On Wed, Jan 27, 2016 at 11:01:53AM +0800, Fei Jie wrote:
> Check how mincore syscall is traced.
[...]
> +int main(void)
> +{
> + char file_name[] = "mincore_XXXXXX";
> + int pg_size = getpagesize();
> + int global_len = pg_size * 2;
> + char *buf = (char *)malloc(global_len);
> + char *global_pointer = NULL;
> + int file_desc, res;
> + memset(buf, 42, global_len);
> +
> + if ((file_desc = mkstemp(file_name)) == -1) {
> + perror_msg_and_fail("Error while creating temporary file");
> + }
> +
> + if (write(file_desc, buf, global_len) == -1) {
> + perror_msg_and_fail("Error while writing to temporary file");
> + }
> + free(buf);
> +
> + global_pointer = (char *)mmap(NULL, global_len,
> + PROT_READ|PROT_WRITE|PROT_EXEC, MAP_SHARED, file_desc, 0);
> + if (global_pointer == MAP_FAILED) {
> + perror_msg_and_fail("Temporary file could not be mmapped");
> + }
What was the reason to do a file backed mmap instead of an anonymous one?
> + unsigned char *global_vec = malloc((global_len + pg_size - 1) /
> pg_size);
> + res = mincore(global_pointer, global_len, global_vec);
> + if (res == -1) {
> + perror_msg_and_fail("mincore fail!\n");
> + }
> + printf("mincore\\(%p, %d, \[[0-1]*\\.\\.\\.]\\) = %d\n",
> + global_pointer, global_len, res);
What I don't like in this test is that it doesn't test the only part
of mincore parser that is buggy and has to be tested first of all --
the way how the result vector is printed. Haven't you noticed that
mincore parser prints a lot of garbage after the real data returned
by the kernel?
I've pushed commit v4.11-185-gdfea1da to address this.
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