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/*
* Copyright (C) 2017 The Android Open Source Project
*
* 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.android.loganalysis.parser;
import com.android.loganalysis.item.TraceFormatItem;
import com.google.common.base.CaseFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Read trace format and generate a regex that matches output of such format.
*
* <p>Traces under /d/tracing specify the output format with a printf string. This parser reads such
* string, finds all parameters, and generates a regex that matches output of such format. Each
* parameter corresponds to a named-capturing group in the regex. The parameter names are converted
* to camel case because Java regex group name must contain only letters and numbers.
*
* <p>An end-to-end example:
*
* <pre>{@code
* List<String> formatLine = Arrays.asList("print fmt: \"foo=%llu, bar:%s\", REC->foo, REC->bar");
* TraceFormatItem parsedFormat = new TraceFormatParser.parse(formatLine);
* parsedFormat.getParameters(); // "foo", "bar"
* parsedFormat.getNumericParameters(); // "foo"
* Matcher matcher = parsedFormat.getRegex.matcher("foo=123, bar:enabled");
* matcher.matches();
* matcher.group("foo") // 123
* matcher.group("bar") // "enabled"
* }</pre>
*
* <p>The initial implementation supports some commonly used specifiers: signed and unsigned integer
* (with or without long or long long modifier), floating point number (with or without precision),
* hexadecimal number (with or without 0's padding), and string (contains only [a-zA-Z_0-9]). It is
* assumed no characters found in the format line need to be escaped.
*
* <p>Some examples of trace format line:
*
* <p>(thermal/tsens_read)
*
* <p>print fmt: "temp=%lu sensor=tsens_tz_sensor%u", REC->temp, REC->sensor
*
* <p>(sched/sched_cpu_hotplug)
*
* <p>print fmt: "cpu %d %s error=%d", REC->affected_cpu, REC->status ? "online" : "offline",
* REC->error
*
* <p>(mmc/mmc_blk_erase_start)
*
* <p>print fmt: "cmd=%u,addr=0x%08x,size=0x%08x", REC->cmd, REC->addr, REC->size
*/
public class TraceFormatParser implements IParser {
// split the raw format line
private static final Pattern SPLIT_FORMAT_LINE =
Pattern.compile(".*?\"(?<printf>.*?)\"(?<params>.*)");
// match parameter names
private static final Pattern SPLIT_PARAMS = Pattern.compile("->(?<param>\\w+)");
// match and categorize common printf specifiers
// use ?: to flag all non-capturing group so any group captured correspond to a specifier
private static final Pattern PRINTF_SPECIFIERS =
Pattern.compile(
"(?<num>%(?:llu|lu|u|lld|ld|d|(?:.\\d*)?f))|(?<hex>%\\d*(?:x|X))|(?<str>%s)");
// regex building blocks to match simple numeric/hex/string parameters, exposed for unit testing
static final String MATCH_NUM = "-?\\\\d+(?:\\\\.\\\\d+)?";
static final String MATCH_HEX = "[\\\\da-fA-F]+";
static final String MATCH_STR = "[\\\\w]*";
/** Parse a trace format line and return an {@link TraceFormatItem} */
@Override
public TraceFormatItem parse(List<String> lines) {
// sanity check
if (lines == null || lines.size() != 1) {
throw new RuntimeException("Cannot parse format line: expect one-line trace format");
}
// split the raw format line
Matcher formatLineMatcher = SPLIT_FORMAT_LINE.matcher(lines.get(0));
if (!formatLineMatcher.matches()) {
throw new RuntimeException("Cannot parse format line: unexpected format");
}
String printfString = formatLineMatcher.group("printf");
String paramsString = formatLineMatcher.group("params");
// list of parameters, to be populated soon
List<String> allParams = new ArrayList<>();
List<String> numParams = new ArrayList<>();
List<String> hexParams = new ArrayList<>();
List<String> strParams = new ArrayList<>();
// find all parameters and convert them to camel case
Matcher paramsMatcher = SPLIT_PARAMS.matcher(paramsString);
while (paramsMatcher.find()) {
String camelCasedParam =
CaseFormat.LOWER_UNDERSCORE.to(
CaseFormat.LOWER_CAMEL, paramsMatcher.group("param"));
allParams.add(camelCasedParam);
}
// scan the printf string, categorizing parameters and generating a matching regex
StringBuffer regexBuilder = new StringBuffer();
int paramIndex = 0;
String currentParam;
Matcher printfMatcher = PRINTF_SPECIFIERS.matcher(printfString);
while (printfMatcher.find()) {
// parameter corresponds to the found specifier
currentParam = allParams.get(paramIndex++);
if (printfMatcher.group("num") != null) {
printfMatcher.appendReplacement(
regexBuilder, createNamedRegexGroup(MATCH_NUM, currentParam));
numParams.add(currentParam);
} else if (printfMatcher.group("hex") != null) {
printfMatcher.appendReplacement(
regexBuilder, createNamedRegexGroup(MATCH_HEX, currentParam));
hexParams.add(currentParam);
} else if (printfMatcher.group("str") != null) {
printfMatcher.appendReplacement(
regexBuilder, createNamedRegexGroup(MATCH_STR, currentParam));
strParams.add(currentParam);
} else {
throw new RuntimeException("Unrecognized specifier: " + printfMatcher.group());
}
}
printfMatcher.appendTail(regexBuilder);
Pattern generatedRegex = Pattern.compile(regexBuilder.toString());
// assemble and return a TraceFormatItem
TraceFormatItem item = new TraceFormatItem();
item.setRegex(generatedRegex);
item.setParameters(allParams);
item.setNumericParameters(numParams);
item.setHexParameters(hexParams);
item.setStringParameters(strParams);
return item;
}
/** Helper function to create a regex group with given name. */
private static String createNamedRegexGroup(String base, String name) {
return String.format("(?<%s>%s)", name, base);
}
}
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