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[lldb] [test] Synchronize before the breakpoint in fork tests

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We set breakpoint on child_func, so synchronization inside it is too
late to guarantee ordering between the parent output and child
breakpoint.  Split the function in two, and perform synchronization
before the breakpoint.

Differential Revision: https://reviews.llvm.org/D109591
This commit is contained in:
Michał Górny
2021-09-10 12:51:13 +02:00
parent 9d1bea9c88
commit caf508d712
1 changed files with 20 additions and 15 deletions
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35
lldb/test/Shell/Subprocess/Inputs/fork.cpp
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@@ -28,19 +28,8 @@ void wait_for_parent() {
assert(ret == 0);
}
int child_func(void *argv0_ptr) {
const char *argv0 = static_cast<char*>(argv0_ptr);
// NB: when using vfork(), the parent may be suspended while running
// this function, so do not rely on any synchronization until we exec
#if defined(TEST_FORK)
if (TEST_FORK != vfork)
#endif
wait_for_parent();
int ret = close(parent_done[1]);
assert(ret == 0);
// This is the function we set breakpoint on.
int child_func(const char *argv0) {
// we need to avoid memory modifications for vfork(), yet we want
// to be able to test watchpoints, so do the next best thing
// and restore the original value
@@ -51,6 +40,22 @@ int child_func(void *argv0_ptr) {
return 1;
}
int child_top_func(void *argv0_ptr) {
const char *argv0 = static_cast<char*>(argv0_ptr);
int ret = close(parent_done[1]);
assert(ret == 0);
// NB: when using vfork(), the parent may be suspended while running
// this function, so do not rely on any synchronization until we exec
#if defined(TEST_FORK)
if (TEST_FORK != vfork)
#endif
wait_for_parent();
return child_func(argv0);
}
int main(int argc, char* argv[]) {
alignas(uintmax_t) char stack[4096];
int ret;
@@ -77,12 +82,12 @@ int main(int argc, char* argv[]) {
assert(ret != -1);
#if defined(TEST_CLONE)
pid_t pid = clone(child_func, &stack[sizeof(stack)], 0, argv[0]);
pid_t pid = clone(child_top_func, &stack[sizeof(stack)], 0, argv[0]);
#elif defined(TEST_FORK)
pid_t pid = TEST_FORK();
// NB: this must be equivalent to the clone() call above
if (pid == 0)
_exit(child_func(argv[0]));
_exit(child_top_func(argv[0]));
#endif
assert(pid != -1);