Added comment header and cleaned up a couple of comments

Author: Ken Gibson

chapter3/pmem_map_file.c

@@ -1,3 +1,34 @@
+/*
+ * Copyright (c) 2019, Intel Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
@@ -15,6 +46,7 @@
 /* using 4k of pmem for this example */
 #define PMEM_LEN 4096
 
+/* define the filename for our example pmem region  */
 #define PATH "/pmem-fs/myfile"
 
 int
@@ -34,12 +66,12 @@ main(int argc, char *argv[])
 	/* store a string to the persistent memory */
 	strcpy(pmemaddr, "hello, persistent memory");
 
-	/* flush above strcpy to persistence */
+	/* flush our string to persistence */
 	if (is_pmem)
 		pmem_persist(pmemaddr, mapped_len);
 	else
 		pmem_msync(pmemaddr, mapped_len);
 
-	/* Delete the mappings. The region is also */
+	/* Delete the mappings. */
 	pmem_unmap(pmemaddr, mapped_len);
 }