OS Course Assignments Lecture foils are available online

OS Course Assignments • Lecture foils are available on-line: http: //www. wright. edu/~travis. doom/courses/CEG 433 • • WSU’s Ca. TS UNIX system: paladin. wright. edu • lab assignments are available as: – ~w 001 ted/pub/ceg 433/labs/lab. XX. worksheet. txt • All lab assignments must: – be turned in complete and on-time (include all required files) T lab. XX. makefile T lab. XX. typescript (man script) T lab. XX. readme – compile without warning or error using your makefile on paladin. wright. edu (Solaris 2). T The compiler must be invoked with the -Wall flag Student information is available in the directory: – ~w 001 ted/pub CEG 433/633 - Operating Systems I Lab. 1 Dr. T. Doom

Grading Guidelines To earn any points, your program must compile on paladin (with -Wall flag and no warnings or errors), with the makefile you submit (using "make -f lab. XX. makefile") to the target executable file "lab. XX" (where XX is the two digit lab number). Implementation/Worksheet (4 points possible): Required: a compiling program / worksheet 4 All features implemented perfectly / all answers correct. 2 Some features implemented / some answers correct. 0 No features implemented / no answers correct. Bugs (2 points possible): Required: most features implemented 2 No bugs found, complete error checking done. 1 A bug found: documented in readme, demonstrated in typescript. 0 An undocumented bug found. Documentation (3 points possible): Required: a compiling program. 2 Extensive README: Discussion of design and implementation decisions, concepts learned, bugs found and corrected, remaining bugs, etc. Demonstrate mastery. 1 Code documentation: o File comment header - including your name and email at least. o Descriptive comment blocks in code file for program and all functions, including: purpose, arguments and flags, return values, and errors handled. o In-code comments (preferably comment blocks for code blocks). Excellence (1 point possible): Required: No points deducted above. Implementation is concise and elegant, code is easy to read (descriptively named variables, all lines less than 80 columns, etc. ), extremely well documented, all possible errors handled and demonstrated in typescript. Generally excellent work. CEG 433/633 - Operating Systems I Lab. 2 Dr. T. Doom

OS Programming in C/C++ • C programs can easily access the services of the UNIX operating system • System calls: routines that make operating system services available to programmers – creating/deleting files, allocating memory, sending signal to processes • In C, system calls are used in the same way you use ordinary C program modules (functions) • A variety of libraries have been developed to support programming in C – libraries are collections of related functions – many libraries functions access basic OS services through system calls – default location is generally /usr/lib CEG 433/633 - Operating Systems I Lab. 3 Dr. T. Doom

OS Programming in C/C++ • • Lines that begin with # are pre-processor directives • Header files for a library contain function prototypes and macros. – When several macro definitions are used in different modules they are typically collected together in a single file called a header (or include) file (these files use the. h extention by convention). – A function prototype is a declaration that tells the compiler what type a function returns, how many argument a function expects, and what the types of the arguments are. This allows the compiler to detect and flag inconsistencies in the use of the function #define: used to define symbolic constants (a macro) – provides mapping from symbolic name to replacement text (macro expansion). Improves readability and modification. #ifndef ALLOC #define ALLOC(type, num) ((type *) malloc(sizeof(type) * (num))) #endif CEG 433/633 - Operating Systems I Lab. 4 Dr. T. Doom

OS Programming in C/C++ • Include files are loaded by the preprocessor using the #include directive. – Angle brackets are used for include files located in the “standard” location (generally /usr/include) – #include <stdio. h> – Double quotes are used for other locations: – #include “/user/doom/soft/include/doom. C. h” – Another way to specify directories to be searched for header files is to use the -I option to the C compiler – #include “doom. C. h” – cc -I /user/doom/soft/include • If you have difficulties with a system call, check the man page and/or the header file – The “technical” details are available in the header files. CEG 433/633 - Operating Systems I Lab. 5 Dr. T. Doom

OS Programming in C/C++ • Each program must well organized into functional modules – Main is the control module - execution begins and ends with the function main – Functions are used to make both development and maintenance of the program more efficient – Every function should have a clearly defined (and documented) purpose T Necessary conditions (pre-conditions) T side-effects (post-conditions) T return values • Generally speaking, a function should consist of 5 to 40 lines of code CEG 433/633 - Operating Systems I Lab. 6 Dr. T. Doom

Programming Tools: man, vi, xemacs • man – Learn to use the man command; it is the single best tool for solving any UNIX problem T ex: man -k fork T ex: man -s 2 sleep – “man man” to start • Editors – vi: powerful and ubiquitous, steep learning curve (but worth it) – emacs (xemacs): powerful yet cumbersome (probably worth it) – pico: weak, small learning curve • X displays can be piped back to remote machines running an xserver: – (remote system): setenv DISPLAY remotesystemname: 0. 0 – (host system): xhost +remotesystemname CEG 433/633 - Operating Systems I Lab. 7 Dr. T. Doom

Programming Tools • GUI - Sun Work. Shop – “workshop”: graphical environment for coding and debugging (licensed from Sun), used to be called “SPARCworks” in the Sun. OS 5 days, includes: T cc: C compiler T sbrowser: source browser T analyzer: performance tuner T debugger or dbx: debugger does a good job with forks (follow parent , child, or both) T rsccs: source code management T dmake: distributed make, similar to GNU make but allows concurrency exploitation T etc. • In my experience, workshop does not work well remotely. CEG 433/633 - Operating Systems I Lab. 8 Dr. T. Doom

Programming Tools: gcc • C (C++) compilers – cc (CC): Sun. Work. Shop Compiler – gcc (g++): GNU C Compiler, freeware, cross-platform, ubiquitous • Compiler flags – man gcc for details! – -l: specify library on command line (must come after all modules to which it applies) – -L: specify additional directories to by searched for library (default /usr/lib and /lib) – -O: invoke compiler optimizer – -o: specify executable name (default a. out) – -W: specify warning level (implicit, return-type, unused, comment, format, all, etc) – ex: gcc -o lab 01 -Wall lab 01. c CEG 433/633 - Operating Systems I Lab. 9 Dr. T. Doom

Programming Tools: gcc – -c: suppress linking phase (create object files (. o) without treating unresolved references as errors) – ex: gcc -c doom. C. c lab 01. c (creates doom. C. o and lab 01. o) – ex: gcc -o lab 01 doom. C. o lab 01. o (creates executable lab 01 by linking object files) – -R: specify location of run-time libraries (default /usr/lib) Absolute pathnames only! T UNIX systems use shared (dynamic) libraries - the library modules are not included in the executable, only the location of the *. so file. Use “ldd” to find out what shared libraries and executable requires. T Do not use the only style LD_LIBRARY_PATH and LD_RUN_PATH environment variables. T The -f. PIC flag to gcc can be used to generate positionindependent code; combined with the ld -G command, you can create your own shared libraries. CEG 433/633 - Operating Systems I Lab. 10 Dr. T. Doom

Programming Tools: Make • Make: Keep a set of programs current – C programs depend on a number of files (system header files, user header files, C source files, object files, executable files, etc. ) – When a changed occurs to a file that others depend on, you MUST recompile all dependent files. – The “make” program allows your to specify dependency relationships to automate this process – Make looks at at dependency lines in the specified file T default: the files Makefile or makefile in the working directory T explicit: specified using the -f flag to make CEG 433/633 - Operating Systems I Lab. 11 Dr. T. Doom

Programming Tools: Make – Each dependency lines specifies a target file that depends on one or more prerequisite files. If any of the files in the dependency list has been modified since the target’s last modification date, then the specified commands are invoked (each line of the commands begins with a TAB) – Syntax: target: prerequisite-list TAB construction-commands lab 01: doom. C. o lab 01. o cc -o lab 01 doom. C. o lab 01. o: lab 01. h cc - c lab 01. c doom. C. o: doom. C. h cc -c doom. C. c clean: rm -f core *. o CEG 433/633 - Operating Systems I Lab. 12 Dr. T. Doom

Programming Tools: Make – Implied dependencies: If you do not include a dependency line for an object file, make assumes that it depends upon a compiler or assembler source code file with the same name. BEWARE: using implied dependencies requires that you use MACROS to pass necessary flags T If no dependency file is specified, only implied dependencies are used T If no target is specified, the first dependency in the file is the default CC=gcc CFLAGS=-Wall $(SRC)= doom. C. c lab 01. c $(OBJ)=($SRC: . c=. o) lab 01: $(SRC) $(OBJ) $(CC) -o lab 01$CFLAGS $(OBJECTS) #(others are implicit) CEG 433/633 - Operating Systems I Lab. 13 Dr. T. Doom

Programming Tools: Debuggers • Debuggers – gdb (xgdb, xxgdb - grahical): powerful, freeware, ubiquitous T use help command at gdb prompt for: list, break, run, set args, print, display, up, down, cont – lint: checks programs for potential bugs and portability problems – truss: trace system calls and signals • Other useful commands – Standard file commands: cp, mv, grep, diff, file, ls, mkdir, cd, rm, chmod, ln – Know the uses for: |, ||, &, &&, fg, bg, jobs – Useful utilities: script, tar, compress, gzip, which, whereis, apropos, who, w, talk, write, man, man CEG 433/633 - Operating Systems I Lab. 14 Dr. T. Doom