koyamanx / os-1

A toy UNIX-like Operating System Version 1

Hi there 👋

os-1's Issues

Implement kill system call

Copy arguments of system calls from user space to kernel space

Copy arguments of system calls from user space to kernel space

Currently, arguments of system calls is modified directly in user space by translating virtual address.
It may destroy user space context if implementation of system calls in kernel space destroy argument by modifying them.
We need to fix them by coping user data in user space when argument is passed by references via pointer.

Implement rmdir system call

Implement rmdir system call

Implement sleep system call

Review all of unsupported features and limitations of implementations

Review all of unsupported features and limitations of implementations

Limitations or features not implemented in kernel must use unimplemented() macros to panic.

Implement mount and umount system call

Implement mount and umount system call

Implement access system call

Implement access system call

Implement sync system call

Implement sync system call

Handle indirect zone to support larger file

Handle indirect zone to support larger file

Support newlib for userland program

Support newlib for userland program

Steps

• Port newlib for user program.
• Support link and include libraries for cmake.
• Replace all of libc function to newlib.

Implement rename system call

Implement rename system call

Add this_cpu() and this_proc() to obtain running context of cpu or proc structures.

Add this_cpu() and this_proc() to obtain running context of cpu or proc structures.

Implement stat and fstat system call

Implement stat and fstat system call

Prototype declarations

int fstat(int fildes, struct stat *buf);
int stat(const char *restrict, struct stat *restrict);

Implement brk system call

Implement brk system call

Implement unlink system call

Implement unlink system call

Implement chdir system call

Implement chdir system call

Change declaration of dev_t typedef to integer type.

Change declaration of dev_t typedef to integer type.

Currently, we use struct type for dev_t, POSIX system call expect it as type of integer(u32).
Fix dev_t type declaration to comply standard.

Implement chmod system call

Implement chmod system call

Implement system calls for minix3 file system

Implement write system call for minix3 filesystem

Features

• Enlarge inode cache
• Read from file in user mode
• Write to file (zone allocation)
• Open system call with flag other than O_CREAT.
• O_TRUNC for open.
• Indirect zone

Implement umask system call

Implement umask system call

Implement buffered I/O for block device

Implement buffered I/O for block device

Abstract

Requesting every reads operation for device will significantly lower the performances.
So read to in-memory buffer first, then use that buffer for operation.
On write, firstly read out to buffer, then write to buffer then do I/O operation so that
next read will hit in buffer.

Buffer struct

struct buf {
  dev_t dev;
  u64 blkno;
  u8 *data;
  bool dirty;
  struct buf *next;
};

Function

• getblk(dev, blkno)
  • Get block associated to device(dev) and blkno pair, if not exist, allocate new entry.
• brelse(buf)
  • Release buffer.
• binit()
  • Init buffer freelist head.
• bwrite(buf)
  • Write buffer to device. buf is not released.
• bread(dev, blkno)
  • Read blk from dev at blkno. If buf is exist, use that entry, otherwise allocate new one.
• bflush(dev)
  • Flush buffer associated to dev.

Implement seek system call

Implement seek system call

Add stress tests for components of kernel like fork, read, open and write

Add stress tests for components of kernel like fork, read, open and write

Implement chdir system call

Implement chdir system call

• Support CWD.
• Support relative path.

Implement truncate system call

Implement truncate system call

Prototype declaration

#include <unistd.h>
int truncate(const char *path, off_t length);

Description

• The truncate() function shall cause the regular file named by path to have a size which shall be equal to length bytes.
• If the file previously was larger than length, the extra data is discarded. If the file was previously shorter than length, its size is increased, and the extended area appears as if it were zero-filled.
• Path should have write permissions.

strncat, strcatを実装する。

strncat, strcat関数をstring.h, string.cファイルに実装してください。

プロトタイプ宣言

char *strcat(char *dest, const char *src);
char *strncat(char *dest, const char *src, size_t n);

strncat説明

文字型配列destの末尾に文字列srcをn要素分コピーします。
destとsrcが重なっている場合には動作は未定義となります。

戻り値

destの値

strcat説明

strncat(dest, src, strlen(src));を内部で呼び出してください。

戻り値

destの値

Implement link system call

Implement link system call

Prototype declaration

int link(const char *path1, const char *path2);

path1 is existing file.
path2 is newly created file.

Description

The link function shall create a new directory entry for existing file, path1.
It share same inode, and reference counter in inode is incremented by one.

If path1 is directory, link fails.

Implement userland program

• ls
• echo
• cat
• rm
• wc

Support exec with argv

Support exec with argv

Support doygen for all files

Support interrupts in kernel

Support interrupts in kernel

Kernel can be lead to deadlock if all of processes enter sleep state.
For example, init process can be set to sleep state by calling waitpid for waiting its child to exit, and all of its children is also enter sleep. In this case, scheduler tries to find processes to run, but none is found, leading to deadlock in kernel.
To avoid this situation, we need to support traps in kernel.
For now, we use waitpid for polling mode in init process to avoid this situation.

Implement chmod system call

Implement chmod system call

Implement utimes system call

Implement utimes system call

Fix doxygen comments for fs.h

Fix doxygen comments for fs.h

• doxygen comments in fs.h does not has brief, details annotation, so it may break render result.