Know Your Tools Edit on Github

The learning objectives for Know Your Tools are:

• Using the tools needed for CS 241

We suggest you read the following from the wikibook before starting Know Your Tools:

• HW0
• System Programming Jokes

• Please introduce yourself (lab assistants should go first) to the rest of your class.
• Tell everyone your name, grade, and one interesting fact about yourself.

In this course, we are using VMs for all our development, so it is important that you learn how to use them. These VMs are part of the CS Cloud, and we will not support any other machines for grading. This means that you should test on your VM and and not any other machine (this includes the CS2XX VM you received in CS 225, EWS, or your local machine). This is to your benefit, since the grading VM is identical to your VM.

Please ssh or FastX into your VM. The IP is in your SVN repo. For example, if you want to ssh in and your netid is bschong2 and your hostname is fa16-cs241-000.cs.illinois.edu, then all you need to do is enter

ssh bschong2@fa16-cs241-000.cs.illinois.edu

into your terminal. If you want a GUI, then you should use FastX and follow these instructions or add the -Y flag to ssh. We also have a nice Developing in 241 Guide to solve your problems and (hopefully) make getting started in setting up your dev environment much easier.

You will be using SVN to submit all your assignments in this course.

Once you are in your VM, please checkout your SVN repo with the following command

svn co https://subversion.ews.illinois.edu/svn/fa16-cs241/YOUR-NETID cs241

which will check out your entire SVN repo into a folder called ‘cs241’ into your current directory. Now change your directory into the ‘cs241’ folder

cd cs241

and create a ‘know_your_tools’ folder

mkdir know_your_tools

Now check the status of your repo

svn status

and notice that you now have a ‘know_your_tools’ folder that needs to be added. Add the ‘know_your_tools’ folder to SVN

svn add know_your_tools

and commit it

svn ci -m "adding the know_your_tools folder"

This is just the bare minimum you might need to know when using SVN. We recommend that you refer to the SVN Bible if you ever have a problem. It is always good to learn the ins and outs of a version control system, since it makes it easier to pick them up when you are working in industry.

In this course, you will need to know how to use Valgrind + GDB + Clang.

Once you are in your VM, please create a file called ‘dumb.c’ in your ‘know_your_tools’ directory that you just made. Now write a valid C program in ‘dumb.c’ that will segfault. Now compile with clang

clang dumb.c -o dumb -g

Run it to make sure it segfaults

./dumb

Run valgrind to see what line it segfaults on

valgrind ./dumb

Run gdb to see what line it segfaults on

gdb ./dumb
run
backtrace

Then exit gdb

quit

Now commit ‘dumb.c’ to your ‘know_your_tools’ folder on svn (I leave this as an exercise to the reader).

These are just the most basic things that you can do with the tools. We highly recommend that you read tutorials on these tools to effectively use them through out this course. Here are just a couple of promising links:

• Valgrind
• GDB
• Clang

All the assignments in this class will use a similar makefile.

Here is what a typical makefile will look like:

# directory to store object files
OBJS_DIR = .objs

# define the EXES
EXE_SHELL=shell
EXES_STUDENT=$(EXE_SHELL)

OBJS_SHELL=$(EXE_SHELL).o format.o

# set up compiler
CC = clang
INCLUDES=-I./includes/
WARNINGS = -Wall -Wextra -Werror -Wno-error=unused-parameter
CFLAGS_DEBUG   = -O0 $(INCLUDES) $(WARNINGS) -g -std=c99 -c -MMD -MP -D_GNU_SOURCE -DDEBUG
CFLAGS_RELEASE = -O2 $(INCLUDES) $(WARNINGS) -g -std=c99 -c -MMD -MP -D_GNU_SOURCE

# set up linker
LD = clang
LDFLAGS = -Llibs/ -lprovided

.PHONY: all
all: release

# build types
# run clean before building debug so that all of the release executables
# disappear
.PHONY: release
.PHONY: debug

release: $(EXES_STUDENT)
debug: clean $(EXES_STUDENT:%=%-debug)

# include dependencies
-include $(OBJS_DIR)/*.d

$(OBJS_DIR):
@mkdir -p $(OBJS_DIR)

# patterns to create objects
# keep the debug and release postfix for object files so that we can always
# separate them correctly
$(OBJS_DIR)/%-debug.o: %.c | $(OBJS_DIR)
$(CC) $(CFLAGS_DEBUG) $< -o $@

$(OBJS_DIR)/%-release.o: %.c | $(OBJS_DIR)
$(CC) $(CFLAGS_RELEASE) $< -o $@

# exes
$(EXE_SHELL)-debug: $(OBJS_SHELL:%.o=$(OBJS_DIR)/%-debug.o)
$(LD) $^ $(LDFLAGS) -o $@

$(EXE_SHELL): $(OBJS_SHELL:%.o=$(OBJS_DIR)/%-release.o)
$(LD) $^ $(LDFLAGS) -o $@

.PHONY: clean
clean:
rm -rf .objs $(EXES_STUDENT) $(EXES_STUDENT:%=%-debug)

This looks scary, but if you google some makefile basics and carefully read the comments it should mostly make sense. However, these are the things you will need to know at the minimum:

• Compile the assignment:

make

• Clean up the assignment directory:

make clean

• Compile a debugable version of your code that you can use gdb on:

make debug

• Compile a release version of your assignment that you test with:

make release

Part of your grade in this class relies on you attending labs. Toward the end of every lab, we will ask you to swipe out. You may only leave early if you show that you have finished the lab to your lab attendant or if the lab attendant calls the time. If you are more than 10 minutes late to class, then your lab attendant reserves the right to not swipe you for the day. You may never swipe yourself out without your lab attendant’s consent (any violation will result in a zero in lab attendance for the semester). Due to seating limitations, you are required to go to the lab section you signed up for. If you wish to go to any other lab section, you may:

• Go to section ADJ at 9-10:20am in 0222. This section only has 7 registered students, and thus there will be room to accommodate you on a first come first served basis.
• Get permission from the TA of another section to go to their section, provided
  • you will be working on your laptop in the room, or
  • there is seating available where registered students get priority.

If choosing the latter option, you must email the TA beforehand.

Remember that lab attendance is required; per course policy, missing 3 or more lab sections will result in a failing grade.

You can still get credit for attending a different section due to special or occasional circumstances by making arangments with the GA at cs241admin@illinois.edu. However, you must change your registered lab if you start regularly going to a different lab. Please contact Holly Bagwell in the academic office SC1210 to change your section without having to drop your enrollment.

We will never grant exemptions for lab attendance (if you have an interview, then you are just going to have to use your drop). You also can not make up lab attendance. All grades (including attendance) will be uploaded to Chara every Friday by 11:59pm. You have until 11:59pm on Friday of the next week to refute attendance grades. Note that forgetting to swipe out is not a valid excuse (your lab attendant is not allowed to vouch for your attendance).

You have already been assigned a HW0 for this class. The lab instructors will go around to make sure that you have made progress on this assignment. HW0 is due with the rest of the lab. If you finish the lab early we recommend sticking around and getting help from the lab assistants.

Please fully read details on Academic Integrity . These are shared between all MPs in CS 241.

We will be using Subversion as our hand-in system this semester. Our grading system will checkout your most recent (pre-deadline) commit for grading. Therefore, to hand in your code, all you have to do is commit it to your Subversion repository.

To check out the provided code for know_your_tools from the class repository, go to your cs241 directory (the one you checked out for "know your tools") and run:

svn up

If you run ls you will now see a know_your_tools folder, where you can find this assignment! To commit your changes (send them to us) type:

svn ci -m "know_your_tools submission"

Your repository directory can be viewed from a web browser from the following URL: https://subversion.ews.illinois.edu/svn/fa16-cs241/NETID/know_your_tools where NETID is your University NetID. It is important to check that the files you expect to be graded are present and up to date in your SVN copy.