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Implement signal handler tail recursion

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GNU Make on Windows now appears to be working reliably. This change also
fixes a bug where, after fork the Windows thread handle wasn't reset and
that caused undefined behavior using SetThreadContext() with our signals
This commit is contained in:
Justine Tunney 2023-10-14 10:29:26 -07:00
parent a657f3e878
commit cdf556e7d2
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GPG key ID: BE714B4575D6E328
15 changed files with 627 additions and 77 deletions
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49
libc/proc/fork.c
View file

@ -27,21 +27,22 @@
#include "libc/intrin/dll.h"
#include "libc/intrin/strace.internal.h"
#include "libc/intrin/weaken.h"
#include "libc/nt/files.h"
#include "libc/nt/process.h"
#include "libc/nt/runtime.h"
#include "libc/nt/synchronization.h"
#include "libc/nt/thread.h"
#include "libc/proc/proc.internal.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/runtime.h"
#include "libc/runtime/syslib.internal.h"
#include "libc/sysv/consts/sig.h"
#include "libc/thread/posixthread.internal.h"
#include "libc/thread/tls.h"
int _fork(uint32_t dwCreationFlags) {
struct Dll *e;
struct CosmoTib *tib;
int ax, dx, tid, parent;
struct PosixThread *me, *other;
parent = __pid;
(void)parent;
BLOCK_SIGNALS;
@ -55,33 +56,55 @@ int _fork(uint32_t dwCreationFlags) {
ax = sys_fork_nt(dwCreationFlags);
}
if (!ax) {
// get new process id
if (!IsWindows()) {
dx = sys_getpid().ax;
} else {
dx = GetCurrentProcessId();
}
__pid = dx;
tib = __get_tls();
me = (struct PosixThread *)tib->tib_pthread;
dll_remove(&_pthread_list, &me->list);
// turn other threads into zombies
// we can't free() them since we're monopolizing all locks
// we assume the operating system already reclaimed system handles
struct CosmoTib *tib = __get_tls();
struct PosixThread *pt = (struct PosixThread *)tib->tib_pthread;
dll_remove(&_pthread_list, &pt->list);
for (e = dll_first(_pthread_list); e; e = dll_next(_pthread_list, e)) {
other = POSIXTHREAD_CONTAINER(e);
atomic_store_explicit(&other->pt_status, kPosixThreadZombie,
atomic_store_explicit(&POSIXTHREAD_CONTAINER(e)->pt_status,
kPosixThreadZombie, memory_order_relaxed);
atomic_store_explicit(&POSIXTHREAD_CONTAINER(e)->tib->tib_syshand, 0,
memory_order_relaxed);
}
dll_make_first(&_pthread_list, &me->list);
dll_make_first(&_pthread_list, &pt->list);
// get new main thread id
tid = IsLinux() || IsXnuSilicon() ? dx : sys_gettid();
atomic_store_explicit(&tib->tib_tid, tid, memory_order_relaxed);
atomic_store_explicit(&me->ptid, tid, memory_order_relaxed);
atomic_store_explicit(&me->pt_canceled, false, memory_order_relaxed);
atomic_store_explicit(&pt->ptid, tid, memory_order_relaxed);
// get new system thread handle
intptr_t syshand = 0;
if (IsXnuSilicon()) {
syshand = __syslib->__pthread_self();
} else if (IsWindows()) {
DuplicateHandle(GetCurrentProcess(), GetCurrentThread(),
GetCurrentProcess(), &syshand, 0, false,
kNtDuplicateSameAccess);
}
atomic_store_explicit(&tib->tib_syshand, syshand, memory_order_relaxed);
// we can't be canceled if the canceler no longer exists
atomic_store_explicit(&pt->pt_canceled, false, memory_order_relaxed);
// run user fork callbacks
if (__threaded && _weaken(_pthread_onfork_child)) {
_weaken(_pthread_onfork_child)();
}
if (IsWindows()) {
__proc_wipe();
}
STRACE("fork() → 0 (child of %d)", parent);
} else {
// this is the parent process
if (__threaded && _weaken(_pthread_onfork_parent)) {
_weaken(_pthread_onfork_parent)();
}