Feature: Issue #29: Alternative shadow blacklist implementation

- Add shadow blacklist feature, but a different implementation from
  nicklan's. 5 matching modes (exact, starts-with, contains, wildcard,
  PCRE) and 3 matching targets (window name, window class instance,
  window general class). Not extensively tested, bugs to be expected.
  It's slower for exact matching than nicklan's as it uses linear search
  instead of hash table. Also, PCRE's JIT optimization may cause issues
  on PaX kernels.

- Add dependency to libpcre. Could be made optional if we have a
  graceful way to handle that in Makefile.

- Some matching functions are GNU extensions of glibc. So this version
  may have troubles running on platforms not using glibc.

- Fix a bug that access freed memory blocks in set_fade_callcack() and
  check_fade_fin(). valgrind found it out.

- Use WM_CLASS to detect client windows instead of WM_STATE. Some client
  windows (like notification windows) have WM_CLASS but not WM_STATE.

- Mark the extents as damaged if shadow state changed in
  determine_shadow().

- Rewrite wid_get_name(). Code clean-up.

- Two debugging options: DEBUG_WINDATA and DEBUG_WINMATCH.

- As the matching system is ready, it should be rather easy to add other
  kinds of blacklists, like fading blacklist.

src/compton.h

@@ -4,6 +4,32 @@
 
 // Throw everything in here.
 
+// === Options ===
+
+#define CAN_DO_USABLE 0
+
+// Debug options, enable them using -D in CFLAGS
+// #define DEBUG_REPAINT 1
+// #define DEBUG_EVENTS 1
+// #define DEBUG_RESTACK 1
+// #define DEBUG_WINTYPE 1
+// #define DEBUG_CLIENTWIN 1
+// #define DEBUG_WINDATA 1
+// #define DEBUG_WINMATCH 1
+// #define MONITOR_REPAINT 1
+
+// Whether to enable PCRE regular expression support in blacklists, enabled
+// by default
+#define CONFIG_REGEX_PCRE 1
+// Whether to enable JIT support of libpcre. This may cause problems on PaX
+// kernels.
+#define CONFIG_REGEX_PCRE_JIT 1
+
+// === Includes ===
+
+// For some special functions
+#define _GNU_SOURCE
+
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -14,6 +40,13 @@
 #include <time.h>
 #include <unistd.h>
 #include <getopt.h>
+#include <stdbool.h>
+#include <locale.h>
+
+#include <fnmatch.h>
+#ifdef CONFIG_REGEX_PCRE
+#include <pcre.h>
+#endif
 
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
@@ -23,20 +56,11 @@
 #include <X11/extensions/Xrender.h>
 #include <X11/extensions/shape.h>
 
+// === Constants ===
 #if COMPOSITE_MAJOR > 0 || COMPOSITE_MINOR >= 2
 #define HAS_NAME_WINDOW_PIXMAP 1
 #endif
 
-#define CAN_DO_USABLE 0
-
-// Debug options, enable them using -D in CFLAGS
-// #define DEBUG_REPAINT 1
-// #define DEBUG_EVENTS 1
-// #define DEBUG_RESTACK 1
-// #define DEBUG_WINTYPE 1
-// #define DEBUG_CLIENTWIN 1
-// #define MONITOR_REPAINT 1
-
 // For printing timestamps
 #include <time.h>
 extern struct timeval time_start;
@@ -83,6 +107,34 @@ typedef struct _ignore {
   unsigned long sequence;
 } ignore;
 
+enum wincond_target {
+  CONDTGT_NAME,
+  CONDTGT_CLASSI,
+  CONDTGT_CLASSG,
+};
+
+enum wincond_type {
+  CONDTP_EXACT,
+  CONDTP_ANYWHERE,
+  CONDTP_FROMSTART,
+  CONDTP_WILDCARD,
+  CONDTP_REGEX_PCRE,
+};
+
+#define CONDF_IGNORECASE 0x0001
+
+typedef struct _wincond {
+  enum wincond_target target;
+  enum wincond_type type;
+  char *pattern;
+#ifdef CONFIG_REGEX_PCRE
+  pcre *regex_pcre;
+  pcre_extra *regex_pcre_extra;
+#endif
+  int16_t flags;
+  struct _wincond *next;
+} wincond;
+
 typedef struct _win {
   struct _win *next;
   Window id;
@@ -109,6 +161,13 @@ typedef struct _win {
   /// Cached width/height of the window including border.
   int widthb, heightb;
 
+  // Blacklist related members
+  char *name;
+  char *class_instance;
+  char *class_general;
+  wincond *cache_sblst;
+  wincond *cache_fblst;
+
   // Opacity-related members
   /// Current window opacity.
   opacity_t opacity;
@@ -206,6 +265,18 @@ set_ignore(Display *dpy, unsigned long sequence);
 static int
 should_ignore(Display *dpy, unsigned long sequence);
 
+/**
+ * Allocate the space and copy a string.
+ */
+static inline char *
+mstrcpy(const char *src) {
+  char *str = malloc(sizeof(char) * (strlen(src) + 1));
+
+  strcpy(str, src);
+
+  return str;
+}
+
 /**
  * Normalize an int value to a specific range.
  *
@@ -425,8 +496,9 @@ set_fade_callback(Display *dpy, win *w,
 static inline void
 check_fade_fin(Display *dpy, win *w) {
   if (w->fade_fin) {
-    set_fade_callback(dpy, w, NULL, True);
     w->fade_fin = False;
+    // Must be the last line as the callback could destroy w!
+    set_fade_callback(dpy, w, NULL, True);
   }
 }
 
@@ -458,6 +530,15 @@ static Picture
 solid_picture(Display *dpy, Bool argb, double a,
               double r, double g, double b);
 
+static bool
+win_match_once(win *w, const wincond *cond);
+
+static bool
+win_match(win *w, wincond *condlst, wincond * *cache);
+
+static Bool
+condlst_add(wincond **pcondlst, const char *pattern);
+
 static long
 determine_evmask(Display *dpy, Window wid, win_evmode_t mode);
 
@@ -594,10 +675,18 @@ error(Display *dpy, XErrorEvent *ev);
 static void
 expose_root(Display *dpy, Window root, XRectangle *rects, int nrects);
 
-#if defined(DEBUG_EVENTS) || defined(DEBUG_RESTACK)
+static Bool
+wid_get_text_prop(Display *dpy, Window wid, Atom prop,
+    char ***pstrlst, int *pnstr);
+
+static Bool
+wid_get_name(Display *dpy, Window w, char **name);
+
 static int
-window_get_name(Window w, char **name);
-#endif
+win_get_name(Display *dpy, win *w);
+
+static Bool
+win_get_class(Display *dpy, win *w);
 
 #ifdef DEBUG_EVENTS
 static int