Project 1 -- Standard I/O and POSIX I/O

Due Tuesday, September 27, 9:00 pm

(Note that due date is later than originally listed in the class schedule.)

NOTE: This assignment, like the other projects in this class, is due at a particular time, listed above. This means that if you are even a minute late, you lose 20%. If you are worried about potentially being late, turn in your project ahead of time. Do this by submitting it electronically before the due date (the electronic copy is what is due by the time given above) then giving the hard copy to me or the TA during office hours or by sliding it under my office door (the hard copy is due within twenty-four hours after the electronic copy is due). Do not send assignments to my personal email address or to the personal email address of the TA. Do not leave hard copies in my departmental mail box or attempt to give them to departmental staff (who cannot and will not accept them).

As discussed in class, there are reasons for having and using both high-level language I/O routines and operating system I/O routines. This assignment will involve you in using both of these.

As further discussed in class, I/O routines from both the language level and the OS level should not be intermingled for the same file at the same time because of possible data corruption. This assignment will investigate this reason for by having you do exactly what you shouldn't - intermingle these I/O routines - so that you can directly observe the consequences.



The Assignment

You are to complete several exercises regarding potential data corruption for various combinations of input, output, language-level, and OS-level routines. For some of these, you will write programs to demonstrate data corruption.

  1. Consider following language-level output routines with OS-level output routines for output to a regular file saved on a hard disk.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.
  2. Consider following OS-level output routines with language-level output routines for output to a regular file saved on a hard disk.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.
  3. Consider following language-level input routines with OS-level input routines for input from a regular file saved on a hard disk.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.
  4. Consider following OS-level input routines with language-level input routines for input from a regular file saved on a hard disk.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.
  5. Consider following language-level output routines with OS-level output routines for output to a terminal.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.
  6. Consider following OS-level output routines with language-level output routines for output to a terminal.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.
  7. Consider following language-level input routines with OS-level input routines for input from a terminal.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.
  8. Consider following OS-level input routines with language-level input routines for input from a terminal.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.
  9. Consider following language-level output routines with OS-level input routines for I/O with a regular file saved on a hard disk.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.
  10. Consider following OS-level input routines with language-level output routines for I/O with a regular file saved on a hard disk.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.
  11. Consider following language-level input routines with OS-level output routines for I/O with a regular file saved on a hard disk.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.
  12. Consider following OS-level output routines with language-level input routines for I/O with a regular file saved on a hard disk.
    1. Could this potentially cause data corruption? Explain why or why not.
    2. If it could, write a program to demonstrate it. For this program, explain whether it will always cause data corruption or may cause data corruption.
    3. If your program won't always cause data corruption, run your program 10 times and report how often you see data corruption.
    4. Give one example of a corrupted data file resulting from running your code.


Notes on this assignment

We will see later in this course that it is possible to redirect input and output. In particular, we'll note things like redirecting standard output to a file. However, to simplify this assignment, you do not need to consider input and output redirection.



What to turn in.

You will turn in both a hard copy and an electronic copy of your assignment. Please follow the instructions on how to send electronic copies. Do not send them to my email address.

Both the hard copy and the electronic copy will contain a write-up giving your answers to the exercises above plus all source code you created for these exercises. The electronic copy will also contain executables of the programs you wrote. The electronic copy of your write-up should not be in a proprietary format (such as MS Word); it should be either in plain ASCII text or in a portable format (such as Postscript or PDF). Your source code for each program should be in a single file called exercise<X>.c or exercise<X>.cxx where <X> is replaced with the appropriate exercise number (e.g., exercise1.c) and your executable code should be called exercise<X> where <X> is again replaced with the appropriate exercise number (e.g., exercise1).

Your source code should be well structured and well commented. It should conform to good coding standards (e.g., no memory leaks).

Your write-up will include 1/2 to 1 page (roughly 80 characters per line, 50 lines per page) explaining the data structures and algorithms used in your code. This page limitation does not include figures used in your explanations, which are encouraged and may take up any amount of space. (The explanations do not remove the requirement that your code be well commented.)



Other

You may write your program from scratch or may start from programs for which the source code is freely available on the web or through other sources (such as friends or student organizations). If you do not start from scratch, you must give a complete and accurate accounting of where all of your code came from and indicate which parts are original or changed, and which you got from which other source. Failure to give credit where credit is due is academic fraud and will be dealt with accordingly.

As noted in the syllabus, you are required to work on this programming assignment in a group of at least two people. It is your responsibility to find other group members and work with them. The group should turn in only one (1) hard copy and one (1) electronic copy of the assignment. Both the electronic and hard copies should contain the names and student ID numbers of all group members. If your group composition changes during the course of working on this assignment (for example, a group of five splits into a group of two and a separate group of three), this must be clearly indicated in your write-up, including the names and student ID numbers of everyone involved and details of when the change occurred and who accomplished what before and after the change.

Each group member is required to contribute equally to each project, as far as is possible. You must thoroughly document which group members were involved in each part of the project. For example, if you have three functions in your program and one function was written by group member one, the second was written by group member two, and the third was written jointly and equally by group members three and four, both your write-up and the comments in your code must clearly indicate this division of labor.