os161 | ops-class.org OS/161 sources

by ops-class C Version: Current License: No License

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kandi X-RAY | os161 Summary

os161 is a C library. os161 has no bugs, it has no vulnerabilities and it has low support. You can download it from GitHub.

ops-class.org OS/161 sources.

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Support

os161 has a low active ecosystem.

It has 102 star(s) with 169 fork(s). There are 14 watchers for this library.

It had no major release in the last 6 months.

There are 1 open issues and 5 have been closed. On average issues are closed in 6 days. There are 2 open pull requests and 0 closed requests.

It has a neutral sentiment in the developer community.

The latest version of os161 is current.

Quality

os161 has no bugs reported.

Security

os161 has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

License

os161 does not have a standard license declared.

Check the repository for any license declaration and review the terms closely.

Without a license, all rights are reserved, and you cannot use the library in your applications.

Reuse

os161 releases are not available. You will need to build from source code and install.

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os161 Key Features

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os161 Examples and Code Snippets

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Community Discussions

Trending Discussions on os161

What happens when setting the O_CREAT bit but only providing two parameters for open()?

How to add the two variations of the open syscall in OS161?

What is the use of the type userptr_t in os161?

What is the use of the argument num in this code?

Incompatible pointer type warning in os161

Makefile Errors - "***missing separator" & "***recipe commences before first target"

Why is the pointer changing for no reason?

QUESTION

What happens when setting the O_CREAT bit but only providing two parameters for open()?

Asked 2020-Sep-06 at 01:34

Here, I was asking about an assignment of implementing the sys_open syscall for OS161 which will be called by the open function.

The definition of the open function is as follows:

...

ANSWER

Answered 2020-Sep-06 at 01:34

The POSIX documentation simply states that the:

mode shall be set to the value of the argument following the oflag argument taken as type mode_t modified as follows: ...

It does not specify what happens when you omit that parameter so you would be well advised to ensure it's there (on the client side). The most likely case will be that it will use what is where the parameter would be (whether in register or memory, depending on calling convention), and the chances of this being the correct value would be slim.

The Linux documentation has this to say on the matter (my emphasis):

The mode argument must be supplied if O_CREAT or O_TMPFILE is specified in flags; if it is not supplied, some arbitrary bytes from the stack will be applied as the file mode.

Now, granted, that's not a standards document where the term "must" is a solid requirement that you do it (or else all bets are off as to the effect), but you should probably read it in that way. Hence, again, you should make sure you supply it.

So I would say that the way you handle it is as follows:

If on the client/caller side, make sure you supply the mode. Anything else is breaking the contract.
On the server/callee side, assume that the caller has supplied it since, if they haven't, they're breaking the contract. There appears to be no suitable error return in POSIX (in either the "shall fail" or "may fail" section) that would be suitable for indicating this issue, even if you could detect it.

Source https://stackoverflow.com/questions/63753992

QUESTION

How to add the two variations of the open syscall in OS161?

Asked 2020-Sep-03 at 11:16

From the man pages of OS161:

Synopsis ...

ANSWER

Answered 2020-Sep-03 at 11:16

First, that OS161 man page is wrong in incorrectly implying that there are two versions of the open() function. There is only one version of open() - C does not support function overloading like that man page implies. Per POSIX the one version of open() is

Source https://stackoverflow.com/questions/63721977

QUESTION

What is the use of the type userptr_t in os161?

Asked 2020-Aug-13 at 01:42

I'm trying to complete an assignment for an operating systems course, Here.

I had a question from the assignment:

What is the purpose of userptr_t?

When I searched the source code for userptr_t, Here, I found this:

...

ANSWER

Answered 2020-Aug-13 at 01:42

This looks like a strong typedef, i.e. a typedef intended to increase type safety by avoiding unintended uses/conversions of the wrapped data.

In your context, most likely intended to differentiate kernel pointers from user space pointers (usually mapped via the MMU).

Source https://stackoverflow.com/questions/63386788

QUESTION

What is the use of the argument num in this code?

Asked 2020-Aug-02 at 06:41

The "os161" operating system contains the following code. Specifically, where the syscalls are defined:

...

ANSWER

Answered 2020-Aug-02 at 06:41

It is used for other tools to ease the maintenance of the source code.
The following is a quote from Understanding System Calls

syscalls.S: This file is created from syscalls-mips.S at compile time and is the actual file assembled into the C library. The actual names of the system calls are placed in this file using a script called callno-parse.sh that reads them from the kernel's header files. This avoids having to make a second list of the system calls. In a real system, typically each system call stub is placed in its own source file, to allow selectively linking them in. OS/161 puts them all together to simplify the makefiles. Adding new entries to callno.h automatically causes new user-level system call procedures to be defined when you re-build the user-level code. Each "SYSCALL(name,num)" macro statement in this file is expanded by the C pre-processor into a declaration of the appropriate system call function.

kern/syscall.h most likely is produce by one of those tools.

Source https://stackoverflow.com/questions/63212933

QUESTION

Incompatible pointer type warning in os161

Asked 2020-Mar-13 at 23:31

I am implementing a fork system call in os161 kernel. I am trying to create a new process and for its thread creation I used thread_fork. I am using the function md_forkentry to allocate heap and stack to the trapframe of the new thread and switch to user mode; but I get this warning after compiling the code: passing arg 4 of 'thread_fork' from incompatible pointer type

...

ANSWER

Answered 2020-Mar-13 at 23:31

Your prototype for md_forkentry() does not match the type of the 4th parameter of thread_fork().

md_forkentry() must be prototyped as:

Source https://stackoverflow.com/questions/60678360

QUESTION

Makefile Errors - "***missing separator" & "***recipe commences before first target"

Asked 2017-May-21 at 10:25

I am trying to build the userland for os161. When I type make in the command line I get the following error:

Makefile 24: ***missing separator (did you mean TAB instead of 8 spaces?). Stop.

I checked the Makefile at line 24 and tried adding a TAB to the start of the line, but that didn't work as I then get another error:

Makefile 24: ***recipe commences before first target. Stop.

Here is the full makefile for reference:

...

ANSWER

Answered 2017-May-20 at 11:37

A separator is a . Please do not use spaces at line begin in a Makefile, Makefile.in ...

Snippet:

Source https://stackoverflow.com/questions/44081364

QUESTION

Why is the pointer changing for no reason?

Asked 2017-Jan-12 at 04:45

I am working on Assignment 2 of ops-class.

The following function bootstraps a file handler array for the process that is being created (eg. user processes for test programs provided here).

...

ANSWER

Answered 2017-Jan-12 at 04:45

The code handle->fh_vnode is setting a pointer to automatic variable ("on the stack"), function parameters are automatic variables. After the function returns this will be a dangling pointer.

To fix this you will need to re-design your code a bit, e.g. perhaps the struct fh should just store file and not a pointer to file.

Source https://stackoverflow.com/questions/41560685

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Vulnerabilities

No vulnerabilities reported

Install os161

You can download it from GitHub.

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