tools/testing/selftests/proc/proc-self-isnt-kthread.c

   1 /*
   2  * Copyright (c) 2024 Alexey Dobriyan <adobriyan@gmail.com>
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16 /* Test that userspace program is not kernel thread. */
  17 #undef NDEBUG
  18 #include <assert.h>
  19 #include <fcntl.h>
  20 #include <string.h>
  21 #include <unistd.h>
  22
  23 int main(void)
  24 {
  25         int fd = open("/proc/self/status", O_RDONLY);
  26         assert(fd >= 0);
  27
  28         char buf[4096];
  29         ssize_t rv = read(fd, buf, sizeof(buf));
  30         assert(0 <= rv && rv < sizeof(buf));
  31         buf[rv] = '\0';
  32
  33         /* This test is very much not kernel thread. */
  34         assert(strstr(buf, "Kthread:\t0\n"));
  35
  36         return 0;
  37 }