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// Copyright 2015 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.build.lib.vfs;
import com.google.common.base.Splitter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.annotation.Nullable;
/**
* Parse and search $PATH, the binary search path for executables.
*/
public class SearchPath {
private static final Splitter SEPARATOR = Splitter.on(':');
/**
* Parses a $PATH value into a list of paths. A Null search path is treated as an empty one.
* Relative entries in $PATH are ignored.
*/
public static List<Path> parse(FileSystem fs, @Nullable String searchPath) {
List<Path> paths = new ArrayList<>();
if (searchPath == null) {
return paths;
}
for (String p : SEPARATOR.split(searchPath)) {
PathFragment pf = PathFragment.create(p);
if (pf.isAbsolute()) {
paths.add(fs.getPath(pf));
}
}
return paths;
}
/**
* Finds the first executable called {@code exe} in the searchPath.
* If {@code exe} is not a basename, it will always return null. This should be equivalent to
* running which(1).
*/
@Nullable
public static Path which(List<Path> searchPath, String exe) {
PathFragment fragment = PathFragment.create(exe);
if (fragment.segmentCount() != 1 || fragment.isAbsolute()) {
return null;
}
for (Path p : searchPath) {
Path ch = p.getChild(exe);
try {
if (ch.exists() && ch.isExecutable()) {
return ch;
}
} catch (IOException e) {
// Like which(1), we ignore any IO exception (disk on fire, permission denied etc.)
}
}
return null;
}
}
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