third_party/linux-syscall-support/tests/getrandom.c

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#include "test_skel.h"

#define BUFFER_SIZE 256

int main(int argc, char *argv[]) {
  char buffer[BUFFER_SIZE];
  // Zero it out so we can check later that it's at least not all 0s.
  memset(buffer, 0, BUFFER_SIZE);
  bool buffer_contains_all_zeros = true;

  // Don't bother passing any flags. (If we're using lss, we might not have the
  // right header files with the flags defined anyway, and we'd have to copy
  // this in here too, and risk getting out of sync in yet another way.)
  const ssize_t r = sys_getrandom(buffer, BUFFER_SIZE, 0);

  // Make sure it either worked, or that it's just not supported.
  assert(r == BUFFER_SIZE || errno == ENOSYS);

  if (r == BUFFER_SIZE) {
    // If all the bytes are 0, it didn't really work.
    for (size_t i = 0; i < BUFFER_SIZE; ++i) {
      if (buffer[i] != 0) {
        buffer_contains_all_zeros = false;
      }
    }
    assert(!buffer_contains_all_zeros);
  }

  return 0;
}