jsscript.c

来自「java script test programing source code」· C语言 代码 · 共 1,718 行 · 第 1/4 页

            index = i;
        if (!JS_XDRUint32(xdr, &index))
            goto bad;

        /*
         * Assert that, when decoding, the read index is valid and points to
         * an unoccupied element of atoms array.
         */
        JS_ASSERT(index < natoms);
        JS_ASSERT(xdr->mode == JSXDR_ENCODE || !atoms[index]);
        if (!js_XDRAtom(xdr, &atoms[index]))
            goto bad;
    }

    return JS_TRUE;

  bad:
    if (xdr->mode == JSXDR_DECODE) {
        JS_free(cx, atoms);
        map->vector = NULL;
        map->length = 0;
    }

    return JS_FALSE;
}

JSBool
js_XDRScript(JSXDRState *xdr, JSScript **scriptp, JSBool *hasMagic)
{
    JSContext *cx;
    JSScript *script, *newscript, *oldscript;
    uint32 length, lineno, depth, magic, nsrcnotes, ntrynotes;
    uint32 prologLength, version;
    JSBool filenameWasSaved;
    jssrcnote *notes, *sn;

    cx = xdr->cx;
    script = *scriptp;
    nsrcnotes = ntrynotes = 0;
    filenameWasSaved = JS_FALSE;
    notes = NULL;

    /*
     * Encode prologLength and version after script->length (_2 or greater),
     * but decode both new (>= _2) and old, prolog&version-free (_1) scripts.
     * Version _3 supports principals serialization.  Version _4 reorders the
     * nsrcnotes and ntrynotes fields to come before everything except magic,
     * length, prologLength, and version, so that srcnote and trynote storage
     * can be allocated as part of the JSScript (along with bytecode storage).
     *
     * So far, the magic number has not changed for every jsopcode.tbl change.
     * We stipulate forward compatibility by requiring old bytecodes never to
     * change or go away (modulo a few exceptions before the XDR interfaces
     * evolved, and a few exceptions during active trunk development).  With
     * the addition of JSOP_STOP to support JS_THREADED_INTERP, we make a new
     * magic number (_5) so that we know to append JSOP_STOP to old scripts
     * when deserializing.
     */
    if (xdr->mode == JSXDR_ENCODE)
        magic = JSXDR_MAGIC_SCRIPT_CURRENT;
    if (!JS_XDRUint32(xdr, &magic))
        return JS_FALSE;
    JS_ASSERT((uint32)JSXDR_MAGIC_SCRIPT_5 - (uint32)JSXDR_MAGIC_SCRIPT_1 == 4);
    if (magic - (uint32)JSXDR_MAGIC_SCRIPT_1 > 4) {
        if (!hasMagic) {
            JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                                 JSMSG_BAD_SCRIPT_MAGIC);
            return JS_FALSE;
        }
        *hasMagic = JS_FALSE;
        return JS_TRUE;
    }
    if (hasMagic)
        *hasMagic = JS_TRUE;

    if (xdr->mode == JSXDR_ENCODE) {
        length = script->length;
        prologLength = PTRDIFF(script->main, script->code, jsbytecode);
        JS_ASSERT((int16)script->version != JSVERSION_UNKNOWN);
        version = (uint32)script->version | (script->numGlobalVars << 16);
        lineno = (uint32)script->lineno;
        depth = (uint32)script->depth;

        /* Count the srcnotes, keeping notes pointing at the first one. */
        notes = SCRIPT_NOTES(script);
        for (sn = notes; !SN_IS_TERMINATOR(sn); sn = SN_NEXT(sn))
            continue;
        nsrcnotes = PTRDIFF(sn, notes, jssrcnote);
        nsrcnotes++;            /* room for the terminator */

        /* Count the trynotes. */
        if (script->trynotes) {
            while (script->trynotes[ntrynotes].catchStart)
                ntrynotes++;
            ntrynotes++;        /* room for the end marker */
        }
    }

    if (!JS_XDRUint32(xdr, &length))
        return JS_FALSE;
    if (magic >= JSXDR_MAGIC_SCRIPT_2) {
        if (!JS_XDRUint32(xdr, &prologLength))
            return JS_FALSE;
        if (!JS_XDRUint32(xdr, &version))
            return JS_FALSE;

        /* To fuse allocations, we need srcnote and trynote counts early. */
        if (magic >= JSXDR_MAGIC_SCRIPT_4) {
            if (!JS_XDRUint32(xdr, &nsrcnotes))
                return JS_FALSE;
            if (!JS_XDRUint32(xdr, &ntrynotes))
                return JS_FALSE;
        }
    }

    if (xdr->mode == JSXDR_DECODE) {
        size_t alloclength = length;
        if (magic < JSXDR_MAGIC_SCRIPT_5)
            ++alloclength;      /* add a byte for JSOP_STOP */

        script = js_NewScript(cx, alloclength, nsrcnotes, ntrynotes);
        if (!script)
            return JS_FALSE;
        if (magic >= JSXDR_MAGIC_SCRIPT_2) {
            script->main += prologLength;
            script->version = (JSVersion) (version & 0xffff);
            script->numGlobalVars = (uint16) (version >> 16);

            /* If we know nsrcnotes, we allocated space for notes in script. */
            if (magic >= JSXDR_MAGIC_SCRIPT_4)
                notes = SCRIPT_NOTES(script);
        }
        *scriptp = script;
    }

    /*
     * Control hereafter must goto error on failure, in order for the DECODE
     * case to destroy script and conditionally free notes, which if non-null
     * in the (DECODE and magic < _4) case must point at a temporary vector
     * allocated just below.
     */
    oldscript = xdr->script;
    xdr->script = script;
    if (!JS_XDRBytes(xdr, (char *)script->code, length * sizeof(jsbytecode)) ||
        !XDRAtomMap(xdr, &script->atomMap)) {
        goto error;
    }

    if (magic < JSXDR_MAGIC_SCRIPT_5) {
        if (xdr->mode == JSXDR_DECODE) {
            /*
             * Append JSOP_STOP to old scripts, to relieve the interpreter
             * from having to bounds-check pc.  Also take care to increment
             * length, as it is used below and must count all bytecode.
             */
            script->code[length++] = JSOP_STOP;
        }

        if (magic < JSXDR_MAGIC_SCRIPT_4) {
            if (!JS_XDRUint32(xdr, &nsrcnotes))
                goto error;
            if (xdr->mode == JSXDR_DECODE) {
                notes = (jssrcnote *)
                        JS_malloc(cx, nsrcnotes * sizeof(jssrcnote));
                if (!notes)
                    goto error;
            }
        }
    }

    if (!JS_XDRBytes(xdr, (char *)notes, nsrcnotes * sizeof(jssrcnote)) ||
        !JS_XDRCStringOrNull(xdr, (char **)&script->filename) ||
        !JS_XDRUint32(xdr, &lineno) ||
        !JS_XDRUint32(xdr, &depth) ||
        (magic < JSXDR_MAGIC_SCRIPT_4 && !JS_XDRUint32(xdr, &ntrynotes))) {
        goto error;
    }

    /* Script principals transcoding support comes with versions >= _3. */
    if (magic >= JSXDR_MAGIC_SCRIPT_3) {
        JSPrincipals *principals;
        uint32 encodeable;

        if (xdr->mode == JSXDR_ENCODE) {
            principals = script->principals;
            encodeable = (cx->runtime->principalsTranscoder != NULL);
            if (!JS_XDRUint32(xdr, &encodeable))
                goto error;
            if (encodeable &&
                !cx->runtime->principalsTranscoder(xdr, &principals)) {
                goto error;
            }
        } else {
            if (!JS_XDRUint32(xdr, &encodeable))
                goto error;
            if (encodeable) {
                if (!cx->runtime->principalsTranscoder) {
                    JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                                         JSMSG_CANT_DECODE_PRINCIPALS);
                    goto error;
                }
                if (!cx->runtime->principalsTranscoder(xdr, &principals))
                    goto error;
                script->principals = principals;
            }
        }
    }

    if (xdr->mode == JSXDR_DECODE) {
        const char *filename = script->filename;
        if (filename) {
            filename = js_SaveScriptFilename(cx, filename);
            if (!filename)
                goto error;
            JS_free(cx, (void *) script->filename);
            script->filename = filename;
            filenameWasSaved = JS_TRUE;
        }
        script->lineno = (uintN)lineno;
        script->depth = (uintN)depth;

        if (magic < JSXDR_MAGIC_SCRIPT_4) {
            /*
             * Argh, we have to reallocate script, copy notes into the extra
             * space after the bytecodes, and free the temporary notes vector.
             * First, add enough slop to nsrcnotes so we can align the address
             * after the srcnotes of the first trynote.
             */
            uint32 osrcnotes = nsrcnotes;

            if (ntrynotes)
                nsrcnotes += JSTRYNOTE_ALIGNMASK;
            newscript = (JSScript *) JS_realloc(cx, script,
                                                sizeof(JSScript) +
                                                length * sizeof(jsbytecode) +
                                                nsrcnotes * sizeof(jssrcnote) +
                                                ntrynotes * sizeof(JSTryNote));
            if (!newscript)
                goto error;

            *scriptp = script = newscript;
            script->code = (jsbytecode *)(script + 1);
            script->main = script->code + prologLength;
            memcpy(script->code + length, notes, osrcnotes * sizeof(jssrcnote));
            JS_free(cx, (void *) notes);
            notes = NULL;
            if (ntrynotes) {
                script->trynotes = (JSTryNote *)
                                   ((jsword)(SCRIPT_NOTES(script) + nsrcnotes) &
                                    ~(jsword)JSTRYNOTE_ALIGNMASK);
                memset(script->trynotes, 0, ntrynotes * sizeof(JSTryNote));
            }
        }
    }

    while (ntrynotes) {
        JSTryNote *tn = &script->trynotes[--ntrynotes];
        uint32 start = (uint32) tn->start,
               catchLength = (uint32) tn->length,
               catchStart = (uint32) tn->catchStart;

        if (!JS_XDRUint32(xdr, &start) ||
            !JS_XDRUint32(xdr, &catchLength) ||
            !JS_XDRUint32(xdr, &catchStart)) {
            goto error;
        }
        tn->start = (ptrdiff_t) start;
        tn->length = (ptrdiff_t) catchLength;
        tn->catchStart = (ptrdiff_t) catchStart;
    }

    xdr->script = oldscript;
    return JS_TRUE;

  error:
    if (xdr->mode == JSXDR_DECODE) {
        if (script->filename && !filenameWasSaved) {
            JS_free(cx, (void *) script->filename);
            script->filename = NULL;
        }
        if (notes && magic < JSXDR_MAGIC_SCRIPT_4)
            JS_free(cx, (void *) notes);
        js_DestroyScript(cx, script);
        *scriptp = NULL;
    }
    return JS_FALSE;
}

#if JS_HAS_XDR_FREEZE_THAW
/*
 * These cannot be exposed to web content, and chrome does not need them, so
 * we take them out of the Mozilla client altogether.  Fortunately, there is
 * no way to serialize a native function (see fun_xdrObject in jsfun.c).
 */

static JSBool
script_freeze(JSContext *cx, JSObject *obj, uintN argc, jsval *argv,
              jsval *rval)
{
    JSXDRState *xdr;
    JSScript *script;
    JSBool ok, hasMagic;
    uint32 len;
    void *buf;
    JSString *str;

    if (!JS_InstanceOf(cx, obj, &js_ScriptClass, argv))
        return JS_FALSE;
    script = (JSScript *) JS_GetPrivate(cx, obj);
    if (!script)
        return JS_TRUE;

    /* create new XDR */
    xdr = JS_XDRNewMem(cx, JSXDR_ENCODE);
    if (!xdr)
        return JS_FALSE;

    /* write  */
    ok = js_XDRScript(xdr, &script, &hasMagic);
    if (!ok)
        goto out;
    if (!hasMagic) {
        *rval = JSVAL_VOID;
        goto out;
    }

    buf = JS_XDRMemGetData(xdr, &len);
    if (!buf) {
        ok = JS_FALSE;
        goto out;
    }

    JS_ASSERT((jsword)buf % sizeof(jschar) == 0);
    len /= sizeof(jschar);
    str = JS_NewUCStringCopyN(cx, (jschar *)buf, len);
    if (!str) {
        ok = JS_FALSE;
        goto out;
    }

#if IS_BIG_ENDIAN
  {
    jschar *chars;
    uint32 i;

    /* Swap bytes in Unichars to keep frozen strings machine-independent. */
    chars = JS_GetStringChars(str);
    for (i = 0; i < len; i++)
        chars[i] = JSXDR_SWAB16(chars[i]);
  }
#endif
    *rval = STRING_TO_JSVAL(str);

out:
    JS_XDRDestroy(xdr);
    return ok;
}

static JSBool
script_thaw(JSContext *cx, JSObject *obj, uintN argc, jsval *argv,
            jsval *rval)
{
    JSXDRState *xdr;
    JSString *str;
    void *buf;
    uint32 len;
    jsval v;
    JSScript *script, *oldscript;
    JSBool ok, hasMagic;

    if (!JS_InstanceOf(cx, obj, &js_ScriptClass, argv))
        return JS_FALSE;

    if (argc == 0)
        return JS_TRUE;
    str = js_ValueToString(cx, argv[0]);
    if (!str)
        return JS_FALSE;
    argv[0] = STRING_TO_JSVAL(str);

    /* create new XDR */
    xdr = JS_XDRNewMem(cx, JSXDR_DECODE);
    if (!xdr)
        return JS_FALSE;

    buf = JS_GetStringChars(str);
    len = JS_GetStringLength(str);
#if IS_BIG_ENDIAN
  {
    jschar *from, *to;
    uint32 i;

    /* Swap bytes in Unichars to keep frozen strings machine-independent. */
    from = (jschar *)buf;
    to = (jschar *) JS_malloc(cx, len * sizeof(jschar));
    if (!to) {
        JS_XDRDestroy(xdr);
        return JS_FALSE;
    }
    for (i = 0; i < len; i++)
        to[i] = JSXDR_SWAB16(from[i]);
    buf = (char *)to;
  }
#endif
    len *= sizeof(jschar);
    JS_XDRMemSetData(xdr, buf, len);

    /* XXXbe should magic mismatch be error, or false return value? */
    ok = js_XDRScript(xdr, &script, &hasMagic);
    if (!ok)
        goto out;
    if (!hasMagic) {
        *rval = JSVAL_FALSE;
        goto out;
    }

    JS_LOCK_OBJ(cx, obj);
    execDepth = GetScriptExecDepth(cx, obj);

    /*
     * execDepth must be 0 to allow compilation here, otherwise the JSScript
     * struct can be released while running.
     */
    if (execDepth > 0) {
        JS_UNLOCK_OBJ(cx, obj);
        JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                             JSMSG_COMPILE_EXECED_SCRIPT);
        goto out;
    }