@@ -26,11 +26,12 @@ static const struct option longopts[] = {
{ "silent", no_argument, NULL, 's' },
{ "rising-edge", no_argument, NULL, 'r' },
{ "falling-edge", no_argument, NULL, 'f' },
+ { "linebuffered", no_argument, NULL, 'b' },
{ "format", required_argument, NULL, 'F' },
{ GETOPT_NULL_LONGOPT },
};
-static const char *const shortopts = "+hvln:srfF:";
+static const char *const shortopts = "+hvln:srfbF:";
static void print_help(void)
{
@@ -46,6 +47,7 @@ static void print_help(void)
printf(" -s, --silent:\t\tdon't print event info\n");
printf(" -r, --rising-edge:\tonly process rising edge events\n");
printf(" -f, --falling-edge:\tonly process falling edge events\n");
+ printf(" -l, --linebuffered:\tset line buffered output\n");
printf(" -F, --format=FMT\tspecify custom output format\n");
printf("\n");
printf("Format specifiers:\n");
@@ -242,6 +244,7 @@ int main(int argc, char **argv)
{
unsigned int offsets[GPIOD_LINE_BULK_MAX_LINES], num_lines = 0, offset;
bool active_low = false, watch_rising = false, watch_falling = false;
+ bool linebuffered = false;
struct timespec timeout = { 10, 0 };
int optc, opti, ret, i, event_type;
struct mon_ctx ctx;
@@ -278,6 +281,9 @@ int main(int argc, char **argv)
case 'f':
watch_falling = true;
break;
+ case 'b':
+ linebuffered = true;
+ break;
case 'F':
ctx.fmt = optarg;
break;
@@ -298,6 +304,9 @@ int main(int argc, char **argv)
else
event_type = GPIOD_CTXLESS_EVENT_BOTH_EDGES;
+ if (linebuffered && setvbuf(stdout, NULL, _IOLBF, 0) != 0)
+ die("failed to set line buffering");
+
if (argc < 1)
die("gpiochip must be specified");
Some applications call gpiomon in a sub process, in which case glibc defaults to block buffered output on stdout. This makes the output arrive to the calling process only when the (4kB) buffer is filled (or when gpiomon exists), making the information obsolete and pretty much useless. Support such scenarios by adding a switch to configure line buffered output on stdout. Similar switches are available in other applications (e.g. `rsync`s --output argument). Signed-off-by: Martin Hundebøll <martin@geanix.com> --- src/tools/gpiomon.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)