Only create the line format once when drawing the browser window

The memory for this format is now statically allocated as well. I
was under the impression its size would depend on wincols, but this is
the format we're talking about, the string does not have to hold the
actual line contents. I must have been sleeping again...

Oh well, this is a slight performance improvement, although it doesn't
seem the be the cause of the browing slowness when running under
valgrind. (Obviously running ncdu with valgrind is supposed to be
slower, but the current performance is rather bad...)

src/browser.c

@@ -90,8 +90,8 @@ void browse_draw_info(struct dir *dr) {
 }
 
 
-void browse_draw_item(struct dir *n, int row) {
-  char *line, ct, dt, *size, gr[11];
+void browse_draw_item(struct dir *n, int row, char *line) {
+  char ct, dt, *size, gr[11];
   int i, o;
   float pc;
 
@@ -141,25 +141,12 @@ void browse_draw_item(struct dir *n, int row) {
   }
 
   /* format and add item to the list */
-  line = malloc(wincols > 35 ? wincols+1 : 36);
   switch(graph) {
-    case 0:
-      sprintf(line, "%%c %%8s  %%c%%-%ds", wincols-13);
-      mvprintw(row, 0, line, ct, size, dt, cropstr(n->name, wincols-13));
-      break;
-    case 1:
-      sprintf(line, "%%c %%8s [%%10s] %%c%%-%ds", wincols-25);
-      mvprintw(row, 0, line, ct, size, gr, dt, cropstr(n->name, wincols-25));
-      break;
-    case 2:
-      sprintf(line, "%%c %%8s [%%5.1f%%%%] %%c%%-%ds", wincols-21);
-      mvprintw(row, 0, line, ct, size, pc, dt, cropstr(n->name, wincols-21));
-      break;
-    case 3:
-      sprintf(line, "%%c %%8s [%%5.1f%%%% %%10s] %%c%%-%ds", wincols-32);
-      mvprintw(row, 0, line, ct, size, pc, gr, dt, cropstr(n->name, wincols-32));
+    case 0: mvprintw(row, 0, line, ct, size, dt, cropstr(n->name, wincols-13)); break;
+    case 1: mvprintw(row, 0, line, ct, size, gr, dt, cropstr(n->name, wincols-25)); break;
+    case 2: mvprintw(row, 0, line, ct, size, pc, dt, cropstr(n->name, wincols-21)); break;
+    case 3: mvprintw(row, 0, line, ct, size, pc, gr, dt, cropstr(n->name, wincols-32));
   }
-  free(line);
 
   if(n->flags & FF_BSEL)
     attroff(A_REVERSE);
@@ -168,7 +155,7 @@ void browse_draw_item(struct dir *n, int row) {
 
 void browse_draw() {
   struct dir *t;
-  char fmtsize[9], *tmp;
+  char fmtsize[9], *tmp, line[35];
   int selected, i;
 
   erase();
@@ -207,9 +194,17 @@ void browse_draw() {
   /* get start position */
   t = dirlist_top(0);
 
+  /* create line format */
+  switch(graph) {
+    case 0: sprintf(line, "%%c %%8s  %%c%%-%ds", wincols-13); break;
+    case 1: sprintf(line, "%%c %%8s [%%10s] %%c%%-%ds", wincols-25); break;
+    case 2: sprintf(line, "%%c %%8s [%%5.1f%%%%] %%c%%-%ds", wincols-21); break;
+    case 3: sprintf(line, "%%c %%8s [%%5.1f%%%% %%10s] %%c%%-%ds", wincols-32);
+  }
+
   /* print the list to the screen */
   for(i=0; t && i<winrows-3; t=dirlist_next(t),i++) {
-    browse_draw_item(t, 2+i);
+    browse_draw_item(t, 2+i, line);
     /* save the selected row number for later */
     if(t->flags & FF_BSEL)
       selected = i;