Enrico Fraccaroli
324 lines
13 KiB
C
324 lines
13 KiB
C
/// @file signal.h
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/// @brief Signals definition.
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/// @copyright (c) 2014-2022 This file is distributed under the MIT License.
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/// See LICENSE.md for details.
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#pragma once
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#include "klib/stdatomic.h"
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#include "klib/spinlock.h"
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#include "klib/list_head.h"
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#include "system/syscall.h"
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/// @brief Signal codes.
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typedef enum {
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SIGHUP = 1, ///< Hang up detected on controlling terminal or death of controlling process.
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SIGINT = 2, ///< Issued if the user sends an interrupt signal (Ctrl + C).
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SIGQUIT = 3, ///< Issued if the user sends a quit signal (Ctrl + D).
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SIGILL = 4, ///< Illegal Instruction.
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SIGTRAP = 5, ///< Trace/breakpoint trap.
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SIGABRT = 6, ///< Abort signal from abort().
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SIGEMT = 7, ///< Emulator trap.
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SIGFPE = 8, ///< Floating-point arithmetic exception.
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SIGKILL = 9, ///< If a process gets this signal it must quit immediately and will not perform any clean-up operations.
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SIGBUS = 10, ///< Bus error (bad memory access).
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SIGSEGV = 11, ///< Invalid memory reference.
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SIGSYS = 12, ///< Bad system call (SVr4).
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SIGPIPE = 13, ///< Broken pipe: write to pipe with no readers.
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SIGALRM = 14, ///< Alarm clock signal (used for timers).
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SIGTERM = 15, ///< Software termination signal (sent by kill by default).
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SIGUSR1 = 16, ///< User-defined signal 1.
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SIGUSR2 = 17, ///< User-defined signal 2.
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SIGCHLD = 18, ///< Child stopped or terminated.
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SIGPWR = 19, ///< Power failure.
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SIGWINCH = 20, ///< Window resize signal.
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SIGURG = 21, ///< Urgent condition on socket.
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SIGPOLL = 22, ///< Pollable event.
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SIGSTOP = 23, ///< Stop process.
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SIGTSTP = 24, ///< Stop typed at terminal.
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SIGCONT = 25, ///< Continue if stopped.
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SIGTTIN = 26, ///< Terminal input for background process.
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SIGTTOU = 27, ///< Terminal output for background process.
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SIGVTALRM = 28, ///< Virtual alarm clock.
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SIGPROF = 29, ///< Profiling timer expired.
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SIGXCPU = 30, ///< CPU time limit exceeded.
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SIGXFSZ = 31, ///< File size limit exceeded.
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NSIG
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} signal_type_t;
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/// @brief Codes that indentify the sender of a signal.
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typedef enum {
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SI_NOINFO, ///< Unable to determine complete signal information.
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// Signal : -
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// Enabled fields : si_pid, si_uid
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SI_USER, ///< Signal sent by kill(), pthread_kill(), raise(), abort() or alarm().
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// Signal : -
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// Enabled fields : -
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SI_KERNEL, ///< Generic kernel function
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// Signal : -
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// Enabled fields : si_pid, si_uid, si_value
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SI_QUEUE, ///< Signal was sent by sigqueue().
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SI_TIMER, ///< Signal was generated by expiration of a timer set by timer_settimer().
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SI_ASYNCIO, ///< Signal was generated by completion of an asynchronous I/O request.
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SI_MESGQ, ///< Signal was generated by arrival of a message on an empty message queue.
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// Signal : SIGILL
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// Enabled fields : si_addr (address of failing instruction)
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ILL_ILLOPC, ///< Illegal opcode.
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ILL_ILLOPN, ///< Illegal operand.
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ILL_ILLADR, ///< Illegal addressing mode.
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ILL_ILLTRP, ///< Illegal trap.
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ILL_PRVOPC, ///< Privileged opcode.
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ILL_PRVREG, ///< Privileged register.
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ILL_COPROC, ///< Coprocessor error.
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ILL_BADSTK, ///< Internal stack error.
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// Signal : SIGFPE
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// Enabled fields : si_addr (address of failing instruction)
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FPE_INTDIV, ///< Integer divide-by-zero.
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FPE_INTOVF, ///< Integer overflow.
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FPE_FLTDIV, ///< Floating point divide-by-zero.
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FPE_FLTOVF, ///< Floating point overflow.
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FPE_FLTUND, ///< Floating point underflow.
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FPE_FLTRES, ///< Floating point inexact result.
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FPE_FLTINV, ///< Invalid floating point operation.
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FPE_FLTSUB, ///< Subscript out of range.
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// Signal : SIGSEGV
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// Enabled fields : si_addr (address of faulting memory reference)
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SEGV_MAPERR, ///< Address not mapped.
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SEGV_ACCERR, ///< Invalid permissions.
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// Signal : SIGBUS
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// Enabled fields : si_addr (address of faulting memory reference)
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BUS_ADRALN, ///< Invalid address alignment.
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BUS_ADRERR, ///< Non-existent physical address.
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BUS_OBJERR, ///< Object-specific hardware error.
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// Signal : SIGTRAP
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// Enabled fields : -
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TRAP_BRKPT, ///< Process breakpoint.
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TRAP_TRACE, ///< Process trace trap.
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// Signal : SIGCHLD
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// Enabled fields : si_pid (child process ID)
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// si_uid (real user ID of process that sent the signal)
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// si_status (exit value or signal)
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CLD_EXITED, ///< Child has exited.
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CLD_KILLED, ///< Child has terminated abnormally and did not create a core file.
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CLD_DUMPED, ///< Child has terminated abnormally and created a core file.
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CLD_TRAPPED, ///< Traced child has trapped.
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CLD_STOPPED, ///< Child has stopped.
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CLD_CONTINUED, ///< Stopped child has continued.
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// Signal : SIGIO/SIGPOLL
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// Enabled fields : si_band
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POLL_IN, ///< Data input available.
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POLL_OUT, ///< Output buffers available.
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POLL_MSG, ///< Input message available.
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POLL_ERR, ///< I/O error.
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POLL_PRI, ///< High priority input available.
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POLL_HUP, ///< Device disconnected.
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} signal_sender_code_t;
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/// @brief Defines what to do with the provided signal mask.
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typedef enum {
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/// @brief The set of blocked signals is the union of the current set
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/// and the set argument.
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SIG_BLOCK,
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/// @brief The signals in set are removed from the current set of
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/// blocked signals. It is permissible to attempt to unblock
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/// a signal which is not blocked.
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SIG_UNBLOCK,
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/// @brief The set of blocked signals is set to the argument set.
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SIG_SETMASK
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} sigmask_how_t;
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/// @defgroup SigactionFlags Flags associated with a sigaction.
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/// @{
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#define SA_NOCLDSTOP 0x00000001U ///< Turn off SIGCHLD when children stop.
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#define SA_NOCLDWAIT 0x00000002U ///< Flag on SIGCHLD to inhibit zombies.
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#define SA_SIGINFO 0x00000004U ///< sa_sigaction specifies the signal-handling function for signum.
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#define SA_ONSTACK 0x08000000U ///< Indicates that a registered stack_t will be used.
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#define SA_RESTART 0x10000000U ///< Flag to get restarting signals (which were the default long ago)
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#define SA_NODEFER 0x40000000U ///< Prevents the current signal from being masked in the handler.
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#define SA_RESETHAND 0x80000000U ///< Clears the handler when the signal is delivered.
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/// @}
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/// Type of a signal handler.
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typedef void (*sighandler_t)(int);
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#define SIG_DFL ((sighandler_t)0) ///< Default signal handling.
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#define SIG_IGN ((sighandler_t)1) ///< ignore signal.
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#define SIG_ERR ((sighandler_t)-1) ///< error return from signal.
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/// @brief Structure used to mask and unmask signals.
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/// @details
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/// Each unsigned long consists of 32 bits, thus, the maximum number of signals
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/// that may be declared is 64.
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/// Signals are divided into two cathegories, identified by the two unsigned longs:
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/// [ 1, 31] corresponds to normal signals;
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/// [32, 64] corresponds to real-time signals.
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typedef struct sigset_t {
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/// Signals divided into two cathegories.
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unsigned long sig[2];
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} sigset_t;
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/// @brief Holds the information on how to handle a specific signal.
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typedef struct sigaction_t {
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/// This field specifies the type of action to be performed; its value can be a pointer
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/// to the signal handler, SIG_DFL (that is, the value 0) to specify that the default
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/// action is performed, or SIG_IGN (that is, the value 1) to specify that the signal is
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/// ignored.
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sighandler_t sa_handler;
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/// This sigset_t variable specifies the signals to be masked when running the signal handler
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sigset_t sa_mask;
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/// This set of flags specifies how the signal must be handled;
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unsigned int sa_flags;
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} sigaction_t;
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/// @brief Describes how each signal must be handled.
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typedef struct sighand_t {
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/// Usage counter of the signal handler descriptor.
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atomic_t count;
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/// Array of structures specifying the actions to be performed upon delivering the signals
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sigaction_t action[NSIG];
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/// Spinlock protecting both the signal descriptor and the signal handler descriptor.
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spinlock_t siglock;
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} sighand_t;
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/// @brief Data passed with signal info.
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typedef union sigval {
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int sival_int; ///< Integer value.
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void *sival_ptr; ///< Pointer value.
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} sigval_t;
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/// @brief Stores information about an occurrence of a specific signal.
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typedef struct siginfo_t {
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/// The signal number.
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int si_signo;
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/// A code identifying who raised the signal (see signal_sender_code_t).
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int si_code;
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/// Signal value.
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sigval_t si_value;
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/// The error code of the instruction that caused the signal to be raised, or 0 if there was no error.
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int si_errno;
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/// Process ID of sending process.
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pid_t si_pid;
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/// Real user ID of sending process.
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uid_t si_uid;
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/// Address at which fault occurred.
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void *si_addr;
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/// Exit value or signal for process termination.
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int si_status;
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/// Band event for SIGPOLL/SIGIO.
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int si_band;
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} siginfo_t;
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/// @brief An entry of the signal queue.
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typedef struct sigqueue_t {
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/// Links for the pending signal queue’s list.
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list_head list;
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/// Flags associated with the queued signal.
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int flags;
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/// Describes the event that raised the signal.
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siginfo_t info;
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// Pointer to the user data structure of the process’s owner.
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//struct user_struct *user;
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} sigqueue_t;
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/// @brief Keeps information of pending signals.
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typedef struct sigpending_t {
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/// Head of the list of pending signals.
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list_head list;
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/// The mask which can be queried to know which signals are pending.
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sigset_t signal;
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} sigpending_t;
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/// These can be the second arg to send_sig_info/send_group_sig_info.
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#define SEND_SIG_NOINFO ((siginfo_t *)0)
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/// @brief Handle the return from a signal handler.
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/// @param f The stack frame when returning from a signal handler.
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/// @return never.
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long sys_sigreturn(struct pt_regs *f);
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/// @brief Handles the signals of the current process.
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/// @param f The address of the stack area where the User Mode register
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/// contents of the current process are saved.
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/// @return If we are handling a signal, thus, `regs` have been modified
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/// to handle it (e.g., eip is now poiting at the handler).
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int do_signal(struct pt_regs *f);
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/// @brief Initialize the signals.
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/// @return 1 on success, 0 on failure.
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int signals_init();
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/// @brief Send signal to one specific process.
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/// @param pid The PID of the process.
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/// @param sig The signal to be sent.
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/// @return
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int sys_kill(pid_t pid, int sig);
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/// @brief Sets the disposition of the signal signum to handler.
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/// @param signum The signal number.
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/// @param handler The handler for the signal.
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/// @return The previous value of the signal handler, or SIG_ERR on error.
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sighandler_t sys_signal(int signum, sighandler_t handler, uint32_t sigreturn_addr);
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/// @brief Examine and change a signal action.
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/// @param signum Specifies the signal and can be any valid signal except SIGKILL and SIGSTOP.
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/// @param act If non-NULL, the new action for signal signum is installed from act.
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/// @param oldact If non-NULL, the previous action is saved in oldact.
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/// @return returns 0 on success; on error, -1 is returned, and errno is set to indicate the error.
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int sys_sigaction(int signum, const sigaction_t *act, sigaction_t *oldact, uint32_t sigreturn_addr);
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/// @brief Examine and change blocked signals.
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/// @param how Determines the behavior of the call.
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/// @param set The set of signals to manage by the function.
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/// @param oldset If non-NULL, the previous value of the signal mask is stored here.
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/// @return returns 0 on success, and -1 on error (errno is set to indicate the cause).
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/// @details
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/// If set is NULL, then the signal mask is unchanged (i.e., how is
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/// ignored), but the current value of the signal mask is
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/// nevertheless returned in oldset (if it is not NULL).
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int sys_sigprocmask(int how, const sigset_t *set, sigset_t *oldset);
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/// @brief Returns the string describing the given signal.
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/// @param sig The signal to inquire.
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/// @return String representing the signal.
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const char *strsignal(int sig);
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/// @brief Prepare an empty set.
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/// @param set The set to manipulate.
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/// @return 0 on success and -1 on error.
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int sigemptyset(sigset_t *set);
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/// @brief Prepare a full set.
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/// @param set The set to manipulate.
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/// @return 0 on success and -1 on error.
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int sigfillset(sigset_t *set);
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/// @brief Adds the given signal to the correct set.
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/// @param set The set to manipulate.
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/// @param signum The signalt to handle.
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/// @return 0 on success and -1 on error.
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int sigaddset(sigset_t *set, int signum);
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/// @brief Removes the given signal to the correct set.
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/// @param set The set to manipulate.
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/// @param signum The signalt to handle.
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/// @return 0 on success and -1 on error.
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int sigdelset(sigset_t *set, int signum);
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/// @brief Checks if the given signal is part of the set.
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/// @param set The set to manipulate.
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/// @param signum The signalt to handle.
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/// @return 1 if signum is a member of set,
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/// 0 if signum is not a member, and -1 on error.
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int sigismember(sigset_t *set, int signum); |