diff options
Diffstat (limited to '')
-rw-r--r-- | src/civetweb/src/third_party/duktape-1.8.0/src-separate/duk_hthread_stacks.c | 476 |
1 files changed, 476 insertions, 0 deletions
diff --git a/src/civetweb/src/third_party/duktape-1.8.0/src-separate/duk_hthread_stacks.c b/src/civetweb/src/third_party/duktape-1.8.0/src-separate/duk_hthread_stacks.c new file mode 100644 index 000000000..59b072d92 --- /dev/null +++ b/src/civetweb/src/third_party/duktape-1.8.0/src-separate/duk_hthread_stacks.c @@ -0,0 +1,476 @@ +/* + * Manipulation of thread stacks (valstack, callstack, catchstack). + * + * Ideally unwinding of stacks should have no side effects, which would + * then favor separate unwinding and shrink check primitives for each + * stack type. A shrink check may realloc and thus have side effects. + * + * However, currently callstack unwinding itself has side effects, as it + * needs to DECREF multiple objects, close environment records, etc. + * Stacks must thus be unwound in the correct order by the caller. + * + * (XXX: This should be probably reworked so that there is a shared + * unwind primitive which handles all stacks as requested, and knows + * the proper order for unwinding.) + * + * Valstack entries above 'top' are always kept initialized to + * "undefined unused". Callstack and catchstack entries above 'top' + * are not zeroed and are left as garbage. + * + * Value stack handling is mostly a part of the API implementation. + */ + +#include "duk_internal.h" + +/* check that there is space for at least one new entry */ +DUK_INTERNAL void duk_hthread_callstack_grow(duk_hthread *thr) { + duk_activation *new_ptr; + duk_size_t old_size; + duk_size_t new_size; + + DUK_ASSERT(thr != NULL); + DUK_ASSERT_DISABLE(thr->callstack_top >= 0); /* avoid warning (unsigned) */ + DUK_ASSERT(thr->callstack_size >= thr->callstack_top); + + if (thr->callstack_top < thr->callstack_size) { + return; + } + + old_size = thr->callstack_size; + new_size = old_size + DUK_CALLSTACK_GROW_STEP; + + /* this is a bit approximate (errors out before max is reached); this is OK */ + if (new_size >= thr->callstack_max) { + DUK_ERROR_RANGE(thr, DUK_STR_CALLSTACK_LIMIT); + } + + DUK_DD(DUK_DDPRINT("growing callstack %ld -> %ld", (long) old_size, (long) new_size)); + + /* + * Note: must use indirect variant of DUK_REALLOC() because underlying + * pointer may be changed by mark-and-sweep. + */ + + DUK_ASSERT(new_size > 0); + new_ptr = (duk_activation *) DUK_REALLOC_INDIRECT(thr->heap, duk_hthread_get_callstack_ptr, (void *) thr, sizeof(duk_activation) * new_size); + if (!new_ptr) { + /* No need for a NULL/zero-size check because new_size > 0) */ + DUK_ERROR_ALLOC_DEFMSG(thr); + } + thr->callstack = new_ptr; + thr->callstack_size = new_size; + + /* note: any entries above the callstack top are garbage and not zeroed */ +} + +DUK_INTERNAL void duk_hthread_callstack_shrink_check(duk_hthread *thr) { + duk_size_t new_size; + duk_activation *p; + + DUK_ASSERT(thr != NULL); + DUK_ASSERT_DISABLE(thr->callstack_top >= 0); /* avoid warning (unsigned) */ + DUK_ASSERT(thr->callstack_size >= thr->callstack_top); + + if (thr->callstack_size - thr->callstack_top < DUK_CALLSTACK_SHRINK_THRESHOLD) { + return; + } + + new_size = thr->callstack_top + DUK_CALLSTACK_SHRINK_SPARE; + DUK_ASSERT(new_size >= thr->callstack_top); + + DUK_DD(DUK_DDPRINT("shrinking callstack %ld -> %ld", (long) thr->callstack_size, (long) new_size)); + + /* + * Note: must use indirect variant of DUK_REALLOC() because underlying + * pointer may be changed by mark-and-sweep. + */ + + /* shrink failure is not fatal */ + p = (duk_activation *) DUK_REALLOC_INDIRECT(thr->heap, duk_hthread_get_callstack_ptr, (void *) thr, sizeof(duk_activation) * new_size); + if (p) { + thr->callstack = p; + thr->callstack_size = new_size; + } else { + /* Because new_size != 0, if condition doesn't need to be + * (p != NULL || new_size == 0). + */ + DUK_ASSERT(new_size != 0); + DUK_D(DUK_DPRINT("callstack shrink failed, ignoring")); + } + + /* note: any entries above the callstack top are garbage and not zeroed */ +} + +DUK_INTERNAL void duk_hthread_callstack_unwind(duk_hthread *thr, duk_size_t new_top) { + duk_size_t idx; + + DUK_DDD(DUK_DDDPRINT("unwind callstack top of thread %p from %ld to %ld", + (void *) thr, + (thr != NULL ? (long) thr->callstack_top : (long) -1), + (long) new_top)); + + DUK_ASSERT(thr); + DUK_ASSERT(thr->heap); + DUK_ASSERT_DISABLE(new_top >= 0); /* unsigned */ + DUK_ASSERT((duk_size_t) new_top <= thr->callstack_top); /* cannot grow */ + + /* + * The loop below must avoid issues with potential callstack + * reallocations. A resize (and other side effects) may happen + * e.g. due to finalizer/errhandler calls caused by a refzero or + * mark-and-sweep. Arbitrary finalizers may run, because when + * an environment record is refzero'd, it may refer to arbitrary + * values which also become refzero'd. + * + * So, the pointer 'p' is re-looked-up below whenever a side effect + * might have changed it. + */ + + idx = thr->callstack_top; + while (idx > new_top) { + duk_activation *act; + duk_hobject *func; +#ifdef DUK_USE_REFERENCE_COUNTING + duk_hobject *tmp; +#endif +#ifdef DUK_USE_DEBUGGER_SUPPORT + duk_heap *heap; +#endif + + idx--; + DUK_ASSERT_DISABLE(idx >= 0); /* unsigned */ + DUK_ASSERT((duk_size_t) idx < thr->callstack_size); /* true, despite side effect resizes */ + + act = thr->callstack + idx; + /* With lightfuncs, act 'func' may be NULL */ + +#ifdef DUK_USE_NONSTD_FUNC_CALLER_PROPERTY + /* + * Restore 'caller' property for non-strict callee functions. + */ + + func = DUK_ACT_GET_FUNC(act); + if (func != NULL && !DUK_HOBJECT_HAS_STRICT(func)) { + duk_tval *tv_caller; + duk_tval tv_tmp; + duk_hobject *h_tmp; + + tv_caller = duk_hobject_find_existing_entry_tval_ptr(thr->heap, func, DUK_HTHREAD_STRING_CALLER(thr)); + + /* The act->prev_caller should only be set if the entry for 'caller' + * exists (as it is only set in that case, and the property is not + * configurable), but handle all the cases anyway. + */ + + if (tv_caller) { + DUK_TVAL_SET_TVAL(&tv_tmp, tv_caller); + if (act->prev_caller) { + /* Just transfer the refcount from act->prev_caller to tv_caller, + * so no need for a refcount update. This is the expected case. + */ + DUK_TVAL_SET_OBJECT(tv_caller, act->prev_caller); + act->prev_caller = NULL; + } else { + DUK_TVAL_SET_NULL(tv_caller); /* no incref needed */ + DUK_ASSERT(act->prev_caller == NULL); + } + DUK_TVAL_DECREF(thr, &tv_tmp); /* side effects */ + } else { + h_tmp = act->prev_caller; + if (h_tmp) { + act->prev_caller = NULL; + DUK_HOBJECT_DECREF(thr, h_tmp); /* side effects */ + } + } + act = thr->callstack + idx; /* avoid side effects */ + DUK_ASSERT(act->prev_caller == NULL); + } +#endif + + /* + * Unwind debugger state. If we unwind while stepping + * (either step over or step into), pause execution. + */ + +#if defined(DUK_USE_DEBUGGER_SUPPORT) + heap = thr->heap; + if (heap->dbg_step_thread == thr && + heap->dbg_step_csindex == idx) { + /* Pause for all step types: step into, step over, step out. + * This is the only place explicitly handling a step out. + */ + DUK_HEAP_SET_PAUSED(heap); + DUK_ASSERT(heap->dbg_step_thread == NULL); + } +#endif + + /* + * Close environment record(s) if they exist. + * + * Only variable environments are closed. If lex_env != var_env, it + * cannot currently contain any register bound declarations. + * + * Only environments created for a NEWENV function are closed. If an + * environment is created for e.g. an eval call, it must not be closed. + */ + + func = DUK_ACT_GET_FUNC(act); + if (func != NULL && !DUK_HOBJECT_HAS_NEWENV(func)) { + DUK_DDD(DUK_DDDPRINT("skip closing environments, envs not owned by this activation")); + goto skip_env_close; + } + /* func is NULL for lightfunc */ + + DUK_ASSERT(act->lex_env == act->var_env); + if (act->var_env != NULL) { + DUK_DDD(DUK_DDDPRINT("closing var_env record %p -> %!O", + (void *) act->var_env, (duk_heaphdr *) act->var_env)); + duk_js_close_environment_record(thr, act->var_env, func, act->idx_bottom); + act = thr->callstack + idx; /* avoid side effect issues */ + } + +#if 0 + if (act->lex_env != NULL) { + if (act->lex_env == act->var_env) { + /* common case, already closed, so skip */ + DUK_DD(DUK_DDPRINT("lex_env and var_env are the same and lex_env " + "already closed -> skip closing lex_env")); + ; + } else { + DUK_DD(DUK_DDPRINT("closing lex_env record %p -> %!O", + (void *) act->lex_env, (duk_heaphdr *) act->lex_env)); + duk_js_close_environment_record(thr, act->lex_env, DUK_ACT_GET_FUNC(act), act->idx_bottom); + act = thr->callstack + idx; /* avoid side effect issues */ + } + } +#endif + + DUK_ASSERT((act->lex_env == NULL) || + ((duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->lex_env, DUK_HTHREAD_STRING_INT_CALLEE(thr)) == NULL) && + (duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->lex_env, DUK_HTHREAD_STRING_INT_VARMAP(thr)) == NULL) && + (duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->lex_env, DUK_HTHREAD_STRING_INT_THREAD(thr)) == NULL) && + (duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->lex_env, DUK_HTHREAD_STRING_INT_REGBASE(thr)) == NULL))); + + DUK_ASSERT((act->var_env == NULL) || + ((duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->var_env, DUK_HTHREAD_STRING_INT_CALLEE(thr)) == NULL) && + (duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->var_env, DUK_HTHREAD_STRING_INT_VARMAP(thr)) == NULL) && + (duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->var_env, DUK_HTHREAD_STRING_INT_THREAD(thr)) == NULL) && + (duk_hobject_find_existing_entry_tval_ptr(thr->heap, act->var_env, DUK_HTHREAD_STRING_INT_REGBASE(thr)) == NULL))); + + skip_env_close: + + /* + * Update preventcount + */ + + if (act->flags & DUK_ACT_FLAG_PREVENT_YIELD) { + DUK_ASSERT(thr->callstack_preventcount >= 1); + thr->callstack_preventcount--; + } + + /* + * Reference count updates + * + * Note: careful manipulation of refcounts. The top is + * not updated yet, so all the activations are reachable + * for mark-and-sweep (which may be triggered by decref). + * However, the pointers are NULL so this is not an issue. + */ + +#ifdef DUK_USE_REFERENCE_COUNTING + tmp = act->var_env; +#endif + act->var_env = NULL; +#ifdef DUK_USE_REFERENCE_COUNTING + DUK_HOBJECT_DECREF_ALLOWNULL(thr, tmp); + act = thr->callstack + idx; /* avoid side effect issues */ +#endif + +#ifdef DUK_USE_REFERENCE_COUNTING + tmp = act->lex_env; +#endif + act->lex_env = NULL; +#ifdef DUK_USE_REFERENCE_COUNTING + DUK_HOBJECT_DECREF_ALLOWNULL(thr, tmp); + act = thr->callstack + idx; /* avoid side effect issues */ +#endif + + /* Note: this may cause a corner case situation where a finalizer + * may see a currently reachable activation whose 'func' is NULL. + */ +#ifdef DUK_USE_REFERENCE_COUNTING + tmp = DUK_ACT_GET_FUNC(act); +#endif + act->func = NULL; +#ifdef DUK_USE_REFERENCE_COUNTING + DUK_HOBJECT_DECREF_ALLOWNULL(thr, tmp); + act = thr->callstack + idx; /* avoid side effect issues */ + DUK_UNREF(act); +#endif + } + + thr->callstack_top = new_top; + + /* + * We could clear the book-keeping variables for the topmost activation, + * but don't do so now. + */ +#if 0 + if (thr->callstack_top > 0) { + duk_activation *act = thr->callstack + thr->callstack_top - 1; + act->idx_retval = 0; + } +#endif + + /* Note: any entries above the callstack top are garbage and not zeroed. + * Also topmost activation idx_retval is garbage (not zeroed), and must + * be ignored. + */ +} + +DUK_INTERNAL void duk_hthread_catchstack_grow(duk_hthread *thr) { + duk_catcher *new_ptr; + duk_size_t old_size; + duk_size_t new_size; + + DUK_ASSERT(thr != NULL); + DUK_ASSERT_DISABLE(thr->catchstack_top); /* avoid warning (unsigned) */ + DUK_ASSERT(thr->catchstack_size >= thr->catchstack_top); + + if (thr->catchstack_top < thr->catchstack_size) { + return; + } + + old_size = thr->catchstack_size; + new_size = old_size + DUK_CATCHSTACK_GROW_STEP; + + /* this is a bit approximate (errors out before max is reached); this is OK */ + if (new_size >= thr->catchstack_max) { + DUK_ERROR_RANGE(thr, DUK_STR_CATCHSTACK_LIMIT); + } + + DUK_DD(DUK_DDPRINT("growing catchstack %ld -> %ld", (long) old_size, (long) new_size)); + + /* + * Note: must use indirect variant of DUK_REALLOC() because underlying + * pointer may be changed by mark-and-sweep. + */ + + DUK_ASSERT(new_size > 0); + new_ptr = (duk_catcher *) DUK_REALLOC_INDIRECT(thr->heap, duk_hthread_get_catchstack_ptr, (void *) thr, sizeof(duk_catcher) * new_size); + if (!new_ptr) { + /* No need for a NULL/zero-size check because new_size > 0) */ + DUK_ERROR_ALLOC_DEFMSG(thr); + } + thr->catchstack = new_ptr; + thr->catchstack_size = new_size; + + /* note: any entries above the catchstack top are garbage and not zeroed */ +} + +DUK_INTERNAL void duk_hthread_catchstack_shrink_check(duk_hthread *thr) { + duk_size_t new_size; + duk_catcher *p; + + DUK_ASSERT(thr != NULL); + DUK_ASSERT_DISABLE(thr->catchstack_top >= 0); /* avoid warning (unsigned) */ + DUK_ASSERT(thr->catchstack_size >= thr->catchstack_top); + + if (thr->catchstack_size - thr->catchstack_top < DUK_CATCHSTACK_SHRINK_THRESHOLD) { + return; + } + + new_size = thr->catchstack_top + DUK_CATCHSTACK_SHRINK_SPARE; + DUK_ASSERT(new_size >= thr->catchstack_top); + + DUK_DD(DUK_DDPRINT("shrinking catchstack %ld -> %ld", (long) thr->catchstack_size, (long) new_size)); + + /* + * Note: must use indirect variant of DUK_REALLOC() because underlying + * pointer may be changed by mark-and-sweep. + */ + + /* shrink failure is not fatal */ + p = (duk_catcher *) DUK_REALLOC_INDIRECT(thr->heap, duk_hthread_get_catchstack_ptr, (void *) thr, sizeof(duk_catcher) * new_size); + if (p) { + thr->catchstack = p; + thr->catchstack_size = new_size; + } else { + /* Because new_size != 0, if condition doesn't need to be + * (p != NULL || new_size == 0). + */ + DUK_ASSERT(new_size != 0); + DUK_D(DUK_DPRINT("catchstack shrink failed, ignoring")); + } + + /* note: any entries above the catchstack top are garbage and not zeroed */ +} + +DUK_INTERNAL void duk_hthread_catchstack_unwind(duk_hthread *thr, duk_size_t new_top) { + duk_size_t idx; + + DUK_DDD(DUK_DDDPRINT("unwind catchstack top of thread %p from %ld to %ld", + (void *) thr, + (thr != NULL ? (long) thr->catchstack_top : (long) -1), + (long) new_top)); + + DUK_ASSERT(thr); + DUK_ASSERT(thr->heap); + DUK_ASSERT_DISABLE(new_top >= 0); /* unsigned */ + DUK_ASSERT((duk_size_t) new_top <= thr->catchstack_top); /* cannot grow */ + + /* + * Since there are no references in the catcher structure, + * unwinding is quite simple. The only thing we need to + * look out for is popping a possible lexical environment + * established for an active catch clause. + */ + + idx = thr->catchstack_top; + while (idx > new_top) { + duk_catcher *p; + duk_activation *act; + duk_hobject *env; + + idx--; + DUK_ASSERT_DISABLE(idx >= 0); /* unsigned */ + DUK_ASSERT((duk_size_t) idx < thr->catchstack_size); + + p = thr->catchstack + idx; + + if (DUK_CAT_HAS_LEXENV_ACTIVE(p)) { + DUK_DDD(DUK_DDDPRINT("unwinding catchstack idx %ld, callstack idx %ld, callstack top %ld: lexical environment active", + (long) idx, (long) p->callstack_index, (long) thr->callstack_top)); + + /* XXX: Here we have a nasty dependency: the need to manipulate + * the callstack means that catchstack must always be unwound by + * the caller before unwinding the callstack. This should be fixed + * later. + */ + + /* Note that multiple catchstack entries may refer to the same + * callstack entry. + */ + act = thr->callstack + p->callstack_index; + DUK_ASSERT(act >= thr->callstack); + DUK_ASSERT(act < thr->callstack + thr->callstack_top); + + DUK_DDD(DUK_DDDPRINT("catchstack_index=%ld, callstack_index=%ld, lex_env=%!iO", + (long) idx, (long) p->callstack_index, + (duk_heaphdr *) act->lex_env)); + + env = act->lex_env; /* current lex_env of the activation (created for catcher) */ + DUK_ASSERT(env != NULL); /* must be, since env was created when catcher was created */ + act->lex_env = DUK_HOBJECT_GET_PROTOTYPE(thr->heap, env); /* prototype is lex_env before catcher created */ + DUK_HOBJECT_DECREF(thr, env); + + /* There is no need to decref anything else than 'env': if 'env' + * becomes unreachable, refzero will handle decref'ing its prototype. + */ + } + } + + thr->catchstack_top = new_top; + + /* note: any entries above the catchstack top are garbage and not zeroed */ +} |