Operating Systems 2019W: Assignment 3 - Revision history

Soma: /* Solutions */

2019-03-30T17:07:08Z

Solutions

← Older revision		Revision as of 17:07, 30 March 2019
Line 85:		Line 85:
	<pre>		<pre>
	COMP 3000 Winter 2019		COMP 3000 Winter 2019
	Assignment 2 solutions		Assignment 3 solutions

	1. [2] What are two reasons Linux kernel code doesn't make system		1. [2] What are two reasons Linux kernel code doesn't make system
Line 116:		Line 116:
	geteuid: from_kuid_munged(current_user_ns(), current_euid());		geteuid: from_kuid_munged(current_user_ns(), current_euid());

	We know this code is correct because it is how the Linux kernel itself implements the getuid and geteuid system calls in kernel/sys.c. See		We know this code is correct because it is how the Linux kernel itself
			implements the getuid and geteuid system calls in kernel/sys.c. See

	https://elixir.bootlin.com/linux/v5.0.2/source/kernel/sys.c#L919		https://elixir.bootlin.com/linux/v5.0.2/source/kernel/sys.c#L919
Line 203:		Line 204:
	following error:		following error:

	Mar 17 12:03:42 soma-1 kernel: [ 24.335105] sysfs: cannot create duplicate fil		Mar 17 12:03:42 soma-1 kernel: [ 24.335105] sysfs: cannot create
	ename '/class/ppp'		duplicate fil ename '/class/ppp'
	[ LONG CALL TRACE HERE INCLUDING KERNEL STACK DUMP AND REGISTERS ]		[ LONG CALL TRACE HERE INCLUDING KERNEL STACK DUMP AND REGISTERS ]
	Mar 17 12:03:42 soma-1 kernel: [ 24.335457] kobject_add_internal failed for ppp with -EEXIST, don't try to register things with the same name in the same directory.		Mar 17 12:03:42 soma-1 kernel: [ 24.335457] kobject_add_internal
	Mar 17 12:03:42 soma-1 kernel: [ 24.335463] Remember: failed to register device class 'ppp'		failed for ppp with -EEXIST, don't try to register things with the
			same name in the same directory.
			Mar 17 12:03:42 soma-1 kernel: [ 24.335463] Remember: failed to
			register device class 'ppp'

	===========================================================================		===========================================================================

Soma at 17:04, 30 March 2019

2019-03-30T17:04:29Z

Show changes

Soma: /* Test Code */

2019-03-23T18:57:18Z

Test Code

← Older revision		Revision as of 18:57, 23 March 2019
Line 34:		Line 34:
	==Test Code==		==Test Code==

	For the programming questions, you should create tests. Here's a fragment of a test program that test for null pointer access when ~~writing~~.		For the programming questions, you should create tests. Here's a fragment of a test program that test for null pointer access when reading.

	<source lang="c" line>		<source lang="c" line>

Soma: /* Test Code */

2019-03-23T18:56:32Z

Test Code

← Older revision		Revision as of 18:56, 23 March 2019
Line 79:		Line 79:
	}		}

	</~~listing~~>		</source>

Soma: /* Test Code */

2019-03-23T18:56:15Z

Test Code

← Older revision		Revision as of 18:56, 23 March 2019
Line 36:		Line 36:
	For the programming questions, you should create tests. Here's a fragment of a test program that test for null pointer access when writing.		For the programming questions, you should create tests. Here's a fragment of a test program that test for null pointer access when writing.

	<~~code~~ lang="c" line>		<source lang="c" line>
	#include <stdio.h>		#include <stdio.h>
	#include <stdlib.h>		#include <stdlib.h>

Soma: /* Test Code */

2019-03-23T18:55:48Z

Test Code

← Older revision		Revision as of 18:55, 23 March 2019
Line 36:		Line 36:
	For the programming questions, you should create tests. Here's a fragment of a test program that test for null pointer access when writing.		For the programming questions, you should create tests. Here's a fragment of a test program that test for null pointer access when writing.

	<~~listing~~ lang="c" line>		<code lang="c" line>
	#include <stdio.h>		#include <stdio.h>
	#include <stdlib.h>		#include <stdlib.h>

Soma at 18:55, 23 March 2019

2019-03-23T18:55:34Z

← Older revision		Revision as of 18:55, 23 March 2019
Line 31:		Line 31:
	</li>		</li>
	</ol>		</ol>

			==Test Code==

			For the programming questions, you should create tests. Here's a fragment of a test program that test for null pointer access when writing.

			<listing lang="c" line>
			#include <stdio.h>
			#include <stdlib.h>
			#include <sys/types.h>
			#include <unistd.h>
			#include <sys/stat.h>
			#include <fcntl.h>

			int open_remember(void) {
			int fd;
			fd = open("/dev/remember", O_RDWR);

			if (fd < 0) {
			fprintf(stderr, "Could not open the remember device.\n");
			exit(-1);
			}

			return fd;
			}

			void read_null_test(void)
			{
			ssize_t c;
			int fd;

			fd = open_remember();

			c = read(fd, NULL, 1024);
			if (c >= 0) {
			printf("read with NULL buffer succeeded\n");
			} else {
			perror("Error reading remember in NULL buffer test");
			}
			close(fd);
			}

			int main(int argc, char *argv)
			{
			read_null_test();

			return 0;
			}

			</listing>

Soma at 18:23, 23 March 2019

2019-03-23T18:23:50Z

← Older revision		Revision as of 18:23, 23 March 2019
Line 1:		Line 1:
	Please submit the answers to the following questions via CULearn by 11:55 PM on ~~Sunday~~, March 24, 2019. There are 20 points in 9 questions.		Please submit the answers to the following questions via CULearn by 11:55 PM on Tuesday, March 26, 2019. There are 20 points in 9 questions.

	Submit your answers as a single text file named "<username>-comp3000-assign3.txt" (where username is your MyCarletonOne username). The first four lines of this file should be "COMP 3000 Assignment 3", your name, student number, and the date of submission. You may wish to format your answers in Markdown to improve their appearance.		Submit your answers as a single text file named "<username>-comp3000-assign3.txt" (where username is your MyCarletonOne username). The first four lines of this file should be "COMP 3000 Assignment 3", your name, student number, and the date of submission. You may wish to format your answers in Markdown to improve their appearance.

Soma at 04:12, 18 March 2019

2019-03-18T04:12:29Z

← Older revision		Revision as of 04:12, 18 March 2019
Line 1:		Line 1:
	~~<div style="background-color: cyan; border-style: dashed;padding-top: 10px;~~
	~~padding-right: 20px;~~
	~~padding-bottom: 10px;~~
	~~padding-left: 20px;">~~
	~~'''This assignment is not yet finalized''' but it is feature complete. Feel free to start working on it, but please check it again after it has been finalized for small changes.~~
	~~</div>~~

	Please submit the answers to the following questions via CULearn by 11:55 PM on Sunday, March 24, 2019. There are 20 points in 9 questions.		Please submit the answers to the following questions via CULearn by 11:55 PM on Sunday, March 24, 2019. There are 20 points in 9 questions.

Soma: /* Questions */

2019-03-18T03:53:12Z

Questions

← Older revision		Revision as of 03:53, 18 March 2019
Line 29:		Line 29:
	<li>[2] In the remember module, modify remember_read() so it uses a non-zero offset properly rather than simply logging an error. Describe the process by which you figured out your answer.</li>		<li>[2] In the remember module, modify remember_read() so it uses a non-zero offset properly rather than simply logging an error. Describe the process by which you figured out your answer.</li>
	<li>[2] Modify the remember module so llseek system calls work as they do on regular files, for whence values of SEEK_CUR and SEEK_SET. You should not allow the offset to be set to a value past the current end of file. Describe the process by which you figured out your answer.</li>		<li>[2] Modify the remember module so llseek system calls work as they do on regular files, for whence values of SEEK_CUR and SEEK_SET. You should not allow the offset to be set to a value past the current end of file. Describe the process by which you figured out your answer.</li>
	<li>[4] Modify the remember module so the behavior of writes change as follows:		<li>[4] Modify the remember module so the behavior of writes change as follows. Explain how you verified each.
	<ol type="a">		<ol type="a">
	<li>[1] Increase the allocation size to 16K of storage.</li>		<li>[1] Increase the allocation size to 16K of storage.</li>