Unix Systems Programming: Lab 3 - stat, file I/O, libraries & make

Purpose and Rationale

Resources

FAQ (submission instructions and other useful stuff)

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Lecture 3 is the primary source for this lab.

All work should be done on a machine in the department's Linux cluster. You can refer to ssh for more information on how to log into a remote machine.

Marks Distribution

LAB 3

• EXERCISE 1: Implement the stat command in C. Write a C program called my_stat that implements the default behavior of the UNIX stat command.  Your output should exactly match the default output of the stat command.  For instance:
  
  File: "/usr/bin/stat"
  Size: 7212          Blocks: 16         IO Block: 4096   Regular File
  Device: 303h/771d    Inode: 311082      Links: 1   
  Access: (0755/-rwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
  Access: Wed Jul 10 23:00:30 2002
  Modify: Wed Aug  8 10:49:41 2001
  Change: Thu Apr  4 12:34:28 2002
  
  Hint: "man stat" and "man 2 stat".  Again, the output of your stat program with the option should match the output of the original stat program.  For those of you using Molay's text, you will find his discussion on the stat call on pages 82ff quite helpful in using the stat call and formatting the output correctly.

  For extra credit (5 points): Implement handling of any one of the following two flags:
  -L (follow Links)
  -c --format (implement a subset of 5 of the formatting options (your choice which 5))

  DELIVERABLES: your source file(s) (e.g., mystat.c), a makefile, and a README as described below in Deliverables

• EXERCISE 2: Implement a simplified version of the UNIX program "cp" , which copies one file to another. Call the file filecopy.c.  This version copies only files, it does not permit the second argument to be a directory. We also ignore all options in command "filecopy".

  Please follow these steps:

  • Read the chapters in the Kerrisk text as per the syllabus.
  • Read and understand these examples: read.c and write.c; (man 2 read; man 2 write if necessary)
  • Use Low-level File Access functions such as creat, open, read, write, close, etc.) to implement this command
  • You must handle the situation when the second argument is the same as the first, i.e., you should not allow a file to be copied over itself.  Handle this situation intelligently.
  • Acctually, you only need to integrate above examples and add only serveral lines.

  DELIVERABLES: your source file(s) (e.g., filecopy.c), a makefile, and a README as described below in Deliverables

• EXERCISE 3: Build Static and Shared Libraries using a Makefile
  

  • Read "make and Makefile" session in Chaper 10 of BLP textbook if you're using that text.  Certainly refer to the online GNU documentation for GNU make.
  
  
  • Write 3 very simple c source files: hello.c, here.c, bye.c, mylib.h . In hello.c, a function should print out "Hello!"; in here.c , another function should print out "I am here!"; and yet another function should print out "Bye bye!" in bye.c. So, actually, in each code file, there is only one C printf statement. mylib.h should include prototypes for the 3 functions you will be writing.
    
  • Write a main.c to call above 3 functions so that the result should display like following
    "Hello!"
    "I am here!"
    "Bye bye!"
    Please note there is no C printf statement in main.c;
  
  
  • Read and understand this makefile first and write your own Makefile called Makefile1 to compile them and build a static lib called mylib.a, comprised of hello.c, here.c, and bye.c (but NOT main.c).
    Review "shared libraries naming structure" and "building a shared library" in lecture 3.
  
  
  • Read and understand this makefile first and write your own makefile called Makefile2 to compile them and build a shared lib with the soname of libmylib.so.5.  Make the minor version .1 and the release .10.  This will mean your actual shared library file will be named "libmylib.so.5.1.10" with .so links set accordingly.
    Note that the two makefiles actually build separate libraries based on the same source code files, one static, the other shared.
  
  DELIVERABLES: your source file(s) (e.g., main.c, hello.c, bye.c, here.c, mylib.h), two makefiles, and a README as described below in Deliverables

1. Please create subdirectories ex1, ex2, and ex3, and place each exercise's materials in its respective directory as described below:
   
   
   • Directory ex1 will include at least three files.
     • Source code files: You may organize your files anyway you like.
     • Makefile: it must build your executable named mystat when we type make on the command line.
     • README : This file must include the correct command line syntax (including the available option in you do the bonus), a brief explanation of your command (including the extra functionality if you do the bonus) and the transcript of one example of your command in the default mode (if you are doing the bonus option, submit a second example showing your option at work.)
       
       
   • Directory ex2 will include at least three files.
     • Source code files: You may organize your files anyway you like.
     • Makefile: it must build your executable name filecopy when we type make on the command line.
     • README : This file must include the correct command line syntax of filecopy and a brief explanation of what it does. There is no need to send a transcript of it in action.
       
       
   • Directory ex3 will include eight files.
     • Source code files : main.c, hello.c, bye.c, here.c, mylib.h
     • Two Make files, which will build an executable called : main
          Makefile1 : for building static library
          Makefile2 : for building shared library
     • README : it will contain two lines, the exact command line argument to build an executable called main
          make -f Makefile1 target
          make -f Makefile2 target
2. When you are finished with your directory you will create a compressed archive file using tar (this utility stores your directory as a single file, then compresses its size.)
          tar -czvf   username.lab3.tgz   username.lab3
   


3. You will email your file to our grader as an attachment. She will send an acknowledgement that your assignment has been received.
   

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1. Maria Power