initial signal implementation

kernel-src/include/kernel/jobctl.h

@@ -13,5 +13,6 @@ pid_t jobctl_getpgid(proc_t *proc);
 pid_t jobctl_getsid(proc_t *proc);
 void jobctl_setctty(proc_t *proc, void *ctty);
 void *jobctl_getctty(proc_t *proc);
+int jobctl_signal(proc_t *proc, int signal);
 
 #endif

kernel-src/include/kernel/scheduler.h

@@ -7,6 +7,7 @@
 #include <kernel/vfs.h>
 #include <semaphore.h>
 #include <mutex.h>
+#include <kernel/signal.h>
 
 #define SCHED_THREAD_FLAGS_QUEUED 1
 #define SCHED_THREAD_FLAGS_RUNNING 2
@@ -48,10 +49,17 @@ typedef struct thread_t {
 	int wakeupreason;
 	bool shouldexit;
 	void *kernelarg;
+	struct {
+		spinlock_t lock;
+		stack_t stack;
+		sigset_t mask;
+		sigset_t pending;
+		sigset_t urgent;
+	} signals;
 } thread_t;
 
 typedef struct proc_t {
-	spinlock_t lock;
+	mutex_t mutex;
 	int refcount;
 	int status;
 	int state;
@@ -84,7 +92,6 @@ typedef struct proc_t {
 		// these are only applicable if the process is leader
 		struct proc_t *foreground; // process group leader, NULL if self
 		void *controllingtty;
-		int processcount; // refcount
 	} session;
 
 	struct {
@@ -96,23 +103,33 @@ typedef struct proc_t {
 
 		// these are only applicable if the process is leader
 		spinlock_t lock; // protects the linked list
-		int processcount; // refcount
 	} pgrp;
+	struct {
+		spinlock_t lock;
+		sigaction_t actions[NSIG];
+		sigset_t pending;
+	} signals;
 } proc_t;
 
 #include <arch/cpu.h>
 
 #define UMASK(mode) ((mode) & ~_cpu()->thread->proc->umask)
 #define PROC_HOLD(v) __atomic_add_fetch(&(v)->refcount, 1, __ATOMIC_SEQ_CST)
+// the acquire of the pid table mutex is done here to prevent a nasty race condition where sched_inactiveproc could be called multiple times
+// due to the pid table itself not holding any references to the process
 #define PROC_RELEASE(v) {\
+		MUTEX_ACQUIRE(&sched_pidtablemutex, false); \
 		if (__atomic_sub_fetch(&(v)->refcount, 1, __ATOMIC_SEQ_CST) == 0) {\
 			sched_inactiveproc(v); \
 			(v) = NULL; \
 		} \
+		MUTEX_RELEASE(&sched_pidtablemutex); \
 	}
 
 extern proc_t *sched_initproc;
+extern mutex_t sched_pidtablemutex;
 
+proc_t *sched_getprocfrompid(int pid);
 void sched_init();
 void sched_stopotherthreads();
 void sched_runinit();

kernel-src/include/kernel/signal.h

@@ -0,0 +1,157 @@
+#ifndef _SIGNAL_H
+#define _SIGNAL_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+typedef struct {
+	void *base;
+	int flags;
+	size_t size;
+} stack_t;
+
+typedef struct {
+	uint64_t sig[1024 / 64];
+} sigset_t;
+
+#define SIGNAL_GET(sigset, signal) ((sigset)->sig[(signal) / 64] & (1lu << ((signal) % 64)))
+#define SIGNAL_SETON(sigset, signal) (sigset)->sig[(signal) / 64] |= (1lu << ((signal) % 64))
+#define SIGNAL_SETOFF(sigset, signal) (sigset)->sig[(signal) / 64] &= ~(1lu << ((signal) % 64))
+
+#define SIG_DFL ((void *)(0))
+#define SIG_IGN ((void *)(1))
+
+#define SA_NOCLDSTOP 1
+#define SA_NOCLDWAIT 2
+#define SA_SIGINFO 4
+#define SA_ONSTACK 0x08000000
+#define SA_RESTART 0x10000000
+#define SA_NODEFER 0x40000000
+#define SA_RESETHAND 0x80000000
+#define SA_RESTORER 0x04000000
+
+#define NSIG 65
+
+typedef struct {
+	void *address;
+	unsigned long flags;
+	void (*restorer)(void);
+	sigset_t mask;
+} sigaction_t;
+
+#define POLL_IN 1
+#define POLL_OUT 2
+#define POLL_MSG 3
+#define POLL_ERR 4
+#define POLL_PRI 5
+#define POLL_HUP 6
+
+union sigval {
+	int sival_int;
+	void *sival_ptr;
+};
+
+typedef long clock_t;
+
+// struct taken from musl.
+
+typedef struct {
+	int si_signo, si_errno, si_code;
+	union {
+		char __pad[128 - 2*sizeof(int) - sizeof(long)];
+		struct {
+			union {
+				struct {
+					pid_t si_pid;
+					uid_t si_uid;
+				} __piduid;
+				struct {
+					int si_timerid;
+					int si_overrun;
+				} __timer;
+			} __first;
+			union {
+				union sigval si_value;
+				struct {
+					int si_status;
+					clock_t si_utime, si_stime;
+				} __sigchld;
+			} __second;
+		} __si_common;
+		struct {
+			void *si_addr;
+			short si_addr_lsb;
+			union {
+				struct {
+					void *si_lower;
+					void *si_upper;
+				} __addr_bnd;
+				unsigned si_pkey;
+			} __first;
+		} __sigfault;
+		struct {
+			long si_band;
+			int si_fd;
+		} __sigpoll;
+		struct {
+			void *si_call_addr;
+			int si_syscall;
+			unsigned si_arch;
+		} __sigsys;
+	} __si_fields;
+} siginfo_t;
+
+#define SIGHUP    1
+#define SIGQUIT   3
+#define SIGTRAP   5
+#define SIGABRT 6
+#define SIGIOT    SIGABRT
+#define SIGBUS    7
+#define SIGKILL   9
+#define SIGUSR1   10
+#define SIGUSR2   12
+#define SIGPIPE   13
+#define SIGALRM   14
+#define SIGSTKFLT 16
+#define SIGCHLD   17
+#define SIGCONT   18
+#define SIGSTOP   19
+#define SIGTSTP   20
+#define SIGTTIN   21
+#define SIGTTOU   22
+#define SIGURG    23
+#define SIGXCPU   24
+#define SIGXFSZ   25
+#define SIGVTALRM 26
+#define SIGWINCH  28
+#define SIGPOLL   29
+#define SIGSYS    31
+#define SIGUNUSED SIGSYS
+#define SIGCANCEL 32
+#define SIGABRT 6
+#define SIGFPE 8
+#define SIGILL 4
+#define SIGINT 2
+#define SIGSEGV 11
+#define SIGTERM 15
+#define SIGPROF 27
+#define SIGIO 29
+#define SIGPWR 30
+#define SIGRTMIN 35
+#define SIGRTMAX 64
+
+#define SIG_BLOCK 0
+#define SIG_UNBLOCK 1
+#define SIG_SETMASK 2
+
+struct proc_t;
+struct thread_t;
+void signal_action(struct proc_t *proc, int signal, sigaction_t *new, sigaction_t *old);
+void signal_altstack(struct thread_t *thread, stack_t *new, stack_t *old);
+void signal_changemask(struct thread_t *thread, int how, sigset_t *new, sigset_t *old);
+void signal_signalproc(struct proc_t *proc, int signal);
+void signal_signalthread(struct thread_t *thread, int signal, bool urgent);
+void signal_pending(struct thread_t *, sigset_t *sigset);
+void signal_check(struct thread_t *thread, context_t *context);
+
+#endif