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diff --git a/src/tools/ceph-diff-sorted.cc b/src/tools/ceph-diff-sorted.cc
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+++ b/src/tools/ceph-diff-sorted.cc
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+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+/*
+ * diffsorted -- a utility to compute a line-by-line diff on two
+ * sorted input files
+ *
+ * Copyright © 2019 Red Hat
+ *
+ * Author: J. Eric Ivancich
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.
+ */
+
+
+/*
+ * SUMMARY
+ *
+ * The `diffsorted` utility does a line-by-line diff on two sorted text
+ * files and indicating lines that are in one file but not the other
+ * using diff-style notation (although line numbers are not indicated).
+ *
+ * USAGE
+ *
+ *     rgw-diff-sorted file1.txt file2.txt
+ *
+ * NOTES
+ *
+ * Each files should have its lines in sorted order and should have no
+ * empty lines.
+ *
+ * A potential input file can be sorted using the `sort` utility provided
+ * that LANG=C to insure byte lexical order. For example:
+ *
+ *     LANG=C sort unsorted.txt >sorted.txt
+ *
+ * or:
+ *
+ *     export LANG=C
+ *     sort unsorted.txt >sorted.txt
+ *
+ * EXIT STATUS
+ *
+ *     0 : files same
+ *     1 : files different
+ *     2 : usage problem (e.g., wrong number of command-line arguments)
+ *     3 : problem opening input file
+ *     4 : bad file content (e.g., unsorted order or empty lines)
+ */
+
+
+#include <iostream>
+#include <fstream>
+
+
+struct FileOfLines {
+  const char* filename;
+  std::ifstream input;
+  std::string this_line, prev_line;
+  bool next_eof;
+  bool is_eof;
+
+  FileOfLines(const char* _filename) :
+    filename(_filename),
+    input(filename),
+    next_eof(false),
+    is_eof(false)
+  { }
+
+  void dump(const std::string& prefix) {
+    do {
+      std::cout << prefix << this_line << std::endl;
+      advance();
+    } while (!eof());
+  }
+
+  bool eof() const {
+    return is_eof;
+  }
+
+  bool good() const {
+    return input.good();
+  }
+
+  void advance() {
+    if (next_eof) {
+      is_eof = true;
+      return;
+    }
+
+    prev_line = this_line;
+    std::getline(input, this_line);
+    if (this_line.empty()) {
+      if (!input.eof()) {
+	std::cerr << "Error: " << filename << " has an empty line." <<
+	  std::endl;
+	exit(4);
+      }
+      is_eof = true;
+      return;
+    } else if (input.eof()) {
+      next_eof = true;
+    }
+
+    if (this_line < prev_line) {
+      std::cerr << "Error: " << filename << " is not in sorted order; \"" <<
+	this_line << "\" follows \"" << prev_line << "\"." << std::endl;
+      exit(4);
+    }
+  }
+
+  const std::string line() const {
+    return this_line;
+  }
+};
+
+int main(int argc, const char* argv[]) {
+  if (argc != 3) {
+    std::cerr << "Usage: " << argv[0] << " <file1> <file2>" << std::endl;
+    exit(2);
+  }
+
+  FileOfLines input1(argv[1]);
+  if (!input1.good()) {
+    std::cerr << "Error opening " << argv[1] <<
+      "." << std::endl;
+    exit(3);
+  }
+
+  FileOfLines input2(argv[2]);
+  if (!input2.good()) {
+    std::cerr << "Error opening " << argv[2] <<
+      "." << std::endl;
+    exit(3);
+  }
+
+  bool files_same = true;
+
+  input1.advance();
+  input2.advance();
+
+  while (!input1.eof() && !input2.eof()) {
+    if (input1.line() == input2.line()) {
+      input1.advance();
+      input2.advance();
+    } else if (input1.line() < input2.line()) {
+      files_same = false;
+      std::cout << "< " << input1.line() << std::endl;
+      input1.advance();
+    } else {
+      files_same = false;
+      std::cout << "> " << input2.line() << std::endl;
+      input2.advance();
+    }
+  }
+
+  if (!input1.eof()) {
+    files_same = false;
+    input1.dump("< ");
+  } else if (!input2.eof()) {
+    files_same = false;
+    input2.dump("> ");
+  }
+
+  if (files_same) {
+    exit(0);
+  } else {
+    exit(1);
+  }
+}