Added a distro symbol (similar to what you'll find in DEs). Not yet functional.

Many users new to dwm find themselves caught out by being kicked out to the login manager (dwm crashing) when they open 50+ clients for demonstration purposes. The number of clients reported varies depending on the resolution of the monitor.

The cause of this is due to how the default tile layout calculates the height of the next client based on the position of the previous client. Because clients have a minimum size the (ty) position can exceed that of the window height, resulting in (m->wh - ty) becoming negative. The negative height stored as an unsigned int results in a very large height ultimately resulting in dwm crashing.

This patch adds safeguards to prevent the ty and my positions from exceeding that of the window height.

config.def.h

@@ -5,6 +5,7 @@ static const unsigned int borderpx  = 1;        /* border pixel of windows */
 static const unsigned int snap      = 32;       /* snap pixel */
 static const int showbar            = 1;        /* 0 means no bar */
 static const int topbar             = 1;        /* 0 means bottom bar */
+static const char *distrosymbol     = "";
 static const char *fonts[]          = { "monospace:size=10" };
 static const char dmenufont[]       = "monospace:size=10";
 static const char col_gray1[]       = "#222222";

config.mk

@@ -25,7 +25,7 @@ INCS = -I${X11INC} -I${FREETYPEINC}
 LIBS = -L${X11LIB} -lX11 ${XINERAMALIBS} ${FREETYPELIBS}
 
 # flags
-CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_POSIX_C_SOURCE=2 -DVERSION=\"${VERSION}\" ${XINERAMAFLAGS}
+CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_POSIX_C_SOURCE=200809L -DVERSION=\"${VERSION}\" ${XINERAMAFLAGS}
 #CFLAGS   = -g -std=c99 -pedantic -Wall -O0 ${INCS} ${CPPFLAGS}
 CFLAGS   = -std=c99 -pedantic -Wall -Wno-deprecated-declarations -Os ${INCS} ${CPPFLAGS}
 LDFLAGS  = ${LIBS}

dwm.c

@@ -113,6 +113,7 @@ typedef struct {
 
 struct Monitor {
 	char ltsymbol[16];
+    char distrosymbol[16];
 	float mfact;
 	int nmaster;
 	int num;
@@ -169,6 +170,7 @@ static void focus(Client *c);
 static void focusin(XEvent *e);
 static void focusmon(const Arg *arg);
 static void focusstack(const Arg *arg);
+static Atom getatomprop(Client *c, Atom prop);
 static int getrootptr(int *x, int *y);
 static long getstate(Window w);
 static int gettextprop(Window w, Atom atom, char *text, unsigned int size);
@@ -430,7 +432,8 @@ buttonpress(XEvent *e)
 		focus(NULL);
 	}
 	if (ev->window == selmon->barwin) {
-		i = x = 0;
+        x = TEXTW(m->distrosymbol);
+		i = 0;
 		do
 			x += TEXTW(tags[i]);
 		while (ev->x >= x && ++i < LENGTH(tags));
@@ -641,6 +644,7 @@ createmon(void)
 	m->lt[0] = &layouts[0];
 	m->lt[1] = &layouts[1 % LENGTH(layouts)];
 	strncpy(m->ltsymbol, layouts[0].symbol, sizeof m->ltsymbol);
+    strncpy(m->distrosymbol, distrosymbol, sizeof m->distrosymbol);
 	return m;
 }
 
@@ -695,7 +699,7 @@ dirtomon(int dir)
 void
 drawbar(Monitor *m)
 {
-	int x, w, sw = 0;
+	int x, w, tw = 0;
 	int boxs = drw->fonts->h / 9;
 	int boxw = drw->fonts->h / 6 + 2;
 	unsigned int i, occ = 0, urg = 0;
@@ -704,8 +708,8 @@ drawbar(Monitor *m)
 	/* draw status first so it can be overdrawn by tags later */
 	if (m == selmon) { /* status is only drawn on selected monitor */
 		drw_setscheme(drw, scheme[SchemeNorm]);
-		sw = TEXTW(stext) - lrpad + 2; /* 2px right padding */
-		drw_text(drw, m->ww - sw, 0, sw, bh, 0, stext, 0);
+		tw = TEXTW(stext) - lrpad + 2; /* 2px right padding */
+		drw_text(drw, m->ww - tw, 0, tw, bh, 0, stext, 0);
 	}
 
 	for (c = m->clients; c; c = c->next) {
@@ -714,6 +718,9 @@ drawbar(Monitor *m)
 			urg |= c->tags;
 	}
 	x = 0;
+	w = blw = TEXTW(m->distrosymbol);
+	drw_setscheme(drw, scheme[SchemeNorm]);
+	x = drw_text(drw, x, 0, w, bh, lrpad / 2, m->distrosymbol, 0);
 	for (i = 0; i < LENGTH(tags); i++) {
 		w = TEXTW(tags[i]);
 		drw_setscheme(drw, scheme[m->tagset[m->seltags] & 1 << i ? SchemeSel : SchemeNorm]);
@@ -728,7 +735,7 @@ drawbar(Monitor *m)
 	drw_setscheme(drw, scheme[SchemeNorm]);
 	x = drw_text(drw, x, 0, w, bh, lrpad / 2, m->ltsymbol, 0);
 
-	if ((w = m->ww - sw - x) > bh) {
+	if ((w = m->ww - tw - x) > bh) {
 		if (m->sel) {
 			drw_setscheme(drw, scheme[m == selmon ? SchemeSel : SchemeNorm]);
 			drw_text(drw, x, 0, w, bh, lrpad / 2, m->sel->name, 0);
@@ -1520,7 +1527,7 @@ setmfact(const Arg *arg)
 	if (!arg || !selmon->lt[selmon->sellt]->arrange)
 		return;
 	f = arg->f < 1.0 ? arg->f + selmon->mfact : arg->f - 1.0;
-	if (f < 0.1 || f > 0.9)
+	if (f < 0.05 || f > 0.95)
 		return;
 	selmon->mfact = f;
 	arrange(selmon);
@@ -1688,11 +1695,13 @@ tile(Monitor *m)
 		if (i < m->nmaster) {
 			h = (m->wh - my) / (MIN(n, m->nmaster) - i);
 			resize(c, m->wx, m->wy + my, mw - (2*c->bw), h - (2*c->bw), 0);
-			my += HEIGHT(c);
+			if (my + HEIGHT(c) < m->wh)
+				my += HEIGHT(c);
 		} else {
 			h = (m->wh - ty) / (n - i);
 			resize(c, m->wx + mw, m->wy + ty, m->ww - mw - (2*c->bw), h - (2*c->bw), 0);
-			ty += HEIGHT(c);
+			if (ty + HEIGHT(c) < m->wh)
+				ty += HEIGHT(c);
 		}
 }