System Call handler definition. More...

Functions
void	syscall_init (void)
	Initialize the system calls.

void	syscall_handler (pt_regs *f)
	Handler for the system calls. More...

pt_regs *	get_current_interrupt_stack_frame (void)
	Returns the current interrupt stack frame. More...

void	sys_exit (int exit_code)

ssize_t	sys_read (int fd, void *buf, size_t nbytes)
	Read data from a file descriptor. More...

ssize_t	sys_write (int fd, const void *buf, size_t nbytes)
	Write data into a file descriptor. More...

off_t	sys_lseek (int fd, off_t offset, int whence)
	Repositions the file offset inside a file. More...

int	sys_open (const char *pathname, int flags, mode_t mode)
	Given a pathname for a file, open() returns a file descriptor, a small, nonnegative integer for use in subsequent system calls. More...

int	sys_close (int fd)

int	sys_unlink (const char *path)
	Delete a name and possibly the file it refers to. More...

pid_t	sys_waitpid (pid_t pid, int *status, int options)
	Suspends execution of the calling thread until a child specified by pid argument has changed state. More...

int	sys_execve (pt_regs *f)
	Replaces the current process image with a new process image. More...

int	sys_chdir (char const *path)
	Changes the working directory. More...

int	sys_fchdir (int fd)
	Changes the working directory. More...

pid_t	sys_getpid (void)
	Returns the process ID (PID) of the calling process. More...

pid_t	sys_getsid (pid_t pid)
	Return session id of the given process. If pid == 0 return the SID of the calling process If pid != 0 return the SID corresponding to the process having identifier == pid. More...

pid_t	sys_setsid (void)
	creates a new session if the calling process is not a process group leader. The calling process is the leader of the new session (i.e., its session ID is made the same as its process ID). The calling process also becomes the process group leader of a new process group in the session (i.e., its process group ID is made the same as its process ID). More...

pid_t	sys_getpgid (pid_t pid)
	returns the Process Group ID (PGID) of the process specified by pid. If pid is zero, the process ID of the calling process is used. More...

int	sys_setpgid (pid_t pid, pid_t pgid)
	Sets the Process Group ID (PGID) of the process specified by pid. If pid is zero, the process ID of the calling process is used. More...

gid_t	sys_getgid (void)
	returns the real group ID of the calling process. More...

int	sys_setgid (gid_t gid)
	sets the group ID of the calling process. More...

gid_t	sys_getegid (void)
	returns the effective group ID of the calling process. More...

int	sys_setregid (gid_t rgid, gid_t egid)
	sets the real and effective group ID of the calling process. More...

pid_t	sys_getppid (void)
	Returns the parent process ID (PPID) of the calling process. More...

uid_t	sys_getuid (void)
	Returns the real User ID (UID) of the calling process. More...

int	sys_setuid (uid_t uid)
	Tries to set the User ID (UID) of the calling process. More...

uid_t	sys_geteuid (void)
	Returns the effective User ID (UID) of the calling process. More...

int	sys_setreuid (uid_t ruid, uid_t euid)
	Set the real and effective User ID (UID) of the calling process. More...

int	sys_nice (int increment)
	Adds the increment to the priority value of the task. More...

int	sys_reboot (int magic1, int magic2, unsigned int cmd, void *arg)
	Reboots the system, or enables/disables the reboot keystroke. More...

char *	sys_getcwd (char *buf, size_t size)
	Get current working directory. More...

pid_t	sys_fork (pt_regs *f)
	Clone the calling process, but without copying the whole address space. The calling process is suspended until the new process exits or is replaced by a call to ‘execve’. More...

int	sys_stat (const char path, stat_t buf)
	Stat the file at the given path. More...

int	sys_fstat (int fd, stat_t *buf)
	Retrieves information about the file at the given location. More...

int	sys_mkdir (const char *path, mode_t mode)
	Creates a new directory at the given path. More...

int	sys_rmdir (const char *path)
	Removes the given directory. More...

int	sys_creat (const char *path, mode_t mode)
	Creates a new file or rewrite an existing one. More...

int	sys_readlink (const char path, char buffer, size_t bufsize)
	Read the symbolic link, if present. More...

int	sys_symlink (const char linkname, const char path)
	Creates a symbolic link. More...

ssize_t	sys_getdents (int fd, dirent_t *dirp, unsigned int count)

time_t	sys_time (time_t *time)
	Returns the current time. More...

Detailed Description

System Call handler definition.

Copyright: (c) 2014-2024 This file is distributed under the MIT License. See LICENSE.md for details.

Function Documentation

◆ get_current_interrupt_stack_frame()

pt_regs* get_current_interrupt_stack_frame ( void )

Returns the current interrupt stack frame.

Returns: Pointer to the stack frame.

◆ sys_chdir()

int sys_chdir ( char const * path )

Changes the working directory.

Parameters

path	The new working directory.

Returns: On success 0. On error -1, and errno indicates the error.

◆ sys_close()

int sys_close ( int fd )

Parameters

fd

Returns

◆ sys_creat()

int sys_creat	(	const char *	path,
		mode_t	mode
	)

Creates a new file or rewrite an existing one.

Parameters

path	path to the file.
mode	mode for file creation.

Returns: file descriptor number, -1 otherwise and errno is set to indicate the error.

It is equivalent to: open(path, O_WRONLY|O_CREAT|O_TRUNC, mode)

◆ sys_execve()

int sys_execve ( pt_regs * f )

Replaces the current process image with a new process image.

Parameters

f	CPU registers whe calling this function.

Returns: 0 on success, -1 on error.

◆ sys_exit()

void sys_exit ( int exit_code )

The exit() function causes normal process termination.

Parameters

exit_code The exit code.

◆ sys_fchdir()

int sys_fchdir ( int fd )

Changes the working directory.

Parameters

fd	File descriptor of the new working directory.

Returns: On success 0. On error -1, and errno indicates the error.

◆ sys_fork()

pid_t sys_fork ( pt_regs * f )

Clone the calling process, but without copying the whole address space. The calling process is suspended until the new process exits or is replaced by a call to ‘execve’.

Parameters

f	CPU registers whe calling this function.

Returns: Return -1 for errors, 0 to the new process, and the process ID of the new process to the old process.

◆ sys_fstat()

int sys_fstat	(	int	fd,
		stat_t *	buf
	)

Retrieves information about the file at the given location.

Parameters

fd	The file descriptor of the file that is being inquired.
buf	A structure where data about the file will be stored.

Returns: Returns a negative value on failure.

◆ sys_getcwd()

char* sys_getcwd	(	char *	buf,
		size_t	size
	)

Get current working directory.

Parameters

buf	The array where the CWD will be copied.
size	The size of the array.

Returns: On success, returns the same pointer to buf. On failure, returnr NULL, and errno is set to indicate the error.

◆ sys_getdents()

ssize_t sys_getdents	(	int	fd,
		dirent_t *	dirp,
		unsigned int	count
	)

Provide access to the directory entries.

Parameters

fd	The file descriptor of the directory for which we accessing the entries.
dirp	The buffer where de data should be placed.
count	The size of the buffer.

Returns: On success, the number of bytes read is returned. On end of directory, 0 is returned. On error, -1 is returned, and errno is set appropriately.

◆ sys_getegid()

gid_t sys_getegid ( void )

returns the effective group ID of the calling process.

Returns: GID of the current process

◆ sys_geteuid()

uid_t sys_geteuid ( void )

Returns the effective User ID (UID) of the calling process.

Returns: The User ID.

◆ sys_getgid()

gid_t sys_getgid ( void )

returns the real group ID of the calling process.

Returns: GID of the current process

◆ sys_getpgid()

pid_t sys_getpgid ( pid_t pid )

returns the Process Group ID (PGID) of the process specified by pid. If pid is zero, the process ID of the calling process is used.

Parameters

pid	process of which we want to know the PGID.

Returns: the PGID of the specified process.

◆ sys_getpid()

pid_t sys_getpid ( void )

Returns the process ID (PID) of the calling process.

Returns: The process ID.

◆ sys_getppid()

pid_t sys_getppid ( void )

Returns the parent process ID (PPID) of the calling process.

Returns: The parent process ID.

◆ sys_getsid()

pid_t sys_getsid ( pid_t pid )

Return session id of the given process. If pid == 0 return the SID of the calling process If pid != 0 return the SID corresponding to the process having identifier == pid.

Parameters

pid	process identifier from wich we want the SID

Returns: On success return SID of the session Otherwise return -1 with errno set on: EPERM or ESRCH

◆ sys_getuid()

uid_t sys_getuid ( void )

Returns the real User ID (UID) of the calling process.

Returns: The User ID.

◆ sys_lseek()

off_t sys_lseek	(	int	fd,
		off_t	offset,
		int	whence
	)

Repositions the file offset inside a file.

Parameters

fd	The file descriptor of the file.
offset	The offest to use for the operation.
whence	The type of operation.

Returns: Upon successful completion, returns the resulting offset location as measured in bytes from the beginning of the file. On error, the value (off_t) -1 is returned and errno is set to indicate the error.

◆ sys_mkdir()

int sys_mkdir	(	const char *	path,
		mode_t	mode
	)

Creates a new directory at the given path.

Parameters

path	The path of the new directory.
mode	The permission of the new directory.

Returns: Returns a negative value on failure.

◆ sys_nice()

int sys_nice ( int increment )

Adds the increment to the priority value of the task.

Parameters

increment The modifier to apply to the nice value.

Returns: The new nice value.

◆ sys_open()

int sys_open	(	const char *	pathname,
		int	flags,
		mode_t	mode
	)

Given a pathname for a file, open() returns a file descriptor, a small, nonnegative integer for use in subsequent system calls.

Parameters

pathname	A pathname for a file.
flags	Used to set the file status flags and file access modes of the open file description.
mode	Specifies the file mode bits be applied when a new file is created.

Returns: Returns a file descriptor, a small, nonnegative integer for use in subsequent system calls.

◆ sys_read()

ssize_t sys_read	(	int	fd,
		void *	buf,
		size_t	nbytes
	)

Read data from a file descriptor.

Parameters

fd	The file descriptor.
buf	The buffer.
nbytes	The number of bytes to read.

Returns: The number of read characters.

◆ sys_readlink()

int sys_readlink	(	const char *	path,
		char *	buffer,
		size_t	bufsize
	)

Read the symbolic link, if present.

Parameters

path	the file for which we want to read the symbolic link information.
buffer	the buffer where we will store the symbolic link path.
bufsize	the size of the buffer.

Returns: The number of read characters on success, -1 otherwise and errno is set to indicate the error.

◆ sys_reboot()

int sys_reboot	(	int	magic1,
		int	magic2,
		unsigned int	cmd,
		void *	arg
	)

Reboots the system, or enables/disables the reboot keystroke.

Parameters

magic1	fails (with the error EINVAL) unless equals LINUX_REBOOT_MAGIC1.
magic2	fails (with the error EINVAL) unless equals LINUX_REBOOT_MAGIC2.
cmd	The command to send to the reboot.
arg	Argument passed with some specific commands.

Returns: For the values of cmd that stop or restart the system, a successful call to reboot() does not return. For the other cmd values, zero is returned on success. In all cases, -1 is returned on failure, and errno is set appropriately.

◆ sys_rmdir()

int sys_rmdir ( const char * path )

Removes the given directory.

Parameters

path	The path to the directory to remove.

Returns: Returns a negative value on failure.

◆ sys_setgid()

int sys_setgid ( gid_t gid )

sets the group ID of the calling process.

Parameters

gid group id

Returns: On success, zero is returned. Otherwise returns -1 with errno set to :EINVAL or EPERM.

◆ sys_setpgid()

int sys_setpgid	(	pid_t	pid,
		pid_t	pgid
	)

Sets the Process Group ID (PGID) of the process specified by pid. If pid is zero, the process ID of the calling process is used.

Parameters

pid	process of which we want to set the PGID.
pgid	the PGID we want to set.

Returns: returns zero. On error, -1 is returned, and errno is set appropriately.

◆ sys_setregid()

int sys_setregid	(	gid_t	rgid,
		gid_t	egid
	)

sets the real and effective group ID of the calling process.

Parameters

rgid	real group id
egid	effective group id

Returns: On success, zero is returned. Otherwise returns -1 with errno set to EPERM.

◆ sys_setreuid()

int sys_setreuid	(	uid_t	ruid,
		uid_t	euid
	)

Set the real and effective User ID (UID) of the calling process.

Parameters

ruid	the new real User ID.
euid	the new effective User ID.

Returns: On success, zero is returned. Otherwise returns -1 with errno set to EPERM.

◆ sys_setsid()

pid_t sys_setsid ( void )

creates a new session if the calling process is not a process group leader. The calling process is the leader of the new session (i.e., its session ID is made the same as its process ID). The calling process also becomes the process group leader of a new process group in the session (i.e., its process group ID is made the same as its process ID).

Returns: On success return SID of the session just created Otherwise return -1 with errno : EPERM

◆ sys_setuid()

int sys_setuid ( uid_t uid )

Tries to set the User ID (UID) of the calling process.

Parameters

uid	the new User ID.

Returns: On success, zero is returned. Otherwise returns -1 with errno set to :EINVAL or EPERM.

◆ sys_stat()

int sys_stat	(	const char *	path,
		stat_t *	buf
	)

Stat the file at the given path.

Parameters

path	Path to the file for which we are retrieving the statistics.
buf	Buffer where we are storing the statistics.

Returns: 0 on success, a negative number if fails and errno is set.

◆ sys_symlink()

int sys_symlink	(	const char *	linkname,
		const char *	path
	)

Creates a symbolic link.

Parameters

linkname	the name of the link.
path	the entity it is linking to.

Returns: 0 on success, a negative number if fails and errno is set.

◆ sys_time()

time_t sys_time ( time_t * time )

Returns the current time.

Parameters

time	Where the time should be stored.

Returns: The current time.

◆ sys_unlink()

int sys_unlink ( const char * path )

Delete a name and possibly the file it refers to.

Parameters

path	A pathname for a file.

Returns: On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

◆ sys_waitpid()

pid_t sys_waitpid	(	pid_t	pid,
		int *	status,
		int	options
	)

Suspends execution of the calling thread until a child specified by pid argument has changed state.

Parameters

pid	The pid to wait.
status	If not NULL, store status information here.
options	Determines the wait behaviour.

Returns: on success, returns the process ID of the terminated child; on error, -1 is returned.

◆ sys_write()

ssize_t sys_write	(	int	fd,
		const void *	buf,
		size_t	nbytes
	)

Write data into a file descriptor.

Parameters

fd	The file descriptor.
buf	The buffer collecting data to written.
nbytes	The number of bytes to write.

Returns: The number of written bytes.

◆ syscall_handler()

void syscall_handler ( pt_regs * f )

Handler for the system calls.

Parameters

f	The interrupt stack frame.

Functions

Detailed Description

Function Documentation

◆ get_current_interrupt_stack_frame()

◆ sys_chdir()

◆ sys_close()

◆ sys_creat()

◆ sys_execve()

◆ sys_exit()

◆ sys_fchdir()

◆ sys_fork()

◆ sys_fstat()

◆ sys_getcwd()

◆ sys_getdents()

◆ sys_getegid()

◆ sys_geteuid()

◆ sys_getgid()

◆ sys_getpgid()

◆ sys_getpid()

◆ sys_getppid()

◆ sys_getsid()

◆ sys_getuid()

◆ sys_lseek()

◆ sys_mkdir()

◆ sys_nice()

◆ sys_open()

◆ sys_read()

◆ sys_readlink()

◆ sys_reboot()

◆ sys_rmdir()

◆ sys_setgid()

◆ sys_setpgid()

◆ sys_setregid()

◆ sys_setreuid()

◆ sys_setsid()

◆ sys_setuid()

◆ sys_stat()

◆ sys_symlink()

◆ sys_time()

◆ sys_unlink()

◆ sys_waitpid()

◆ sys_write()

◆ syscall_handler()