determ/process.patch

diff --git a/build.sh b/build.sh
index ae2e905..740bf6f 100755
--- a/build.sh
+++ b/build.sh
@@ -60,6 +60,8 @@ then
 	clang-format -i src/devices/controller.c
 	clang-format -i src/devices/datetime.h
 	clang-format -i src/devices/datetime.c
+	clang-format -i src/devices/console.h
+	clang-format -i src/devices/console.c
 	clang-format -i src/uxnasm.c
 	clang-format -i src/uxnemu.c
 	clang-format -i src/uxncli.c
@@ -83,7 +85,7 @@ Darwin) # macOS
 	UXNEMU_LDFLAGS="$(brew --prefix)/lib/libSDL2.a $(sdl2-config --cflags --static-libs | sed -e 's/-lSDL2 //')"
 	;;
 Linux|*)
-	UXNEMU_LDFLAGS="-L/usr/local/lib $(sdl2-config --cflags --libs)"
+	UXNEMU_LDFLAGS="-L/usr/local/lib $(sdl2-config --cflags --libs) -lutil"
 	;;
 esac
 
@@ -99,7 +101,7 @@ fi
 
 echo "Building.."
 ${CC} ${CFLAGS} src/uxnasm.c -o bin/uxnasm
-${CC} ${CFLAGS} ${CORE} src/devices/system.c src/devices/file.c src/devices/datetime.c src/devices/mouse.c src/devices/controller.c src/devices/screen.c src/devices/audio.c src/uxnemu.c ${UXNEMU_LDFLAGS} ${FILE_LDFLAGS} -o bin/uxnemu
+${CC} ${CFLAGS} ${CORE} src/devices/system.c src/devices/file.c src/devices/datetime.c src/devices/mouse.c src/devices/controller.c src/devices/screen.c src/devices/audio.c src/devices/console.c src/uxnemu.c ${UXNEMU_LDFLAGS} ${FILE_LDFLAGS} -o bin/uxnemu
 ${CC} ${CFLAGS} ${CORE} src/devices/system.c src/devices/file.c src/devices/datetime.c src/uxncli.c ${FILE_LDFLAGS} -o bin/uxncli
 
 if [ $install = 1 ]
diff --git a/src/devices/console.c b/src/devices/console.c
new file mode 100644
index 0000000..eda58ea
--- /dev/null
+++ b/src/devices/console.c
@@ -0,0 +1,212 @@
+/*
+Copyright (c) 2023 d_m
+
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE.
+*/
+
+#undef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 200112L
+
+#include "../uxn.h"
+
+#include <stdio.h>
+#include <unistd.h>
+
+#include <pty.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/select.h>
+#include <sys/wait.h>
+
+/* process */
+static char *fork_args[32];
+static pid_t child_pid;
+static int child_mode;
+static int pty_fd;
+static int to_child_fd[2];
+static int from_child_fd[2];
+static int saved_in;
+static int saved_out;
+
+static void
+parse_args(Uint8 *d, Uxn *u)
+{
+	int addr = (d[0x3] << 8) | d[0x4];
+	char *pos = (char *)&u->ram[addr];
+	int i = 0;
+	do {
+		fork_args[i++] = pos;
+		while (*pos != 0) pos++;
+		pos++;
+	} while (*pos != '\0');
+	fork_args[i] = NULL;
+}
+
+/* call after we're sure the process has exited */
+static void
+clean_after_child()
+{
+	child_pid = 0;
+	if (child_mode >= 0x80) {
+		close(pty_fd);
+		dup2(saved_in, 0);
+		dup2(saved_out, 1);
+	} else {
+		if (child_mode & 0x01) {
+			close(to_child_fd[1]);
+			dup2(saved_out, 1);
+		}
+		if (child_mode & 0x06) {
+			close(from_child_fd[0]);
+			dup2(saved_in, 0);
+		}
+	}
+	child_mode = 0;
+	saved_in = -1;
+	saved_out = -1;
+}
+
+static void
+kill_child(Uint8 *d)
+{
+	if (child_pid) {
+		kill(child_pid, 9);
+		int wstatus;
+		if (waitpid(child_pid, &wstatus, 0)) {
+			d[0x6] = 1;
+			d[0x7] = WEXITSTATUS(wstatus);
+			clean_after_child();
+		}
+	}
+}
+
+static void
+start_fork_pty(Uint8 *d, Uxn *u)
+{
+	int fd = -1;
+	pid_t pid = forkpty(&fd, NULL, NULL, NULL);
+	if (pid < 0) { /* failure */
+		d[0x6] = 0xff;
+		fprintf(stderr, "fork failure");
+	} else if (pid == 0) { /* child */
+		setenv("TERM", "ansi", 1);
+		execvp(fork_args[0], fork_args);
+		d[0x6] = 0xff;
+		fprintf(stderr, "exec failure");
+	} else { /*parent*/
+		child_pid = pid;
+		pty_fd = fd;
+		struct winsize ws = {24, 80, 8, 12};
+		ioctl(fd, TIOCSWINSZ, &ws);
+		saved_in = dup(0);
+		saved_out = dup(1);
+		dup2(fd, 0);
+		dup2(fd, 1);
+	}
+}
+
+static void
+start_fork_pipe(Uint8 *d, Uxn *u)
+{
+	if (child_mode & 0x01) {
+		/* parent writes to child's stdin */
+		if (pipe(to_child_fd) == -1) {
+			d[0x6] = 0xff;
+			fprintf(stderr, "pipe error: to child");
+			return;
+		}
+	}
+
+	if (child_mode & 0x06) {
+		/* parent reads from child's stdout and/or stderr */
+		if (pipe(from_child_fd) == -1) {
+			d[0x6] = 0xff;
+			fprintf(stderr, "pipe error: to child");
+			return;
+		}
+	}
+
+	pid_t pid = fork();
+	if (pid < 0) { /* failure */
+		d[0x6] = 0xff;
+		fprintf(stderr, "fork failure");
+	} else if (pid == 0) { /* child */
+		if (child_mode & 0x01) {
+			dup2(to_child_fd[0], 0);
+			close(to_child_fd[1]);
+		}
+		if (child_mode & 0x06) {
+			if (child_mode & 0x02) dup2(from_child_fd[1], 1);
+			if (child_mode & 0x04) dup2(from_child_fd[1], 2);
+			close(from_child_fd[0]);
+		}
+		execvp(fork_args[0], fork_args);
+		d[0x6] = 0xff;
+		fprintf(stderr, "exec failure");
+	} else { /*parent*/
+		child_pid = pid;
+		if (child_mode & 0x01) {
+			saved_out = dup(1);
+			dup2(to_child_fd[1], 1);
+			close(to_child_fd[0]);
+		}
+		if (child_mode & 0x06) {
+			saved_in = dup(0);
+			dup2(from_child_fd[0], 0);
+			close(from_child_fd[1]);
+		}
+	}
+}
+
+static void
+start_fork(Uint8 *d, Uxn *u)
+{
+	kill_child(d);
+	child_mode = d[0x5];
+	parse_args(d, u);
+	if (child_mode >= 0x80) {
+		start_fork_pty(d, u);
+	} else {
+		start_fork_pipe(d, u);
+	}
+}
+
+Uint8
+console_dei(Uint8 *d, Uint8 port)
+{
+	switch(port) {
+	case 0x6:
+	case 0x7:
+		if (child_pid) {
+			int wstatus;
+			if (waitpid(child_pid, &wstatus, WNOHANG)) {
+				d[0x6] = 1;
+				d[0x7] = WEXITSTATUS(wstatus);
+				clean_after_child();
+			}
+		}
+	}
+	return d[port];
+}
+
+void
+console_deo(Uint8 *d, Uint8 port, Uxn *u)
+{
+	FILE *fd = NULL;
+	switch(port) {
+	case 0x5: start_fork(d, u); break;
+	case 0x6: kill_child(d); break;
+	case 0x8: fd = stdout; break;
+	case 0x9: fd = stderr; break;
+	}
+
+	if(fd) {
+		fputc(d[port], fd);
+		fflush(fd);
+	}
+}
diff --git a/src/devices/console.h b/src/devices/console.h
new file mode 100644
index 0000000..3eb8e19
--- /dev/null
+++ b/src/devices/console.h
@@ -0,0 +1,13 @@
+/*
+Copyright (c) 2023 d_m
+
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE.
+*/
+
+Uint8 console_dei(Uint8 *d, Uint8 port);
+void console_deo(Uint8 *d, Uint8 port, Uxn *u);
diff --git a/src/uxnemu.c b/src/uxnemu.c
index 39c4300..7291d76 100644
--- a/src/uxnemu.c
+++ b/src/uxnemu.c
@@ -16,12 +16,15 @@
 #include "devices/controller.h"
 #include "devices/mouse.h"
 #include "devices/datetime.h"
+#include "devices/console.h"
 #ifdef _WIN32
 #include <processthreadsapi.h>
 #endif
 #pragma GCC diagnostic pop
 #pragma clang diagnostic pop
 
+#include <sys/select.h>
+
 /*
 Copyright (c) 2021-2023 Devine Lu Linvega, Andrew Alderwick
 
@@ -70,17 +73,6 @@ console_input(Uxn *u, char c)
 	return uxn_eval(u, GETVEC(d));
 }
 
-static void
-console_deo(Uint8 *d, Uint8 port)
-{
-	FILE *fd = port == 0x8 ? stdout : port == 0x9 ? stderr
-												  : 0;
-	if(fd) {
-		fputc(d[port], fd);
-		fflush(fd);
-	}
-}
-
 static Uint8
 audio_dei(int instance, Uint8 *d, Uint8 port)
 {
@@ -109,6 +101,7 @@ emu_dei(Uxn *u, Uint8 addr)
 {
 	Uint8 p = addr & 0x0f, d = addr & 0xf0;
 	switch(d) {
+	case 0x10: return console_dei(&u->dev[d], p);
 	case 0x20: return screen_dei(&u->dev[d], p);
 	case 0x30: return audio_dei(0, &u->dev[d], p);
 	case 0x40: return audio_dei(1, &u->dev[d], p);
@@ -133,7 +126,7 @@ emu_deo(Uxn *u, Uint8 addr, Uint8 v)
 		if(p > 0x7 && p < 0xe)
 			screen_palette(&uxn_screen, &u->dev[0x8]);
 		break;
-	case 0x10: console_deo(&u->dev[d], p); break;
+	case 0x10: console_deo(&u->dev[d], p, u); break;
 	case 0x20: screen_deo(u->ram, &u->dev[d], p); break;
 	case 0x30: audio_deo(0, &u->dev[d], p, u); break;
 	case 0x40: audio_deo(1, &u->dev[d], p, u); break;
@@ -171,9 +164,23 @@ static int
 stdin_handler(void *p)
 {
 	SDL_Event event;
+	fd_set rds;
+	struct timeval tv;
+	int retval;
+	int ok = 1;
 	event.type = stdin_event;
-	while(read(0, &event.cbutton.button, 1) > 0 && SDL_PushEvent(&event) >= 0)
-		;
+	while(ok) {
+		FD_ZERO(&rds);
+		FD_SET(0, &rds); /* read from stdin */
+		tv.tv_sec = 0;
+		tv.tv_usec = 100000; /* wait 100ms */
+		retval = select(1, &rds, NULL, NULL, &tv);
+		if (retval > 0) {
+			ok = read(0, &event.cbutton.button, 1) > 0 && SDL_PushEvent(&event) >= 0;
+		} else if (retval < 0) {
+			ok = 0;
+		}
+	}
 	return 0;
 	(void)p;
 }