swapcontext_test.cpp
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// Check that ASan plays well with easy cases of makecontext/swapcontext.
// RUN: %clangxx_asan -O0 %s -o %t && %run %t 2>&1 | FileCheck %s
// RUN: %clangxx_asan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
// RUN: %clangxx_asan -O2 %s -o %t && %run %t 2>&1 | FileCheck %s
// RUN: %clangxx_asan -O3 %s -o %t && %run %t 2>&1 | FileCheck %s
//
// This test is too sublte to try on non-x86 arch for now.
// Android does not support swapcontext.
// REQUIRES: x86-target-arch && !android
#include <stdio.h>
#include <ucontext.h>
#include <unistd.h>
ucontext_t orig_context;
ucontext_t child_context;
const int kStackSize = 1 << 20;
__attribute__((noinline))
void Throw() {
throw 1;
}
__attribute__((noinline))
void ThrowAndCatch() {
try {
Throw();
} catch(int a) {
printf("ThrowAndCatch: %d\n", a);
}
}
void Child(int mode) {
char x[32] = {0}; // Stack gets poisoned.
printf("Child: %p\n", x);
ThrowAndCatch(); // Simulate __asan_handle_no_return().
// (a) Do nothing, just return to parent function.
// (b) Jump into the original function. Stack remains poisoned unless we do
// something.
if (mode == 1) {
if (swapcontext(&child_context, &orig_context) < 0) {
perror("swapcontext");
_exit(0);
}
}
}
int Run(int arg, int mode, char *child_stack) {
printf("Child stack: %p\n", child_stack);
// Setup child context.
getcontext(&child_context);
child_context.uc_stack.ss_sp = child_stack;
child_context.uc_stack.ss_size = kStackSize / 2;
if (mode == 0) {
child_context.uc_link = &orig_context;
}
makecontext(&child_context, (void (*)())Child, 1, mode);
if (swapcontext(&orig_context, &child_context) < 0) {
perror("swapcontext");
return 0;
}
// Touch childs's stack to make sure it's unpoisoned.
for (int i = 0; i < kStackSize; i++) {
child_stack[i] = i;
}
return child_stack[arg];
}
int main(int argc, char **argv) {
char stack[kStackSize + 1];
// CHECK: WARNING: ASan doesn't fully support makecontext/swapcontext
int ret = 0;
ret += Run(argc - 1, 0, stack);
printf("Test1 passed\n");
// CHECK: Test1 passed
ret += Run(argc - 1, 1, stack);
printf("Test2 passed\n");
// CHECK: Test2 passed
char *heap = new char[kStackSize + 1];
ret += Run(argc - 1, 0, heap);
printf("Test3 passed\n");
// CHECK: Test3 passed
ret += Run(argc - 1, 1, heap);
printf("Test4 passed\n");
// CHECK: Test4 passed
delete [] heap;
return ret;
}