Fix possibles segfaults, dead assignment and other division by zero.

Thanks to clang build report

src/event.c

@@ -370,7 +370,6 @@ void
 enternotify(XCrossingEvent *ev)
 {
      Client *c;
-     Systray *s;
      int n;
 
      if((ev->mode != NotifyNormal
@@ -379,7 +378,7 @@ enternotify(XCrossingEvent *ev)
           return;
 
      /* Don't handle EnterNotify event if it's about systray */
-     if((s = systray_find(ev->window)) || ev->window == traywin)
+     if(systray_find(ev->window) || ev->window == traywin)
           return;
 
      if(conf.focus_fmouse)
@@ -525,7 +524,6 @@ void
 maprequest(XMapRequestEvent *ev)
 {
      XWindowAttributes at;
-     Client *c;
      Systray *s;
 
      CHECK(XGetWindowAttributes(dpy, ev->window, &at));
@@ -536,7 +534,7 @@ maprequest(XMapRequestEvent *ev)
           ewmh_send_message(s->win, s->win, "_XEMBED", CurrentTime, XEMBED_WINDOW_ACTIVATE, 0, 0, 0);
           systray_update();
      }
-     else if(!(c = client_gb_win(ev->window)))
+     else if(!client_gb_win(ev->window))
           client_manage(ev->window, &at, True);
 
      return;

src/infobar.c

@@ -220,7 +220,7 @@ infobar_draw_selbar(int sc)
 void
 infobar_draw_taglist(int sc)
 {
-     int i, x, j;
+     int i, x;
      Client *c = NULL;
      Bool is_occupied[MAXTAG + 1];
 
@@ -234,7 +234,7 @@ infobar_draw_taglist(int sc)
           if(c->screen == sc)
                is_occupied[c->tag] = True;
 
-     for(i = 1, x = j = 0; i < conf.ntag[sc] + 1; ++i)
+     for(i = 1, x = 0; i < conf.ntag[sc] + 1; ++i)
      {
           /* Autohide tag feature */
           if(conf.tagautohide)

src/launcher.c

@@ -179,7 +179,7 @@ launcher_execute(Launcher *launcher)
                     lastwastab = True;
 
                     /* start a new round of tabbing */
-                    if (!found)
+                    if (found == False)
                          tabhits = 0;
 
                     pos = strlen(buf);
@@ -280,19 +280,20 @@ complete_on_command(char *start, size_t hits)
           }
           dirname = strtok(NULL, ":");
      }
-     qsort(namelist, n, sizeof(char *), qsort_string_compare);
 
      free(path);
 
      if(n > 0)
      {
+          qsort(namelist, n, sizeof(char *), qsort_string_compare);
           ret = xstrdup(namelist[((hits > 0) ? hits - 1 : 0) % n] + strlen(start));
 
           for(i = 0; i < n; i++)
                free(namelist[i]);
-     }
 
           free(namelist);
+     }
+
      return ret;
 }
 

src/layout.c

@@ -325,7 +325,10 @@ multi_tile(int screen, Position type)
      {
           if(type == Top)
                mastergeo.y = (n <= nmaster) ? (uint)sg.y : sg.y + (sg.height - mwfact) - BORDH;
+          if (nmaster != 0)
                mastergeo.width = (sg.width / nmaster) - (BORDH * 4);
+          else
+               mastergeo.width = sg.width - (BORDH * 4);
           mastergeo.height = (n <= nmaster) ? (uint)(sg.height - BORDH) : mwfact;
      }
      else
@@ -333,7 +336,10 @@ multi_tile(int screen, Position type)
           if(type == Left)
                mastergeo.x = (n <= nmaster) ? (uint)sg.x : (sg.x + sg.width) - mwfact - (BORDH * 2);
           mastergeo.width = (n <= nmaster) ? (uint)(sg.width - (BORDH * 2)) : mwfact;
-          mastergeo.height = (sg.height / nmaster) - BORDH;
+          if (nmaster != 0)
+               mastergeo.height = sg.height - BORDH;
+          else
+               mastergeo.height = BORDH;
      }
 
      /* TILED SIZE */

src/parse.c

@@ -100,7 +100,7 @@ push_keyword(struct keyword *tail, enum keyword_t type, char *buf, size_t *offse
      if (*offset != 0) {
           buf[*offset] = '\0';
           if (!strcmp(buf, INCLUDE_CMD))
-               type = kw->type = INCLUDE;
+               kw->type = INCLUDE;
           else
                kw->name = strdup(buf);
           *offset = 0;

src/status.c

@@ -195,7 +195,7 @@ void
 statustext_handle(int sc, char *str)
 {
      char *lastst;
-     int i, nr, ng, ns, len, sw = 0;
+     int i, nr, ng, ns, sw = 0;
      StatusRec r[128];
      StatusGraph g[128];
      StatusText s[128];
@@ -213,7 +213,6 @@ statustext_handle(int sc, char *str)
      lastst = infobar[sc].statustext;
 
      infobar[sc].statustext = xstrdup(str);
-     len = ((strlen(str) > MAXSTATUS) ? MAXSTATUS : strlen(str));
 
      /* Store rectangles, located text & images properties. */
      nr = statustext_rectangle(r, str);

src/tag.c

@@ -625,10 +625,10 @@ void
 uicb_tag_rename(uicb_t cmd)
 {
      screen_get_sel();
-     size_t len;
      char *str;
+     size_t len;
 
-     if(!cmd || !(len = strlen(cmd)))
+     if(!cmd || !strlen(cmd))
           return;
 
      str = tags[selscreen][seltag[selscreen]].name;

src/wmfs.c

@@ -36,7 +36,6 @@ int
 errorhandler(Display *d, XErrorEvent *event)
 {
      char mess[256];
-     Client *c;
 
      /* Check if there is another WM running */
      if(BadAccess == event->error_code
@@ -48,7 +47,7 @@ errorhandler(Display *d, XErrorEvent *event)
       * 42 = X_SetInputFocus
       * 28 = X_GrabButton
       */
-     if((c = client_gb_win(event->resourceid)))
+     if(client_gb_win(event->resourceid))
           if(event->error_code == BadWindow
              || event->request_code == 42
                ||  event->request_code == 28)