Error message when using gerrit query --files without patch set info.

If --files is set but neither --patch-sets nor --current-patch-set
is set, the query goes through, but no file information is in the
response. Added an error so that it is clearer how the --files
option is supposed to be used.

Change-Id: I2a3d9bf4850a9c48a7dee16535ecbbf08904a290

Documentation/cmd-query.txt

@@ -64,6 +64,8 @@ OPTIONS
 --files::
 	Support for listing files with patch sets and their
 	attributes (ADDED, MODIFIED, DELETED, RENAMED, COPIED).
+	Note that this option requires either the --current-patch-set
+	or the --patch-sets option in order to give any file information.
 
 --comments::
 	Include comments for all changes. If combined with the

gerrit-server/src/main/java/com/google/gerrit/server/query/change/QueryProcessor.java

@@ -100,10 +100,18 @@ public class QueryProcessor {
     includePatchSets = on;
   }
 
+  public boolean getIncludePatchSets() {
+    return includePatchSets;
+  }
+
   public void setIncludeCurrentPatchSet(boolean on) {
     includeCurrentPatchSet = on;
   }
 
+  public boolean getIncludeCurrentPatchSet() {
+    return includeCurrentPatchSet;
+  }
+
   public void setIncludeApprovals(boolean on) {
     includeApprovals = on;
   }
@@ -116,6 +124,10 @@ public class QueryProcessor {
     includeFiles = on;
   }
 
+  public boolean getIncludeFiles() {
+    return includeFiles;
+  }
+
   public void setIncludeCommitMessage(boolean on) {
     includeCommitMessage = on;
   }

gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/Query.java

@@ -76,11 +76,19 @@ class Query extends BaseCommand {
       public void run() throws Exception {
         processor.setOutput(out, QueryProcessor.OutputFormat.TEXT);
         parseCommandLine();
+        verifyCommandLine();
         processor.query(join(query, " "));
       }
     });
   }
 
+  private void verifyCommandLine() throws UnloggedFailure {
+    if (processor.getIncludeFiles() &&
+        !(processor.getIncludePatchSets() || processor.getIncludeCurrentPatchSet())) {
+      throw new UnloggedFailure(1, "--files option needs --patch-sets or --current-patch-set");
+    }
+  }
+
   private static String join(List<String> list, String sep) {
     StringBuilder r = new StringBuilder();
     for (int i = 0; i < list.size(); i++) {