Operating Systems 2019W: Assignment 1 - Revision history

Soma: /* Question 2 */

2019-02-04T22:24:40Z

Question 2

← Older revision		Revision as of 22:24, 4 February 2019
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	===Question 2===		===Question 2===
	If this line is removed, then 3000shell will never wait for a process to finish. Thus, all processes will be run in "the background".		If this line is removed, then 3000shell will never wait for a process to finish (the wait system call is only invoked on SIGCHLD). Thus, all processes will be run in "the background".

	===Question 3===		===Question 3===

Soma: /* Question 3 */

2019-02-04T22:06:12Z

Question 3

← Older revision		Revision as of 22:06, 4 February 2019
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	===Question 3===		===Question 3===
	If lines 299 and 300 were removed, 3000shell would behave the same as before unless execve fails. Then, instead of printing the error, the execve would fail silently.		If lines 299 and 300 were removed, 3000shell would behave the same as before unless execve fails. Then, instead of printing the error, the execve would fail silently. Also, since the child doesn't exit, you'll have 2 processes running 3000shell (accessing the same terminal).

	===Question 4===		===Question 4===

Soma: /* Question 9 */

2019-02-02T20:37:16Z

Question 9

← Older revision		Revision as of 20:37, 2 February 2019
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	Wait for user input, but the read gets interrupted by SIGCHLD		Wait for user input, but the read gets interrupted by SIGCHLD
	read(0, 0x5594b3dfa670, 1024) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)		read(0, 0x5594b3dfa670, 1024) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
	--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=14692, si_uid=1000, si_status=0, si_utime=0, si_stime=0} ---		--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=14692, si_uid=1000, si_status=0, si_utime=0, si_stime=0} ---
	Run the signal handler		Run the signal handler
	wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 14692		wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 14692
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	write(1, "soma $ ", 7) = 7		write(1, "soma $ ", 7) = 7
	read(0, 0x5608fcb95670, 1024) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)		read(0, 0x5608fcb95670, 1024) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
	--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=14934, si_uid=1000, si_status=0, si_utime=0, si_stime=0} ---		--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=14934, si_uid=1000, si_status=0, si_utime=0, si_stime=0} ---
	wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 14934		wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 14934
	write(2, "\nProcess 14934 exited with statu"..., 37) = 37		write(2, "\nProcess 14934 exited with statu"..., 37) = 37

Soma: /* Solutions */

2019-02-02T20:35:30Z

Solutions

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	* rt_sigaction(SIGHUP, {sa_handler=0x555aba3971d0, sa_mask=[], sa_flags=SA_RESTORER\|SA_RESTART, sa_restorer=0x7f24880a9f20}, NULL, 8) = 0		* rt_sigaction(SIGHUP, {sa_handler=0x555aba3971d0, sa_mask=[], sa_flags=SA_RESTORER\|SA_RESTART, sa_restorer=0x7f24880a9f20}, NULL, 8) = 0
	fstat(1, {st_mode=S_IFCHR\|0620, st_rdev=makedev(136, 1), ...}) = 0		fstat(1, {st_mode=S_IFCHR\|0620, st_rdev=makedev(136, 1), ...}) = 0
	The *'d lines are not present when lines 245-251 are commented out, but the other calls are the the same. (Note that the arguments to the system calls vary but their order ~~otherwis~~ is consistent.)		The *'d lines are not present when lines 245-251 are commented out, but the other calls are the the same. (Note that the arguments to the system calls vary but their order is otherwise consistent.)

	===Question 6===		===Question 6===

Soma at 20:34, 2 February 2019

2019-02-02T20:34:54Z

Show changes

Soma at 19:21, 25 January 2019

2019-01-25T19:21:12Z

← Older revision		Revision as of 19:21, 25 January 2019
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	Please submit the answers to the following questions via CULearn by 4 PM on January 28, 2019. There are 20 points in 11 questions.		Please submit the answers to the following questions via CULearn by 11:55 PM on January 29, 2019. There are 20 points in 11 questions.

	Submit your answers as a single text file named "<username>-comp3000-assign1.txt" (where username is your MyCarletonOne username). The first four lines of this file should be "COMP 3000 Assignment 1", 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-assign1.txt" (where username is your MyCarletonOne username). The first four lines of this file should be "COMP 3000 Assignment 1", your name, student number, and the date of submission. You may wish to format your answers in Markdown to improve their appearance.

Soma: /* Questions */

2019-01-25T19:12:36Z

Questions

← Older revision		Revision as of 19:12, 25 January 2019
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	# [2] How can <tt>execve</tt> overwrite all of a process's memory while also preserving its file descriptors? Specifically, does preserving file descriptors require execve to avoid erasing some process memory?		# [2] How can <tt>execve</tt> overwrite all of a process's memory while also preserving its file descriptors? Specifically, does preserving file descriptors require execve to avoid erasing some process memory?
	# [2] Is the SA_RESTART flag on a signal handler (e.g., line 243) interpreted by code running in the process or in the kernel? Give evidence for your answer.		# [2] Is the SA_RESTART flag on a signal handler (e.g., line 243) interpreted by code running in the process or in the kernel? Give evidence for your answer.
	# [3] Implement a "listfiles" command that lists the files in the current directory. Give the code for the listfiles() function and show how you'd change the rest of the code so that typing "listfiles" runs this function. Show your changes by using <tt>diff -c</tt>.		# [3] Implement a "listfiles" command that lists the files in the current directory. Give the code for the listfiles() function and show how you'd change the rest of the code so that typing "listfiles" runs this function. Your solution should not invoke an external executable; instead, it should do something similar to plist(). Show your changes by using <tt>diff -c</tt>.
	# [3] Implement an "input from file" feature to 3000shell that works as follows. If you run <pre>$ bc infile=foo.bc</pre> then 3000shell should have bc read the contents of foo.bc from standard input. You may assume that the "infile=" parameter is the last one (other than perhaps &). Show your changes from the standard 3000shell.c using <tt>diff -c</tt>.		# [3] Implement an "input from file" feature to 3000shell that works as follows. If you run <pre>$ bc infile=foo.bc</pre> then 3000shell should have bc read the contents of foo.bc from standard input. You may assume that the "infile=" parameter is the last one (other than perhaps &). Show your changes from the standard 3000shell.c using <tt>diff -c</tt>.

Soma at 15:26, 23 January 2019

2019-01-23T15:26:26Z

← Older revision		Revision as of 15:26, 23 January 2019
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	# [2] Is the SA_RESTART flag on a signal handler (e.g., line 243) interpreted by code running in the process or in the kernel? Give evidence for your answer.		# [2] Is the SA_RESTART flag on a signal handler (e.g., line 243) interpreted by code running in the process or in the kernel? Give evidence for your answer.
	# [3] Implement a "listfiles" command that lists the files in the current directory. Give the code for the listfiles() function and show how you'd change the rest of the code so that typing "listfiles" runs this function. Show your changes by using <tt>diff -c</tt>.		# [3] Implement a "listfiles" command that lists the files in the current directory. Give the code for the listfiles() function and show how you'd change the rest of the code so that typing "listfiles" runs this function. Show your changes by using <tt>diff -c</tt>.
	# [3] Implement an "input from file" feature to 3000shell that works as follows. If you run <pre>$ bc infile=foo.bc</pre> then 3000shell should have bc read the contents of foo.bc from standard input. You may assume that the "infile=" parameter is the last one (other than perhaps &). Show your changes from the standard ~~csimpleshell~~.c using <tt>diff -c</tt>.		# [3] Implement an "input from file" feature to 3000shell that works as follows. If you run <pre>$ bc infile=foo.bc</pre> then 3000shell should have bc read the contents of foo.bc from standard input. You may assume that the "infile=" parameter is the last one (other than perhaps &). Show your changes from the standard 3000shell.c using <tt>diff -c</tt>.

Soma at 14:05, 23 January 2019

2019-01-23T14:05:28Z

← Older revision		Revision as of 14:05, 23 January 2019
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	Don't forget to include what outside resources you used to complete each of your answers, including other students, man pages, and web resources. You do not need to list help from the instructor, TA, or information found in the textbook.		Don't forget to include what outside resources you used to complete each of your answers, including other students, man pages, and web resources. You do not need to list help from the instructor, TA, or information found in the textbook.

			Note that all questions below refer to 3000shell.c from Tutorial 2.

	==Questions==		==Questions==

Soma: /* Questions */

2019-01-23T14:04:16Z

Questions

← Older revision		Revision as of 14:04, 23 January 2019
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	# [2] Is the SA_RESTART flag on a signal handler (e.g., line 243) interpreted by code running in the process or in the kernel? Give evidence for your answer.		# [2] Is the SA_RESTART flag on a signal handler (e.g., line 243) interpreted by code running in the process or in the kernel? Give evidence for your answer.
	# [3] Implement a "listfiles" command that lists the files in the current directory. Give the code for the listfiles() function and show how you'd change the rest of the code so that typing "listfiles" runs this function. Show your changes by using <tt>diff -c</tt>.		# [3] Implement a "listfiles" command that lists the files in the current directory. Give the code for the listfiles() function and show how you'd change the rest of the code so that typing "listfiles" runs this function. Show your changes by using <tt>diff -c</tt>.
	# [3] Implement an "input from file" feature to ~~csimpleshell~~ that works as follows. If you run <pre>$ bc infile=foo.bc</pre> then ~~csimpleshell~~ should have bc read the contents of foo.bc from standard input. You may assume that the "infile=" parameter is the last one (other than perhaps &). Show your changes from the standard csimpleshell.c using <tt>diff -c</tt>.		# [3] Implement an "input from file" feature to 3000shell that works as follows. If you run <pre>$ bc infile=foo.bc</pre> then 3000shell should have bc read the contents of foo.bc from standard input. You may assume that the "infile=" parameter is the last one (other than perhaps &). Show your changes from the standard csimpleshell.c using <tt>diff -c</tt>.