Update from Google.

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MOE_MIGRATED_REVID=85702957

1 files changed, 132 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/shell/Shell.java b/src/main/java/com/google/devtools/build/lib/shell/Shell.java
new file mode 100644
index 0000000000..2cae24ec15
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+++ b/src/main/java/com/google/devtools/build/lib/shell/Shell.java
@@ -0,0 +1,132 @@
+// Copyright 2014 Google Inc. 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.shell;
+
+import java.util.logging.Logger;
+
+/**
+ * <p>Represents an OS shell, such as "cmd" on Windows or "sh" on Unix-like
+ * platforms. Currently, Linux and Windows XP are supported.</p>
+ *
+ * <p>This class encapsulates shell-specific logic, like how to
+ * create a command line that uses the shell to invoke another command.
+ */
+public abstract class Shell {
+
+  private static final Logger log =
+    Logger.getLogger("com.google.devtools.build.lib.shell.Shell");
+  
+  private static final Shell platformShell;
+
+  static {
+    final String osName = System.getProperty("os.name");
+    if ("Linux".equals(osName)) {
+      platformShell = new SHShell();
+    } else if ("Windows XP".equals(osName)) {
+      platformShell = new WindowsCMDShell();
+    } else {
+      log.severe("OS not supported; will not be able to execute commands");
+      platformShell = null;
+    }
+    log.config("Loaded shell support '" + platformShell +
+               "' for OS '" + osName + "'");
+  }
+
+  private Shell() {
+    // do nothing
+  }
+
+  /**
+   * @return {@link Shell} subclass appropriate for the current platform
+   * @throws UnsupportedOperationException if no such subclass exists
+   */
+  public static Shell getPlatformShell() {
+    if (platformShell == null) {
+      throw new UnsupportedOperationException("OS is not supported");
+    }
+    return platformShell;
+  }
+
+  /**
+   * Creates a command line suitable for execution by
+   * {@link Runtime#exec(String[])} from the given command string,
+   * a command line which uses a shell appropriate for a particular
+   * platform to execute the command (e.g. "/bin/sh" on Linux).
+   *
+   * @param command command for which to create a command line
+   * @return String[] suitable for execution by
+   *  {@link Runtime#exec(String[])}
+   */
+  public abstract String[] shellify(final String command);
+
+
+  /**
+   * Represents the <code>sh</code> shell commonly found on Unix-like
+   * operating systems, including Linux.
+   */
+  private static final class SHShell extends Shell {
+
+    /**
+     * <p>Returns a command line which uses <code>cmd</code> to execute
+     * the {@link Command}. Given the command <code>foo bar baz</code>,
+     * for example, this will return a String array corresponding
+     * to the command line:</p>
+     *
+     * <p><code>/bin/sh -c "foo bar baz"</code></p>
+     *
+     * <p>That is, it always returns a 3-element array.</p>
+     *
+     * @param command command for which to create a command line
+     * @return String[] suitable for execution by
+     *  {@link Runtime#exec(String[])}
+     */
+    @Override public String[] shellify(final String command) {
+      if (command == null || command.length() == 0) {
+        throw new IllegalArgumentException("command is null or empty");
+      }
+      return new String[] { "/bin/sh", "-c", command };
+    }
+
+  }
+
+  /**
+   * Represents the Windows command shell <code>cmd</code>.
+   */
+  private static final class WindowsCMDShell extends Shell {
+
+    /**
+     * <p>Returns a command line which uses <code>cmd</code> to execute
+     * the {@link Command}. Given the command <code>foo bar baz</code>,
+     * for example, this will return a String array corresponding
+     * to the command line:</p>
+     *
+     * <p><code>cmd /S /C "foo bar baz"</code></p>
+     *
+     * <p>That is, it always returns a 4-element array.</p>
+     *
+     * @param command command for which to create a command line
+     * @return String[] suitable for execution by
+     *  {@link Runtime#exec(String[])}
+     */
+    @Override public String[] shellify(final String command) {
+      if (command == null || command.length() == 0) {
+        throw new IllegalArgumentException("command is null or empty");
+      }
+      return new String[] { "cmd", "/S", "/C", command };
+    }
+
+  }
+
+}