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// Copyright 2017 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.devtools.common.options;
import java.io.IOException;
import java.io.Reader;
import java.nio.charset.StandardCharsets;
import java.nio.file.FileSystem;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.List;
import java.util.NoSuchElementException;
/**
* Defines an {@link ArgsPreProcessor} that will determine if the arguments list contains a "params"
* file that contains a list of options to be parsed.
*
* <p>Params files are used when the argument list of {@link Option} exceed the shells commandline
* length. A params file argument is defined as a path starting with @. It will also be the only
* entry in an argument list.
*/
public class ParamsFilePreProcessor implements ArgsPreProcessor {
static final String ERROR_MESSAGE_FORMAT = "Error reading params file: %s %s";
static final String TOO_MANY_ARGS_ERROR_MESSAGE_FORMAT =
"A params file must be the only argument: %s";
static final String UNFINISHED_QUOTE_MESSAGE_FORMAT = "Unfinished quote %s at %s";
private final FileSystem fs;
ParamsFilePreProcessor(FileSystem fs) {
this.fs = fs;
}
/**
* Parses the param file path and replaces the arguments list with the contents if one exists.
*
* @param args A list of arguments that may contain @<path> to a params file.
* @return A list of areguments suitable for parsing.
* @throws OptionsParsingException if the path does not exist.
*/
@Override
public List<String> preProcess(List<String> args) throws OptionsParsingException {
if (!args.isEmpty() && args.get(0).startsWith("@")) {
if (args.size() > 1) {
throw new OptionsParsingException(
String.format(TOO_MANY_ARGS_ERROR_MESSAGE_FORMAT, args), args.get(0));
}
Path path = fs.getPath(args.get(0).substring(1));
try (Reader params = Files.newBufferedReader(path, StandardCharsets.UTF_8)) {
List<String> newArgs = new ArrayList<>();
StringBuilder arg = new StringBuilder();
CharIterator iterator = CharIterator.wrap(params);
while (iterator.hasNext()) {
char next = iterator.next();
if (Character.isWhitespace(next) && !iterator.isInQuote() && !iterator.isEscaped()) {
newArgs.add(arg.toString());
arg = new StringBuilder();
} else {
arg.append(next);
}
}
// If there is an arg in the buffer, add it.
if (arg.length() > 0) {
newArgs.add(arg.toString());
}
// If we're still in a quote by the end of the file, throw an error.
if (iterator.isInQuote()) {
throw new OptionsParsingException(
String.format(ERROR_MESSAGE_FORMAT, path, iterator.getUnmatchedQuoteMessage()));
}
return newArgs;
} catch (RuntimeException | IOException e) {
throw new OptionsParsingException(
String.format(ERROR_MESSAGE_FORMAT, path, e.getMessage()), args.get(0), e);
}
}
return args;
}
// Doesn't implement iterator to avoid autoboxing and to throw exceptions.
static class CharIterator {
private final Reader reader;
private int readerPosition = 0;
private int singleQuoteStart = -1;
private int doubleQuoteStart = -1;
private boolean escaped = false;
private char lastChar = (char) -1;
public static CharIterator wrap(Reader reader) {
return new CharIterator(reader);
}
public CharIterator(Reader reader) {
this.reader = reader;
}
public boolean hasNext() throws IOException {
return peek() != -1;
}
private int peek() throws IOException {
reader.mark(1);
int next = reader.read();
reader.reset();
return next;
}
public boolean isInQuote() {
return singleQuoteStart != -1 || doubleQuoteStart != -1;
}
public boolean isEscaped() {
return escaped;
}
public String getUnmatchedQuoteMessage() {
StringBuilder message = new StringBuilder();
if (singleQuoteStart != -1) {
message.append(String.format(UNFINISHED_QUOTE_MESSAGE_FORMAT, "'", singleQuoteStart));
}
if (doubleQuoteStart != -1) {
message.append(String.format(UNFINISHED_QUOTE_MESSAGE_FORMAT, "\"", doubleQuoteStart));
}
return message.toString();
}
public char next() throws IOException {
if (!hasNext()) {
throw new NoSuchElementException();
}
char current = (char) reader.read();
// check for \r\n line endings. If found, drop the \r for normalized parsing.
if (current == '\r' && peek() == '\n') {
current = (char) reader.read();
}
// check to see if the current position is escaped
escaped = (lastChar == '\\');
if (!escaped && current == '\'') {
singleQuoteStart = singleQuoteStart == -1 ? readerPosition : -1;
}
if (!escaped && current == '"') {
doubleQuoteStart = doubleQuoteStart == -1 ? readerPosition : -1;
}
readerPosition++;
lastChar = current;
return current;
}
}
}
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