Linux simple task

The files files write example.c and files read example.c were used to demonstrate the operations with files on UNIX. Your task is to modify files write example.c so that it writes all the records using only the last mmap based technique. It should not be too hard to do so. The other two methods of access, i.e. using write and stdio functions should not be used anymore. However, much of the logic remains the same. What’s more, Linux provides the function mremap that can change the size of the mapping after the file size changes. On the down side, other UNIX versions including the Mac OS X do not, making it not portable. Your next task will be to write a function that can extend the size of the mapping using the ftruncate, msync munmap and mmap functions. On the other hand, this approach is of course going to be less efficient. ftruncate truncates the file to a specified size. It will also increase the size of the file by filling it up with zeros to increase the size of the file if the specified size is larger than the current size. For our purposes we will simply double the size of the file each time we run out of space. The file will then be mapped again to include the newly created free space. Once all the data is entered, you will have to call ftruncate once more, this time to reduce the size of the file to the actually used space. While you are making changes, the code from files read example.c must always be able to correctly read what your modified code writes. You can use it to check whether your code is working properly.