6bcb4e3ad9
Note how, in the `if (this.stateManager.stateStack.length !== 0) {` branch, we're attempting to access the not yet defined variable[1] `args`. If this code-path is ever hit, an Error will be thrown and parsing will thus be aborted immediately (likely leading to e.g. rendering bugs).
Note that I found this purely by accident, since I happened to glance at the LGTM report. However, I've since found that the error is also present during the unit-test[2] and with this patch we're actually testing the *intended* thing here.
As part of fixing this, and to avoid re-introducing a similar bug in the future, we'll now instead always reset `args.length` *before* attempting to read the next operator.
Also, we can use the existing `EvaluatorPreprocessor.savedStatesDepth` getter to simplify the save/restore detection a tiny bit.
---
[1] The ESLint rule `no-use-before-define` would have helped catch this problem, but unfortunately we cannot enable that without quite a bit of refactoring all over the code-base.
[2] The unit-test was updated such that it would fail in the `master`-branch.
100 lines
3.0 KiB
JavaScript
100 lines
3.0 KiB
JavaScript
/* Copyright 2020 Mozilla Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import { isName, Name } from "./primitives.js";
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import { OPS, warn } from "../shared/util.js";
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import { ColorSpace } from "./colorspace.js";
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import { escapePDFName } from "./core_utils.js";
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import { EvaluatorPreprocessor } from "./evaluator.js";
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import { StringStream } from "./stream.js";
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class DefaultAppearanceEvaluator extends EvaluatorPreprocessor {
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constructor(str) {
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super(new StringStream(str));
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}
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parse() {
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const operation = {
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fn: 0,
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args: [],
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};
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const result = {
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fontSize: 0,
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fontName: Name.get(""),
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fontColor: new Uint8ClampedArray([0, 0, 0]) /* black */,
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};
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try {
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while (true) {
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operation.args.length = 0; // Ensure that `args` it's always reset.
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if (!this.read(operation)) {
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break;
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}
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if (this.savedStatesDepth !== 0) {
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continue; // Don't get info in save/restore sections.
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}
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const { fn, args } = operation;
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switch (fn | 0) {
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case OPS.setFont:
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const [fontName, fontSize] = args;
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if (isName(fontName)) {
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result.fontName = fontName;
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}
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if (typeof fontSize === "number" && fontSize > 0) {
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result.fontSize = fontSize;
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}
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break;
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case OPS.setFillRGBColor:
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ColorSpace.singletons.rgb.getRgbItem(args, 0, result.fontColor, 0);
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break;
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case OPS.setFillGray:
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ColorSpace.singletons.gray.getRgbItem(args, 0, result.fontColor, 0);
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break;
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case OPS.setFillColorSpace:
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ColorSpace.singletons.cmyk.getRgbItem(args, 0, result.fontColor, 0);
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break;
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}
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}
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} catch (reason) {
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warn(`parseDefaultAppearance - ignoring errors: "${reason}".`);
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}
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return result;
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}
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}
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// Parse DA to extract font and color information.
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function parseDefaultAppearance(str) {
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return new DefaultAppearanceEvaluator(str).parse();
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}
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// Create default appearance string from some information.
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function createDefaultAppearance({ fontSize, fontName, fontColor }) {
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let colorCmd;
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if (fontColor.every(c => c === 0)) {
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colorCmd = "0 g";
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} else {
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colorCmd =
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Array.from(fontColor)
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.map(c => (c / 255).toFixed(2))
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.join(" ") + " rg";
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}
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return `/${escapePDFName(fontName.name)} ${fontSize} Tf ${colorCmd}`;
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}
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export { createDefaultAppearance, parseDefaultAppearance };
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