[DTrace-devel] [PATCH 10/12] Add support for copyin() subroutine

[Eugene Loh]

On 7/21/22 13:03, Kris Van Hees wrote:

> On Thu, Jul 21, 2022 at 11:08:45AM -0700, Eugene Loh via DTrace-devel wrote:
>>   Reviewed-by: Eugene Loh <eugene.loh at oracle.com>
>> On 7/13/22 12:17, Kris Van Hees via DTrace-devel wrote:
>>> diff --git a/test/unittest/funcs/copyin/tst.copyin.d b/test/unittest/funcs/copyin/tst.copyin.d
>>> new file mode 100644
>> The test test/unittest/funcs/copyin/tst.copyin.d should ideally check the
>> output.  I know it's hard, but the test is kind of toothless otherwise.
> Well, yes and no.  The main point we're testing here is that we *can* read
> the data.  I would like to come up with a test where I can also verify the
> correctness of the data but thus far I have not found a truly reproducible
> way for doing that.
How about something like this?

$ cat a.c
#include <stdio.h>
#include <string.h>

#include <sys/types.h> /* open */
#include <sys/stat.h>
#include <fcntl.h>

#include <unistd.h> /* write */

int main(int c, char **v) {
   char *s = "hello world, how are you?";
   int fd = open("/dev/null", O_WRONLY);

   write(fd, s, strlen(s));
   close(fd);

   return 0;
}

# dtrace -c ./a.out -qn 'syscall::write:entry /pid == $target/ { 
printf("'%s'", (string)copyin(arg1, 256)); }'
hello world, how are you?