From 764b955f0678f34c23ba27b87b23bce280ce909c Mon Sep 17 00:00:00 2001
From: Louis Burda <quent.burda@gmail.com>
Date: Thu, 28 Sep 2023 02:16:32 +0200
Subject: Display message when screen is locked

---
 slock.c | 138 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 133 insertions(+), 5 deletions(-)

(limited to 'slock.c')

diff --git a/slock.c b/slock.c
index 42b4df3..6217dce 100644
--- a/slock.c
+++ b/slock.c
@@ -15,6 +15,7 @@
 #include <unistd.h>
 #include <sys/types.h>
 #include <X11/extensions/Xrandr.h>
+#include <X11/extensions/Xinerama.h>
 #include <X11/extensions/dpms.h>
 #include <X11/keysym.h>
 #include <X11/Xlib.h>
@@ -26,6 +27,9 @@
 
 char *argv0;
 
+/* global count to prevent repeated error messages */
+int count_error = 0;
+
 enum {
 	INIT,
 	INPUT,
@@ -88,6 +92,106 @@ dontkillme(void)
 }
 #endif
 
+static void
+writemessage(Display *dpy, Window win, int screen, const char* message)
+{
+	int msg_len, max_line_len, max_line_width, xoffset, yoffset, screen_width,
+		screen_height, i, j, k, line_count, tab_replace, tab_size, font_height;
+	XGCValues gr_values;
+	XFontStruct *fontinfo;
+	XColor fg_color, bg_color, dummy;
+	XineramaScreenInfo *xsi;
+	GC fg_gc, bg_gc;
+	fontinfo = XLoadQueryFont(dpy, font_name);
+
+	if (fontinfo == NULL) {
+		if (count_error == 0) {
+			fprintf(stderr, "slock: Unable to load font \"%s\"\n", font_name);
+			fprintf(stderr, "slock: Try listing fonts with 'slock -f'\n");
+			count_error++;
+		}
+		return;
+	}
+
+	tab_size = 4 * XTextWidth(fontinfo, " ", 1);
+
+	XAllocNamedColor(dpy, DefaultColormap(dpy, screen),
+		 text_fg_color, &fg_color, &dummy);
+
+	gr_values.font = fontinfo->fid;
+	gr_values.foreground = fg_color.pixel;
+	fg_gc = XCreateGC(dpy, win, GCFont+GCForeground, &gr_values);
+
+	XAllocNamedColor(dpy, DefaultColormap(dpy, screen),
+		 text_bg_color, &bg_color, &dummy);
+
+	gr_values.foreground = bg_color.pixel;
+	bg_gc = XCreateGC(dpy, win, GCFont+GCForeground, &gr_values);
+
+	/*  To prevent "Uninitialized" warnings. */
+	xsi = NULL;
+
+	msg_len = strlen(message);
+
+	/* Calculate max line length, j : last line, k : longest line */
+	max_line_len = 0;
+	line_count = 0;
+	for (i = j = k = 0; i <= msg_len; i++) {
+		if (i == msg_len || message[i] == '\n') {
+			if (i - j > max_line_len) {
+				max_line_len = i - j;
+				k = j;
+			}
+			line_count++;
+			j = i + 1;
+		}
+	}
+
+	max_line_width = XTextWidth(fontinfo, message + k, max_line_len);
+
+	if (XineramaIsActive(dpy)) {
+		xsi = XineramaQueryScreens(dpy, &i);
+		screen_width = xsi[0].width;
+		screen_height = xsi[0].height;
+	} else {
+		screen_width = DisplayWidth(dpy, screen);
+		screen_height = DisplayHeight(dpy, screen);
+	}
+
+	font_height = fontinfo->ascent + fontinfo->descent;
+	yoffset = screen_height * 3 / 7 - line_count * font_height / 3;
+	xoffset  = (screen_width - max_line_width) / 2;
+
+	/* Draw background rect */
+	XFillRectangle(dpy, win, bg_gc, xoffset - 1, yoffset - fontinfo->ascent,
+		max_line_width + 2, line_count * font_height);
+
+	/* Print line by line, j : last line, k : line counter */
+	for (i = j = k = 0; i <= msg_len; i++) {
+		if (i == msg_len || message[i] == '\n') {
+			tab_replace = 0;
+			while (message[j] == '\t' && j < i) {
+				tab_replace++;
+				j++;
+			}
+
+			XDrawString(dpy, win, fg_gc, xoffset + tab_size * tab_replace,
+				yoffset + 20 * k, message + j, i - j);
+			while (i < msg_len && message[i] == '\n') {
+				i++;
+				j = i;
+				k++;
+			}
+		}
+	}
+
+	/* xsi should not be NULL anyway if Xinerama is active, but to be safe */
+	if (XineramaIsActive(dpy) && xsi != NULL)
+			XFree(xsi);
+}
+
+
+
 static const char *
 gethash(void)
 {
@@ -194,13 +298,22 @@ readpw(Display *dpy, struct xrandr *rr, struct lock **locks, int nscreens,
 				break;
 			}
 			color = len ? INPUT : ((failure || failonclear) ? FAILED : INIT);
-			if (running && oldc != color) {
+			if (running) {
 				for (screen = 0; screen < nscreens; screen++) {
                     if(locks[screen]->bgmap)
                         XSetWindowBackgroundPixmap(dpy, locks[screen]->win, locks[screen]->bgmap);
                     else
                         XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[0]);
 					XClearWindow(dpy, locks[screen]->win);
+					if (len) {
+						char* passwd_mask = malloc(len + 1);
+						memset(passwd_mask, '*', len);
+						passwd_mask[len] = '\0';
+						writemessage(dpy, locks[screen]->win, screen, passwd_mask);
+						free(passwd_mask);
+					} else {
+						writemessage(dpy, locks[screen]->win, screen, lock_message);
+					}
 				}
 				oldc = color;
 			}
@@ -320,7 +433,7 @@ lockscreen(Display *dpy, struct xrandr *rr, int screen)
 static void
 usage(void)
 {
-	die("usage: slock [-v] [cmd [arg ...]]\n");
+	die("usage: slock [-v] [-f] [-m message] [cmd [arg ...]]\n");
 }
 
 int
@@ -333,13 +446,26 @@ main(int argc, char **argv) {
 	gid_t dgid;
 	const char *hash;
 	Display *dpy;
-	int s, nlocks, nscreens;
+	int i, s, nlocks, nscreens;
+	int count_fonts;
+	char **font_names;
 	CARD16 standby, suspend, off;
 
 	ARGBEGIN {
 	case 'v':
 		fprintf(stderr, "slock-"VERSION"\n");
 		return 0;
+	case 'm':
+		lock_message = EARGF(usage());
+		break;
+	case 'f':
+		if (!(dpy = XOpenDisplay(NULL)))
+			die("slock: cannot open display\n");
+		font_names = XListFonts(dpy, "*", 10000 /* list 10000 fonts*/, &count_fonts);
+		for (i=0; i<count_fonts; i++) {
+			fprintf(stderr, "%s\n", *(font_names+i));
+		}
+		return 0;
 	default:
 		usage();
 	} ARGEND
@@ -438,10 +564,12 @@ main(int argc, char **argv) {
 	if (!(locks = calloc(nscreens, sizeof(struct lock *))))
 		die("slock: out of memory\n");
 	for (nlocks = 0, s = 0; s < nscreens; s++) {
-		if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL)
+		if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL) {
+			writemessage(dpy, locks[s]->win, s, lock_message);
 			nlocks++;
-		else
+		} else {
 			break;
+		}
 	}
 	XSync(dpy, 0);
 
-- 
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