What to do if Read_Line returns -1

[Eran Kravitz]

In the project description it says to modify the shell to handle the
possibility when Read_Line() returns -1. How are we expected to act when
such a case occurs? Do we need to kill the shell, or print out an error
message, or anything else?

Thanks.

[Saurabh Srivastava]

| In the project description it says to modify the shell to handle the
| possibility when Read_Line() returns -1. How are we expected to act when
| such a case occurs? Do we need to kill the shell, or print out an error
| message, or anything else?

You can just Exit the shell.

In the general case, it would be better to have a scenario in which
threads waiting for input were somehow `suspended' on some queue, waiting
to be foregrounded. But that facility being unavailable in GeekOS as of
the moment, you do not have any option but to exit the shell.

[cs412]

two questions regarding this:

1. read_line() returns void. how are we supposed to return -1?!
2. ive tried to just Exit like you said, and included kthread.h at the top,
but still it doesnt compile.

somebody please clarify

Post by Saurabh Srivastava
| In the project description it says to modify the shell to handle the
| possibility when Read_Line() returns -1. How are we expected to act when
| such a case occurs? Do we need to kill the shell, or print out an error
| message, or anything else?
You can just Exit the shell.
In the general case, it would be better to have a scenario in which
threads waiting for input were somehow `suspended' on some queue, waiting
to be foregrounded. But that facility being unavailable in GeekOS as of
the moment, you do not have any option but to exit the shell.

[Saurabh Srivastava]

| 1. read_line() returns void. how are we supposed to return -1?!

read_line is user space wrapper around Get_Key. Your Get_Key should return
-1 on not being able to read input. When that happens you should handle
that properly in read_line and then you should be able to exit the shell
when that happens.

| 2. ive tried to just Exit like you said, and included kthread.h at the top,
| but still it doesnt compile.

what i meant was that you 'exit' the shell; ie end the user space program
by calling return -1 or something.