text: /*
   * vim:ts=4:sw=4:expandtab
   *
   * i3bar - an xcb-based status- and ws-bar for i3
   * © 2010 Axel Wagner and contributors (see also: LICENSE)
   *
   * child.c: Getting input for the statusline
   *
   */
  #include <stdlib.h>
  #include <unistd.h>
  #include <sys/types.h>
  #include <sys/wait.h>
  #include <signal.h>
  #include <stdio.h>
  #include <stdarg.h>
  #include <fcntl.h>
  #include <string.h>
  #include <errno.h>
  #include <err.h>
  #include <ev.h>
  #include <yajl/yajl_common.h>
  #include <yajl/yajl_parse.h>
  #include <yajl/yajl_version.h>
  #include <yajl/yajl_gen.h>
  #include <paths.h>
  
  #include "common.h"
  
  /* Global variables for child_*() */
  i3bar_child child;
  
  /* stdin- and SIGCHLD-watchers */
  ev_io *stdin_io;
  ev_child *child_sig;
  
  /* JSON parser for stdin */
  yajl_handle parser;
  
  /* JSON generator for stdout */
  yajl_gen gen;
  
  typedef struct parser_ctx {
      /* True if one of the parsed blocks was urgent */
      bool has_urgent;
  
      /* A copy of the last JSON map key. */
      char *last_map_key;
  
      /* The current block. Will be filled, then copied and put into the list of
       * blocks. */
      struct status_block block;
  } parser_ctx;
  
  parser_ctx parser_context;
  
  struct statusline_head statusline_head = TAILQ_HEAD_INITIALIZER(statusline_head);
  /* Used temporarily while reading a statusline */
  struct statusline_head statusline_buffer = TAILQ_HEAD_INITIALIZER(statusline_buffer);
  
  int child_stdin;
  
  /*
   * Remove all blocks from the given statusline.
   * If free_resources is set, the fields of each status block will be free'd.
   */
  static void clear_statusline(struct statusline_head *head, bool free_resources) {
      struct status_block *first;
      while (!TAILQ_EMPTY(head)) {
          first = TAILQ_FIRST(head);
          if (free_resources) {
              I3STRING_FREE(first->full_text);
              I3STRING_FREE(first->short_text);
              FREE(first->color);
              FREE(first->name);
              FREE(first->instance);
              FREE(first->min_width_str);
              FREE(first->background);
              FREE(first->border);
          }
  
          TAILQ_REMOVE(head, first, blocks);
          free(first);
      }
  }
  
  static void copy_statusline(struct statusline_head *from, struct statusline_head *to) {
      struct status_block *current;
      TAILQ_FOREACH(current, from, blocks) {
          struct status_block *new_block = smalloc(sizeof(struct status_block));
          memcpy(new_block, current, sizeof(struct status_block));
          TAILQ_INSERT_TAIL(to, new_block, blocks);
      }
  }
  
  /*
   * Replaces the statusline in memory with an error message. Pass a format
   * string and format parameters as you would in `printf'. The next time
   * `draw_bars' is called, the error message text will be drawn on the bar in
   * the space allocated for the statusline.
   */
  __attribute__((format(printf, 1, 2))) static void set_statusline_error(const char *format, ...) {
      clear_statusline(&statusline_head, true);
  
      char *message;
      va_list args;
      va_start(args, format);
      (void)vasprintf(&message, format, args);
  
      struct status_block *err_block = scalloc(1, sizeof(struct status_block));
      err_block->full_text = i3string_from_utf8("Error: ");
      err_block->name = sstrdup("error");
      err_block->color = sstrdup("red");
      err_block->no_separator = true;
  
      struct status_block *message_block = scalloc(1, sizeof(struct status_block));
      message_block->full_text = i3string_from_utf8(message);
      message_block->name = sstrdup("error_message");
      message_block->color = sstrdup("red");
      message_block->no_separator = true;
  
      TAILQ_INSERT_HEAD(&statusline_head, err_block, blocks);
      TAILQ_INSERT_TAIL(&statusline_head, message_block, blocks);
  
      FREE(message);
      va_end(args);
  }
  
  /*
   * Stop and free() the stdin- and SIGCHLD-watchers
   *
   */
  void cleanup(void) {
      if (stdin_io != NULL) {
          ev_io_stop(main_loop, stdin_io);
          FREE(stdin_io);
      }
  
      if (child_sig != NULL) {
          ev_child_stop(main_loop, child_sig);
          FREE(child_sig);
      }
  
      memset(&child, 0, sizeof(i3bar_child));
  }
  
  /*
   * The start of a new array is the start of a new status line, so we clear all
   * previous entries from the buffer.
   */
  static int stdin_start_array(void *context) {
      // the blocks are still used by statusline_head, so we won't free the
      // resources here.
      clear_statusline(&statusline_buffer, false);
      return 1;
  }
  
  /*
   * The start of a map is the start of a single block of the status line.
   *
   */
  static int stdin_start_map(void *context) {
      parser_ctx *ctx = context;
      memset(&(ctx->block), '\0', sizeof(struct status_block));
  
      /* Default width of the separator block. */
      if (config.separator_symbol == NULL)
          ctx->block.sep_block_width = logical_px(9);
      else
          ctx->block.sep_block_width = logical_px(8) + separator_symbol_width;
  
      return 1;
  }
  
  static int stdin_map_key(void *context, const unsigned char *key, size_t len) {
      parser_ctx *ctx = context;
      FREE(ctx->last_map_key);
      sasprintf(&(ctx->last_map_key), "%.*s", len, key);
      return 1;
  }
  
  static int stdin_boolean(void *context, int val) {
      parser_ctx *ctx = context;
      if (strcasecmp(ctx->last_map_key, "urgent") == 0) {
          ctx->block.urgent = val;
          return 1;
      }
      if (strcasecmp(ctx->last_map_key, "separator") == 0) {
          ctx->block.no_separator = !val;
          return 1;
      }
  
      return 1;
  }
  
  static int stdin_string(void *context, const unsigned char *val, size_t len) {
      parser_ctx *ctx = context;
      if (strcasecmp(ctx->last_map_key, "full_text") == 0) {
          ctx->block.full_text = i3string_from_markup_with_length((const char *)val, len);
          return 1;
      }
      if (strcasecmp(ctx->last_map_key, "short_text") == 0) {
          ctx->block.short_text = i3string_from_markup_with_length((const char *)val, len);
          return 1;
      }
      if (strcasecmp(ctx->last_map_key, "color") == 0) {
          sasprintf(&(ctx->block.color), "%.*s", len, val);
          return 1;
      }
      if (strcasecmp(ctx->last_map_key, "background") == 0) {
          sasprintf(&(ctx->block.background), "%.*s", len, val);
          return 1;
      }
      if (strcasecmp(ctx->last_map_key, "border") == 0) {
          sasprintf(&(ctx->block.border), "%.*s", len, val);
          return 1;
      }
      if (strcasecmp(ctx->last_map_key, "markup") == 0) {
          ctx->block.pango_markup = (len == strlen("pango") && !strncasecmp((const char *)val, "pango", strlen("pango")));
          return 1;
      }
      if (strcasecmp(ctx->last_map_key, "align") == 0) {
          if (len == strlen("center") && !strncmp((const char *)val, "center", strlen("center"))) {
              ctx->block.align = ALIGN_CENTER;
          } else if (len == strlen("right") && !strncmp((const char *)val, "right", strlen("right"))) {
              ctx->block.align = ALIGN_RIGHT;
          } else {
              ctx->block.align = ALIGN_LEFT;
          }
          return 1;
      }
      if (strcasecmp(ctx->last_map_key, "min_width") == 0) {
          sasprintf(&(ctx->block.min_width_str), "%.*s", len, val);
          return 1;
      }
      if (strcasecmp(ctx->last_map_key, "name") == 0) {
          sasprintf(&(ctx->block.name), "%.*s", len, val);
          return 1;
      }
      if (strcasecmp(ctx->last_map_key, "instance") == 0) {
          sasprintf(&(ctx->block.instance), "%.*s", len, val);
          return 1;
      }
  
      return 1;
  }
  
  static int stdin_integer(void *context, long long val) {
      parser_ctx *ctx = context;
      if (strcasecmp(ctx->last_map_key, "min_width") == 0) {
          ctx->block.min_width = (uint32_t)val;
          return 1;
      }
      if (strcasecmp(ctx->last_map_key, "separator_block_width") == 0) {
          ctx->block.sep_block_width = (uint32_t)val;
          return 1;
      }
  
      return 1;
  }
  
  /*
   * When a map is finished, we have an entire status block.
   * Move it from the parser's context to the statusline buffer.
   */
  static int stdin_end_map(void *context) {
      parser_ctx *ctx = context;
      struct status_block *new_block = smalloc(sizeof(struct status_block));
      memcpy(new_block, &(ctx->block), sizeof(struct status_block));
      /* Ensure we have a full_text set, so that when it is missing (or null),
       * i3bar doesn’t crash and the user gets an annoying message. */
      if (!new_block->full_text)
          new_block->full_text = i3string_from_utf8("SPEC VIOLATION: full_text is NULL!");
      if (new_block->urgent)
          ctx->has_urgent = true;
  
      if (new_block->min_width_str) {
          i3String *text = i3string_from_utf8(new_block->min_width_str);
          i3string_set_markup(text, new_block->pango_markup);
          new_block->min_width = (uint32_t)predict_text_width(text);
          i3string_free(text);
      }
  
      i3string_set_markup(new_block->full_text, new_block->pango_markup);
  
      if (new_block->short_text != NULL)
          i3string_set_markup(new_block->short_text, new_block->pango_markup);
  
      TAILQ_INSERT_TAIL(&statusline_buffer, new_block, blocks);
      return 1;
  }
  
  /*
   * When an array is finished, we have an entire statusline.
   * Copy it from the buffer to the actual statusline.
   */
  static int stdin_end_array(void *context) {
      DLOG("copying statusline_buffer to statusline_head\n");
      clear_statusline(&statusline_head, true);
      copy_statusline(&statusline_buffer, &statusline_head);
  
      DLOG("dumping statusline:\n");
      struct status_block *current;
      TAILQ_FOREACH(current, &statusline_head, blocks) {
          DLOG("full_text = %s\n", i3string_as_utf8(current->full_text));
          DLOG("short_text = %s\n", (current->short_text == NULL ? NULL : i3string_as_utf8(current->short_text)));
          DLOG("color = %s\n", current->color);
      }
      DLOG("end of dump\n");
      return 1;
  }
  
  /*
   * Helper function to read stdin
   *
   * Returns NULL on EOF.
   *
   */
  static unsigned char *get_buffer(ev_io *watcher, int *ret_buffer_len) {
      int fd = watcher->fd;
      int n = 0;
      int rec = 0;
      int buffer_len = STDIN_CHUNK_SIZE;
      unsigned char *buffer = smalloc(buffer_len + 1);
      buffer[0] = '\0';
      while (1) {
          n = read(fd, buffer + rec, buffer_len - rec);
          if (n == -1) {
              if (errno == EAGAIN) {
                  /* finish up */
                  break;
              }
              ELOG("read() failed!: %s\n", strerror(errno));
              exit(EXIT_FAILURE);
          }
          if (n == 0) {
              ELOG("stdin: received EOF\n");
              *ret_buffer_len = -1;
              return NULL;
          }
          rec += n;
  
          if (rec == buffer_len) {
              buffer_len += STDIN_CHUNK_SIZE;
              buffer = srealloc(buffer, buffer_len);
          }
      }
      if (*buffer == '\0') {
          FREE(buffer);
          rec = -1;
      }
      *ret_buffer_len = rec;
      return buffer;
  }
  
  static void read_flat_input(char *buffer, int length) {
      struct status_block *first = TAILQ_FIRST(&statusline_head);
      /* Clear the old buffer if any. */
      I3STRING_FREE(first->full_text);
      /* Remove the trailing newline and terminate the string at the same
       * time. */
      if (buffer[length - 1] == '\n' || buffer[length - 1] == '\r')
          buffer[length - 1] = '\0';
      else
          buffer[length] = '\0';
      first->full_text = i3string_from_markup(buffer);
  }
  
  static bool read_json_input(unsigned char *input, int length) {
      yajl_status status = yajl_parse(parser, input, length);
      bool has_urgent = false;
      if (status != yajl_status_ok) {
          char *message = (char *)yajl_get_error(parser, 0, input, length);
  
          /* strip the newline yajl adds to the error message */
          if (message[strlen(message) - 1] == '\n')
              message[strlen(message) - 1] = '\0';
  
          fprintf(stderr, "[i3bar] Could not parse JSON input (code = %d, message = %s): %.*s\n",
                  status, message, length, input);
  
          set_statusline_error("Could not parse JSON (%s)", message);
          yajl_free_error(parser, (unsigned char *)message);
          draw_bars(false);
      } else if (parser_context.has_urgent) {
          has_urgent = true;
      }
      return has_urgent;
  }
  
  /*
   * Callbalk for stdin. We read a line from stdin and store the result
   * in statusline
   *
   */
  void stdin_io_cb(struct ev_loop *loop, ev_io *watcher, int revents) {
      int rec;
      unsigned char *buffer = get_buffer(watcher, &rec);
      if (buffer == NULL)
          return;
      bool has_urgent = false;
      if (child.version > 0) {
          has_urgent = read_json_input(buffer, rec);
      } else {
          read_flat_input((char *)buffer, rec);
      }
      free(buffer);
      draw_bars(has_urgent);
  }
  
  /*
   * Callbalk for stdin first line. We read the first line to detect
   * whether this is JSON or plain text
   *
   */
  void stdin_io_first_line_cb(struct ev_loop *loop, ev_io *watcher, int revents) {
      int rec;
      unsigned char *buffer = get_buffer(watcher, &rec);
      if (buffer == NULL)
          return;
      DLOG("Detecting input type based on buffer *%.*s*\n", rec, buffer);
      /* Detect whether this is JSON or plain text. */
      unsigned int consumed = 0;
      /* At the moment, we don’t care for the version. This might change
       * in the future, but for now, we just discard it. */
      parse_json_header(&child, buffer, rec, &consumed);
      if (child.version > 0) {
          /* If hide-on-modifier is set, we start of by sending the
           * child a SIGSTOP, because the bars aren't mapped at start */
          if (config.hide_on_modifier) {
              stop_child();
          }
          draw_bars(read_json_input(buffer + consumed, rec - consumed));
      } else {
          /* In case of plaintext, we just add a single block and change its
           * full_text pointer later. */
          struct status_block *new_block = scalloc(1, sizeof(struct status_block));
          TAILQ_INSERT_TAIL(&statusline_head, new_block, blocks);
          read_flat_input((char *)buffer, rec);
      }
      free(buffer);
      ev_io_stop(main_loop, stdin_io);
      ev_io_init(stdin_io, &stdin_io_cb, STDIN_FILENO, EV_READ);
      ev_io_start(main_loop, stdin_io);
  }
  
  /*
   * We received a SIGCHLD, meaning, that the child process terminated.
   * We simply free the respective data structures and don't care for input
   * anymore
   *
   */
  void child_sig_cb(struct ev_loop *loop, ev_child *watcher, int revents) {
      int exit_status = WEXITSTATUS(watcher->rstatus);
  
      ELOG("Child (pid: %d) unexpectedly exited with status %d\n",
           child.pid,
           exit_status);
  
      /* this error is most likely caused by a user giving a nonexecutable or
       * nonexistent file, so we will handle those cases separately. */
      if (exit_status == 126)
          set_statusline_error("status_command is not executable (exit %d)", exit_status);
      else if (exit_status == 127)
          set_statusline_error("status_command not found or is missing a library dependency (exit %d)", exit_status);
      else
          set_statusline_error("status_command process exited unexpectedly (exit %d)", exit_status);
  
      cleanup();
      draw_bars(false);
  }
  
  void child_write_output(void) {
      if (child.click_events) {
          const unsigned char *output;
          size_t size;
          ssize_t n;
  
          yajl_gen_get_buf(gen, &output, &size);
  
          n = writeall(child_stdin, output, size);
          if (n != -1)
              n = writeall(child_stdin, "\n", 1);
  
          yajl_gen_clear(gen);
  
          if (n == -1) {
              child.click_events = false;
              kill_child();
              set_statusline_error("child_write_output failed");
              draw_bars(false);
          }
      }
  }
  
  /*
   * Start a child process with the specified command and reroute stdin.
   * We actually start a $SHELL to execute the command so we don't have to care
   * about arguments and such.
   *
   * If `command' is NULL, such as in the case when no `status_command' is given
   * in the bar config, no child will be started.
   *
   */
  void start_child(char *command) {
      if (command == NULL)
          return;
  
      /* Allocate a yajl parser which will be used to parse stdin. */
      static yajl_callbacks callbacks = {
          .yajl_boolean = stdin_boolean,
          .yajl_integer = stdin_integer,
          .yajl_string = stdin_string,
          .yajl_start_map = stdin_start_map,
          .yajl_map_key = stdin_map_key,
          .yajl_end_map = stdin_end_map,
          .yajl_start_array = stdin_start_array,
          .yajl_end_array = stdin_end_array,
      };
      parser = yajl_alloc(&callbacks, NULL, &parser_context);
  
      gen = yajl_gen_alloc(NULL);
  
      int pipe_in[2];  /* pipe we read from */
      int pipe_out[2]; /* pipe we write to */
  
      if (pipe(pipe_in) == -1)
          err(EXIT_FAILURE, "pipe(pipe_in)");
      if (pipe(pipe_out) == -1)
          err(EXIT_FAILURE, "pipe(pipe_out)");
  
      child.pid = fork();
      switch (child.pid) {
          case -1:
              ELOG("Couldn't fork(): %s\n", strerror(errno));
              exit(EXIT_FAILURE);
          case 0:
              /* Child-process. Reroute streams and start shell */
  
              close(pipe_in[0]);
              close(pipe_out[1]);
  
              dup2(pipe_in[1], STDOUT_FILENO);
              dup2(pipe_out[0], STDIN_FILENO);
  
              setpgid(child.pid, 0);
              execl(_PATH_BSHELL, _PATH_BSHELL, "-c", command, (char *)NULL);
              return;
          default:
              /* Parent-process. Reroute streams */
  
              close(pipe_in[1]);
              close(pipe_out[0]);
  
              dup2(pipe_in[0], STDIN_FILENO);
              child_stdin = pipe_out[1];
  
              break;
      }
  
      /* We set O_NONBLOCK because blocking is evil in event-driven software */
      fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK);
  
      stdin_io = smalloc(sizeof(ev_io));
      ev_io_init(stdin_io, &stdin_io_first_line_cb, STDIN_FILENO, EV_READ);
      ev_io_start(main_loop, stdin_io);
  
      /* We must cleanup, if the child unexpectedly terminates */
      child_sig = smalloc(sizeof(ev_child));
      ev_child_init(child_sig, &child_sig_cb, child.pid, 0);
      ev_child_start(main_loop, child_sig);
  
      atexit(kill_child_at_exit);
  }
  
  void child_click_events_initialize(void) {
      if (!child.click_events_init) {
          yajl_gen_array_open(gen);
          child_write_output();
          child.click_events_init = true;
      }
  }
  
  void child_click_events_key(const char *key) {
      yajl_gen_string(gen, (const unsigned char *)key, strlen(key));
  }
  
  /*
   * Generates a click event, if enabled.
   *
   */
  void send_block_clicked(int button, const char *name, const char *instance, int x, int y) {
      if (!child.click_events) {
          return;
      }
  
      child_click_events_initialize();
  
      yajl_gen_map_open(gen);
  
      if (name) {
          child_click_events_key("name");
          yajl_gen_string(gen, (const unsigned char *)name, strlen(name));
      }
  
      if (instance) {
          child_click_events_key("instance");
          yajl_gen_string(gen, (const unsigned char *)instance, strlen(instance));
      }
  
      child_click_events_key("button");
      yajl_gen_integer(gen, button);
  
      child_click_events_key("x");
      yajl_gen_integer(gen, x);
  
      child_click_events_key("y");
      yajl_gen_integer(gen, y);
  
      yajl_gen_map_close(gen);
      child_write_output();
  }
  
  /*
   * kill()s the child process (if any). Called when exit()ing.
   *
   */
  void kill_child_at_exit(void) {
      if (child.pid > 0) {
          if (child.cont_signal > 0 && child.stopped)
              killpg(child.pid, child.cont_signal);
          killpg(child.pid, SIGTERM);
      }
  }
  
  /*
   * kill()s the child process (if existent) and closes and
   * free()s the stdin- and SIGCHLD-watchers
   *
   */
  void kill_child(void) {
      if (child.pid > 0) {
          if (child.cont_signal > 0 && child.stopped)
              killpg(child.pid, child.cont_signal);
          killpg(child.pid, SIGTERM);
          int status;
          waitpid(child.pid, &status, 0);
          cleanup();
      }
  }
  
  /*
   * Sends a SIGSTOP to the child process (if existent)
   *
   */
  void stop_child(void) {
      if (child.stop_signal > 0 && !child.stopped) {
          child.stopped = true;
          killpg(child.pid, child.stop_signal);
      }
  }
  
  /*
   * Sends a SIGCONT to the child process (if existent)
   *
   */
  void cont_child(void) {
      if (child.cont_signal > 0 && child.stopped) {
          child.stopped = false;
          killpg(child.pid, child.cont_signal);
      }
  }
  
  /*
   * Whether or not the child want click events
   *
   */
  bool child_want_click_events(void) {
      return child.click_events;
  }
  