[PATCH] Documentation/watchdog: Fix the file descriptor leak when no cmdline arg given

[PATCH] Documentation/watchdog: Fix the file descriptor leak when no cmdline arg given

[Devendra Naga]

we start a infinite loop when user gives ./watchdog-test, and when user
ctrl + c's the program, we just exit immeadiately with out closing the
filedescriptor of the watchdog device. a signal handler is used to
do the job of closing the filedescriptor and exiting the program.

Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
---
 Documentation/watchdog/src/watchdog-test.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/watchdog/src/watchdog-test.c b/Documentation/watchdog/src/watchdog-test.c
index 23084f2..73ff5cc 100644
--- a/Documentation/watchdog/src/watchdog-test.c
+++ b/Documentation/watchdog/src/watchdog-test.c
@@ -7,6 +7,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <signal.h>
 #include <sys/ioctl.h>
 #include <linux/types.h>
 #include <linux/watchdog.h>
@@ -29,6 +30,14 @@ static void keep_alive(void)
  * The main program.  Run the program with "-d" to disable the card,
  * or "-e" to enable the card.
  */
+
+void term(int sig)
+{
+    close(fd);
+    fprintf(stderr, "Stopping watchdog ticks...\n");
+    exit(0);
+}
+
 int main(int argc, char *argv[])
 {
     int flags;
@@ -65,6 +74,8 @@ int main(int argc, char *argv[])
 	fflush(stderr);
     }
 
+    signal(SIGINT, term);
+
     while(1) {
 	keep_alive();
 	sleep(1);
-- 
1.7.9.5

Re: [PATCH] Documentation/watchdog: Fix the file descriptor leak when no cmdline arg given

[Rob Landley]

On 05/17/2012 04:36 AM, Devendra Naga wrote:
> we start a infinite loop when user gives ./watchdog-test, and when user
> ctrl + c's the program, we just exit immeadiately with out closing the
> filedescriptor of the watchdog device. a signal handler is used to
> do the job of closing the filedescriptor and exiting the program.

Doesn't exiting a process close all its filehandles already?

Rob
-- 
GNU/Linux isn't: Linux=GPLv2, GNU=GPLv3+, they can't share code.
Either it's "mere aggregation", or a license violation.  Pick one.

Re: [PATCH] Documentation/watchdog: Fix the file descriptor leak when no cmdline arg given

[devendra.aaru]

On Thu, May 17, 2012 at 7:43 PM, Rob Landley <rob@landley.net> wrote:
> On 05/17/2012 04:36 AM, Devendra Naga wrote:
>> we start a infinite loop when user gives ./watchdog-test, and when user
>> ctrl + c's the program, we just exit immeadiately with out closing the
>> filedescriptor of the watchdog device. a signal handler is used to
>> do the job of closing the filedescriptor and exiting the program.
>
> Doesn't exiting a process close all its filehandles already?

I think kernel will take care of releasing process resources. i am not
so sure of it.
but running valgrind --track-fds=yes ./a.out as root shows a descriptor leak.

BTW, there is another miss, if the user is non-root we still leak a
file descriptor.
>
> Rob
> --
> GNU/Linux isn't: Linux=GPLv2, GNU=GPLv3+, they can't share code.
> Either it's "mere aggregation", or a license violation.  Pick one.

Thanks,
Devendra.
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[PATCH] Documentation/watchdog: Fix the file descriptor leak when no cmdline arg given

[Devendra Naga]

we start a infinite loop when user gives ./watchdog-test, and when user
ctrl + c's the program, we just exit immeadiately with out closing the
filedescriptor of the watchdog device. a signal handler is used to
do the job of closing the filedescriptor and exiting the program.

Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
---
 Documentation/watchdog/src/watchdog-test.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/watchdog/src/watchdog-test.c b/Documentation/watchdog/src/watchdog-test.c
index 23084f2..73ff5cc 100644
--- a/Documentation/watchdog/src/watchdog-test.c
+++ b/Documentation/watchdog/src/watchdog-test.c
@@ -7,6 +7,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <signal.h>
 #include <sys/ioctl.h>
 #include <linux/types.h>
 #include <linux/watchdog.h>
@@ -29,6 +30,14 @@ static void keep_alive(void)
  * The main program.  Run the program with "-d" to disable the card,
  * or "-e" to enable the card.
  */
+
+void term(int sig)
+{
+    close(fd);
+    fprintf(stderr, "Stopping watchdog ticks...\n");
+    exit(0);
+}
+
 int main(int argc, char *argv[])
 {
     int flags;
@@ -65,6 +74,8 @@ int main(int argc, char *argv[])
 	fflush(stderr);
     }
 
+    signal(SIGINT, term);
+
     while(1) {
 	keep_alive();
 	sleep(1);
-- 
1.7.9.5