Apply IPC patch

IPCClient.c

@@ -0,0 +1,66 @@
+#include "IPCClient.h"
+
+#include <string.h>
+#include <sys/epoll.h>
+
+#include "util.h"
+
+IPCClient *
+ipc_client_new(int fd)
+{
+  IPCClient *c = (IPCClient *)malloc(sizeof(IPCClient));
+
+  if (c == NULL) return NULL;
+
+  // Initialize struct
+  memset(&c->event, 0, sizeof(struct epoll_event));
+
+  c->buffer_size = 0;
+  c->buffer = NULL;
+  c->fd = fd;
+  c->event.data.fd = fd;
+  c->next = NULL;
+  c->prev = NULL;
+  c->subscriptions = 0;
+
+  return c;
+}
+
+void
+ipc_list_add_client(IPCClientList *list, IPCClient *nc)
+{
+  DEBUG("Adding client with fd %d to list\n", nc->fd);
+
+  if (*list == NULL) {
+    // List is empty, point list at first client
+    *list = nc;
+  } else {
+    IPCClient *c;
+    // Go to last client in list
+    for (c = *list; c && c->next; c = c->next)
+      ;
+    c->next = nc;
+    nc->prev = c;
+  }
+}
+
+void
+ipc_list_remove_client(IPCClientList *list, IPCClient *c)
+{
+  IPCClient *cprev = c->prev;
+  IPCClient *cnext = c->next;
+
+  if (cprev != NULL) cprev->next = c->next;
+  if (cnext != NULL) cnext->prev = c->prev;
+  if (c == *list) *list = c->next;
+}
+
+IPCClient *
+ipc_list_get_client(IPCClientList list, int fd)
+{
+  for (IPCClient *c = list; c; c = c->next) {
+    if (c->fd == fd) return c;
+  }
+
+  return NULL;
+}

IPCClient.h

@@ -0,0 +1,61 @@
+#ifndef IPC_CLIENT_H_
+#define IPC_CLIENT_H_
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/epoll.h>
+
+typedef struct IPCClient IPCClient;
+/**
+ * This structure contains the details of an IPC Client and pointers for a
+ * linked list
+ */
+struct IPCClient {
+  int fd;
+  int subscriptions;
+
+  char *buffer;
+  uint32_t buffer_size;
+
+  struct epoll_event event;
+  IPCClient *next;
+  IPCClient *prev;
+};
+
+typedef IPCClient *IPCClientList;
+
+/**
+ * Allocate memory for new IPCClient with the specified file descriptor and
+ * initialize struct.
+ *
+ * @param fd File descriptor of IPC client
+ *
+ * @return Address to allocated IPCClient struct
+ */
+IPCClient *ipc_client_new(int fd);
+
+/**
+ * Add an IPC Client to the specified list
+ *
+ * @param list Address of the list to add the client to
+ * @param nc Address of the IPCClient
+ */
+void ipc_list_add_client(IPCClientList *list, IPCClient *nc);
+
+/**
+ * Remove an IPCClient from the specified list
+ *
+ * @param list Address of the list to remove the client from
+ * @param c Address of the IPCClient
+ */
+void ipc_list_remove_client(IPCClientList *list, IPCClient *c);
+
+/**
+ * Get an IPCClient from the specified IPCClient list
+ *
+ * @param list List to remove the client from
+ * @param fd File descriptor of the IPCClient
+ */
+IPCClient *ipc_list_get_client(IPCClientList list, int fd);
+
+#endif  // IPC_CLIENT_H_

Makefile

@@ -6,7 +6,7 @@ include config.mk
 SRC = drw.c dwm.c util.c
 OBJ = ${SRC:.c=.o}
 
-all: options dwm
+all: options dwm dwm-msg
 
 options:
 	@echo dwm build options:
@@ -25,8 +25,11 @@ config.h:
 dwm: ${OBJ}
 	${CC} -o $@ ${OBJ} ${LDFLAGS}
 
+dwm-msg: dwm-msg.o
+	${CC} -o $@ $< ${LDFLAGS}
+
 clean:
-	rm -f dwm ${OBJ} dwm-${VERSION}.tar.gz
+	rm -f dwm dwm-msg ${OBJ} dwm-${VERSION}.tar.gz
 
 dist: clean
 	mkdir -p dwm-${VERSION}
@@ -38,8 +41,9 @@ dist: clean
 
 install: all
 	mkdir -p ${DESTDIR}${PREFIX}/bin
-	cp -f dwm ${DESTDIR}${PREFIX}/bin
+	cp -f dwm dwm-msg ${DESTDIR}${PREFIX}/bin
 	chmod 755 ${DESTDIR}${PREFIX}/bin/dwm
+	chmod 755 ${DESTDIR}${PREFIX}/bin/dwm-msg
 	mkdir -p ${DESTDIR}${MANPREFIX}/man1
 	sed "s/VERSION/${VERSION}/g" < dwm.1 > ${DESTDIR}${MANPREFIX}/man1/dwm.1
 	chmod 644 ${DESTDIR}${MANPREFIX}/man1/dwm.1

config.def.h

@@ -114,3 +114,21 @@ static Button buttons[] = {
 	{ ClkTagBar,            MODKEY,         Button3,        toggletag,      {0} },
 };
 
+static const char *ipcsockpath = "/tmp/dwm.sock";
+static IPCCommand ipccommands[] = {
+  IPCCOMMAND(  view,                1,      {ARG_TYPE_UINT}   ),
+  IPCCOMMAND(  toggleview,          1,      {ARG_TYPE_UINT}   ),
+  IPCCOMMAND(  tag,                 1,      {ARG_TYPE_UINT}   ),
+  IPCCOMMAND(  toggletag,           1,      {ARG_TYPE_UINT}   ),
+  IPCCOMMAND(  tagmon,              1,      {ARG_TYPE_UINT}   ),
+  IPCCOMMAND(  focusmon,            1,      {ARG_TYPE_SINT}   ),
+  IPCCOMMAND(  focusstack,          1,      {ARG_TYPE_SINT}   ),
+  IPCCOMMAND(  zoom,                1,      {ARG_TYPE_NONE}   ),
+  IPCCOMMAND(  incnmaster,          1,      {ARG_TYPE_SINT}   ),
+  IPCCOMMAND(  killclient,          1,      {ARG_TYPE_SINT}   ),
+  IPCCOMMAND(  togglefloating,      1,      {ARG_TYPE_NONE}   ),
+  IPCCOMMAND(  setmfact,            1,      {ARG_TYPE_FLOAT}  ),
+  IPCCOMMAND(  setlayoutsafe,       1,      {ARG_TYPE_PTR}    ),
+  IPCCOMMAND(  quit,                1,      {ARG_TYPE_NONE}   )
+};
+

config.mk

@@ -20,9 +20,13 @@ FREETYPEINC = /usr/include/freetype2
 # OpenBSD (uncomment)
 #FREETYPEINC = ${X11INC}/freetype2
 
+# yajl
+YAJLLIBS = -lyajl
+YAJLINC = /usr/include/yajl
+
 # includes and libs
-INCS = -I${X11INC} -I${FREETYPEINC}
-LIBS = -L${X11LIB} -lX11 ${XINERAMALIBS} ${FREETYPELIBS}
+INCS = -I${X11INC} -I${FREETYPEINC} -I${YAJLINC}
+LIBS = -L${X11LIB} -lX11 ${XINERAMALIBS} ${FREETYPELIBS} ${YAJLLIBS}
 
 # flags
 CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_POSIX_C_SOURCE=200809L -DVERSION=\"${VERSION}\" ${XINERAMAFLAGS}

dwm-msg.c

@@ -0,0 +1,548 @@
+#include <ctype.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+#include <yajl/yajl_gen.h>
+
+#define IPC_MAGIC "DWM-IPC"
+// clang-format off
+#define IPC_MAGIC_ARR { 'D', 'W', 'M', '-', 'I', 'P', 'C' }
+// clang-format on
+#define IPC_MAGIC_LEN 7  // Not including null char
+
+#define IPC_EVENT_TAG_CHANGE "tag_change_event"
+#define IPC_EVENT_CLIENT_FOCUS_CHANGE "client_focus_change_event"
+#define IPC_EVENT_LAYOUT_CHANGE "layout_change_event"
+#define IPC_EVENT_MONITOR_FOCUS_CHANGE "monitor_focus_change_event"
+#define IPC_EVENT_FOCUSED_TITLE_CHANGE "focused_title_change_event"
+#define IPC_EVENT_FOCUSED_STATE_CHANGE "focused_state_change_event"
+
+#define YSTR(str) yajl_gen_string(gen, (unsigned char *)str, strlen(str))
+#define YINT(num) yajl_gen_integer(gen, num)
+#define YDOUBLE(num) yajl_gen_double(gen, num)
+#define YBOOL(v) yajl_gen_bool(gen, v)
+#define YNULL() yajl_gen_null(gen)
+#define YARR(body)                                                             \
+  {                                                                            \
+    yajl_gen_array_open(gen);                                                  \
+    body;                                                                      \
+    yajl_gen_array_close(gen);                                                 \
+  }
+#define YMAP(body)                                                             \
+  {                                                                            \
+    yajl_gen_map_open(gen);                                                    \
+    body;                                                                      \
+    yajl_gen_map_close(gen);                                                   \
+  }
+
+typedef unsigned long Window;
+
+const char *DEFAULT_SOCKET_PATH = "/tmp/dwm.sock";
+static int sock_fd = -1;
+static unsigned int ignore_reply = 0;
+
+typedef enum IPCMessageType {
+  IPC_TYPE_RUN_COMMAND = 0,
+  IPC_TYPE_GET_MONITORS = 1,
+  IPC_TYPE_GET_TAGS = 2,
+  IPC_TYPE_GET_LAYOUTS = 3,
+  IPC_TYPE_GET_DWM_CLIENT = 4,
+  IPC_TYPE_SUBSCRIBE = 5,
+  IPC_TYPE_EVENT = 6
+} IPCMessageType;
+
+// Every IPC message must begin with this
+typedef struct dwm_ipc_header {
+  uint8_t magic[IPC_MAGIC_LEN];
+  uint32_t size;
+  uint8_t type;
+} __attribute((packed)) dwm_ipc_header_t;
+
+static int
+recv_message(uint8_t *msg_type, uint32_t *reply_size, uint8_t **reply)
+{
+  uint32_t read_bytes = 0;
+  const int32_t to_read = sizeof(dwm_ipc_header_t);
+  char header[to_read];
+  char *walk = header;
+
+  // Try to read header
+  while (read_bytes < to_read) {
+    ssize_t n = read(sock_fd, header + read_bytes, to_read - read_bytes);
+
+    if (n == 0) {
+      if (read_bytes == 0) {
+        fprintf(stderr, "Unexpectedly reached EOF while reading header.");
+        fprintf(stderr,
+                "Read %" PRIu32 " bytes, expected %" PRIu32 " total bytes.\n",
+                read_bytes, to_read);
+        return -2;
+      } else {
+        fprintf(stderr, "Unexpectedly reached EOF while reading header.");
+        fprintf(stderr,
+                "Read %" PRIu32 " bytes, expected %" PRIu32 " total bytes.\n",
+                read_bytes, to_read);
+        return -3;
+      }
+    } else if (n == -1) {
+      return -1;
+    }
+
+    read_bytes += n;
+  }
+
+  // Check if magic string in header matches
+  if (memcmp(walk, IPC_MAGIC, IPC_MAGIC_LEN) != 0) {
+    fprintf(stderr, "Invalid magic string. Got '%.*s', expected '%s'\n",
+            IPC_MAGIC_LEN, walk, IPC_MAGIC);
+    return -3;
+  }
+
+  walk += IPC_MAGIC_LEN;
+
+  // Extract reply size
+  memcpy(reply_size, walk, sizeof(uint32_t));
+  walk += sizeof(uint32_t);
+
+  // Extract message type
+  memcpy(msg_type, walk, sizeof(uint8_t));
+  walk += sizeof(uint8_t);
+
+  (*reply) = malloc(*reply_size);
+
+  // Extract payload
+  read_bytes = 0;
+  while (read_bytes < *reply_size) {
+    ssize_t n = read(sock_fd, *reply + read_bytes, *reply_size - read_bytes);
+
+    if (n == 0) {
+      fprintf(stderr, "Unexpectedly reached EOF while reading payload.");
+      fprintf(stderr, "Read %" PRIu32 " bytes, expected %" PRIu32 " bytes.\n",
+              read_bytes, *reply_size);
+      free(*reply);
+      return -2;
+    } else if (n == -1) {
+      if (errno == EINTR || errno == EAGAIN) continue;
+      free(*reply);
+      return -1;
+    }
+
+    read_bytes += n;
+  }
+
+  return 0;
+}
+
+static int
+read_socket(IPCMessageType *msg_type, uint32_t *msg_size, char **msg)
+{
+  int ret = -1;
+
+  while (ret != 0) {
+    ret = recv_message((uint8_t *)msg_type, msg_size, (uint8_t **)msg);
+
+    if (ret < 0) {
+      // Try again (non-fatal error)
+      if (ret == -1 && (errno == EINTR || errno == EAGAIN)) continue;
+
+      fprintf(stderr, "Error receiving response from socket. ");
+      fprintf(stderr, "The connection might have been lost.\n");
+      exit(2);
+    }
+  }
+
+  return 0;
+}
+
+static ssize_t
+write_socket(const void *buf, size_t count)
+{
+  size_t written = 0;
+
+  while (written < count) {
+    const ssize_t n =
+        write(sock_fd, ((uint8_t *)buf) + written, count - written);
+
+    if (n == -1) {
+      if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
+        continue;
+      else
+        return n;
+    }
+    written += n;
+  }
+  return written;
+}
+
+static void
+connect_to_socket()
+{
+  struct sockaddr_un addr;
+
+  int sock = socket(AF_UNIX, SOCK_STREAM, 0);
+
+  // Initialize struct to 0
+  memset(&addr, 0, sizeof(struct sockaddr_un));
+
+  addr.sun_family = AF_UNIX;
+  strcpy(addr.sun_path, DEFAULT_SOCKET_PATH);
+
+  connect(sock, (const struct sockaddr *)&addr, sizeof(struct sockaddr_un));
+
+  sock_fd = sock;
+}
+
+static int
+send_message(IPCMessageType msg_type, uint32_t msg_size, uint8_t *msg)
+{
+  dwm_ipc_header_t header = {
+      .magic = IPC_MAGIC_ARR, .size = msg_size, .type = msg_type};
+
+  size_t header_size = sizeof(dwm_ipc_header_t);
+  size_t total_size = header_size + msg_size;
+
+  uint8_t buffer[total_size];
+
+  // Copy header to buffer
+  memcpy(buffer, &header, header_size);
+  // Copy message to buffer
+  memcpy(buffer + header_size, msg, header.size);
+
+  write_socket(buffer, total_size);
+
+  return 0;
+}
+
+static int
+is_float(const char *s)
+{
+  size_t len = strlen(s);
+  int is_dot_used = 0;
+  int is_minus_used = 0;
+
+  // Floats can only have one decimal point in between or digits
+  // Optionally, floats can also be below zero (negative)
+  for (int i = 0; i < len; i++) {
+    if (isdigit(s[i]))
+      continue;
+    else if (!is_dot_used && s[i] == '.' && i != 0 && i != len - 1) {
+      is_dot_used = 1;
+      continue;
+    } else if (!is_minus_used && s[i] == '-' && i == 0) {
+      is_minus_used = 1;
+      continue;
+    } else
+      return 0;
+  }
+
+  return 1;
+}
+
+static int
+is_unsigned_int(const char *s)
+{
+  size_t len = strlen(s);
+
+  // Unsigned int can only have digits
+  for (int i = 0; i < len; i++) {
+    if (isdigit(s[i]))
+      continue;
+    else
+      return 0;
+  }
+
+  return 1;
+}
+
+static int
+is_signed_int(const char *s)
+{
+  size_t len = strlen(s);
+
+  // Signed int can only have digits and a negative sign at the start
+  for (int i = 0; i < len; i++) {
+    if (isdigit(s[i]))
+      continue;
+    else if (i == 0 && s[i] == '-') {
+      continue;
+    } else
+      return 0;
+  }
+
+  return 1;
+}
+
+static void
+flush_socket_reply()
+{
+  IPCMessageType reply_type;
+  uint32_t reply_size;
+  char *reply;
+
+  read_socket(&reply_type, &reply_size, &reply);
+
+  free(reply);
+}
+
+static void
+print_socket_reply()
+{
+  IPCMessageType reply_type;
+  uint32_t reply_size;
+  char *reply;
+
+  read_socket(&reply_type, &reply_size, &reply);
+
+  printf("%.*s\n", reply_size, reply);
+  fflush(stdout);
+  free(reply);
+}
+
+static int
+run_command(const char *name, char *args[], int argc)
+{
+  const unsigned char *msg;
+  size_t msg_size;
+
+  yajl_gen gen = yajl_gen_alloc(NULL);
+
+  // Message format:
+  // {
+  //   "command": "<name>",
+  //   "args": [ ... ]
+  // }
+  // clang-format off
+  YMAP(
+    YSTR("command"); YSTR(name);
+    YSTR("args"); YARR(
+      for (int i = 0; i < argc; i++) {
+        if (is_signed_int(args[i])) {
+          long long num = atoll(args[i]);
+          YINT(num);
+        } else if (is_float(args[i])) {
+          float num = atof(args[i]);
+          YDOUBLE(num);
+        } else {
+          YSTR(args[i]);
+        }
+      }
+    )
+  )
+  // clang-format on
+
+  yajl_gen_get_buf(gen, &msg, &msg_size);
+
+  send_message(IPC_TYPE_RUN_COMMAND, msg_size, (uint8_t *)msg);
+
+  if (!ignore_reply)
+    print_socket_reply();
+  else
+    flush_socket_reply();
+
+  yajl_gen_free(gen);
+
+  return 0;
+}
+
+static int
+get_monitors()
+{
+  send_message(IPC_TYPE_GET_MONITORS, 1, (uint8_t *)"");
+  print_socket_reply();
+  return 0;
+}
+
+static int
+get_tags()
+{
+  send_message(IPC_TYPE_GET_TAGS, 1, (uint8_t *)"");
+  print_socket_reply();
+
+  return 0;
+}
+
+static int
+get_layouts()
+{
+  send_message(IPC_TYPE_GET_LAYOUTS, 1, (uint8_t *)"");
+  print_socket_reply();
+
+  return 0;
+}
+
+static int
+get_dwm_client(Window win)
+{
+  const unsigned char *msg;
+  size_t msg_size;
+
+  yajl_gen gen = yajl_gen_alloc(NULL);
+
+  // Message format:
+  // {
+  //   "client_window_id": "<win>"
+  // }
+  // clang-format off
+  YMAP(
+    YSTR("client_window_id"); YINT(win);
+  )
+  // clang-format on
+
+  yajl_gen_get_buf(gen, &msg, &msg_size);
+
+  send_message(IPC_TYPE_GET_DWM_CLIENT, msg_size, (uint8_t *)msg);
+
+  print_socket_reply();
+
+  yajl_gen_free(gen);
+
+  return 0;
+}
+
+static int
+subscribe(const char *event)
+{
+  const unsigned char *msg;
+  size_t msg_size;
+
+  yajl_gen gen = yajl_gen_alloc(NULL);
+
+  // Message format:
+  // {
+  //   "event": "<event>",
+  //   "action": "subscribe"
+  // }
+  // clang-format off
+  YMAP(
+    YSTR("event"); YSTR(event);
+    YSTR("action"); YSTR("subscribe");
+  )
+  // clang-format on
+
+  yajl_gen_get_buf(gen, &msg, &msg_size);
+
+  send_message(IPC_TYPE_SUBSCRIBE, msg_size, (uint8_t *)msg);
+
+  if (!ignore_reply)
+    print_socket_reply();
+  else
+    flush_socket_reply();
+
+  yajl_gen_free(gen);
+
+  return 0;
+}
+
+static void
+usage_error(const char *prog_name, const char *format, ...)
+{
+  va_list args;
+  va_start(args, format);
+
+  fprintf(stderr, "Error: ");
+  vfprintf(stderr, format, args);
+  fprintf(stderr, "\nusage: %s <command> [...]\n", prog_name);
+  fprintf(stderr, "Try '%s help'\n", prog_name);
+
+  va_end(args);
+  exit(1);
+}
+
+static void
+print_usage(const char *name)
+{
+  printf("usage: %s [options] <command> [...]\n", name);
+  puts("");
+  puts("Commands:");
+  puts("  run_command <name> [args...]    Run an IPC command");
+  puts("");
+  puts("  get_monitors                    Get monitor properties");
+  puts("");
+  puts("  get_tags                        Get list of tags");
+  puts("");
+  puts("  get_layouts                     Get list of layouts");
+  puts("");
+  puts("  get_dwm_client <window_id>      Get dwm client proprties");
+  puts("");
+  puts("  subscribe [events...]           Subscribe to specified events");
+  puts("                                  Options: " IPC_EVENT_TAG_CHANGE ",");
+  puts("                                  " IPC_EVENT_LAYOUT_CHANGE ",");
+  puts("                                  " IPC_EVENT_CLIENT_FOCUS_CHANGE ",");
+  puts("                                  " IPC_EVENT_MONITOR_FOCUS_CHANGE ",");
+  puts("                                  " IPC_EVENT_FOCUSED_TITLE_CHANGE ",");
+  puts("                                  " IPC_EVENT_FOCUSED_STATE_CHANGE);
+  puts("");
+  puts("  help                            Display this message");
+  puts("");
+  puts("Options:");
+  puts("  --ignore-reply                  Don't print reply messages from");
+  puts("                                  run_command and subscribe.");
+  puts("");
+}
+
+int
+main(int argc, char *argv[])
+{
+  const char *prog_name = argv[0];
+
+  connect_to_socket();
+  if (sock_fd == -1) {
+    fprintf(stderr, "Failed to connect to socket\n");
+    return 1;
+  }
+
+  int i = 1;
+  if (i < argc && strcmp(argv[i], "--ignore-reply") == 0) {
+    ignore_reply = 1;
+    i++;
+  }
+
+  if (i >= argc) usage_error(prog_name, "Expected an argument, got none");
+
+  if (strcmp(argv[i], "help") == 0)
+    print_usage(prog_name);
+  else if (strcmp(argv[i], "run_command") == 0) {
+    if (++i >= argc) usage_error(prog_name, "No command specified");
+    // Command name
+    char *command = argv[i];
+    // Command arguments are everything after command name
+    char **command_args = argv + ++i;
+    // Number of command arguments
+    int command_argc = argc - i;
+    run_command(command, command_args, command_argc);
+  } else if (strcmp(argv[i], "get_monitors") == 0) {
+    get_monitors();
+  } else if (strcmp(argv[i], "get_tags") == 0) {
+    get_tags();
+  } else if (strcmp(argv[i], "get_layouts") == 0) {
+    get_layouts();
+  } else if (strcmp(argv[i], "get_dwm_client") == 0) {
+    if (++i < argc) {
+      if (is_unsigned_int(argv[i])) {
+        Window win = atol(argv[i]);
+        get_dwm_client(win);
+      } else
+        usage_error(prog_name, "Expected unsigned integer argument");
+    } else
+      usage_error(prog_name, "Expected the window id");
+  } else if (strcmp(argv[i], "subscribe") == 0) {
+    if (++i < argc) {
+      for (int j = i; j < argc; j++) subscribe(argv[j]);
+    } else
+      usage_error(prog_name, "Expected event name");
+    // Keep listening for events forever
+    while (1) {
+      print_socket_reply();
+    }
+  } else
+    usage_error(prog_name, "Invalid argument '%s'", argv[i]);
+
+  return 0;
+}

dwm.c

@@ -30,6 +30,7 @@
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <sys/epoll.h>
 #include <X11/cursorfont.h>
 #include <X11/keysym.h>
 #include <X11/Xatom.h>
@@ -67,9 +68,21 @@ enum { WMProtocols, WMDelete, WMState, WMTakeFocus, WMLast }; /* default atoms *
 enum { ClkTagBar, ClkLtSymbol, ClkStatusText, ClkWinTitle,
        ClkClientWin, ClkRootWin, ClkLast }; /* clicks */
 
+typedef struct TagState TagState;
+struct TagState {
+	int selected;
+	int occupied;
+	int urgent;
+};
+
+typedef struct ClientState ClientState;
+struct ClientState {
+	int isfixed, isfloating, isurgent, neverfocus, oldstate, isfullscreen;
+};
+
 typedef union {
-	int i;
-	unsigned int ui;
+	long i;
+	unsigned long ui;
 	float f;
 	const void *v;
 } Arg;
@@ -97,6 +110,7 @@ struct Client {
 	Client *snext;
 	Monitor *mon;
 	Window win;
+	ClientState prevstate;
 };
 
 typedef struct {
@@ -111,8 +125,10 @@ typedef struct {
 	void (*arrange)(Monitor *);
 } Layout;
 
+
 struct Monitor {
 	char ltsymbol[16];
+	char lastltsymbol[16];
 	float mfact;
 	int nmaster;
 	int num;
@@ -122,14 +138,17 @@ struct Monitor {
 	unsigned int seltags;
 	unsigned int sellt;
 	unsigned int tagset[2];
+	TagState tagstate;
 	int showbar;
 	int topbar;
 	Client *clients;
 	Client *sel;
+	Client *lastsel;
 	Client *stack;
 	Monitor *next;
 	Window barwin;
 	const Layout *lt[2];
+	const Layout *lastlt;
 };
 
 typedef struct {
@@ -175,6 +194,7 @@ static long getstate(Window w);
 static int gettextprop(Window w, Atom atom, char *text, unsigned int size);
 static void grabbuttons(Client *c, int focused);
 static void grabkeys(void);
+static int handlexevent(struct epoll_event *ev);
 static void incnmaster(const Arg *arg);
 static void keypress(XEvent *e);
 static void killclient(const Arg *arg);
@@ -201,8 +221,10 @@ static void setclientstate(Client *c, long state);
 static void setfocus(Client *c);
 static void setfullscreen(Client *c, int fullscreen);
 static void setlayout(const Arg *arg);
+static void setlayoutsafe(const Arg *arg);
 static void setmfact(const Arg *arg);
 static void setup(void);
+static void setupepoll(void);
 static void seturgent(Client *c, int urg);
 static void showhide(Client *c);
 static void sigchld(int unused);
@@ -261,17 +283,27 @@ static void (*handler[LASTEvent]) (XEvent *) = {
 	[UnmapNotify] = unmapnotify
 };
 static Atom wmatom[WMLast], netatom[NetLast];
+static int epoll_fd;
+static int dpy_fd;
 static int running = 1;
 static Cur *cursor[CurLast];
 static Clr **scheme;
 static Display *dpy;
 static Drw *drw;
-static Monitor *mons, *selmon;
+static Monitor *mons, *selmon, *lastselmon;
 static Window root, wmcheckwin;
 
+#include "ipc.h"
+
 /* configuration, allows nested code to access above variables */
 #include "config.h"
 
+#ifdef VERSION
+#include "IPCClient.c"
+#include "yajl_dumps.c"
+#include "ipc.c"
+#endif
+
 /* compile-time check if all tags fit into an unsigned int bit array. */
 struct NumTags { char limitexceeded[LENGTH(tags) > 31 ? -1 : 1]; };
 
@@ -492,6 +524,12 @@ cleanup(void)
 	XSync(dpy, False);
 	XSetInputFocus(dpy, PointerRoot, RevertToPointerRoot, CurrentTime);
 	XDeleteProperty(dpy, root, netatom[NetActiveWindow]);
+
+	ipc_cleanup();
+
+	if (close(epoll_fd) < 0) {
+			fprintf(stderr, "Failed to close epoll file descriptor\n");
+	}
 }
 
 void
@@ -967,6 +1005,25 @@ grabkeys(void)
 	}
 }
 
+int
+handlexevent(struct epoll_event *ev)
+{
+	if (ev->events & EPOLLIN) {
+		XEvent ev;
+		while (running && XPending(dpy)) {
+			XNextEvent(dpy, &ev);
+			if (handler[ev.type]) {
+				handler[ev.type](&ev); /* call handler */
+				ipc_send_events(mons, &lastselmon, selmon);
+			}
+		}
+	} else if (ev-> events & EPOLLHUP) {
+		return -1;
+	}
+
+	return 0;
+}
+
 void
 incnmaster(const Arg *arg)
 {
@@ -1376,12 +1433,40 @@ restack(Monitor *m)
 void
 run(void)
 {
-	XEvent ev;
-	/* main event loop */
+	int event_count = 0;
+	const int MAX_EVENTS = 10;
+	struct epoll_event events[MAX_EVENTS];
+
 	XSync(dpy, False);
-	while (running && !XNextEvent(dpy, &ev))
-		if (handler[ev.type])
-			handler[ev.type](&ev); /* call handler */
+
+	/* main event loop */
+	while (running) {
+		event_count = epoll_wait(epoll_fd, events, MAX_EVENTS, -1);
+
+		for (int i = 0; i < event_count; i++) {
+			int event_fd = events[i].data.fd;
+			DEBUG("Got event from fd %d\n", event_fd);
+
+			if (event_fd == dpy_fd) {
+				// -1 means EPOLLHUP
+				if (handlexevent(events + i) == -1)
+					return;
+			} else if (event_fd == ipc_get_sock_fd()) {
+				ipc_handle_socket_epoll_event(events + i);
+			} else if (ipc_is_client_registered(event_fd)){
+				if (ipc_handle_client_epoll_event(events + i, mons, &lastselmon, selmon,
+							tags, LENGTH(tags), layouts, LENGTH(layouts)) < 0) {
+					fprintf(stderr, "Error handling IPC event on fd %d\n", event_fd);
+				}
+			} else {
+				fprintf(stderr, "Got event from unknown fd %d, ptr %p, u32 %d, u64 %lu",
+						event_fd, events[i].data.ptr, events[i].data.u32,
+						events[i].data.u64);
+				fprintf(stderr, " with events %d\n", events[i].events);
+				return;
+			}
+		}
+	}
 }
 
 void
@@ -1515,6 +1600,18 @@ setlayout(const Arg *arg)
 		drawbar(selmon);
 }
 
+void
+setlayoutsafe(const Arg *arg)
+{
+	const Layout *ltptr = (Layout *)arg->v;
+	if (ltptr == 0)
+			setlayout(arg);
+	for (int i = 0; i < LENGTH(layouts); i++) {
+		if (ltptr == &layouts[i])
+			setlayout(arg);
+	}
+}
+
 /* arg > 1.0 will set mfact absolutely */
 void
 setmfact(const Arg *arg)
@@ -1598,8 +1695,37 @@ setup(void)
 	XSelectInput(dpy, root, wa.event_mask);
 	grabkeys();
 	focus(NULL);
+	setupepoll();
 }
 
+void
+setupepoll(void)
+{
+	epoll_fd = epoll_create1(0);
+	dpy_fd = ConnectionNumber(dpy);
+	struct epoll_event dpy_event;
+
+	// Initialize struct to 0
+	memset(&dpy_event, 0, sizeof(dpy_event));
+
+	DEBUG("Display socket is fd %d\n", dpy_fd);
+
+	if (epoll_fd == -1) {
+		fputs("Failed to create epoll file descriptor", stderr);
+	}
+
+	dpy_event.events = EPOLLIN;
+	dpy_event.data.fd = dpy_fd;
+	if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, dpy_fd, &dpy_event)) {
+		fputs("Failed to add display file descriptor to epoll", stderr);
+		close(epoll_fd);
+		exit(1);
+	}
+
+	if (ipc_init(ipcsockpath, epoll_fd, ipccommands, LENGTH(ipccommands)) < 0) {
+		fputs("Failed to initialize IPC\n", stderr);
+	}
+}
 
 void
 seturgent(Client *c, int urg)
@@ -2001,10 +2127,18 @@ updatestatus(void)
 void
 updatetitle(Client *c)
 {
+	char oldname[sizeof(c->name)];
+	strcpy(oldname, c->name);
+
 	if (!gettextprop(c->win, netatom[NetWMName], c->name, sizeof c->name))
 		gettextprop(c->win, XA_WM_NAME, c->name, sizeof c->name);
 	if (c->name[0] == '\0') /* hack to mark broken clients */
 		strcpy(c->name, broken);
+
+	for (Monitor *m = mons; m; m = m->next) {
+		if (m->sel == c && strcmp(oldname, c->name) != 0)
+			ipc_focused_title_change_event(m->num, c->win, oldname, c->name);
+	}
 }
 
 void

ipc.h

@@ -0,0 +1,320 @@
+#ifndef IPC_H_
+#define IPC_H_
+
+#include <stdint.h>
+#include <sys/epoll.h>
+#include <yajl/yajl_gen.h>
+
+#include "IPCClient.h"
+
+// clang-format off
+#define IPC_MAGIC "DWM-IPC"
+#define IPC_MAGIC_ARR { 'D', 'W', 'M', '-', 'I', 'P', 'C'}
+#define IPC_MAGIC_LEN 7 // Not including null char
+
+#define IPCCOMMAND(FUNC, ARGC, TYPES)                                          \
+  { #FUNC, {FUNC }, ARGC, (ArgType[ARGC])TYPES }
+// clang-format on
+
+typedef enum IPCMessageType {
+  IPC_TYPE_RUN_COMMAND = 0,
+  IPC_TYPE_GET_MONITORS = 1,
+  IPC_TYPE_GET_TAGS = 2,
+  IPC_TYPE_GET_LAYOUTS = 3,
+  IPC_TYPE_GET_DWM_CLIENT = 4,
+  IPC_TYPE_SUBSCRIBE = 5,
+  IPC_TYPE_EVENT = 6
+} IPCMessageType;
+
+typedef enum IPCEvent {
+  IPC_EVENT_TAG_CHANGE = 1 << 0,
+  IPC_EVENT_CLIENT_FOCUS_CHANGE = 1 << 1,
+  IPC_EVENT_LAYOUT_CHANGE = 1 << 2,
+  IPC_EVENT_MONITOR_FOCUS_CHANGE = 1 << 3,
+  IPC_EVENT_FOCUSED_TITLE_CHANGE = 1 << 4,
+  IPC_EVENT_FOCUSED_STATE_CHANGE = 1 << 5
+} IPCEvent;
+
+typedef enum IPCSubscriptionAction {
+  IPC_ACTION_UNSUBSCRIBE = 0,
+  IPC_ACTION_SUBSCRIBE = 1
+} IPCSubscriptionAction;
+
+/**
+ * Every IPC packet starts with this structure
+ */
+typedef struct dwm_ipc_header {
+  uint8_t magic[IPC_MAGIC_LEN];
+  uint32_t size;
+  uint8_t type;
+} __attribute((packed)) dwm_ipc_header_t;
+
+typedef enum ArgType {
+  ARG_TYPE_NONE = 0,
+  ARG_TYPE_UINT = 1,
+  ARG_TYPE_SINT = 2,
+  ARG_TYPE_FLOAT = 3,
+  ARG_TYPE_PTR = 4,
+  ARG_TYPE_STR = 5
+} ArgType;
+
+/**
+ * An IPCCommand function can have either of these function signatures
+ */
+typedef union ArgFunction {
+  void (*single_param)(const Arg *);
+  void (*array_param)(const Arg *, int);
+} ArgFunction;
+
+typedef struct IPCCommand {
+  char *name;
+  ArgFunction func;
+  unsigned int argc;
+  ArgType *arg_types;
+} IPCCommand;
+
+typedef struct IPCParsedCommand {
+  char *name;
+  Arg *args;
+  ArgType *arg_types;
+  unsigned int argc;
+} IPCParsedCommand;
+
+/**
+ * Initialize the IPC socket and the IPC module
+ *
+ * @param socket_path Path to create the socket at
+ * @param epoll_fd File descriptor for epoll
+ * @param commands Address of IPCCommands array defined in config.h
+ * @param commands_len Length of commands[] array
+ *
+ * @return int The file descriptor of the socket if it was successfully created,
+ *   -1 otherwise
+ */
+int ipc_init(const char *socket_path, const int p_epoll_fd,
+             IPCCommand commands[], const int commands_len);
+
+/**
+ * Uninitialize the socket and module. Free allocated memory and restore static
+ * variables to their state before ipc_init
+ */
+void ipc_cleanup();
+
+/**
+ * Get the file descriptor of the IPC socket
+ *
+ * @return int File descriptor of IPC socket, -1 if socket not created.
+ */
+int ipc_get_sock_fd();
+
+/**
+ * Get address to IPCClient with specified file descriptor
+ *
+ * @param fd File descriptor of IPC Client
+ *
+ * @return Address to IPCClient with specified file descriptor, -1 otherwise
+ */
+IPCClient *ipc_get_client(int fd);
+
+/**
+ * Check if an IPC client exists with the specified file descriptor
+ *
+ * @param fd File descriptor
+ *
+ * @return int 1 if client exists, 0 otherwise
+ */
+int ipc_is_client_registered(int fd);
+
+/**
+ * Disconnect an IPCClient from the socket and remove the client from the list
+ *   of known connected clients
+ *
+ * @param c Address of IPCClient
+ *
+ * @return 0 if the client's file descriptor was closed successfully, the
+ * result of executing close() on the file descriptor otherwise.
+ */
+int ipc_drop_client(IPCClient *c);
+
+/**
+ * Accept an IPC Client requesting to connect to the socket and add it to the
+ *   list of clients
+ *
+ * @return File descriptor of new client, -1 on error
+ */
+int ipc_accept_client();
+
+/**
+ * Read an incoming message from an accepted IPC client
+ *
+ * @param c Address of IPCClient
+ * @param msg_type Address to IPCMessageType variable which will be assigned
+ *   the message type of the received message
+ * @param msg_size Address to uint32_t variable which will be assigned the size
+ *   of the received message
+ * @param msg Address to char* variable which will be assigned the address of
+ *   the received message. This must be freed using free().
+ *
+ * @return 0 on success, -1 on error reading message, -2 if reading the message
+ * resulted in EAGAIN, EINTR, or EWOULDBLOCK.
+ */
+int ipc_read_client(IPCClient *c, IPCMessageType *msg_type, uint32_t *msg_size,
+                    char **msg);
+
+/**
+ * Write any pending buffer of the client to the client's socket
+ *
+ * @param c Client whose buffer to write
+ *
+ * @return Number of bytes written >= 0, -1 otherwise. errno will still be set
+ * from the write operation.
+ */
+ssize_t ipc_write_client(IPCClient *c);
+
+/**
+ * Prepare a message in the specified client's buffer.
+ *
+ * @param c Client to prepare message for
+ * @param msg_type Type of message to prepare
+ * @param msg_size Size of the message in bytes. Should not exceed
+ *   MAX_MESSAGE_SIZE
+ * @param msg Message to prepare (not including header). This pointer can be
+ *   freed after the function invocation.
+ */
+void ipc_prepare_send_message(IPCClient *c, const IPCMessageType msg_type,
+                              const uint32_t msg_size, const char *msg);
+
+/**
+ * Prepare an error message in the specified client's buffer
+ *
+ * @param c Client to prepare message for
+ * @param msg_type Type of message
+ * @param format Format string following vsprintf
+ * @param ... Arguments for format string
+ */
+void ipc_prepare_reply_failure(IPCClient *c, IPCMessageType msg_type,
+                               const char *format, ...);
+
+/**
+ * Prepare a success message in the specified client's buffer
+ *
+ * @param c Client to prepare message for
+ * @param msg_type Type of message
+ */
+void ipc_prepare_reply_success(IPCClient *c, IPCMessageType msg_type);
+
+/**
+ * Send a tag_change_event to all subscribers. Should be called only when there
+ * has been a tag state change.
+ *
+ * @param mon_num The index of the monitor (Monitor.num property)
+ * @param old_state The old tag state
+ * @param new_state The new (now current) tag state
+ */
+void ipc_tag_change_event(const int mon_num, TagState old_state,
+                          TagState new_state);
+
+/**
+ * Send a client_focus_change_event to all subscribers. Should be called only
+ * when the client focus changes.
+ *
+ * @param mon_num The index of the monitor (Monitor.num property)
+ * @param old_client The old DWM client selection (Monitor.oldsel)
+ * @param new_client The new (now current) DWM client selection
+ */
+void ipc_client_focus_change_event(const int mon_num, Client *old_client,
+                                   Client *new_client);
+
+/**
+ * Send a layout_change_event to all subscribers. Should be called only
+ * when there has been a layout change.
+ *
+ * @param mon_num The index of the monitor (Monitor.num property)
+ * @param old_symbol The old layout symbol
+ * @param old_layout Address to the old Layout
+ * @param new_symbol The new (now current) layout symbol
+ * @param new_layout Address to the new Layout
+ */
+void ipc_layout_change_event(const int mon_num, const char *old_symbol,
+                             const Layout *old_layout, const char *new_symbol,
+                             const Layout *new_layout);
+
+/**
+ * Send a monitor_focus_change_event to all subscribers. Should be called only
+ * when the monitor focus changes.
+ *
+ * @param last_mon_num The index of the previously selected monitor
+ * @param new_mon_num The index of the newly selected monitor
+ */
+void ipc_monitor_focus_change_event(const int last_mon_num,
+                                    const int new_mon_num);
+
+/**
+ * Send a focused_title_change_event to all subscribers. Should only be called
+ * if a selected client has a title change.
+ *
+ * @param mon_num Index of the client's monitor
+ * @param client_id Window XID of client
+ * @param old_name Old name of the client window
+ * @param new_name New name of the client window
+ */
+void ipc_focused_title_change_event(const int mon_num, const Window client_id,
+                                    const char *old_name, const char *new_name);
+
+/**
+ * Send a focused_state_change_event to all subscribers. Should only be called
+ * if a selected client has a state change.
+ *
+ * @param mon_num Index of the client's monitor
+ * @param client_id Window XID of client
+ * @param old_state Old state of the client
+ * @param new_state New state of the client
+ */
+void ipc_focused_state_change_event(const int mon_num, const Window client_id,
+                                    const ClientState *old_state,
+                                    const ClientState *new_state);
+/**
+ * Check to see if an event has occured and call the *_change_event functions
+ * accordingly
+ *
+ * @param mons Address of Monitor pointing to start of linked list
+ * @param lastselmon Address of pointer to previously selected monitor
+ * @param selmon Address of selected Monitor
+ */
+void ipc_send_events(Monitor *mons, Monitor **lastselmon, Monitor *selmon);
+
+/**
+ * Handle an epoll event caused by a registered IPC client. Read, process, and
+ * handle any received messages from clients. Write pending buffer to client if
+ * the client is ready to receive messages. Drop clients that have sent an
+ * EPOLLHUP.
+ *
+ * @param ev Associated epoll event returned by epoll_wait
+ * @param mons Address of Monitor pointing to start of linked list
+ * @param selmon Address of selected Monitor
+ * @param lastselmon Address of pointer to previously selected monitor
+ * @param tags Array of tag names
+ * @param tags_len Length of tags array
+ * @param layouts Array of available layouts
+ * @param layouts_len Length of layouts array
+ *
+ * @return 0 if event was successfully handled, -1 on any error receiving
+ * or handling incoming messages or unhandled epoll event.
+ */
+int ipc_handle_client_epoll_event(struct epoll_event *ev, Monitor *mons,
+                                  Monitor **lastselmon, Monitor *selmon,
+                                  const char *tags[], const int tags_len,
+                                  const Layout *layouts, const int layouts_len);
+
+/**
+ * Handle an epoll event caused by the IPC socket. This function only handles an
+ * EPOLLIN event indicating a new client requesting to connect to the socket.
+ *
+ * @param ev Associated epoll event returned by epoll_wait
+ *
+ * @return 0, if the event was successfully handled, -1 if not an EPOLLIN event
+ * or if a new IPC client connection request could not be accepted.
+ */
+int ipc_handle_socket_epoll_event(struct epoll_event *ev);
+
+#endif /* IPC_H_ */

util.c

@@ -3,6 +3,8 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <errno.h>
+#include <sys/stat.h>
 
 #include "util.h"
 
@@ -33,3 +35,136 @@ die(const char *fmt, ...) {
 
 	exit(1);
 }
+
+int
+normalizepath(const char *path, char **normal)
+{
+  size_t len = strlen(path);
+  *normal = (char *)malloc((len + 1) * sizeof(char));
+  const char *walk = path;
+  const char *match;
+  size_t newlen = 0;
+
+  while ((match = strchr(walk, '/'))) {
+    // Copy everything between match and walk
+    strncpy(*normal + newlen, walk, match - walk);
+    newlen += match - walk;
+    walk += match - walk;
+
+    // Skip all repeating slashes
+    while (*walk == '/')
+      walk++;
+
+    // If not last character in path
+    if (walk != path + len)
+      (*normal)[newlen++] = '/';
+  }
+
+  (*normal)[newlen++] = '\0';
+
+  // Copy remaining path
+  strcat(*normal, walk);
+  newlen += strlen(walk);
+
+  *normal = (char *)realloc(*normal, newlen * sizeof(char));
+
+  return 0;
+}
+
+int
+parentdir(const char *path, char **parent)
+{
+  char *normal;
+  char *walk;
+
+  normalizepath(path, &normal);
+
+  // Pointer to last '/'
+  if (!(walk = strrchr(normal, '/'))) {
+    free(normal);
+    return -1;
+  }
+
+  // Get path up to last '/'
+  size_t len = walk - normal;
+  *parent = (char *)malloc((len + 1) * sizeof(char));
+
+  // Copy path up to last '/'
+  strncpy(*parent, normal, len);
+  // Add null char
+  (*parent)[len] = '\0';
+
+  free(normal);
+
+  return 0;
+}
+
+int
+mkdirp(const char *path)
+{
+  char *normal;
+  char *walk;
+  size_t normallen;
+
+  normalizepath(path, &normal);
+  normallen = strlen(normal);
+  walk = normal;
+
+  while (walk < normal + normallen + 1) {
+    // Get length from walk to next /
+    size_t n = strcspn(walk, "/");
+
+    // Skip path /
+    if (n == 0) {
+      walk++;
+      continue;
+    }
+
+    // Length of current path segment
+    size_t curpathlen = walk - normal + n;
+    char curpath[curpathlen + 1];
+    struct stat s;
+
+    // Copy path segment to stat
+    strncpy(curpath, normal, curpathlen);
+    strcpy(curpath + curpathlen, "");
+    int res = stat(curpath, &s);
+
+    if (res < 0) {
+      if (errno == ENOENT) {
+        DEBUG("Making directory %s\n", curpath);
+        if (mkdir(curpath, 0700) < 0) {
+          fprintf(stderr, "Failed to make directory %s\n", curpath);
+          perror("");
+          free(normal);
+          return -1;
+        }
+      } else {
+        fprintf(stderr, "Error statting directory %s\n", curpath);
+        perror("");
+        free(normal);
+        return -1;
+      }
+    }
+
+    // Continue to next path segment
+    walk += n;
+  }
+
+  free(normal);
+
+  return 0;
+}
+
+int
+nullterminate(char **str, size_t *len)
+{
+  if ((*str)[*len - 1] == '\0')
+    return 0;
+
+  (*len)++;
+  *str = (char*)realloc(*str, *len * sizeof(char));
+  (*str)[*len - 1] = '\0';
+
+  return 0;
+}

util.h

@@ -4,5 +4,15 @@
 #define MIN(A, B)               ((A) < (B) ? (A) : (B))
 #define BETWEEN(X, A, B)        ((A) <= (X) && (X) <= (B))
 
+#ifdef _DEBUG
+#define DEBUG(...) fprintf(stderr, __VA_ARGS__)
+#else
+#define DEBUG(...)
+#endif
+
 void die(const char *fmt, ...);
 void *ecalloc(size_t nmemb, size_t size);
+int normalizepath(const char *path, char **normal);
+int mkdirp(const char *path);
+int parentdir(const char *path, char **parent);
+int nullterminate(char **str, size_t *len);

yajl_dumps.c

@@ -0,0 +1,351 @@
+#include "yajl_dumps.h"
+
+#include <stdint.h>
+
+int
+dump_tag(yajl_gen gen, const char *name, const int tag_mask)
+{
+  // clang-format off
+  YMAP(
+    YSTR("bit_mask"); YINT(tag_mask);
+    YSTR("name"); YSTR(name);
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_tags(yajl_gen gen, const char *tags[], int tags_len)
+{
+  // clang-format off
+  YARR(
+    for (int i = 0; i < tags_len; i++)
+      dump_tag(gen, tags[i], 1 << i);
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_client(yajl_gen gen, Client *c)
+{
+  // clang-format off
+  YMAP(
+    YSTR("name"); YSTR(c->name);
+    YSTR("tags"); YINT(c->tags);
+    YSTR("window_id"); YINT(c->win);
+    YSTR("monitor_number"); YINT(c->mon->num);
+
+    YSTR("geometry"); YMAP(
+      YSTR("current"); YMAP (
+        YSTR("x"); YINT(c->x);
+        YSTR("y"); YINT(c->y);
+        YSTR("width"); YINT(c->w);
+        YSTR("height"); YINT(c->h);
+      )
+      YSTR("old"); YMAP(
+        YSTR("x"); YINT(c->oldx);
+        YSTR("y"); YINT(c->oldy);
+        YSTR("width"); YINT(c->oldw);
+        YSTR("height"); YINT(c->oldh);
+      )
+    )
+
+    YSTR("size_hints"); YMAP(
+      YSTR("base"); YMAP(
+        YSTR("width"); YINT(c->basew);
+        YSTR("height"); YINT(c->baseh);
+      )
+      YSTR("step"); YMAP(
+        YSTR("width"); YINT(c->incw);
+        YSTR("height"); YINT(c->inch);
+      )
+      YSTR("max"); YMAP(
+        YSTR("width"); YINT(c->maxw);
+        YSTR("height"); YINT(c->maxh);
+      )
+      YSTR("min"); YMAP(
+        YSTR("width"); YINT(c->minw);
+        YSTR("height"); YINT(c->minh);
+      )
+      YSTR("aspect_ratio"); YMAP(
+        YSTR("min"); YDOUBLE(c->mina);
+        YSTR("max"); YDOUBLE(c->maxa);
+      )
+    )
+
+    YSTR("border_width"); YMAP(
+      YSTR("current"); YINT(c->bw);
+      YSTR("old"); YINT(c->oldbw);
+    )
+
+    YSTR("states"); YMAP(
+      YSTR("is_fixed"); YBOOL(c->isfixed);
+      YSTR("is_floating"); YBOOL(c->isfloating);
+      YSTR("is_urgent"); YBOOL(c->isurgent);
+      YSTR("never_focus"); YBOOL(c->neverfocus);
+      YSTR("old_state"); YBOOL(c->oldstate);
+      YSTR("is_fullscreen"); YBOOL(c->isfullscreen);
+    )
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_monitor(yajl_gen gen, Monitor *mon, int is_selected)
+{
+  // clang-format off
+  YMAP(
+    YSTR("master_factor"); YDOUBLE(mon->mfact);
+    YSTR("num_master"); YINT(mon->nmaster);
+    YSTR("num"); YINT(mon->num);
+    YSTR("is_selected"); YBOOL(is_selected);
+
+    YSTR("monitor_geometry"); YMAP(
+      YSTR("x"); YINT(mon->mx);
+      YSTR("y"); YINT(mon->my);
+      YSTR("width"); YINT(mon->mw);
+      YSTR("height"); YINT(mon->mh);
+    )
+
+    YSTR("window_geometry"); YMAP(
+      YSTR("x"); YINT(mon->wx);
+      YSTR("y"); YINT(mon->wy);
+      YSTR("width"); YINT(mon->ww);
+      YSTR("height"); YINT(mon->wh);
+    )
+
+    YSTR("tagset"); YMAP(
+      YSTR("current");  YINT(mon->tagset[mon->seltags]);
+      YSTR("old"); YINT(mon->tagset[mon->seltags ^ 1]);
+    )
+
+    YSTR("tag_state"); dump_tag_state(gen, mon->tagstate);
+
+    YSTR("clients"); YMAP(
+      YSTR("selected"); YINT(mon->sel ? mon->sel->win : 0);
+      YSTR("stack"); YARR(
+        for (Client* c = mon->stack; c; c = c->snext)
+          YINT(c->win);
+      )
+      YSTR("all"); YARR(
+        for (Client* c = mon->clients; c; c = c->next)
+          YINT(c->win);
+      )
+    )
+
+    YSTR("layout"); YMAP(
+      YSTR("symbol"); YMAP(
+        YSTR("current"); YSTR(mon->ltsymbol);
+        YSTR("old"); YSTR(mon->lastltsymbol);
+      )
+      YSTR("address"); YMAP(
+        YSTR("current"); YINT((uintptr_t)mon->lt[mon->sellt]);
+        YSTR("old"); YINT((uintptr_t)mon->lt[mon->sellt ^ 1]);
+      )
+    )
+
+    YSTR("bar"); YMAP(
+      YSTR("y"); YINT(mon->by);
+      YSTR("is_shown"); YBOOL(mon->showbar);
+      YSTR("is_top"); YBOOL(mon->topbar);
+      YSTR("window_id"); YINT(mon->barwin);
+    )
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_monitors(yajl_gen gen, Monitor *mons, Monitor *selmon)
+{
+  // clang-format off
+  YARR(
+    for (Monitor *mon = mons; mon; mon = mon->next) {
+      if (mon == selmon)
+        dump_monitor(gen, mon, 1);
+      else
+        dump_monitor(gen, mon, 0);
+    }
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_layouts(yajl_gen gen, const Layout layouts[], const int layouts_len)
+{
+  // clang-format off
+  YARR(
+    for (int i = 0; i < layouts_len; i++) {
+      YMAP(
+        // Check for a NULL pointer. The cycle layouts patch adds an entry at
+        // the end of the layouts array with a NULL pointer for the symbol
+        YSTR("symbol"); YSTR((layouts[i].symbol ? layouts[i].symbol : ""));
+        YSTR("address"); YINT((uintptr_t)(layouts + i));
+      )
+    }
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_tag_state(yajl_gen gen, TagState state)
+{
+  // clang-format off
+  YMAP(
+    YSTR("selected"); YINT(state.selected);
+    YSTR("occupied"); YINT(state.occupied);
+    YSTR("urgent"); YINT(state.urgent);
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_tag_event(yajl_gen gen, int mon_num, TagState old_state,
+               TagState new_state)
+{
+  // clang-format off
+  YMAP(
+    YSTR("tag_change_event"); YMAP(
+      YSTR("monitor_number"); YINT(mon_num);
+      YSTR("old_state"); dump_tag_state(gen, old_state);
+      YSTR("new_state"); dump_tag_state(gen, new_state);
+    )
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_client_focus_change_event(yajl_gen gen, Client *old_client,
+                               Client *new_client, int mon_num)
+{
+  // clang-format off
+  YMAP(
+    YSTR("client_focus_change_event"); YMAP(
+      YSTR("monitor_number"); YINT(mon_num);
+      YSTR("old_win_id"); old_client == NULL ? YNULL() : YINT(old_client->win);
+      YSTR("new_win_id"); new_client == NULL ? YNULL() : YINT(new_client->win);
+    )
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_layout_change_event(yajl_gen gen, const int mon_num,
+                         const char *old_symbol, const Layout *old_layout,
+                         const char *new_symbol, const Layout *new_layout)
+{
+  // clang-format off
+  YMAP(
+    YSTR("layout_change_event"); YMAP(
+      YSTR("monitor_number"); YINT(mon_num);
+      YSTR("old_symbol"); YSTR(old_symbol);
+      YSTR("old_address"); YINT((uintptr_t)old_layout);
+      YSTR("new_symbol"); YSTR(new_symbol);
+      YSTR("new_address"); YINT((uintptr_t)new_layout);
+    )
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_monitor_focus_change_event(yajl_gen gen, const int last_mon_num,
+                                const int new_mon_num)
+{
+  // clang-format off
+  YMAP(
+    YSTR("monitor_focus_change_event"); YMAP(
+      YSTR("old_monitor_number"); YINT(last_mon_num);
+      YSTR("new_monitor_number"); YINT(new_mon_num);
+    )
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_focused_title_change_event(yajl_gen gen, const int mon_num,
+                                const Window client_id, const char *old_name,
+                                const char *new_name)
+{
+  // clang-format off
+  YMAP(
+    YSTR("focused_title_change_event"); YMAP(
+      YSTR("monitor_number"); YINT(mon_num);
+      YSTR("client_window_id"); YINT(client_id);
+      YSTR("old_name"); YSTR(old_name);
+      YSTR("new_name"); YSTR(new_name);
+    )
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_client_state(yajl_gen gen, const ClientState *state)
+{
+  // clang-format off
+  YMAP(
+    YSTR("old_state"); YBOOL(state->oldstate);
+    YSTR("is_fixed"); YBOOL(state->isfixed);
+    YSTR("is_floating"); YBOOL(state->isfloating);
+    YSTR("is_fullscreen"); YBOOL(state->isfullscreen);
+    YSTR("is_urgent"); YBOOL(state->isurgent);
+    YSTR("never_focus"); YBOOL(state->neverfocus);
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_focused_state_change_event(yajl_gen gen, const int mon_num,
+                                const Window client_id,
+                                const ClientState *old_state,
+                                const ClientState *new_state)
+{
+  // clang-format off
+  YMAP(
+    YSTR("focused_state_change_event"); YMAP(
+      YSTR("monitor_number"); YINT(mon_num);
+      YSTR("client_window_id"); YINT(client_id);
+      YSTR("old_state"); dump_client_state(gen, old_state);
+      YSTR("new_state"); dump_client_state(gen, new_state);
+    )
+  )
+  // clang-format on
+
+  return 0;
+}
+
+int
+dump_error_message(yajl_gen gen, const char *reason)
+{
+  // clang-format off
+  YMAP(
+    YSTR("result"); YSTR("error");
+    YSTR("reason"); YSTR(reason);
+  )
+  // clang-format on
+
+  return 0;
+}

yajl_dumps.h

@@ -0,0 +1,65 @@
+#ifndef YAJL_DUMPS_H_
+#define YAJL_DUMPS_H_
+
+#include <string.h>
+#include <yajl/yajl_gen.h>
+
+#define YSTR(str) yajl_gen_string(gen, (unsigned char *)str, strlen(str))
+#define YINT(num) yajl_gen_integer(gen, num)
+#define YDOUBLE(num) yajl_gen_double(gen, num)
+#define YBOOL(v) yajl_gen_bool(gen, v)
+#define YNULL() yajl_gen_null(gen)
+#define YARR(body)                                                             \
+  {                                                                            \
+    yajl_gen_array_open(gen);                                                  \
+    body;                                                                      \
+    yajl_gen_array_close(gen);                                                 \
+  }
+#define YMAP(body)                                                             \
+  {                                                                            \
+    yajl_gen_map_open(gen);                                                    \
+    body;                                                                      \
+    yajl_gen_map_close(gen);                                                   \
+  }
+
+int dump_tag(yajl_gen gen, const char *name, const int tag_mask);
+
+int dump_tags(yajl_gen gen, const char *tags[], int tags_len);
+
+int dump_client(yajl_gen gen, Client *c);
+
+int dump_monitor(yajl_gen gen, Monitor *mon, int is_selected);
+
+int dump_monitors(yajl_gen gen, Monitor *mons, Monitor *selmon);
+
+int dump_layouts(yajl_gen gen, const Layout layouts[], const int layouts_len);
+
+int dump_tag_state(yajl_gen gen, TagState state);
+
+int dump_tag_event(yajl_gen gen, int mon_num, TagState old_state,
+                   TagState new_state);
+
+int dump_client_focus_change_event(yajl_gen gen, Client *old_client,
+                                   Client *new_client, int mon_num);
+
+int dump_layout_change_event(yajl_gen gen, const int mon_num,
+                             const char *old_symbol, const Layout *old_layout,
+                             const char *new_symbol, const Layout *new_layout);
+
+int dump_monitor_focus_change_event(yajl_gen gen, const int last_mon_num,
+                                    const int new_mon_num);
+
+int dump_focused_title_change_event(yajl_gen gen, const int mon_num,
+                                    const Window client_id,
+                                    const char *old_name, const char *new_name);
+
+int dump_client_state(yajl_gen gen, const ClientState *state);
+
+int dump_focused_state_change_event(yajl_gen gen, const int mon_num,
+                                    const Window client_id,
+                                    const ClientState *old_state,
+                                    const ClientState *new_state);
+
+int dump_error_message(yajl_gen gen, const char *reason);
+
+#endif  // YAJL_DUMPS_H_