[PATCH] tools/gputop: Fix zero output when stdout is not a terminal

[Vidya Srinivas <vidya.srinivas@intel.com>]

When gputop output is redirected to a file or run via adb shell
(e.g., on Android), update_console_size() calls ioctl(0, TIOCGWINSZ)
on stdin which may not be a terminal. If stdin is a pipe or
redirected, the ioctl returns -1 and con_w/con_h remain at their
initial value of -1.

This causes the main display loop to immediately break since
lines >= con_h evaluates to true (0 >= -1), resulting in zero
output being produced.

Fix this by initializing con_w and con_h to default values of
80 and 50 respectively, so that when ioctl fails the display
loop still produces output with sensible dimensions.

v2: Try stdout, stdin, and stderr for terminal size before falling
    back to defaults (Soham Purkait)

v3: Initialize defaults in main() instead of adding fallback logic
    in update_console_size() (Soham Purkait)

Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>
Reviewed-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>
Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>
---
 tools/gputop.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/gputop.c b/tools/gputop.c
index 9b2e8cb6f..0ed5af456 100644
--- a/tools/gputop.c
+++ b/tools/gputop.c
@@ -609,7 +609,7 @@ int main(int argc, char **argv)
 	unsigned int period_us;
 	struct igt_profiled_device *profiled_devices = NULL;
 	struct igt_drm_clients *clients = NULL;
-	int con_w = -1, con_h = -1;
+	int con_w = 80, con_h = 50;
 	int ret;
 	long n;
 
-- 
2.45.2