patch: dynamically updated the displayed notification

Makefile

@@ -1,4 +1,5 @@
 CFLAGS = -Wall -Wextra -pedantic -lX11 -lXft -I/usr/include/freetype2 -pthread
+CFLAGS += -lrt
 
 PREFIX ?= /usr/local
 CC ?= cc

herbe.c

@@ -1,13 +1,19 @@
-#include <X11/Xlib.h>
 #include <X11/Xft/Xft.h>
+#include <X11/Xlib.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <fcntl.h>
+#include <mqueue.h>
+#include <semaphore.h>
+#include <signal.h>
+#include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <signal.h>
-#include <unistd.h>
 #include <string.h>
-#include <stdarg.h>
-#include <fcntl.h>
-#include <semaphore.h>
+#include <sys/file.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <unistd.h>
 
 #include "config.h"
 
@@ -16,9 +22,19 @@
 #define EXIT_DISMISS 2
 
 Display *display;
+XftFont *font;
 Window window;
+int num_of_lines;
+char **lines;
 int exit_code = EXIT_DISMISS;
 
+struct mq_object {
+	pid_t pid;
+	long timestamp;
+	char  buffer[1024];
+};
+long lastTimestamp;
+
 static void die(const char *format, ...)
 {
 	va_list ap;
@@ -70,6 +86,81 @@ int get_max_len(char *string, XftFont *font, int max_text_width)
 		return ++eol;
 }
 
+void freeLines() {
+	if(lines) {
+		for (int i = 0; i < num_of_lines; i++)
+			free(lines[i]);
+		free(lines);
+	}
+}
+
+void constructLines(char* strList[], int numberOfStrings) {
+	freeLines();
+	int max_text_width = width - 2 * padding;
+	num_of_lines = 0;
+	int lines_size = 5;
+	lines = malloc(lines_size * sizeof(char *));
+	if (!lines)
+		die("malloc failed");
+
+	for (int i = 0; i < numberOfStrings; i++)
+	{
+		for (unsigned int eol = get_max_len(strList[i], font, max_text_width); eol; strList[i] += eol, num_of_lines++, eol = get_max_len(strList[i], font, max_text_width))
+		{
+			if (lines_size <= num_of_lines)
+			{
+				lines = realloc(lines, (lines_size += 5) * sizeof(char *));
+				if (!lines)
+					die("realloc failed");
+			}
+			lines[num_of_lines] = malloc((eol + 1) * sizeof(char));
+			if (!lines[num_of_lines])
+				die("malloc failed");
+
+			strncpy(lines[num_of_lines], strList[i], eol);
+			lines[num_of_lines][eol] = '\0';
+		}
+	}
+}
+
+void reload(union sigval sv);
+void readAllEvents(mqd_t mqd) {
+
+	struct sigevent event = {.sigev_notify=SIGEV_THREAD, .sigev_signo=SIGHUP, .sigev_value.sival_int=mqd, .sigev_notify_function=reload};
+	if(mq_notify(mqd, &event) == -1) {
+		perror("mq_notify failed");
+		exit(1);
+	}
+	struct mq_object object;
+	while(1) {
+		int ret = mq_receive(mqd, (char*)&object, sizeof(object), NULL);
+		if(ret==-1) {
+			if(errno == EAGAIN)
+				return;
+			perror("mq_receive");
+			exit(1);
+		}
+		if(object.timestamp && lastTimestamp > object.timestamp)
+			return;
+		if(object.timestamp)
+			lastTimestamp = object.timestamp;
+		char *buffer = object.buffer;
+
+		constructLines(&buffer, 1);
+		kill(object.pid, SIGTERM);
+	}
+}
+void reload(union sigval sv) {
+	// we've already timed out
+	if(alarm(duration) == 0)
+		return;
+	readAllEvents(sv.sival_int);
+	XEvent event;
+	event.type = Expose;
+	XSendEvent(display, window, 0, 0, &event);
+	XFlush(display);
+}
+
 void expire(int sig)
 {
 	XEvent event;
@@ -79,6 +170,11 @@ void expire(int sig)
 	XFlush(display);
 }
 
+
+void exitSuccess() {
+       exit(0);
+}
+
 int main(int argc, char *argv[])
 {
 	if (argc == 1)
@@ -87,6 +183,44 @@ int main(int argc, char *argv[])
 		die("Usage: %s body", argv[0]);
 	}
 
+	const char* id =getenv("HERBE_ID");
+	mqd_t mqd=-1;
+	if(id) {
+		struct mq_attr attr = { .mq_maxmsg = 10, .mq_msgsize = sizeof(struct mq_object) };
+		mqd = mq_open(id, O_RDWR|O_CREAT|O_NONBLOCK, 0722, &attr);
+		if(mqd==-1){
+			perror("mq_open");
+			die("mq_open");
+		}
+		while (1) {
+			if(flock(mqd, LOCK_EX|LOCK_NB) == 0) {
+				// if we get the lock, register for events
+				break;
+			}
+			if(errno != EWOULDBLOCK) {
+				perror("flock");
+				exit(1);
+			}
+			// someone else is listening for events
+			char* ts_str = getenv("NOTIFICATION_ID");
+			lastTimestamp = ts_str?atol(ts_str):0;
+			struct mq_object object = {getpid(), lastTimestamp, {0}};
+			char *buffer=object.buffer;
+			for(int i=1;i<argc;i++) {
+				strcat(buffer, argv[i]);
+				strcat(buffer, "\n");
+			}
+			signal(SIGTERM, exitSuccess);
+			if(mq_send(mqd, (char*)&object, sizeof(object), 1)==-1) {
+				perror("mq_send");
+				exit(1);
+			}
+			signal(SIGALRM, SIG_IGN);
+			alarm(1);
+			pause();
+		}
+	}
+
 	struct sigaction act_expire, act_ignore;
 
 	act_expire.sa_handler = expire;
@@ -121,35 +255,9 @@ int main(int argc, char *argv[])
 	attributes.background_pixel = color.pixel;
 	XftColorAllocName(display, visual, colormap, border_color, &color);
 	attributes.border_pixel = color.pixel;
+	font = XftFontOpenName(display, screen, font_pattern);
 
-	int num_of_lines = 0;
-	int max_text_width = width - 2 * padding;
-	int lines_size = 5;
-	char **lines = malloc(lines_size * sizeof(char *));
-	if (!lines)
-		die("malloc failed");
-
-	XftFont *font = XftFontOpenName(display, screen, font_pattern);
-
-	for (int i = 1; i < argc; i++)
-	{
-		for (unsigned int eol = get_max_len(argv[i], font, max_text_width); eol; argv[i] += eol, num_of_lines++, eol = get_max_len(argv[i], font, max_text_width))
-		{
-			if (lines_size <= num_of_lines)
-			{
-				lines = realloc(lines, (lines_size += 5) * sizeof(char *));
-				if (!lines)
-					die("realloc failed");
-			}
-
-			lines[num_of_lines] = malloc((eol + 1) * sizeof(char));
-			if (!lines[num_of_lines])
-				die("malloc failed");
-
-			strncpy(lines[num_of_lines], argv[i], eol);
-			lines[num_of_lines][eol] = '\0';
-		}
-	}
+	constructLines(argv+1, argc-1);
 
 	unsigned int x = pos_x;
 	unsigned int y = pos_y;
@@ -180,6 +288,10 @@ int main(int argc, char *argv[])
 	if (duration != 0)
 		alarm(duration);
 
+	if(id) {
+		readAllEvents(mqd);
+	}
+
 	for (;;)
 	{
 		XEvent event;
@@ -207,14 +319,16 @@ int main(int argc, char *argv[])
 	sem_post(mutex);
 	sem_close(mutex);
 
-	for (int i = 0; i < num_of_lines; i++)
-		free(lines[i]);
+	freeLines();
 
-	free(lines);
 	XftDrawDestroy(draw);
 	XftColorFree(display, visual, colormap, &color);
 	XftFontClose(display, font);
 	XCloseDisplay(display);
 
+	if(id) {
+		mq_close(mqd);
+	}
+
 	return exit_code;
-}
+}