libposix: honor SIG_IGN by doing nothing (DRAFT)

sys/include/posix.h

@@ -213,7 +213,14 @@ extern int libposix_translate_exit_status(PosixExitStatusTranslator translator);
 
 /* Dispatch the signal to the registered handlers.
  */
-typedef int (*PosixSignalTrampoline)(int signal);
+typedef enum PosixSignalAction
+{
+	SignalCatched = 1,
+	SignalIgnored,
+	SignalError,
+	SignalDefault
+} PosixSignalAction;
+typedef PosixSignalAction (*PosixSignalTrampoline)(int signal);
 
 extern int libposix_set_signal_trampoline(PosixSignalTrampoline trampoline);
 
@@ -221,6 +228,7 @@ extern int libposix_define_signal(PosixSignals signal, int code);
 
 extern int libposix_define_realtime_signals(int sigrtmin, int sigrtmax);
 
+
 /* Enable SIGCHLD emulation
  */
 extern int libposix_emulate_SIGCHLD(void);

sys/src/lib/posix/files.c

@@ -143,8 +143,11 @@ POSIX_read(int *errnop, int fd, char *buf, size_t len)
 		*errnop = __libposix_get_errno(PosixEBADF);
 		return -1;
 	}
+SignalReenter:
 	r = sys_pread(fd, buf, len, -1);
 	if(r < 0){
+		if(__libposix_restart_syscall())
+			goto SignalReenter;
 		*errnop = __libposix_translate_errstr((uintptr_t)POSIX_read);
 		return -1;
 	}
@@ -160,8 +163,11 @@ POSIX_write(int *errnop, int fd, const void *buf, size_t len)
 		*errnop = __libposix_get_errno(PosixEBADF);
 		return -1;
 	}
+SignalReenter:
 	w = sys_pwrite(fd, buf, len, -1);
 	if(w < 0){
+		if(__libposix_restart_syscall())
+			goto SignalReenter;
 		*errnop = __libposix_translate_errstr((uintptr_t)POSIX_write);
 		return -1;
 	}
@@ -269,9 +275,12 @@ POSIX_fstat(int *errnop, int file, void *pstat)
 		*errnop = __libposix_get_errno(PosixEBADF);
 		return -1;
 	}
+SignalReenter:
 	d = dirfstat(file);
 	if(d == nil)
 	{
+		if(__libposix_restart_syscall())
+			goto SignalReenter;
 		*errnop = __libposix_translate_errstr((uintptr_t)POSIX_fstat);
 		return -1;
 	}

sys/src/lib/posix/initlib.c

@@ -24,6 +24,9 @@ extern int *__libposix_errors_codes;
 extern WaitList **__libposix_wait_list;
 extern ChildList **__libposix_child_list;
 static int __initialized;
+static unsigned char signals_to_code[256];
+static unsigned char code_to_signal[256];
+
 
 int *__libposix_sigchld_target_pid;
 
@@ -43,16 +46,16 @@ libposix_init(int argc, char *argv[], PosixInit init)
 	extern unsigned char *__signals_to_code_map;
 	extern unsigned char *__code_to_signal_map;
 	extern int *__handling_external_signal;
+	extern int *__restart_syscall;
 	extern int *__libposix_sigchld_target_pid;
 
 	WaitList *wait_list;
 	ChildList *child_list;
 	int status;
 	int error_codes[ERRNO_LAST-ERRNO_FIRST];
-	unsigned char signals_to_code[256];
-	unsigned char code_to_signal[256];
 	int handling_signal;
 	int sigchld_target_pid;
+	int restart_syscall;
 
 	assert(__initialized == 0);
 
@@ -69,10 +72,10 @@ libposix_init(int argc, char *argv[], PosixInit init)
 	__libposix_child_list = &child_list;
 
 	/* initialize signal handling */
-	memset(signals_to_code, 0, sizeof(signals_to_code));
-	memset(code_to_signal, 0, sizeof(code_to_signal));
+	restart_syscall = 0;
 	handling_signal = 0;
 	sigchld_target_pid = 0;
+	__restart_syscall = &restart_syscall;
 	__signals_to_code_map = signals_to_code;
 	__code_to_signal_map = code_to_signal;
 	__handling_external_signal = &handling_signal;

sys/src/lib/posix/internal.h

@@ -62,3 +62,5 @@ extern int __libposix_send_control_msg(int pid, char *msg);
 extern PosixError __libposix_notify_signal_to_process(int pid, int signal);
 
 extern PosixError __libposix_receive_signal(int sig);
+
+extern int __libposix_restart_syscall(void);

sys/src/lib/posix/processes.c

@@ -204,8 +204,11 @@ POSIX_wait(int *errnop, int *status)
 		return pid;
 	}
 
+SignalReenter:
 	w = wait();
 	if(w == nil){
+		if(__libposix_restart_syscall())
+			goto SignalReenter;
 		*errnop = __libposix_get_errno(PosixECHILD);
 		return -1;
 	}
@@ -290,8 +293,11 @@ POSIX_waitpid(int *errnop, int reqpid, int *status, int options)
 	}
 
 WaitAgain:
+SignalReenter:
 	w = wait();
 	if(w == nil){
+		if(__libposix_restart_syscall())
+			goto SignalReenter;
 		*errnop = __libposix_get_errno(PosixECHILD);
 		return -1;
 	}

sys/src/lib/posix/signals.c

@@ -124,6 +124,7 @@
 unsigned char *__signals_to_code_map;
 unsigned char *__code_to_signal_map;
 int *__handling_external_signal;
+int *__restart_syscall;
 
 static int __sigrtmin;
 static int __sigrtmax;
@@ -189,14 +190,19 @@ ErrorBeforeOpen:
 static int
 execute_disposition(int sig, PosixSignalDisposition action)
 {
+	int aborted_by_signal;
+
 	switch(action){
 	case ResumeTheProcess:	// the sender resumed us already
 	case SignalHandled:
 		return 1;
 	case TerminateTheProcess:
-	case TerminateTheProcessAndCoreDump:
 		terminated_by_signal(sig);
 		break;
+	case TerminateTheProcessAndCoreDump:
+		aborted_by_signal = 0;
+		assert(aborted_by_signal);
+		break;
 	case StopTheProcess:
 		return __libposix_send_control_msg(getpid(), "stop");
 	}
@@ -254,16 +260,29 @@ default_signal_disposition(int code)
 PosixError
 __libposix_receive_signal(int sig)
 {
-	PosixSignalDisposition action;
+	PosixSignalAction action = SignalDefault;
 	PosixSignals psig = __code_to_signal_map[sig];
+	PosixSignalDisposition disposition;
 	
-	if(psig != PosixSIGKILL && psig != PosixSIGSTOP
-	&& __libposix_signal_trampoline(sig))
-		action = SignalHandled;
-	else
-		action = default_signal_disposition(sig);
-	if(!execute_disposition(sig, action))
-		return PosixEPERM;
+	if(psig != PosixSIGKILL && psig != PosixSIGSTOP)
+		action = __libposix_signal_trampoline(sig);
+	if(psig == PosixSIGABRT)
+		action = SignalDefault;	// lets abort despite the user will
+
+	switch(action){
+	case SignalCatched:
+		return 0;
+	case SignalIgnored:
+		*__restart_syscall = 1;
+		return 0;
+	case SignalDefault:
+		disposition = default_signal_disposition(sig);
+		if(!execute_disposition(sig, disposition))
+			return PosixEPERM;
+		break;
+	case SignalError:
+		return PosixEINVAL;
+	}
 	return 0;
 }
 
@@ -427,6 +446,14 @@ libposix_set_signal_trampoline(PosixSignalTrampoline trampoline)
 	return 1;
 }
 
+int
+__libposix_restart_syscall(void)
+{
+	int r = *__restart_syscall;
+	*__restart_syscall = 0;
+	return r;
+}
+
 void
 __libposix_signal_check_conf(void)
 {