COMP 3000 Lab 5 2010 - Revision history

Mbingham: added \n

2010-11-09T15:33:12Z

added \n

← Older revision		Revision as of 15:33, 9 November 2010
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	} else {		} else {
	/* child */		/* child */
	printf("I am the child!");		printf("I am the child!\n");
	}		}
	return 0;		return 0;

Soma: /* Code */

2010-11-08T18:47:24Z

Code

@@ Line 24: / Line 24: @@
          printf("Hello, world!\n");
          return 0;
+  }
 ==Hints==

Soma at 16:59, 8 November 2010

2010-11-08T16:59:40Z

← Older revision		Revision as of 16:59, 8 November 2010
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	In this lab you will work with the commands '''ltrace''' and '''strace'''. You may need to install these programs; if so, on Debian and Ubuntu systems type "sudo aptitude install strace ltrace".		In this lab you will work with the commands '''ltrace''' and '''strace'''. You may need to install these programs; if so, on Debian and Ubuntu systems type ''sudo aptitude install strace ltrace''.

	==Questions==		==Questions==

Soma: Created page with "In this lab you will work with the commands '''ltrace''' and '''strace'''. You may need to install these programs; if so, on Debian and Ubuntu systems type "sudo aptitude instal…"

2010-11-08T16:59:17Z

Created page with "In this lab you will work with the commands '''ltrace''' and '''strace'''. You may need to install these programs; if so, on Debian and Ubuntu systems type "sudo aptitude instal…"

New page

In this lab you will work with the commands '''ltrace''' and '''strace'''. You may need to install these programs; if so, on Debian and Ubuntu systems type "sudo aptitude install strace ltrace".

==Questions==

Answer all of the following questions.

# Compile hello.c with the command ''gcc -O hello.c -o hello-dyn''. Run ''ltrace ./hello-dyn''. What dynamic functions did hello call?
# Run ''strace ./hello-dyn''. How many system calls did hello make?
# Re-compile hello.c using the command ''gcc -static -O hello.c -o hello-static''. Run hello-static using ltrace and strace. How does the output compare with that from the previous two questions? (Explain at a high level.)
# How big are the binaries of hello-dyn and hello-static? Why is one so much bigger than the other one? Explain.
# Add a ''while(1) sleep(1);'' loop to hello.c so that it waits forever after saying hello. Recompile statically and dynamically. What is the resident and virtual memory used by both?
# Compile and run hello-fork.c. Note that hello-fork.c produces a ''zombie'' process. How do you fix hello-fork.c so that the zombie exits properly?
# How can you modify hello-fork.c so that the child process would run ''/bin/ls'' using the execve() function?
# strace and ltrace examine the behavior of a running program. The entire design of UNIX is such that each process lives in its own address space. How can these programs work? What mechanism must they use? '''Extra credit:''' what is that mechanism? '''Extra extra credit:''' make a program that tells you the PIDs of all forked children of a monitored process.

==Code==

/* hello.c */
#include <stdio.h>
#include <unistd.h>

int main(int argc, char *argv[])
{

printf("Hello, world!\n");
return 0;
}

==Hints==