OpenZFS 7431 - ZFS Channel Programs

Authored by: Chris Williamson <[email protected]>
Reviewed by: Matthew Ahrens <[email protected]>
Reviewed by: George Wilson <[email protected]>
Reviewed by: John Kennedy <[email protected]>
Reviewed by: Dan Kimmel <[email protected]>
Approved by: Garrett D'Amore <[email protected]>
Ported-by: Don Brady <[email protected]>
Ported-by: John Kennedy <[email protected]>

OpenZFS-issue: https://www.illumos.org/issues/7431
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/dfc11533

Porting Notes:
* The CLI long option arguments for '-t' and '-m' don't parse on linux
* Switched from kmem_alloc to vmem_alloc in zcp_lua_alloc
* Lua implementation is built as its own module (zlua.ko)
* Lua headers consumed directly by zfs code moved to 'include/sys/lua/'
* There is no native setjmp/longjump available in stock Linux kernel.
  Brought over implementations from illumos and FreeBSD
* The get_temporary_prop() was adapted due to VFS platform differences
* Use of inline functions in lua parser to reduce stack usage per C call
* Skip some ZFS Test Suite ZCP tests on sparc64 to avoid stack overflow

1 files changed, 722 insertions, 0 deletions

diff --git a/module/lua/ldo.c b/module/lua/ldo.c
new file mode 100644
index 000000000..ead29427e
--- /dev/null
+++ b/module/lua/ldo.c
@@ -0,0 +1,722 @@
+/* BEGIN CSTYLED */
+/*
+** $Id: ldo.c,v 2.108.1.3 2013/11/08 18:22:50 roberto Exp $
+** Stack and Call structure of Lua
+** See Copyright Notice in lua.h
+*/
+
+
+#define ldo_c
+#define LUA_CORE
+
+#include <sys/lua/lua.h>
+
+#include "lapi.h"
+#include "ldebug.h"
+#include "ldo.h"
+#include "lfunc.h"
+#include "lgc.h"
+#include "lmem.h"
+#include "lobject.h"
+#include "lopcodes.h"
+#include "lparser.h"
+#include "lstate.h"
+#include "lstring.h"
+#include "ltable.h"
+#include "ltm.h"
+#include "lundump.h"
+#include "lvm.h"
+#include "lzio.h"
+
+
+
+
+/*
+** {======================================================
+** Error-recovery functions
+** =======================================================
+*/
+
+/*
+** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By
+** default, Lua handles errors with exceptions when compiling as
+** C++ code, with _longjmp/_setjmp when asked to use them, and with
+** longjmp/setjmp otherwise.
+*/
+#if !defined(LUAI_THROW)
+
+#ifdef _KERNEL
+
+#if defined(__i386__)
+#define	JMP_BUF_CNT	6
+#elif defined(__x86_64__)
+#define	JMP_BUF_CNT	8
+#elif defined(__sparc__) && defined(__arch64__)
+#define	JMP_BUF_CNT	6
+#elif defined(__powerpc__)
+#define	JMP_BUF_CNT	26
+#elif defined(__aarch64__)
+#define	JMP_BUF_CNT	64
+#elif defined(__arm__)
+#define	JMP_BUF_CNT	65
+#elif defined(__mips__)
+#define JMP_BUF_CNT	12
+#elif defined(__s390x__)
+#define JMP_BUF_CNT	9
+#else
+#define	JMP_BUF_CNT	1
+#endif
+
+typedef	struct _label_t { long long unsigned val[JMP_BUF_CNT]; } label_t;
+
+int setjmp(label_t *) __attribute__ ((__nothrow__));
+extern void longjmp(label_t *) __attribute__((__noreturn__));
+
+#define LUAI_THROW(L,c)		longjmp(&(c)->b)
+#define LUAI_TRY(L,c,a)		if (setjmp(&(c)->b) == 0) { a }
+#define luai_jmpbuf		label_t
+
+/* unsupported archs will build but not be able to run lua programs */
+#if JMP_BUF_CNT == 1
+int setjmp (label_t *buf) {
+	return 1;
+}
+
+void longjmp (label_t * buf) {
+	for (;;);
+}
+#endif
+
+#else /* _KERNEL */
+
+#if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)
+/* C++ exceptions */
+#define LUAI_THROW(L,c)		throw(c)
+#define LUAI_TRY(L,c,a) \
+	try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
+#define luai_jmpbuf		int  /* dummy variable */
+
+#elif defined(LUA_USE_ULONGJMP)
+/* in Unix, try _longjmp/_setjmp (more efficient) */
+#define LUAI_THROW(L,c)		_longjmp((c)->b, 1)
+#define LUAI_TRY(L,c,a)		if (_setjmp((c)->b) == 0) { a }
+#define luai_jmpbuf		jmp_buf
+
+#else
+/* default handling with long jumps */
+#define LUAI_THROW(L,c)		longjmp((c)->b, 1)
+#define LUAI_TRY(L,c,a)		if (setjmp((c)->b) == 0) { a }
+#define luai_jmpbuf		jmp_buf
+
+#endif
+
+#endif /* _KERNEL */
+
+#endif /* LUAI_THROW */
+
+
+/* chain list of long jump buffers */
+struct lua_longjmp {
+  struct lua_longjmp *previous;
+  luai_jmpbuf b;
+  volatile int status;  /* error code */
+};
+
+
+static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
+  switch (errcode) {
+    case LUA_ERRMEM: {  /* memory error? */
+      setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
+      break;
+    }
+    case LUA_ERRERR: {
+      setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
+      break;
+    }
+    default: {
+      setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */
+      break;
+    }
+  }
+  L->top = oldtop + 1;
+}
+
+
+l_noret luaD_throw (lua_State *L, int errcode) {
+  if (L->errorJmp) {  /* thread has an error handler? */
+    L->errorJmp->status = errcode;  /* set status */
+    LUAI_THROW(L, L->errorJmp);  /* jump to it */
+  }
+  else {  /* thread has no error handler */
+    L->status = cast_byte(errcode);  /* mark it as dead */
+    if (G(L)->mainthread->errorJmp) {  /* main thread has a handler? */
+      setobjs2s(L, G(L)->mainthread->top++, L->top - 1);  /* copy error obj. */
+      luaD_throw(G(L)->mainthread, errcode);  /* re-throw in main thread */
+    }
+    else {  /* no handler at all; abort */
+      if (G(L)->panic) {  /* panic function? */
+        lua_unlock(L);
+        G(L)->panic(L);  /* call it (last chance to jump out) */
+      }
+      panic("no error handler");
+    }
+  }
+}
+
+
+int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
+  unsigned short oldnCcalls = L->nCcalls;
+  struct lua_longjmp lj;
+  lj.status = LUA_OK;
+  lj.previous = L->errorJmp;  /* chain new error handler */
+  L->errorJmp = &lj;
+  LUAI_TRY(L, &lj,
+    (*f)(L, ud);
+  );
+  L->errorJmp = lj.previous;  /* restore old error handler */
+  L->nCcalls = oldnCcalls;
+  return lj.status;
+}
+
+/* }====================================================== */
+
+
+static void correctstack (lua_State *L, TValue *oldstack) {
+  CallInfo *ci;
+  GCObject *up;
+  L->top = (L->top - oldstack) + L->stack;
+  for (up = L->openupval; up != NULL; up = up->gch.next)
+    gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
+  for (ci = L->ci; ci != NULL; ci = ci->previous) {
+    ci->top = (ci->top - oldstack) + L->stack;
+    ci->func = (ci->func - oldstack) + L->stack;
+    if (isLua(ci))
+      ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
+  }
+}
+
+
+/* some space for error handling */
+#define ERRORSTACKSIZE	(LUAI_MAXSTACK + 200)
+
+
+void luaD_reallocstack (lua_State *L, int newsize) {
+  TValue *oldstack = L->stack;
+  int lim = L->stacksize;
+  lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
+  lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
+  luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
+  for (; lim < newsize; lim++)
+    setnilvalue(L->stack + lim); /* erase new segment */
+  L->stacksize = newsize;
+  L->stack_last = L->stack + newsize - EXTRA_STACK;
+  correctstack(L, oldstack);
+}
+
+
+void luaD_growstack (lua_State *L, int n) {
+  int size = L->stacksize;
+  if (size > LUAI_MAXSTACK)  /* error after extra size? */
+    luaD_throw(L, LUA_ERRERR);
+  else {
+    int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
+    int newsize = 2 * size;
+    if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
+    if (newsize < needed) newsize = needed;
+    if (newsize > LUAI_MAXSTACK) {  /* stack overflow? */
+      luaD_reallocstack(L, ERRORSTACKSIZE);
+      luaG_runerror(L, "stack overflow");
+    }
+    else
+      luaD_reallocstack(L, newsize);
+  }
+}
+
+
+static int stackinuse (lua_State *L) {
+  CallInfo *ci;
+  StkId lim = L->top;
+  for (ci = L->ci; ci != NULL; ci = ci->previous) {
+    lua_assert(ci->top <= L->stack_last);
+    if (lim < ci->top) lim = ci->top;
+  }
+  return cast_int(lim - L->stack) + 1;  /* part of stack in use */
+}
+
+
+void luaD_shrinkstack (lua_State *L) {
+  int inuse = stackinuse(L);
+  int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK;
+  if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK;
+  if (inuse > LUAI_MAXSTACK ||  /* handling stack overflow? */
+      goodsize >= L->stacksize)  /* would grow instead of shrink? */
+    condmovestack(L);  /* don't change stack (change only for debugging) */
+  else
+    luaD_reallocstack(L, goodsize);  /* shrink it */
+}
+
+
+void luaD_hook (lua_State *L, int event, int line) {
+  lua_Hook hook = L->hook;
+  if (hook && L->allowhook) {
+    CallInfo *ci = L->ci;
+    ptrdiff_t top = savestack(L, L->top);
+    ptrdiff_t ci_top = savestack(L, ci->top);
+    lua_Debug ar;
+    ar.event = event;
+    ar.currentline = line;
+    ar.i_ci = ci;
+    luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
+    ci->top = L->top + LUA_MINSTACK;
+    lua_assert(ci->top <= L->stack_last);
+    L->allowhook = 0;  /* cannot call hooks inside a hook */
+    ci->callstatus |= CIST_HOOKED;
+    lua_unlock(L);
+    (*hook)(L, &ar);
+    lua_lock(L);
+    lua_assert(!L->allowhook);
+    L->allowhook = 1;
+    ci->top = restorestack(L, ci_top);
+    L->top = restorestack(L, top);
+    ci->callstatus &= ~CIST_HOOKED;
+  }
+}
+
+
+static void callhook (lua_State *L, CallInfo *ci) {
+  int hook = LUA_HOOKCALL;
+  ci->u.l.savedpc++;  /* hooks assume 'pc' is already incremented */
+  if (isLua(ci->previous) &&
+      GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
+    ci->callstatus |= CIST_TAIL;
+    hook = LUA_HOOKTAILCALL;
+  }
+  luaD_hook(L, hook, -1);
+  ci->u.l.savedpc--;  /* correct 'pc' */
+}
+
+
+static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
+  int i;
+  int nfixargs = p->numparams;
+  StkId base, fixed;
+  lua_assert(actual >= nfixargs);
+  /* move fixed parameters to final position */
+  luaD_checkstack(L, p->maxstacksize);  /* check again for new 'base' */
+  fixed = L->top - actual;  /* first fixed argument */
+  base = L->top;  /* final position of first argument */
+  for (i=0; i<nfixargs; i++) {
+    setobjs2s(L, L->top++, fixed + i);
+    setnilvalue(fixed + i);
+  }
+  return base;
+}
+
+
+static StkId tryfuncTM (lua_State *L, StkId func) {
+  const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
+  StkId p;
+  ptrdiff_t funcr = savestack(L, func);
+  if (!ttisfunction(tm))
+    luaG_typeerror(L, func, "call");
+  /* Open a hole inside the stack at `func' */
+  for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
+  incr_top(L);
+  func = restorestack(L, funcr);  /* previous call may change stack */
+  setobj2s(L, func, tm);  /* tag method is the new function to be called */
+  return func;
+}
+
+
+
+#define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
+
+
+/*
+** returns true if function has been executed (C function)
+*/
+int luaD_precall (lua_State *L, StkId func, int nresults) {
+  lua_CFunction f;
+  CallInfo *ci;
+  int n;  /* number of arguments (Lua) or returns (C) */
+  ptrdiff_t funcr = savestack(L, func);
+  switch (ttype(func)) {
+    case LUA_TLCF:  /* light C function */
+      f = fvalue(func);
+      goto Cfunc;
+    case LUA_TCCL: {  /* C closure */
+      f = clCvalue(func)->f;
+     Cfunc:
+      luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
+      ci = next_ci(L);  /* now 'enter' new function */
+      ci->nresults = nresults;
+      ci->func = restorestack(L, funcr);
+      ci->top = L->top + LUA_MINSTACK;
+      lua_assert(ci->top <= L->stack_last);
+      ci->callstatus = 0;
+      luaC_checkGC(L);  /* stack grow uses memory */
+      if (L->hookmask & LUA_MASKCALL)
+        luaD_hook(L, LUA_HOOKCALL, -1);
+      lua_unlock(L);
+      n = (*f)(L);  /* do the actual call */
+      lua_lock(L);
+      api_checknelems(L, n);
+      luaD_poscall(L, L->top - n);
+      return 1;
+    }
+    case LUA_TLCL: {  /* Lua function: prepare its call */
+      StkId base;
+      Proto *p = clLvalue(func)->p;
+      n = cast_int(L->top - func) - 1;  /* number of real arguments */
+      luaD_checkstack(L, p->maxstacksize);
+      for (; n < p->numparams; n++)
+        setnilvalue(L->top++);  /* complete missing arguments */
+      if (!p->is_vararg) {
+        func = restorestack(L, funcr);
+        base = func + 1;
+      }
+      else {
+        base = adjust_varargs(L, p, n);
+        func = restorestack(L, funcr);  /* previous call can change stack */
+      }
+      ci = next_ci(L);  /* now 'enter' new function */
+      ci->nresults = nresults;
+      ci->func = func;
+      ci->u.l.base = base;
+      ci->top = base + p->maxstacksize;
+      lua_assert(ci->top <= L->stack_last);
+      ci->u.l.savedpc = p->code;  /* starting point */
+      ci->callstatus = CIST_LUA;
+      L->top = ci->top;
+      luaC_checkGC(L);  /* stack grow uses memory */
+      if (L->hookmask & LUA_MASKCALL)
+        callhook(L, ci);
+      return 0;
+    }
+    default: {  /* not a function */
+      func = tryfuncTM(L, func);  /* retry with 'function' tag method */
+      return luaD_precall(L, func, nresults);  /* now it must be a function */
+    }
+  }
+}
+
+
+int luaD_poscall (lua_State *L, StkId firstResult) {
+  StkId res;
+  int wanted, i;
+  CallInfo *ci = L->ci;
+  if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
+    if (L->hookmask & LUA_MASKRET) {
+      ptrdiff_t fr = savestack(L, firstResult);  /* hook may change stack */
+      luaD_hook(L, LUA_HOOKRET, -1);
+      firstResult = restorestack(L, fr);
+    }
+    L->oldpc = ci->previous->u.l.savedpc;  /* 'oldpc' for caller function */
+  }
+  res = ci->func;  /* res == final position of 1st result */
+  wanted = ci->nresults;
+  L->ci = ci = ci->previous;  /* back to caller */
+  /* move results to correct place */
+  for (i = wanted; i != 0 && firstResult < L->top; i--)
+    setobjs2s(L, res++, firstResult++);
+  while (i-- > 0)
+    setnilvalue(res++);
+  L->top = res;
+  return (wanted - LUA_MULTRET);  /* 0 iff wanted == LUA_MULTRET */
+}
+
+
+/*
+** Call a function (C or Lua). The function to be called is at *func.
+** The arguments are on the stack, right after the function.
+** When returns, all the results are on the stack, starting at the original
+** function position.
+*/
+void luaD_call (lua_State *L, StkId func, int nResults, int allowyield) {
+  if (++L->nCcalls >= LUAI_MAXCCALLS) {
+    if (L->nCcalls == LUAI_MAXCCALLS)
+      luaG_runerror(L, "C stack overflow");
+    else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
+      luaD_throw(L, LUA_ERRERR);  /* error while handing stack error */
+  }
+  if (!allowyield) L->nny++;
+  if (!luaD_precall(L, func, nResults))  /* is a Lua function? */
+    luaV_execute(L);  /* call it */
+  if (!allowyield) L->nny--;
+  L->nCcalls--;
+}
+
+
+static void finishCcall (lua_State *L) {
+  CallInfo *ci = L->ci;
+  int n;
+  lua_assert(ci->u.c.k != NULL);  /* must have a continuation */
+  lua_assert(L->nny == 0);
+  if (ci->callstatus & CIST_YPCALL) {  /* was inside a pcall? */
+    ci->callstatus &= ~CIST_YPCALL;  /* finish 'lua_pcall' */
+    L->errfunc = ci->u.c.old_errfunc;
+  }
+  /* finish 'lua_callk'/'lua_pcall' */
+  adjustresults(L, ci->nresults);
+  /* call continuation function */
+  if (!(ci->callstatus & CIST_STAT))  /* no call status? */
+    ci->u.c.status = LUA_YIELD;  /* 'default' status */
+  lua_assert(ci->u.c.status != LUA_OK);
+  ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED;
+  lua_unlock(L);
+  n = (*ci->u.c.k)(L);
+  lua_lock(L);
+  api_checknelems(L, n);
+  /* finish 'luaD_precall' */
+  luaD_poscall(L, L->top - n);
+}
+
+
+static void unroll (lua_State *L, void *ud) {
+  UNUSED(ud);
+  for (;;) {
+    if (L->ci == &L->base_ci)  /* stack is empty? */
+      return;  /* coroutine finished normally */
+    if (!isLua(L->ci))  /* C function? */
+      finishCcall(L);
+    else {  /* Lua function */
+      luaV_finishOp(L);  /* finish interrupted instruction */
+      luaV_execute(L);  /* execute down to higher C 'boundary' */
+    }
+  }
+}
+
+
+/*
+** check whether thread has a suspended protected call
+*/
+static CallInfo *findpcall (lua_State *L) {
+  CallInfo *ci;
+  for (ci = L->ci; ci != NULL; ci = ci->previous) {  /* search for a pcall */
+    if (ci->callstatus & CIST_YPCALL)
+      return ci;
+  }
+  return NULL;  /* no pending pcall */
+}
+
+
+static int recover (lua_State *L, int status) {
+  StkId oldtop;
+  CallInfo *ci = findpcall(L);
+  if (ci == NULL) return 0;  /* no recovery point */
+  /* "finish" luaD_pcall */
+  oldtop = restorestack(L, ci->extra);
+  luaF_close(L, oldtop);
+  seterrorobj(L, status, oldtop);
+  L->ci = ci;
+  L->allowhook = ci->u.c.old_allowhook;
+  L->nny = 0;  /* should be zero to be yieldable */
+  luaD_shrinkstack(L);
+  L->errfunc = ci->u.c.old_errfunc;
+  ci->callstatus |= CIST_STAT;  /* call has error status */
+  ci->u.c.status = status;  /* (here it is) */
+  return 1;  /* continue running the coroutine */
+}
+
+
+/*
+** signal an error in the call to 'resume', not in the execution of the
+** coroutine itself. (Such errors should not be handled by any coroutine
+** error handler and should not kill the coroutine.)
+*/
+static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) {
+  L->top = firstArg;  /* remove args from the stack */
+  setsvalue2s(L, L->top, luaS_new(L, msg));  /* push error message */
+  api_incr_top(L);
+  luaD_throw(L, -1);  /* jump back to 'lua_resume' */
+}
+
+
+/*
+** do the work for 'lua_resume' in protected mode
+*/
+static void resume_cb (lua_State *L, void *ud) {
+  int nCcalls = L->nCcalls;
+  StkId firstArg = cast(StkId, ud);
+  CallInfo *ci = L->ci;
+  if (nCcalls >= LUAI_MAXCCALLS)
+    resume_error(L, "C stack overflow", firstArg);
+  if (L->status == LUA_OK) {  /* may be starting a coroutine */
+    if (ci != &L->base_ci)  /* not in base level? */
+      resume_error(L, "cannot resume non-suspended coroutine", firstArg);
+    /* coroutine is in base level; start running it */
+    if (!luaD_precall(L, firstArg - 1, LUA_MULTRET))  /* Lua function? */
+      luaV_execute(L);  /* call it */
+  }
+  else if (L->status != LUA_YIELD)
+    resume_error(L, "cannot resume dead coroutine", firstArg);
+  else {  /* resuming from previous yield */
+    L->status = LUA_OK;
+    ci->func = restorestack(L, ci->extra);
+    if (isLua(ci))  /* yielded inside a hook? */
+      luaV_execute(L);  /* just continue running Lua code */
+    else {  /* 'common' yield */
+      if (ci->u.c.k != NULL) {  /* does it have a continuation? */
+        int n;
+        ci->u.c.status = LUA_YIELD;  /* 'default' status */
+        ci->callstatus |= CIST_YIELDED;
+        lua_unlock(L);
+        n = (*ci->u.c.k)(L);  /* call continuation */
+        lua_lock(L);
+        api_checknelems(L, n);
+        firstArg = L->top - n;  /* yield results come from continuation */
+      }
+      luaD_poscall(L, firstArg);  /* finish 'luaD_precall' */
+    }
+    unroll(L, NULL);
+  }
+  lua_assert(nCcalls == L->nCcalls);
+}
+
+
+LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
+  int status;
+  int oldnny = L->nny;  /* save 'nny' */
+  lua_lock(L);
+  luai_userstateresume(L, nargs);
+  L->nCcalls = (from) ? from->nCcalls + 1 : 1;
+  L->nny = 0;  /* allow yields */
+  api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
+  status = luaD_rawrunprotected(L, resume_cb, L->top - nargs);
+  if (status == -1)  /* error calling 'lua_resume'? */
+    status = LUA_ERRRUN;
+  else {  /* yield or regular error */
+    while (status != LUA_OK && status != LUA_YIELD) {  /* error? */
+      if (recover(L, status))  /* recover point? */
+        status = luaD_rawrunprotected(L, unroll, NULL);  /* run continuation */
+      else {  /* unrecoverable error */
+        L->status = cast_byte(status);  /* mark thread as `dead' */
+        seterrorobj(L, status, L->top);
+        L->ci->top = L->top;
+        break;
+      }
+    }
+    lua_assert(status == L->status);
+  }
+  L->nny = oldnny;  /* restore 'nny' */
+  L->nCcalls--;
+  lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
+  lua_unlock(L);
+  return status;
+}
+
+
+LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) {
+  CallInfo *ci = L->ci;
+  luai_userstateyield(L, nresults);
+  lua_lock(L);
+  api_checknelems(L, nresults);
+  if (L->nny > 0) {
+    if (L != G(L)->mainthread)
+      luaG_runerror(L, "attempt to yield across a C-call boundary");
+    else
+      luaG_runerror(L, "attempt to yield from outside a coroutine");
+  }
+  L->status = LUA_YIELD;
+  ci->extra = savestack(L, ci->func);  /* save current 'func' */
+  if (isLua(ci)) {  /* inside a hook? */
+    api_check(L, k == NULL, "hooks cannot continue after yielding");
+  }
+  else {
+    if ((ci->u.c.k = k) != NULL)  /* is there a continuation? */
+      ci->u.c.ctx = ctx;  /* save context */
+    ci->func = L->top - nresults - 1;  /* protect stack below results */
+    luaD_throw(L, LUA_YIELD);
+  }
+  lua_assert(ci->callstatus & CIST_HOOKED);  /* must be inside a hook */
+  lua_unlock(L);
+  return 0;  /* return to 'luaD_hook' */
+}
+
+
+int luaD_pcall (lua_State *L, Pfunc func, void *u,
+                ptrdiff_t old_top, ptrdiff_t ef) {
+  int status;
+  CallInfo *old_ci = L->ci;
+  lu_byte old_allowhooks = L->allowhook;
+  unsigned short old_nny = L->nny;
+  ptrdiff_t old_errfunc = L->errfunc;
+  L->errfunc = ef;
+  status = luaD_rawrunprotected(L, func, u);
+  if (status != LUA_OK) {  /* an error occurred? */
+    StkId oldtop = restorestack(L, old_top);
+    luaF_close(L, oldtop);  /* close possible pending closures */
+    seterrorobj(L, status, oldtop);
+    L->ci = old_ci;
+    L->allowhook = old_allowhooks;
+    L->nny = old_nny;
+    luaD_shrinkstack(L);
+  }
+  L->errfunc = old_errfunc;
+  return status;
+}
+
+
+
+/*
+** Execute a protected parser.
+*/
+struct SParser {  /* data to `f_parser' */
+  ZIO *z;
+  Mbuffer buff;  /* dynamic structure used by the scanner */
+  Dyndata dyd;  /* dynamic structures used by the parser */
+  const char *mode;
+  const char *name;
+};
+
+
+static void checkmode (lua_State *L, const char *mode, const char *x) {
+  if (mode && strchr(mode, x[0]) == NULL) {
+    luaO_pushfstring(L,
+       "attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
+    luaD_throw(L, LUA_ERRSYNTAX);
+  }
+}
+
+
+static void f_parser (lua_State *L, void *ud) {
+  int i;
+  Closure *cl;
+  struct SParser *p = cast(struct SParser *, ud);
+  int c = zgetc(p->z);  /* read first character */
+  if (c == LUA_SIGNATURE[0]) {
+    checkmode(L, p->mode, "binary");
+    cl = luaU_undump(L, p->z, &p->buff, p->name);
+  }
+  else {
+    checkmode(L, p->mode, "text");
+    cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
+  }
+  lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
+  for (i = 0; i < cl->l.nupvalues; i++) {  /* initialize upvalues */
+    UpVal *up = luaF_newupval(L);
+    cl->l.upvals[i] = up;
+    luaC_objbarrier(L, cl, up);
+  }
+}
+
+
+int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
+                                        const char *mode) {
+  struct SParser p;
+  int status;
+  L->nny++;  /* cannot yield during parsing */
+  p.z = z; p.name = name; p.mode = mode;
+  p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
+  p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
+  p.dyd.label.arr = NULL; p.dyd.label.size = 0;
+  luaZ_initbuffer(L, &p.buff);
+  status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
+  luaZ_freebuffer(L, &p.buff);
+  luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
+  luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
+  luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
+  L->nny--;
+  return status;
+}
+/* END CSTYLED */