dwm

ipc.c (34017B)

---

 #include "ipc.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/epoll.h>
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <unistd.h>
 #include <yajl/yajl_gen.h>
 #include <yajl/yajl_tree.h>
 
 #include "util.h"
 #include "yajl_dumps.h"
 
 static struct sockaddr_un sockaddr;
 static struct epoll_event sock_epoll_event;
 static IPCClientList ipc_clients = NULL;
 static int epoll_fd = -1;
 static int sock_fd = -1;
 static IPCCommand *ipc_commands;
 static unsigned int ipc_commands_len;
 // Max size is 1 MB
 static const uint32_t MAX_MESSAGE_SIZE = 1000000;
 static const int IPC_SOCKET_BACKLOG = 5;
 
 /**
  * Create IPC socket at specified path and return file descriptor to socket.
  * This initializes the static variable sockaddr.
  */
 static int
 ipc_create_socket(const char *filename)
 {
   char *normal_filename;
   char *parent;
   const size_t addr_size = sizeof(struct sockaddr_un);
   const int sock_type = SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC;
 
   normalizepath(filename, &normal_filename);
 
   // In case socket file exists
   unlink(normal_filename);
 
   // For portability clear the addr structure, since some implementations have
   // nonstandard fields in the structure
   memset(&sockaddr, 0, addr_size);
 
   parentdir(normal_filename, &parent);
   // Create parent directories
   mkdirp(parent);
   free(parent);
 
   sockaddr.sun_family = AF_LOCAL;
   strcpy(sockaddr.sun_path, normal_filename);
   free(normal_filename);
 
   sock_fd = socket(AF_LOCAL, sock_type, 0);
   if (sock_fd == -1) {
     fputs("Failed to create socket\n", stderr);
     return -1;
   }
 
   DEBUG("Created socket at %s\n", sockaddr.sun_path);
 
   if (bind(sock_fd, (const struct sockaddr *)&sockaddr, addr_size) == -1) {
     fputs("Failed to bind socket\n", stderr);
     return -1;
   }
 
   DEBUG("Socket binded\n");
 
   if (listen(sock_fd, IPC_SOCKET_BACKLOG) < 0) {
     fputs("Failed to listen for connections on socket\n", stderr);
     return -1;
   }
 
   DEBUG("Now listening for connections on socket\n");
 
   return sock_fd;
 }
 
 /**
  * Internal function used to receive IPC messages from a given file descriptor.
  *
  * Returns -1 on error reading (could be EAGAIN or EINTR)
  * Returns -2 if EOF before header could be read
  * Returns -3 if invalid IPC header
  * Returns -4 if message length exceeds MAX_MESSAGE_SIZE
  */
 static int
 ipc_recv_message(int fd, 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) {
     const ssize_t n = read(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) {
       // errno will still be set
       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);
 
   if (*reply_size > MAX_MESSAGE_SIZE) {
     fprintf(stderr, "Message too long: %" PRIu32 " bytes. ", *reply_size);
     fprintf(stderr, "Maximum message size is: %d\n", MAX_MESSAGE_SIZE);
     return -4;
   }
 
   // Extract message type
   memcpy(msg_type, walk, sizeof(uint8_t));
   walk += sizeof(uint8_t);
 
   if (*reply_size > 0)
     (*reply) = malloc(*reply_size);
   else
     return 0;
 
   read_bytes = 0;
   while (read_bytes < *reply_size) {
     const ssize_t n = read(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) {
       // TODO: Should we return and wait for another epoll event?
       // This would require saving the partial read in some way.
       if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) continue;
 
       free(*reply);
       return -1;
     }
 
     read_bytes += n;
   }
 
   return 0;
 }
 
 /**
  * Internal function used to write a buffer to a file descriptor
  *
  * Returns number of bytes written if successful write
  * Returns 0 if no bytes were written due to EAGAIN or EWOULDBLOCK
  * Returns -1 on unknown error trying to write, errno will carry over from
  *   write() call
  */
 static ssize_t
 ipc_write_message(int fd, const void *buf, size_t count)
 {
   size_t written = 0;
 
   while (written < count) {
     const ssize_t n = write(fd, (uint8_t *)buf + written, count - written);
 
     if (n == -1) {
       if (errno == EAGAIN || errno == EWOULDBLOCK)
         return written;
       else if (errno == EINTR)
         continue;
       else
         return n;
     }
 
     written += n;
     DEBUG("Wrote %zu/%zu to client at fd %d\n", written, count, fd);
   }
 
   return written;
 }
 
 /**
  * Initialization for generic event message. This is used to allocate the yajl
  * handle, set yajl options, and in the future any other initialization that
  * should occur for event messages.
  */
 static void
 ipc_event_init_message(yajl_gen *gen)
 {
   *gen = yajl_gen_alloc(NULL);
   yajl_gen_config(*gen, yajl_gen_beautify, 1);
 }
 
 /**
  * Prepares buffers of IPC subscribers of specified event using buffer from yajl
  * handle.
  */
 static void
 ipc_event_prepare_send_message(yajl_gen gen, IPCEvent event)
 {
   const unsigned char *buffer;
   size_t len = 0;
 
   yajl_gen_get_buf(gen, &buffer, &len);
   len++;  // For null char
 
   for (IPCClient *c = ipc_clients; c; c = c->next) {
     if (c->subscriptions & event) {
       DEBUG("Sending selected client change event to fd %d\n", c->fd);
       ipc_prepare_send_message(c, IPC_TYPE_EVENT, len, (char *)buffer);
     }
   }
 
   // Not documented, but this frees temp_buffer
   yajl_gen_free(gen);
 }
 
 /**
  * Initialization for generic reply message. This is used to allocate the yajl
  * handle, set yajl options, and in the future any other initialization that
  * should occur for reply messages.
  */
 static void
 ipc_reply_init_message(yajl_gen *gen)
 {
   *gen = yajl_gen_alloc(NULL);
   yajl_gen_config(*gen, yajl_gen_beautify, 1);
 }
 
 /**
  * Prepares the IPC client's buffer with a message using the buffer of the yajl
  * handle.
  */
 static void
 ipc_reply_prepare_send_message(yajl_gen gen, IPCClient *c,
                                IPCMessageType msg_type)
 {
   const unsigned char *buffer;
   size_t len = 0;
 
   yajl_gen_get_buf(gen, &buffer, &len);
   len++;  // For null char
 
   ipc_prepare_send_message(c, msg_type, len, (const char *)buffer);
 
   // Not documented, but this frees temp_buffer
   yajl_gen_free(gen);
 }
 
 /**
  * Find the IPCCommand with the specified name
  *
  * Returns 0 if a command with the specified name was found
  * Returns -1 if a command with the specified name could not be found
  */
 static int
 ipc_get_ipc_command(const char *name, IPCCommand *ipc_command)
 {
   for (int i = 0; i < ipc_commands_len; i++) {
     if (strcmp(ipc_commands[i].name, name) == 0) {
       *ipc_command = ipc_commands[i];
       return 0;
     }
   }
 
   return -1;
 }
 
 /**
  * Parse a IPC_TYPE_RUN_COMMAND message from a client. This function extracts
  * the arguments, argument count, argument types, and command name and returns
  * the parsed information as an IPCParsedCommand. If this function returns
  * successfully, the parsed_command must be freed using
  * ipc_free_parsed_command_members.
  *
  * Returns 0 if the message was successfully parsed
  * Returns -1 otherwise
  */
 static int
 ipc_parse_run_command(char *msg, IPCParsedCommand *parsed_command)
 {
   char error_buffer[1000];
   yajl_val parent = yajl_tree_parse(msg, error_buffer, 1000);
 
   if (parent == NULL) {
     fputs("Failed to parse command from client\n", stderr);
     fprintf(stderr, "%s\n", error_buffer);
     fprintf(stderr, "Tried to parse: %s\n", msg);
     return -1;
   }
 
   // Format:
   // {
   //   "command": "<command name>"
   //   "args": [ "arg1", "arg2", ... ]
   // }
   const char *command_path[] = {"command", 0};
   yajl_val command_val = yajl_tree_get(parent, command_path, yajl_t_string);
 
   if (command_val == NULL) {
     fputs("No command key found in client message\n", stderr);
     yajl_tree_free(parent);
     return -1;
   }
 
   const char *command_name = YAJL_GET_STRING(command_val);
   size_t command_name_len = strlen(command_name);
   parsed_command->name = (char *)malloc((command_name_len + 1) * sizeof(char));
   strcpy(parsed_command->name, command_name);
 
   DEBUG("Received command: %s\n", parsed_command->name);
 
   const char *args_path[] = {"args", 0};
   yajl_val args_val = yajl_tree_get(parent, args_path, yajl_t_array);
 
   if (args_val == NULL) {
     fputs("No args key found in client message\n", stderr);
     yajl_tree_free(parent);
     return -1;
   }
 
   unsigned int *argc = &parsed_command->argc;
   Arg **args = &parsed_command->args;
   ArgType **arg_types = &parsed_command->arg_types;
 
   *argc = args_val->u.array.len;
 
   // If no arguments are specified, make a dummy argument to pass to the
   // function. This is just the way dwm's void(Arg*) functions are setup.
   if (*argc == 0) {
     *args = (Arg *)malloc(sizeof(Arg));
     *arg_types = (ArgType *)malloc(sizeof(ArgType));
     (*arg_types)[0] = ARG_TYPE_NONE;
     (*args)[0].f = 0;
     (*argc)++;
   } else if (*argc > 0) {
     *args = (Arg *)calloc(*argc, sizeof(Arg));
     *arg_types = (ArgType *)malloc(*argc * sizeof(ArgType));
 
     for (int i = 0; i < *argc; i++) {
       yajl_val arg_val = args_val->u.array.values[i];
 
       if (YAJL_IS_NUMBER(arg_val)) {
         if (YAJL_IS_INTEGER(arg_val)) {
           // Any values below 0 must be a signed int
           if (YAJL_GET_INTEGER(arg_val) < 0) {
             (*args)[i].i = YAJL_GET_INTEGER(arg_val);
             (*arg_types)[i] = ARG_TYPE_SINT;
             DEBUG("i=%ld\n", (*args)[i].i);
             // Any values above 0 should be an unsigned int
           } else if (YAJL_GET_INTEGER(arg_val) >= 0) {
             (*args)[i].ui = YAJL_GET_INTEGER(arg_val);
             (*arg_types)[i] = ARG_TYPE_UINT;
             DEBUG("ui=%ld\n", (*args)[i].i);
           }
           // If the number is not an integer, it must be a float
         } else {
           (*args)[i].f = (float)YAJL_GET_DOUBLE(arg_val);
           (*arg_types)[i] = ARG_TYPE_FLOAT;
           DEBUG("f=%f\n", (*args)[i].f);
           // If argument is not a number, it must be a string
         }
       } else if (YAJL_IS_STRING(arg_val)) {
         char *arg_s = YAJL_GET_STRING(arg_val);
         size_t arg_s_size = (strlen(arg_s) + 1) * sizeof(char);
         (*args)[i].v = (char *)malloc(arg_s_size);
         (*arg_types)[i] = ARG_TYPE_STR;
         strcpy((char *)(*args)[i].v, arg_s);
       }
     }
   }
 
   yajl_tree_free(parent);
 
   return 0;
 }
 
 /**
  * Free the members of a IPCParsedCommand struct
  */
 static void
 ipc_free_parsed_command_members(IPCParsedCommand *command)
 {
   for (int i = 0; i < command->argc; i++) {
     if (command->arg_types[i] == ARG_TYPE_STR) free((void *)command->args[i].v);
   }
   free(command->args);
   free(command->arg_types);
   free(command->name);
 }
 
 /**
  * Check if the given arguments are the correct length and type. Also do any
  * casting to correct the types.
  *
  * Returns 0 if the arguments were the correct length and types
  * Returns -1 if the argument count doesn't match
  * Returns -2 if the argument types don't match
  */
 static int
 ipc_validate_run_command(IPCParsedCommand *parsed, const IPCCommand actual)
 {
   if (actual.argc != parsed->argc) return -1;
 
   for (int i = 0; i < parsed->argc; i++) {
     ArgType ptype = parsed->arg_types[i];
     ArgType atype = actual.arg_types[i];
 
     if (ptype != atype) {
       if (ptype == ARG_TYPE_UINT && atype == ARG_TYPE_PTR)
         // If this argument is supposed to be a void pointer, cast it
         parsed->args[i].v = (void *)parsed->args[i].ui;
       else if (ptype == ARG_TYPE_UINT && atype == ARG_TYPE_SINT)
         // If this argument is supposed to be a signed int, cast it
         parsed->args[i].i = parsed->args[i].ui;
       else
         return -2;
     }
   }
 
   return 0;
 }
 
 /**
  * Convert event name to their IPCEvent equivalent enum value
  *
  * Returns 0 if a valid event name was given
  * Returns -1 otherwise
  */
 static int
 ipc_event_stoi(const char *subscription, IPCEvent *event)
 {
   if (strcmp(subscription, "tag_change_event") == 0)
     *event = IPC_EVENT_TAG_CHANGE;
   else if (strcmp(subscription, "client_focus_change_event") == 0)
     *event = IPC_EVENT_CLIENT_FOCUS_CHANGE;
   else if (strcmp(subscription, "layout_change_event") == 0)
     *event = IPC_EVENT_LAYOUT_CHANGE;
   else if (strcmp(subscription, "monitor_focus_change_event") == 0)
     *event = IPC_EVENT_MONITOR_FOCUS_CHANGE;
   else if (strcmp(subscription, "focused_title_change_event") == 0)
     *event = IPC_EVENT_FOCUSED_TITLE_CHANGE;
   else if (strcmp(subscription, "focused_state_change_event") == 0)
     *event = IPC_EVENT_FOCUSED_STATE_CHANGE;
   else
     return -1;
   return 0;
 }
 
 /**
  * Parse a IPC_TYPE_SUBSCRIBE message from a client. This function extracts the
  * event name and the subscription action from the message.
  *
  * Returns 0 if message was successfully parsed
  * Returns -1 otherwise
  */
 static int
 ipc_parse_subscribe(const char *msg, IPCSubscriptionAction *subscribe,
                     IPCEvent *event)
 {
   char error_buffer[100];
   yajl_val parent = yajl_tree_parse((char *)msg, error_buffer, 100);
 
   if (parent == NULL) {
     fputs("Failed to parse command from client\n", stderr);
     fprintf(stderr, "%s\n", error_buffer);
     return -1;
   }
 
   // Format:
   // {
   //   "event": "<event name>"
   //   "action": "<subscribe|unsubscribe>"
   // }
   const char *event_path[] = {"event", 0};
   yajl_val event_val = yajl_tree_get(parent, event_path, yajl_t_string);
 
   if (event_val == NULL) {
     fputs("No 'event' key found in client message\n", stderr);
     return -1;
   }
 
   const char *event_str = YAJL_GET_STRING(event_val);
   DEBUG("Received event: %s\n", event_str);
 
   if (ipc_event_stoi(event_str, event) < 0) return -1;
 
   const char *action_path[] = {"action", 0};
   yajl_val action_val = yajl_tree_get(parent, action_path, yajl_t_string);
 
   if (action_val == NULL) {
     fputs("No 'action' key found in client message\n", stderr);
     return -1;
   }
 
   const char *action = YAJL_GET_STRING(action_val);
 
   if (strcmp(action, "subscribe") == 0)
     *subscribe = IPC_ACTION_SUBSCRIBE;
   else if (strcmp(action, "unsubscribe") == 0)
     *subscribe = IPC_ACTION_UNSUBSCRIBE;
   else {
     fputs("Invalid action specified for subscription\n", stderr);
     return -1;
   }
 
   yajl_tree_free(parent);
 
   return 0;
 }
 
 /**
  * Parse an IPC_TYPE_GET_DWM_CLIENT message from a client. This function
  * extracts the window id from the message.
  *
  * Returns 0 if message was successfully parsed
  * Returns -1 otherwise
  */
 static int
 ipc_parse_get_dwm_client(const char *msg, Window *win)
 {
   char error_buffer[100];
 
   yajl_val parent = yajl_tree_parse(msg, error_buffer, 100);
 
   if (parent == NULL) {
     fputs("Failed to parse message from client\n", stderr);
     fprintf(stderr, "%s\n", error_buffer);
     return -1;
   }
 
   // Format:
   // {
   //   "client_window_id": <client window id>
   // }
   const char *win_path[] = {"client_window_id", 0};
   yajl_val win_val = yajl_tree_get(parent, win_path, yajl_t_number);
 
   if (win_val == NULL) {
     fputs("No client window id found in client message\n", stderr);
     return -1;
   }
 
   *win = YAJL_GET_INTEGER(win_val);
 
   yajl_tree_free(parent);
 
   return 0;
 }
 
 /**
  * Called when an IPC_TYPE_RUN_COMMAND message is received from a client. This
  * function parses, executes the given command, and prepares a reply message to
  * the client indicating success/failure.
  *
  * NOTE: There is currently no check for argument validity beyond the number of
  * arguments given and types of arguments. There is also no way to check if the
  * function succeeded based on dwm's void(const Arg*) function types. Pointer
  * arguments can cause crashes if they are not validated in the function itself.
  *
  * Returns 0 if message was successfully parsed
  * Returns -1 on failure parsing message
  */
 static int
 ipc_run_command(IPCClient *ipc_client, char *msg)
 {
   IPCParsedCommand parsed_command;
   IPCCommand ipc_command;
 
   // Initialize struct
   memset(&parsed_command, 0, sizeof(IPCParsedCommand));
 
   if (ipc_parse_run_command(msg, &parsed_command) < 0) {
     ipc_prepare_reply_failure(ipc_client, IPC_TYPE_RUN_COMMAND,
                               "Failed to parse run command");
     return -1;
   }
 
   if (ipc_get_ipc_command(parsed_command.name, &ipc_command) < 0) {
     ipc_prepare_reply_failure(ipc_client, IPC_TYPE_RUN_COMMAND,
                               "Command %s not found", parsed_command.name);
     ipc_free_parsed_command_members(&parsed_command);
     return -1;
   }
 
   int res = ipc_validate_run_command(&parsed_command, ipc_command);
   if (res < 0) {
     if (res == -1)
       ipc_prepare_reply_failure(ipc_client, IPC_TYPE_RUN_COMMAND,
                                 "%u arguments provided, %u expected",
                                 parsed_command.argc, ipc_command.argc);
     else if (res == -2)
       ipc_prepare_reply_failure(ipc_client, IPC_TYPE_RUN_COMMAND,
                                 "Type mismatch");
     ipc_free_parsed_command_members(&parsed_command);
     return -1;
   }
 
   if (parsed_command.argc == 1)
     ipc_command.func.single_param(parsed_command.args);
   else if (parsed_command.argc > 1)
     ipc_command.func.array_param(parsed_command.args, parsed_command.argc);
 
   DEBUG("Called function for command %s\n", parsed_command.name);
 
   ipc_free_parsed_command_members(&parsed_command);
 
   ipc_prepare_reply_success(ipc_client, IPC_TYPE_RUN_COMMAND);
   return 0;
 }
 
 /**
  * Called when an IPC_TYPE_GET_MONITORS message is received from a client. It
  * prepares a reply with the properties of all of the monitors in JSON.
  */
 static void
 ipc_get_monitors(IPCClient *c, Monitor *mons, Monitor *selmon)
 {
   yajl_gen gen;
   ipc_reply_init_message(&gen);
   dump_monitors(gen, mons, selmon);
 
   ipc_reply_prepare_send_message(gen, c, IPC_TYPE_GET_MONITORS);
 }
 
 /**
  * Called when an IPC_TYPE_GET_TAGS message is received from a client. It
  * prepares a reply with info about all the tags in JSON.
  */
 static void
 ipc_get_tags(IPCClient *c, const int tags_len)
 {
   yajl_gen gen;
   ipc_reply_init_message(&gen);
 
   dump_tags(gen, tags_len);
 
   ipc_reply_prepare_send_message(gen, c, IPC_TYPE_GET_TAGS);
 }
 
 /**
  * Called when an IPC_TYPE_GET_LAYOUTS message is received from a client. It
  * prepares a reply with a JSON array of available layouts
  */
 static void
 ipc_get_layouts(IPCClient *c, const Layout layouts[], const int layouts_len)
 {
   yajl_gen gen;
   ipc_reply_init_message(&gen);
 
   dump_layouts(gen, layouts, layouts_len);
 
   ipc_reply_prepare_send_message(gen, c, IPC_TYPE_GET_LAYOUTS);
 }
 
 /**
  * Called when an IPC_TYPE_GET_DWM_CLIENT message is received from a client. It
  * prepares a JSON reply with the properties of the client with the specified
  * window XID.
  *
  * Returns 0 if the message was successfully parsed and if the client with the
  *   specified window XID was found
  * Returns -1 if the message could not be parsed
  */
 static int
 ipc_get_dwm_client(IPCClient *ipc_client, const char *msg, const Monitor *mons)
 {
   Window win;
 
   if (ipc_parse_get_dwm_client(msg, &win) < 0) return -1;
 
   // Find client with specified window XID
   for (const Monitor *m = mons; m; m = m->next)
     for (Client *c = m->clients; c; c = c->next)
       if (c->win == win) {
         yajl_gen gen;
         ipc_reply_init_message(&gen);
 
         dump_client(gen, c);
 
         ipc_reply_prepare_send_message(gen, ipc_client,
                                        IPC_TYPE_GET_DWM_CLIENT);
 
         return 0;
       }
 
   ipc_prepare_reply_failure(ipc_client, IPC_TYPE_GET_DWM_CLIENT,
                             "Client with window id %d not found", win);
   return -1;
 }
 
 /**
  * Called when an IPC_TYPE_SUBSCRIBE message is received from a client. It
  * subscribes/unsubscribes the client from the specified event and replies with
  * the result.
  *
  * Returns 0 if the message was successfully parsed.
  * Returns -1 if the message could not be parsed
  */
 static int
 ipc_subscribe(IPCClient *c, const char *msg)
 {
   IPCSubscriptionAction action = IPC_ACTION_SUBSCRIBE;
   IPCEvent event = 0;
 
   if (ipc_parse_subscribe(msg, &action, &event)) {
     ipc_prepare_reply_failure(c, IPC_TYPE_SUBSCRIBE, "Event does not exist");
     return -1;
   }
 
   if (action == IPC_ACTION_SUBSCRIBE) {
     DEBUG("Subscribing client on fd %d to %d\n", c->fd, event);
     c->subscriptions |= event;
   } else if (action == IPC_ACTION_UNSUBSCRIBE) {
     DEBUG("Unsubscribing client on fd %d to %d\n", c->fd, event);
     c->subscriptions ^= event;
   } else {
     ipc_prepare_reply_failure(c, IPC_TYPE_SUBSCRIBE,
                               "Invalid subscription action");
     return -1;
   }
 
   ipc_prepare_reply_success(c, IPC_TYPE_SUBSCRIBE);
   return 0;
 }
 
 int
 ipc_init(const char *socket_path, const int p_epoll_fd, IPCCommand commands[],
          const int commands_len)
 {
   // Initialize struct to 0
   memset(&sock_epoll_event, 0, sizeof(sock_epoll_event));
 
   int socket_fd = ipc_create_socket(socket_path);
   if (socket_fd < 0) return -1;
 
   ipc_commands = commands;
   ipc_commands_len = commands_len;
 
   epoll_fd = p_epoll_fd;
 
   // Wake up to incoming connection requests
   sock_epoll_event.data.fd = socket_fd;
   sock_epoll_event.events = EPOLLIN;
   if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, socket_fd, &sock_epoll_event)) {
     fputs("Failed to add sock file descriptor to epoll", stderr);
     return -1;
   }
 
   return socket_fd;
 }
 
 void
 ipc_cleanup()
 {
   IPCClient *c = ipc_clients;
   // Free clients and their buffers
   while (c) {
     ipc_drop_client(c);
     c = ipc_clients;
   }
 
   // Stop waking up for socket events
   epoll_ctl(epoll_fd, EPOLL_CTL_DEL, sock_fd, &sock_epoll_event);
 
   // Uninitialize all static variables
   epoll_fd = -1;
   sock_fd = -1;
   ipc_commands = NULL;
   ipc_commands_len = 0;
   memset(&sock_epoll_event, 0, sizeof(struct epoll_event));
   memset(&sockaddr, 0, sizeof(struct sockaddr_un));
 
   // Delete socket
   unlink(sockaddr.sun_path);
 
   shutdown(sock_fd, SHUT_RDWR);
   close(sock_fd);
 }
 
 int
 ipc_get_sock_fd()
 {
   return sock_fd;
 }
 
 IPCClient *
 ipc_get_client(int fd)
 {
   return ipc_list_get_client(ipc_clients, fd);
 }
 
 int
 ipc_is_client_registered(int fd)
 {
   return (ipc_get_client(fd) != NULL);
 }
 
 int
 ipc_accept_client()
 {
   int fd = -1;
 
   struct sockaddr_un client_addr;
   socklen_t len = 0;
 
   // For portability clear the addr structure, since some implementations
   // have nonstandard fields in the structure
   memset(&client_addr, 0, sizeof(struct sockaddr_un));
 
   fd = accept(sock_fd, (struct sockaddr *)&client_addr, &len);
   if (fd < 0 && errno != EINTR) {
     fputs("Failed to accept IPC connection from client", stderr);
     return -1;
   }
 
   if (fcntl(fd, F_SETFD, FD_CLOEXEC) < 0) {
     shutdown(fd, SHUT_RDWR);
     close(fd);
     fputs("Failed to set flags on new client fd", stderr);
   }
 
   IPCClient *nc = ipc_client_new(fd);
   if (nc == NULL) return -1;
 
   // Wake up to messages from this client
   nc->event.data.fd = fd;
   nc->event.events = EPOLLIN | EPOLLHUP;
   epoll_ctl(epoll_fd, EPOLL_CTL_ADD, fd, &nc->event);
 
   ipc_list_add_client(&ipc_clients, nc);
 
   DEBUG("%s%d\n", "New client at fd: ", fd);
 
   return fd;
 }
 
 int
 ipc_drop_client(IPCClient *c)
 {
   int fd = c->fd;
   shutdown(fd, SHUT_RDWR);
   int res = close(fd);
 
   if (res == 0) {
     struct epoll_event ev;
 
     // Stop waking up to messages from this client
     epoll_ctl(epoll_fd, EPOLL_CTL_DEL, fd, &ev);
     ipc_list_remove_client(&ipc_clients, c);
 
     free(c->buffer);
     free(c);
 
     DEBUG("Successfully removed client on fd %d\n", fd);
   } else if (res < 0 && res != EINTR) {
     fprintf(stderr, "Failed to close fd %d\n", fd);
   }
 
   return res;
 }
 
 int
 ipc_read_client(IPCClient *c, IPCMessageType *msg_type, uint32_t *msg_size,
                 char **msg)
 {
   int fd = c->fd;
   int ret =
       ipc_recv_message(fd, (uint8_t *)msg_type, msg_size, (uint8_t **)msg);
 
   if (ret < 0) {
     // This will happen if these errors occur while reading header
     if (ret == -1 &&
         (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
       return -2;
 
     fprintf(stderr, "Error reading message: dropping client at fd %d\n", fd);
     ipc_drop_client(c);
 
     return -1;
   }
 
   // Make sure receive message is null terminated to avoid parsing issues
   if (*msg_size > 0) {
     size_t len = *msg_size;
     nullterminate(msg, &len);
     *msg_size = len;
   }
 
   DEBUG("[fd %d] ", fd);
   if (*msg_size > 0)
     DEBUG("Received message: '%.*s' ", *msg_size, *msg);
   else
     DEBUG("Received empty message ");
   DEBUG("Message type: %" PRIu8 " ", (uint8_t)*msg_type);
   DEBUG("Message size: %" PRIu32 "\n", *msg_size);
 
   return 0;
 }
 
 ssize_t
 ipc_write_client(IPCClient *c)
 {
   const ssize_t n = ipc_write_message(c->fd, c->buffer, c->buffer_size);
 
   if (n < 0) return n;
 
   // TODO: Deal with client timeouts
 
   if (n == c->buffer_size) {
     c->buffer_size = 0;
     free(c->buffer);
     // No dangling pointers!
     c->buffer = NULL;
     // Stop waking up when client is ready to receive messages
     if (c->event.events & EPOLLOUT) {
       c->event.events -= EPOLLOUT;
       epoll_ctl(epoll_fd, EPOLL_CTL_MOD, c->fd, &c->event);
     }
     return n;
   }
 
   // Shift unwritten buffer to beginning of buffer and reallocate
   c->buffer_size -= n;
   memmove(c->buffer, c->buffer + n, c->buffer_size);
   c->buffer = (char *)realloc(c->buffer, c->buffer_size);
 
   return n;
 }
 
 void
 ipc_prepare_send_message(IPCClient *c, const IPCMessageType msg_type,
                          const uint32_t msg_size, const char *msg)
 {
   dwm_ipc_header_t header = {
       .magic = IPC_MAGIC_ARR, .type = msg_type, .size = msg_size};
 
   uint32_t header_size = sizeof(dwm_ipc_header_t);
   uint32_t packet_size = header_size + msg_size;
 
   if (c->buffer == NULL)
     c->buffer = (char *)malloc(c->buffer_size + packet_size);
   else
     c->buffer = (char *)realloc(c->buffer, c->buffer_size + packet_size);
 
   // Copy header to end of client buffer
   memcpy(c->buffer + c->buffer_size, &header, header_size);
   c->buffer_size += header_size;
 
   // Copy message to end of client buffer
   memcpy(c->buffer + c->buffer_size, msg, msg_size);
   c->buffer_size += msg_size;
 
   // Wake up when client is ready to receive messages
   c->event.events |= EPOLLOUT;
   epoll_ctl(epoll_fd, EPOLL_CTL_MOD, c->fd, &c->event);
 }
 
 void
 ipc_prepare_reply_failure(IPCClient *c, IPCMessageType msg_type,
                           const char *format, ...)
 {
   yajl_gen gen;
   va_list args;
 
   // Get output size
   va_start(args, format);
   size_t len = vsnprintf(NULL, 0, format, args);
   va_end(args);
   char *buffer = (char *)malloc((len + 1) * sizeof(char));
 
   ipc_reply_init_message(&gen);
 
   va_start(args, format);
   vsnprintf(buffer, len + 1, format, args);
   va_end(args);
   dump_error_message(gen, buffer);
 
   ipc_reply_prepare_send_message(gen, c, msg_type);
   fprintf(stderr, "[fd %d] Error: %s\n", c->fd, buffer);
 
   free(buffer);
 }
 
 void
 ipc_prepare_reply_success(IPCClient *c, IPCMessageType msg_type)
 {
   const char *success_msg = "{\"result\":\"success\"}";
   const size_t msg_len = strlen(success_msg) + 1;  // +1 for null char
 
   ipc_prepare_send_message(c, msg_type, msg_len, success_msg);
 }
 
 void
 ipc_tag_change_event(int mon_num, TagState old_state, TagState new_state)
 {
   yajl_gen gen;
   ipc_event_init_message(&gen);
   dump_tag_event(gen, mon_num, old_state, new_state);
   ipc_event_prepare_send_message(gen, IPC_EVENT_TAG_CHANGE);
 }
 
 void
 ipc_client_focus_change_event(int mon_num, Client *old_client,
                               Client *new_client)
 {
   yajl_gen gen;
   ipc_event_init_message(&gen);
   dump_client_focus_change_event(gen, old_client, new_client, mon_num);
   ipc_event_prepare_send_message(gen, IPC_EVENT_CLIENT_FOCUS_CHANGE);
 }
 
 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)
 {
   yajl_gen gen;
   ipc_event_init_message(&gen);
   dump_layout_change_event(gen, mon_num, old_symbol, old_layout, new_symbol,
                            new_layout);
   ipc_event_prepare_send_message(gen, IPC_EVENT_LAYOUT_CHANGE);
 }
 
 void
 ipc_monitor_focus_change_event(const int last_mon_num, const int new_mon_num)
 {
   yajl_gen gen;
   ipc_event_init_message(&gen);
   dump_monitor_focus_change_event(gen, last_mon_num, new_mon_num);
   ipc_event_prepare_send_message(gen, IPC_EVENT_MONITOR_FOCUS_CHANGE);
 }
 
 void
 ipc_focused_title_change_event(const int mon_num, const Window client_id,
                                const char *old_name, const char *new_name)
 {
   yajl_gen gen;
   ipc_event_init_message(&gen);
   dump_focused_title_change_event(gen, mon_num, client_id, old_name, new_name);
   ipc_event_prepare_send_message(gen, IPC_EVENT_FOCUSED_TITLE_CHANGE);
 }
 
 void
 ipc_focused_state_change_event(const int mon_num, const Window client_id,
                                const ClientState *old_state,
                                const ClientState *new_state)
 {
   yajl_gen gen;
   ipc_event_init_message(&gen);
   dump_focused_state_change_event(gen, mon_num, client_id, old_state,
                                   new_state);
   ipc_event_prepare_send_message(gen, IPC_EVENT_FOCUSED_STATE_CHANGE);
 }
 
 void
 ipc_send_events(Monitor *mons, Monitor **lastselmon, Monitor *selmon)
 {
   for (Monitor *m = mons; m; m = m->next) {
     unsigned int urg = 0, occ = 0, tagset = 0;
 
     for (Client *c = m->clients; c; c = c->next) {
       occ |= c->tags;
 
       if (c->isurgent) urg |= c->tags;
     }
     tagset = m->tagset[m->seltags];
 
     TagState new_state = {.selected = tagset, .occupied = occ, .urgent = urg};
 
     if (memcmp(&m->tagstate, &new_state, sizeof(TagState)) != 0) {
       ipc_tag_change_event(m->num, m->tagstate, new_state);
       m->tagstate = new_state;
     }
 
     if (m->lastsel != m->sel) {
       ipc_client_focus_change_event(m->num, m->lastsel, m->sel);
       m->lastsel = m->sel;
     }
 
     if (strcmp(m->ltsymbol, m->lastltsymbol) != 0 ||
         m->lastlt != m->lt[m->sellt]) {
       ipc_layout_change_event(m->num, m->lastltsymbol, m->lastlt, m->ltsymbol,
                               m->lt[m->sellt]);
       strcpy(m->lastltsymbol, m->ltsymbol);
       m->lastlt = m->lt[m->sellt];
     }
 
     if (*lastselmon != selmon) {
       if (*lastselmon != NULL)
         ipc_monitor_focus_change_event((*lastselmon)->num, selmon->num);
       *lastselmon = selmon;
     }
 
     Client *sel = m->sel;
     if (!sel) continue;
     ClientState *o = &m->sel->prevstate;
     ClientState n = {.oldstate = sel->oldstate,
                      .isfixed = sel->isfixed,
                      .isfloating = sel->isfloating,
                      .isfullscreen = sel->isfullscreen,
                      .isurgent = sel->isurgent,
                      .neverfocus = sel->neverfocus};
     if (memcmp(o, &n, sizeof(ClientState)) != 0) {
       ipc_focused_state_change_event(m->num, m->sel->win, o, &n);
       *o = n;
     }
   }
 }
 
 int
 ipc_handle_client_epoll_event(struct epoll_event *ev, Monitor *mons,
                               Monitor **lastselmon, Monitor *selmon, const int tags_len,
                               const Layout *layouts, const int layouts_len)
 {
   int fd = ev->data.fd;
   IPCClient *c = ipc_get_client(fd);
 
   if (ev->events & EPOLLHUP) {
     DEBUG("EPOLLHUP received from client at fd %d\n", fd);
     ipc_drop_client(c);
   } else if (ev->events & EPOLLOUT) {
     DEBUG("Sending message to client at fd %d...\n", fd);
     if (c->buffer_size) ipc_write_client(c);
   } else if (ev->events & EPOLLIN) {
     IPCMessageType msg_type = 0;
     uint32_t msg_size = 0;
     char *msg = NULL;
 
     DEBUG("Received message from fd %d\n", fd);
     if (ipc_read_client(c, &msg_type, &msg_size, &msg) < 0) return -1;
 
     if (msg_type == IPC_TYPE_GET_MONITORS)
       ipc_get_monitors(c, mons, selmon);
     else if (msg_type == IPC_TYPE_GET_TAGS)
       ipc_get_tags(c, tags_len);
     else if (msg_type == IPC_TYPE_GET_LAYOUTS)
       ipc_get_layouts(c, layouts, layouts_len);
     else if (msg_type == IPC_TYPE_RUN_COMMAND) {
       if (ipc_run_command(c, msg) < 0) return -1;
       ipc_send_events(mons, lastselmon, selmon);
     } else if (msg_type == IPC_TYPE_GET_DWM_CLIENT) {
       if (ipc_get_dwm_client(c, msg, mons) < 0) return -1;
     } else if (msg_type == IPC_TYPE_SUBSCRIBE) {
       if (ipc_subscribe(c, msg) < 0) return -1;
     } else {
       fprintf(stderr, "Invalid message type received from fd %d", fd);
       ipc_prepare_reply_failure(c, msg_type, "Invalid message type: %d",
                                 msg_type);
     }
     free(msg);
   } else {
     fprintf(stderr, "Epoll event returned %d from fd %d\n", ev->events, fd);
     return -1;
   }
 
   return 0;
 }
 
 int
 ipc_handle_socket_epoll_event(struct epoll_event *ev)
 {
   if (!(ev->events & EPOLLIN)) return -1;
 
   // EPOLLIN means incoming client connection request
   fputs("Received EPOLLIN event on socket\n", stderr);
   int new_fd = ipc_accept_client();
 
   return new_fd;
 }