Signals definition. More...

Macros
#define	__DEBUG_HEADER__ "[SIGNAL]"
	Change header.

#define	__DEBUG_LEVEL__ LOGLEVEL_NOTICE
	Set log level.

#define	GET_EXIT_STATUS(status) (((status) & 0x00FF) << 8)
	Extracts the exit status.

Functions
static void	__copy_sigaction (sigaction_t to, const sigaction_t from)
	Copies the sigaction. More...

static void	__copy_sigset (sigset_t to, const sigset_t from)
	Copies a signal set. More...

static void	__copy_siginfo (siginfo_t to, const siginfo_t from)
	Copies a signal information structure. More...

static void	__clear_siginfo (siginfo_t *info)
	Clears the memory of a signal information structure. More...

static void	__lock_task_sighand (struct task_struct *t)
	Locks the signal handling of a given task. More...

static void	__unlock_task_sighand (struct task_struct *t)
	Unlocks the signal handling of a given task. More...

static sighandler_t	__get_handler (struct task_struct *t, int sig)
	Returns the handler for a given signal, for a given task. More...

static int	__sig_is_ignored (struct task_struct *t, int sig)
	Checks if the given signal is ignored. More...

static sigqueue_t *	__sigqueue_alloc (struct task_struct *t, int sig, gfp_t flags)
	Allocate a new signal queue record. More...

static void	__sigqueue_dealloc (sigqueue_t *sigqueue)
	Freest the memory of a signal queue. More...

static int	__send_signal (int sig, siginfo_t info, struct task_struct t)
	Sends a signal. More...

static int	__next_signal (sigpending_t pending, sigset_t mask)
	Gets the next signal that abides by the given mask. More...

static void	__collect_signal (int sig, sigpending_t list, siginfo_t info)
	Collects the signals from the list. More...

static int	__dequeue_signal (sigpending_t pending, sigset_t mask, siginfo_t *info)
	Dequeues a signal that abides by the mask. More...

static int	__handle_signal (int signr, siginfo_t info, sigaction_t ka, struct pt_regs *regs)
	Handels the signals for the current process. More...

long	sys_sigreturn (struct pt_regs *f)
	Handle the return from a signal handler. More...

static int	__notify_parent (struct task_struct *current, int signr)
	Send signal to parent. More...

static void	__rm_from_queue (sigset_t mask, sigpending_t q)
	Removes from the pending signal queue q the pending signals corresponding to the bit mask mask. More...

static void	__do_signal_stop (struct task_struct current, struct pt_regs f, int signr)
	We do not consider group stopping because for now we don't have thread groups. More...

int	do_signal (struct pt_regs *f)
	Handles the signals of the current process. More...

int	signals_init (void)
	Initialize the signals. More...

void	handle_stop_signal (int sig, siginfo_t info, struct task_struct p)
	Checks for some types of signals that might nullify other pending signals for the destination thread group. More...

int	__send_sig_info (int sig, siginfo_t info, struct task_struct p)
	Send siginfo to target process. More...

int	sys_kill (pid_t pid, int sig)
	Send signal to one specific process. More...

sighandler_t	sys_signal (int signum, sighandler_t handler, uint32_t sigreturn_addr)
	Sets the disposition of the signal signum to handler. More...

int	sys_sigaction (int signum, const sigaction_t act, sigaction_t oldact, uint32_t sigreturn_addr)
	Examine and change a signal action. More...

int	sys_sigprocmask (int how, const sigset_t set, sigset_t oldset)
	Examine and change blocked signals. More...

int	sys_sigpending (sigset_t *set)
	Provides a snapshot of pending signals. More...

const char *	strsignal (int sig)
	Returns the string describing the given signal. More...

int	sigemptyset (sigset_t *set)
	Prepare an empty set. More...

int	sigfillset (sigset_t *set)
	Prepare a full set. More...

int	sigaddset (sigset_t *set, int signum)
	Adds the given signal to the correct set. More...

int	sigdelset (sigset_t *set, int signum)
	Removes the given signal to the correct set. More...

int	sigismember (sigset_t *set, int signum)
	Checks if the given signal is part of the set. More...

Variables
static kmem_cache_t *	sigqueue_cachep
	SLAB caches for signal bits.

static struct wait_queue_head_t	stopped_queue
	Contains all stopped process waiting for a continue signal.

static const char *	sys_siglist []
	The list of signal names.

Detailed Description

Signals definition.

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

Function Documentation

◆ __clear_siginfo()

static void __clear_siginfo ( siginfo_t * info )

inlinestatic

Clears the memory of a signal information structure.

Parameters

info	the signal information structure.

◆ __collect_signal()

static void __collect_signal	(	int	sig,
		sigpending_t *	list,
		siginfo_t *	info
	)

inlinestatic

Collects the signals from the list.

Parameters

sig	the signal.
list	the list of pending signals.
info	the where we store the signal information.

◆ __copy_sigaction()

static void __copy_sigaction	(	sigaction_t *	to,
		const sigaction_t *	from
	)

inlinestatic

Copies the sigaction.

Parameters

to	the target.
from	the source.

◆ __copy_siginfo()

static void __copy_siginfo	(	siginfo_t *	to,
		const siginfo_t *	from
	)

inlinestatic

Copies a signal information structure.

Parameters

to	the target.
from	the source.

◆ __copy_sigset()

static void __copy_sigset	(	sigset_t *	to,
		const sigset_t *	from
	)

inlinestatic

Copies a signal set.

Parameters

to	the target.
from	the source.

◆ __dequeue_signal()

static int __dequeue_signal	(	sigpending_t *	pending,
		sigset_t *	mask,
		siginfo_t *	info
	)

inlinestatic

Dequeues a signal that abides by the mask.

Parameters

pending	the list of pending signals.
mask	the mask used to select the signals.
info	the signal information, where we store the information of the dequeued signal.

Returns: the signal index on success, a negative value on failure.

◆ __do_signal_stop()

static void __do_signal_stop	(	struct task_struct *	current,
		struct pt_regs *	f,
		int	signr
	)

static

We do not consider group stopping because for now we don't have thread groups.

Parameters

current	the current process.
f	the stack frame.
signr	signal number.

◆ __get_handler()

static sighandler_t __get_handler	(	struct task_struct *	t,
		int	sig
	)

static

Returns the handler for a given signal, for a given task.

Parameters

t	the task.
sig	the signal index.

Returns: a pointer to the handler.

◆ __handle_signal()

static int __handle_signal	(	int	signr,
		siginfo_t *	info,
		sigaction_t *	ka,
		struct pt_regs *	regs
	)

inlinestatic

Handels the signals for the current process.

Parameters

signr	the signal number.
info	the signal information.
ka	the action associated with the signal.
regs	the current registers.

Returns: 1 on success, 0 on failure.

◆ __lock_task_sighand()

static void __lock_task_sighand ( struct task_struct * t )

inlinestatic

Locks the signal handling of a given task.

Parameters

t the task.

◆ __next_signal()

static int __next_signal	(	sigpending_t *	pending,
		sigset_t *	mask
	)

inlinestatic

Gets the next signal that abides by the given mask.

Parameters

pending	the list of pending signals.
mask	the mask we are checking against.

Returns: index of the next signal to handle.

◆ __notify_parent()

static int __notify_parent	(	struct task_struct *	current,
		int	signr
	)

static

Send signal to parent.

Parameters

current	the current task.
signr	the signal number.

Returns: the result of the operation.

◆ __rm_from_queue()

static void __rm_from_queue	(	sigset_t *	mask,
		sigpending_t *	q
	)

static

Removes from the pending signal queue q the pending signals corresponding to the bit mask mask.

Parameters

mask	the mask we use to guide signals removal.
q	pensing signals.

◆ __send_sig_info()

int __send_sig_info	(	int	sig,
		siginfo_t *	info,
		struct task_struct *	p
	)

Send siginfo to target process.

Parameters

sig	Signal number
info	siginfo struct of the signal to be sent
p	Target process where the signal will be sent

Returns: Returns 0 if there is no error, otherwise returns an error code

◆ __send_signal()

static int __send_signal	(	int	sig,
		siginfo_t *	info,
		struct task_struct *	t
	)

static

Sends a signal.

Parameters

sig	Signal to be sent.
info	The signal info
t	The process to which we send the signal.

Returns: 0 on success, a negative value on failure.

◆ __sig_is_ignored()

static int __sig_is_ignored	(	struct task_struct *	t,
		int	sig
	)

static

Checks if the given signal is ignored.

Parameters

t	the task.
sig	the signal to check.

Returns: 0 if not ignored, 1 if ignored.

◆ __sigqueue_alloc()

static sigqueue_t* __sigqueue_alloc	(	struct task_struct *	t,
		int	sig,
		gfp_t	flags
	)

inlinestatic

Allocate a new signal queue record.

Parameters

t	The task to which the signal belongs.
sig	The signal to set.
flags	Flags identifying from where we are going to take the memory.

Returns: a pointer to the newly allocated signal queue.

◆ __sigqueue_dealloc()

static void __sigqueue_dealloc ( sigqueue_t * sigqueue )

inlinestatic

Freest the memory of a signal queue.

Parameters

sigqueue the signal queue to free.

◆ __unlock_task_sighand()

static void __unlock_task_sighand ( struct task_struct * t )

inlinestatic

Unlocks the signal handling of a given task.

Parameters

t the task.

◆ do_signal()

int do_signal ( struct pt_regs * f )

Handles the signals of the current process.

Parameters

f	The address of the stack area where the User Mode register contents of the current process are saved.

Returns: If we are handling a signal, thus, regs have been modified to handle it (e.g., eip is now poiting at the handler).

◆ handle_stop_signal()

void handle_stop_signal	(	int	sig,
		siginfo_t *	info,
		struct task_struct *	p
	)

Checks for some types of signals that might nullify other pending signals for the destination thread group.

Parameters

sig	Signal number
info	siginfo struct of the signal
p	Target process of the signal

◆ sigaddset()

int sigaddset	(	sigset_t *	set,
		int	signum
	)

Adds the given signal to the correct set.

Parameters

set	The set to manipulate.
signum	The signalt to handle.

Returns: 0 on success and -1 on error.

◆ sigdelset()

int sigdelset	(	sigset_t *	set,
		int	signum
	)

Removes the given signal to the correct set.

Parameters

set	The set to manipulate.
signum	The signalt to handle.

Returns: 0 on success and -1 on error.

◆ sigemptyset()

int sigemptyset ( sigset_t * set )

Prepare an empty set.

Parameters

set	The set to manipulate.

Returns: 0 on success and -1 on error.

◆ sigfillset()

int sigfillset ( sigset_t * set )

Prepare a full set.

Parameters

set	The set to manipulate.

Returns: 0 on success and -1 on error.

◆ sigismember()

int sigismember	(	sigset_t *	set,
		int	signum
	)

Checks if the given signal is part of the set.

Parameters

set	The set to manipulate.
signum	The signalt to handle.

Returns: 1 if signum is a member of set, 0 if signum is not a member, and -1 on error.

◆ signals_init()

int signals_init ( void )

Initialize the signals.

Returns: 1 on success, 0 on failure.

◆ strsignal()

const char* strsignal ( int sig )

Returns the string describing the given signal.

Parameters

sig	The signal to inquire.

Returns: String representing the signal.

◆ sys_kill()

int sys_kill	(	pid_t	pid,
		int	sig
	)

Send signal to one specific process.

Parameters

pid	The PID of the process.
sig	The signal to be sent.

Returns

◆ sys_sigaction()

int sys_sigaction	(	int	signum,
		const sigaction_t *	act,
		sigaction_t *	oldact,
		uint32_t	sigreturn_addr
	)

Examine and change a signal action.

Parameters

signum	Specifies the signal and can be any valid signal except SIGKILL and SIGSTOP.
act	If non-NULL, the new action for signal signum is installed from act.
oldact	If non-NULL, the previous action is saved in oldact.
sigreturn_addr	The address of the sigreturn function.

Returns: returns 0 on success; on error, -1 is returned, and errno is set to indicate the error.

◆ sys_signal()

sighandler_t sys_signal	(	int	signum,
		sighandler_t	handler,
		uint32_t	sigreturn_addr
	)

Sets the disposition of the signal signum to handler.

Parameters

signum	The signal number.
handler	The handler for the signal.
sigreturn_addr	The address of the sigreturn function.

Returns: The previous value of the signal handler, or SIG_ERR on error.

◆ sys_sigpending()

int sys_sigpending ( sigset_t * set )

Provides a snapshot of pending signals.

Parameters

set	where the set of pending signals is returned.

Returns: 0 on success, -1 on failure and errno is set to indicate the error.

◆ sys_sigprocmask()

int sys_sigprocmask	(	int	how,
		const sigset_t *	set,
		sigset_t *	oldset
	)

Examine and change blocked signals.

Parameters

how	Determines the behavior of the call.
set	The set of signals to manage by the function.
oldset	If non-NULL, the previous value of the signal mask is stored here.

Returns: returns 0 on success, and -1 on error (errno is set to indicate the cause).

If set is NULL, then the signal mask is unchanged (i.e., how is ignored), but the current value of the signal mask is nevertheless returned in oldset (if it is not NULL).

◆ sys_sigreturn()

long sys_sigreturn ( struct pt_regs * f )

Handle the return from a signal handler.

Parameters

f	The stack frame when returning from a signal handler.

Returns: never.

Macros

Functions

Variables

Detailed Description

Function Documentation

◆ __clear_siginfo()

◆ __collect_signal()

◆ __copy_sigaction()

◆ __copy_siginfo()

◆ __copy_sigset()

◆ __dequeue_signal()

◆ __do_signal_stop()

◆ __get_handler()

◆ __handle_signal()

◆ __lock_task_sighand()

◆ __next_signal()

◆ __notify_parent()

◆ __rm_from_queue()

◆ __send_sig_info()

◆ __send_signal()

◆ __sig_is_ignored()

◆ __sigqueue_alloc()

◆ __sigqueue_dealloc()

◆ __unlock_task_sighand()

◆ do_signal()

◆ handle_stop_signal()

◆ sigaddset()

◆ sigdelset()

◆ sigemptyset()

◆ sigfillset()

◆ sigismember()

◆ signals_init()

◆ strsignal()

◆ sys_kill()

◆ sys_sigaction()

◆ sys_signal()

◆ sys_sigpending()

◆ sys_sigprocmask()

◆ sys_sigreturn()