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// RUN: %clangxx_msan -O0 %s -o %t && %run %t
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <ucontext.h>
#include <unistd.h>
#include <sanitizer/msan_interface.h>
namespace {
const int kStackSize = 1 << 20;
char fiber_stack[kStackSize] = {};
ucontext_t main_ctx;
ucontext_t fiber_ctx;
void fiber() {
printf("%s: entering fiber\n", __FUNCTION__);
// This fiber was switched into from main. Verify the details of main's stack
// have been populated by MSAN.
const void *previous_stack_bottom = nullptr;
size_t previous_stack_size = 0;
__msan_finish_switch_fiber(&previous_stack_bottom, &previous_stack_size);
assert(previous_stack_bottom != nullptr);
assert(previous_stack_size != 0);
printf("%s: implicitly swapcontext to main\n", __FUNCTION__);
__msan_start_switch_fiber(previous_stack_bottom, previous_stack_size);
}
} // namespace
// Set up a fiber, switch to it, and switch back, invoking __msan_*_switch_fiber
// functions along the way. At each step, validate the correct stack addresses and
// sizes are returned from those functions.
int main(int argc, char **argv) {
if (getcontext(&fiber_ctx) == -1) {
perror("getcontext");
_exit(1);
}
fiber_ctx.uc_stack.ss_sp = fiber_stack;
fiber_ctx.uc_stack.ss_size = sizeof(fiber_stack);
fiber_ctx.uc_link = &main_ctx;
makecontext(&fiber_ctx, fiber, 0);
// Tell MSAN a fiber switch is about to occur, then perform the switch
printf("%s: swapcontext to fiber\n", __FUNCTION__);
__msan_start_switch_fiber(fiber_stack, kStackSize);
if (swapcontext(&main_ctx, &fiber_ctx) == -1) {
perror("swapcontext");
_exit(1);
}
// The fiber switched to above now switched back here. Tell MSAN that switch
// is complete and verify the fiber details return by MSAN are correct.
const void *previous_stack_bottom = nullptr;
size_t previous_stack_size = 0;
__msan_finish_switch_fiber(&previous_stack_bottom, &previous_stack_size);
assert(previous_stack_bottom == fiber_stack);
assert(previous_stack_size == kStackSize);
printf("%s: exiting\n", __FUNCTION__);
return 0;
}
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