Moved the pty->stdout routine and the im display routine to seperate threads

issue is that the im_display routine is overzealous

1 files changed, 100 insertions, 65 deletions

diff --git a/ptyim.c b/ptyim.c
index c402684..5ff0eee 100644
--- a/ptyim.c
+++ b/ptyim.c
@@ -3,14 +3,18 @@
 #define _DEFAULT_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+#include <fcntl.h>
 #include <sys/ioctl.h>
 #include <termios.h>
-#include <string.h>
+
 #include <signal.h>
-#include <sys/prctl.h>
+#include <pthread.h>
+#include <semaphore.h>
+
 #include "im.h"
 #include "escape.h"
 #define WRITE_BUFFER_LEN 128
@@ -41,7 +45,14 @@ void winchhook(int a) {
 }
 //child process pids
 pid_t shell_pid;
-pid_t om_pid;
+pthread_t om_thread;
+pthread_t im_disp_thread;
+//stdout semaphore
+sem_t out_sem;
+//tracks whether the screen has been updated by om
+int  om_updated = 1;
+
+
 //return 0 on success, -1 on error
 //sets the global vars pty_master and pty_slave
 int make_pty() {
@@ -88,10 +99,51 @@ void condition_stdin() {
 void restore_stdin() {
 	tcsetattr(STDIN_FILENO,TCSANOW,&stdin_termio_bk);
 }
+void * om_routine( void *arg) {
+	//thread handling pty -> stdout
+	while (running) {
+		//output manager child process
+		//buffer for reading from pty_master and writing to stdout
+		char write_buffer[WRITE_BUFFER_LEN] = {0};
+		//only read/write syscalls work well for this, printfs
+		//etcs do not work, this is blocking which is why its its own
+		//thread
+		// pty_master -> STDOUT
+		int wchars_read = read(pty_master,write_buffer, WRITE_BUFFER_LEN);
+		if (wchars_read >0) {
+			out_state = update_esc_state(write_buffer, wchars_read, out_state);
+			fprintf(stderr, "%c: %d\n", write_buffer[wchars_read-1], out_state);
+			sem_wait(&out_sem);
+			write(STDOUT_FILENO,write_buffer,wchars_read);
+			sem_post(&out_sem);
+			//sets update flag, im_disp_routine will set it to 0
+			om_updated = 1;
+		}
+	}
+}
+void * im_disp_routine (void *args) {
+	while (running) {
+		// Every run of this loop, it checks to see if im_buffer has
+		// updated, if it has, and no escape sequences have been written
+		// so far, it will display the im
+		if (im_updated |om_updated) {
+			fprintf(stderr, "printing im statusline\n");
+			if (safe_state(out_state)) {
+				sem_wait(&out_sem);
+				disp_im(STDIN_FILENO, trows, tcols);
+				sem_post(&out_sem);
+				im_updated = 0;
+				om_updated = 0;
+			}
+		}
+	}
+}
 //main thread exit
 void exit_main() {
 	//kill shell , can not be blocked
 	kill(shell_pid, SIGKILL);
+	pthread_cancel(om_thread);
+	pthread_cancel(im_disp_thread);
 	//exit, only the master process should reach this point
 	close(pty_master);
 	close(pty_slave);
@@ -155,71 +207,54 @@ int main (int argc, char * argv[], char * envp[]) {
 		//should automatically close any file descriptors
 		_exit(0);
 	} else {
-		//forks for read and write, master process handles im, child
-		//process just handles transfering pty output to stdout
-		om_pid = fork();
-		if (om_pid == 0) {
-			//sets the name for cleaner ps output
-			prctl(PR_SET_NAME, "ptyim om thread");
-			//output manager child process
-			//runs forever until SIGKILL'd
-			while (true) {
-				//output manager child process
-				//buffer for reading from pty_master and writing to stdout
-				char write_buffer[WRITE_BUFFER_LEN] = {0};
-				//only read/write syscalls work well for this, printfs
-				//etcs do not work
-				// pty_master -> STDOUT
-				int wchars_read = read(pty_master,write_buffer, WRITE_BUFFER_LEN);
-				if (wchars_read >0) {
-					write(STDOUT_FILENO,write_buffer,wchars_read);
-				}
-				// stdin -> pty_master, im logic is also here
-			}
-			//child process exit
-			_exit(0);
-		} else {
-			//master process
-			//registers interrupts
-			signal(SIGCHLD, childhook);
-			signal(SIGWINCH, winchhook);
-			//display the im for the first time
-			disp_im(STDIN_FILENO, trows, tcols);
+		//creates stdout semaphire
+		if (sem_init(&out_sem, 0, 1)) {
+			fprintf(stderr, "errno: %d, Error creating output sempahore\n", errno);
+			exit_main();
+		}
+		//creates a thread that just handles pty -> stdout transfers
+		if (pthread_create(&om_thread, NULL, &om_routine, NULL) ) {
+			fprintf(stderr, "errno: %d, Error creating om thread\n", errno);
+			exit_main();
+		}
+		if (pthread_create(&im_disp_thread, NULL, &im_disp_routine, NULL) ) {
+			fprintf(stderr, "errno: %d, Error creating im display thread\n", errno);
+			exit_main();
+		}
+		//master process
+		//registers interrupts
+		signal(SIGCHLD, childhook);
+		signal(SIGWINCH, winchhook);
 
-			//1 char buffer for reading from stdin and writing to pty_master
-			char read_buffer[1] = {0};
+		//1 char buffer for reading from stdin and writing to pty_master
+		char read_buffer[1] = {0};
 
-			//open
-			while (running) {
-				int rchars_read = read(STDIN_FILENO, read_buffer, 1);
-				if (rchars_read > 0) {
-					//feeds input char into the escape state
-					//machine
-					in_state = update_esc_state(read_buffer, 1, in_state);
-					//skips if the char was anything but
-					//normal
-					if (in_state == NORMAL || in_state ==DOUBLE_ESC) {
-						//feeds the input char into the im state machine
-						char input_buffer[IM_TABLE_ENTRY_LEN+1] = {0};
-						int im_chars = update_im_state(read_buffer[0],
-								input_buffer);
-						//just in case it wasn't null terminated right
-						input_buffer[im_chars] = 0;
-						if (im_chars >0) {
-							//writes the input into pty_master if
-							//there was an output from the state
-							//machine
-							write(pty_master,input_buffer,im_chars);
-						}
-					} else {
-						write(pty_master,read_buffer,1);
+		//open
+		while (running) {
+			int rchars_read = read(STDIN_FILENO, read_buffer, 1);
+			if (rchars_read > 0) {
+				//feeds input char into the escape state
+				//machine
+				in_state = update_esc_state(read_buffer, 1, in_state);
+				//skips if the char was anything but
+				//normal
+				if (in_state == NORMAL || in_state ==DOUBLE_ESC) {
+					//feeds the input char into the im state machine
+					char input_buffer[IM_TABLE_ENTRY_LEN+1] = {0};
+					int im_chars = update_im_state(read_buffer[0],
+							input_buffer);
+					//just in case it wasn't null terminated right
+					input_buffer[im_chars] = 0;
+					if (im_chars >0) {
+						//writes the input into pty_master if
+						//there was an output from the state
+						//machine
+						write(pty_master,input_buffer,im_chars);
 					}
-					//any input update will lead to a disp_im update
-					disp_im(STDIN_FILENO, trows, tcols);
+				} else {
+					write(pty_master,read_buffer,1);
 				}
 			}
-			//at the end of the main process, kil lthe om process
-			kill(om_pid, SIGKILL);
 		}
 	}
 	exit_main();