIC, NULL));
> +	setlocale(LC_NUMERIC, "C");
> +
>  	if (channel_has_attr(chn, "input")) {
>  		iio_channel_attr_read(chn, "input", buf,
> sizeof(buf));
>  		val = strtod(buf, NULL);
> @@ -82,6 +87,9 @@ static double get_channel_value(struct iio_channel
> *chn)
>  		}
>  	}
>  
> +	setlocale(LC_NUMERIC, old_locale);
> +	free(old_locale);
> +
>  	return val / 1000.0;
>  }
>  

Applied. Thanks!

-Paul

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