util.c

#include "owl.h"
#include <pwd.h>
#include <sys/stat.h>
#include <stdarg.h>
#include <glib/gstdio.h>
#include <glib-object.h>

const char *skiptokens(const char *buff, int n) {
  /* skips n tokens and returns where that would be. */
  char quote = 0;
  while (*buff && n>0) {
      while (*buff == ' ') buff++;
      while (*buff && (quote || *buff != ' ')) {
        if(quote) {
          if(*buff == quote) quote = 0;
        } else if(*buff == '"' || *buff == '\'') {
          quote = *buff;
        }
        buff++;
      }
      while (*buff == ' ') buff++;
      n--;
  }
  return buff;
}

CALLER_OWN char *owl_util_homedir_for_user(const char *name)
{
  int err;
  struct passwd pw_buf;
  struct passwd *pw;

  char *pw_strbuf, *ret;
  long pw_strbuf_len = sysconf(_SC_GETPW_R_SIZE_MAX);
  if (pw_strbuf_len < 0) {
    /* If we really hate ourselves, we can be fancy and loop until we stop
     * getting ERANGE. For now just pick a random number. */
    owl_function_error("owl_util_homedir_for_user: Could not get _SC_GETPW_R_SIZE_MAX");
    pw_strbuf_len = 16384;
  }
  pw_strbuf = g_new0(char, pw_strbuf_len);
  err = getpwnam_r(name, &pw_buf, pw_strbuf, pw_strbuf_len, &pw);
  if (err) {
    owl_function_error("getpwuid_r: %s", strerror(err));
    /* Fall through; pw will be NULL. */
  }
  ret = pw ? g_strdup(pw->pw_dir) : NULL;
  g_free(pw_strbuf);
  return ret;
}

/* Return a "nice" version of the path.  Tilde expansion is done, and
 * duplicate slashes are removed.  Caller must free the return.
 */
CALLER_OWN char *owl_util_makepath(const char *in)
{
  char *out;
  int i, j;
  if (in[0] == '~') {
    /* Attempt tilde-expansion of the first component. Get the
       tilde-prefix, which goes up to the next slash. */
    const char *end = strchr(in + 1, '/');
    if (end == NULL)
      end = in + strlen(in);

    /* Patch together a new path. Replace the ~ and tilde-prefix with
       the homedir, if available. */
    if (end == in + 1) {
      /* My home directory. Use the one in owl_global for consistency with
       * owl_zephyr_dotfile. */
      out = g_strconcat(owl_global_get_homedir(&g), end, NULL);
    } else {
      /* Someone else's home directory. */
      char *user = g_strndup(in + 1, end - (in + 1));
      char *home = owl_util_homedir_for_user(user);
      if (home) {
        out = g_strconcat(home, end, NULL);
      } else {
        out = g_strdup(in);
      }
      g_free(home);
      g_free(user);
    }
  } else {
    out = g_strdup(in);
  }

  /* And a quick pass to remove duplicate slashes. */
  for (i = j = 0; out[i] != '\0'; i++) {
    if (out[i] != '/' || i == 0 || out[i-1] != '/')
      out[j++] = out[i];
  }
  out[j] = '\0';
  return out;
}

void owl_ptr_array_free(GPtrArray *array, GDestroyNotify element_free_func)
{
  /* TODO: when we move to requiring glib 2.22+, use
   * g_ptr_array_new_with_free_func instead. */
  if (element_free_func)
    g_ptr_array_foreach(array, (GFunc)element_free_func, NULL);
  g_ptr_array_free(array, true);
}

/* Break a command line up into argv, argc.  The caller must free
   the returned values with g_strfreev.  If there is an error argc will be set
   to -1, argv will be NULL and the caller does not need to free anything. The
   returned vector is NULL-terminated. */
CALLER_OWN char **owl_parseline(const char *line, int *argc)
{
  GPtrArray *argv;
  int i, len, between=1;
  GString *curarg;
  char quote;

  argv = g_ptr_array_new();
  len=strlen(line);
  curarg = g_string_new("");
  quote='\0';
  if (argc) *argc=0;
  for (i=0; i<len+1; i++) {
    /* find the first real character */
    if (between) {
      if (line[i]==' ' || line[i]=='\t' || line[i]=='\0') {
	continue;
      } else {
	between=0;
	i--;
	continue;
      }
    }

    /* deal with a quote character */
    if (line[i]=='"' || line[i]=="'"[0]) {
      /* if this type of quote is open, close it */
      if (quote==line[i]) {
	quote='\0';
	continue;
      }

      /* if no quoting is open then open with this */
      if (quote=='\0') {
	quote=line[i];
	continue;
      }

      /* if another type of quote is open then treat this as a literal */
      g_string_append_c(curarg, line[i]);
      continue;
    }

    /* if it's not a space or end of command, then use it */
    if (line[i]!=' ' && line[i]!='\t' && line[i]!='\n' && line[i]!='\0') {
      g_string_append_c(curarg, line[i]);
      continue;
    }

    /* otherwise, if we're not in quotes, add the whole argument */
    if (quote=='\0') {
      /* add the argument */
      g_ptr_array_add(argv, g_string_free(curarg, false));
      curarg = g_string_new("");
      between=1;
      continue;
    }

    /* if it is a space and we're in quotes, then use it */
    g_string_append_c(curarg, line[i]);
  }

  if (argc) *argc = argv->len;
  g_ptr_array_add(argv, NULL);
  g_string_free(curarg, true);

  /* check for unbalanced quotes */
  if (quote!='\0') {
    owl_ptr_array_free(argv, g_free);
    if (argc) *argc = -1;
    return(NULL);
  }

  return (char**)g_ptr_array_free(argv, false);
}

/* Appends a quoted version of arg suitable for placing in a
 * command-line to a GString. Does not append a space. */
void owl_string_append_quoted_arg(GString *buf, const char *arg)
{
  const char *argp;
  if (arg[0] == '\0') {
    /* Quote the empty string. */
    g_string_append(buf, "''");
  } else if (arg[strcspn(arg, "'\" \n\t")] == '\0') {
    /* If there are no nasty characters, return as-is. */
    g_string_append(buf, arg);
  } else if (!strchr(arg, '\'')) {
    /* Single-quote if possible. */
    g_string_append_c(buf, '\'');
    g_string_append(buf, arg);
    g_string_append_c(buf, '\'');
  } else {
    /* Nasty case: double-quote, but change all internal "s to "'"'"
     * so that they are single-quoted because we're too cool for
     * backslashes.
     */
    g_string_append_c(buf, '"');
    for (argp = arg; *argp; argp++) {
      if (*argp == '"')
	g_string_append(buf, "\"'\"'\"");
      else
	g_string_append_c(buf, *argp);
    }
    g_string_append_c(buf, '"');
  }
}

/*
 * Appends 'tmpl' to 'buf', replacing any instances of '%q' with arguments from
 * the varargs provided, quoting them to be safe for placing in a BarnOwl
 * command line.
 */
void owl_string_appendf_quoted(GString *buf, const char *tmpl, ...)
{
  va_list ap;
  va_start(ap, tmpl);
  owl_string_vappendf_quoted(buf, tmpl, ap);
  va_end(ap);
}

void owl_string_vappendf_quoted(GString *buf, const char *tmpl, va_list ap)
{
  const char *p = tmpl, *last = tmpl;
  while (true) {
    p = strchr(p, '%');
    if (p == NULL) break;
    if (*(p+1) != 'q') {
      p++;
      if (*p) p++;
      continue;
    }
    g_string_append_len(buf, last, p - last);
    owl_string_append_quoted_arg(buf, va_arg(ap, char *));
    p += 2; last = p;
  }

  g_string_append(buf, last);
}

CALLER_OWN char *owl_string_build_quoted(const char *tmpl, ...)
{
  GString *buf = g_string_new("");
  va_list ap;
  va_start(ap, tmpl);
  owl_string_vappendf_quoted(buf, tmpl, ap);
  va_end(ap);
  return g_string_free(buf, false);  
}

/* Returns a quoted version of arg suitable for placing in a
 * command-line. Result should be freed with g_free. */
CALLER_OWN char *owl_arg_quote(const char *arg)
{
  GString *buf = g_string_new("");
  owl_string_append_quoted_arg(buf, arg);
  return g_string_free(buf, false);
}

/* Returns a quoted version of argv. owl_parseline on the result should give
 * back the input. */
CALLER_OWN char *owl_argv_quote(int argc, const char *const *argv)
{
  int i;
  GString *buf = g_string_new("");
  for (i = 0; i < argc; i++) {
    if (i > 0)
      g_string_append_c(buf, ' ');
    owl_string_append_quoted_arg(buf, argv[i]);
  }
  return g_string_free(buf, false);
}

/* caller must free the return */
CALLER_OWN char *owl_util_format_minutes(int in)
{
  int days, hours;
  long run;
  char *out;

  run=in;

  days=run/1440;
  run-=days*1440;
  hours=run/60;
  run-=hours*60;

  if (days>0) {
    out=g_strdup_printf("%i d %2.2i:%2.2li", days, hours, run);
  } else {
    out=g_strdup_printf("    %2.2i:%2.2li", hours, run);
  }
  return(out);
}

CALLER_OWN char *owl_util_format_time(const struct tm *time)
{
  /* 32 chosen for first attempt because timestr will end up being
   * something like "Www Mmm dd hh:mm:ss AM yyyy UTC\0" */ 
  size_t timestr_size = 16;
  char *timestr = NULL;
  do {
    timestr_size *= 2;
    timestr = g_renew(char, timestr, timestr_size);
  } while (strftime(timestr, timestr_size, "%c", time) == 0);
  return timestr;
}

/* These are in order of their value in owl.h */
static const struct {
  int number;
  const char *name;
} color_map[] = {
  {OWL_COLOR_INVALID, "invalid"},
  {OWL_COLOR_DEFAULT, "default"},
  {OWL_COLOR_BLACK, "black"},
  {OWL_COLOR_RED, "red"},
  {OWL_COLOR_GREEN, "green"},
  {OWL_COLOR_YELLOW,"yellow"},
  {OWL_COLOR_BLUE, "blue"},
  {OWL_COLOR_MAGENTA, "magenta"},
  {OWL_COLOR_CYAN, "cyan"},
  {OWL_COLOR_WHITE, "white"},
};

/* Return the owl color associated with the named color.  Return -1
 * if the named color is not available
 */
int owl_util_string_to_color(const char *color)
{
  int c, i;
  char *p;

  for (i = 0; i < (sizeof(color_map)/sizeof(color_map[0])); i++)
    if (strcasecmp(color, color_map[i].name) == 0)
      return color_map[i].number;

  c = strtol(color, &p, 10);
  if (p != color && c >= -1 && c < COLORS) {
    return(c);
  }
  return(OWL_COLOR_INVALID);
}

/* Return a string name of the given owl color */
const char *owl_util_color_to_string(int color)
{
  if (color >= OWL_COLOR_INVALID && color <= OWL_COLOR_WHITE)
    return color_map[color - OWL_COLOR_INVALID].name;
  return("Unknown color");
}

/* Get the default tty name.  Caller must free the return */
CALLER_OWN char *owl_util_get_default_tty(void)
{
  const char *tmp;
  char *out;

  if (getenv("DISPLAY")) {
    out=g_strdup(getenv("DISPLAY"));
  } else if ((tmp=ttyname(fileno(stdout)))!=NULL) {
    out=g_strdup(tmp);
    if (!strncmp(out, "/dev/", 5)) {
      g_free(out);
      out=g_strdup(tmp+5);
    }
  } else {
    out=g_strdup("unknown");
  }
  return(out);
}

/* strip leading and trailing new lines.  Caller must free the
 * return.
 */
CALLER_OWN char *owl_util_stripnewlines(const char *in)
{
  
  char  *tmp, *ptr1, *ptr2, *out;

  ptr1=tmp=g_strdup(in);
  while (ptr1[0]=='\n') {
    ptr1++;
  }
  ptr2=ptr1+strlen(ptr1)-1;
  while (ptr2>ptr1 && ptr2[0]=='\n') {
    ptr2[0]='\0';
    ptr2--;
  }

  out=g_strdup(ptr1);
  g_free(tmp);
  return(out);
}


/* If filename is a link, recursively resolve symlinks.  Otherwise, return the filename
 * unchanged.  On error, call owl_function_error and return NULL.
 *
 * This function assumes that filename eventually resolves to an acutal file.
 * If you want to check this, you should stat() the file first.
 *
 * The caller of this function is responsible for freeing the return value.
 *
 * Error conditions are the same as g_file_read_link.
 */
CALLER_OWN gchar *owl_util_recursive_resolve_link(const char *filename)
{
  gchar *last_path = g_strdup(filename);
  GError *err = NULL;

  while (g_file_test(last_path, G_FILE_TEST_IS_SYMLINK)) {
    gchar *link_path = g_file_read_link(last_path, &err);
    if (link_path == NULL) {
      owl_function_error("Cannot resolve symlink %s: %s",
			 last_path, err->message);
      g_error_free(err);
      g_free(last_path);
      return NULL;
    }

    /* Deal with obnoxious relative paths. If we really care, all this
     * is racy. Whatever. */
    if (!g_path_is_absolute(link_path)) {
      char *last_dir = g_path_get_dirname(last_path);
      char *tmp = g_build_filename(last_dir, link_path, NULL);
      g_free(last_dir);
      g_free(link_path);
      link_path = tmp;
    }

    g_free(last_path);
    last_path = link_path;
  }
  return last_path;
}

/* Delete all lines matching "line" from the named file.  If no such
 * line is found the file is left intact.  If backup==1 then leave a
 * backup file containing the original contents.  The match is
 * case-insensitive.
 *
 * Returns the number of lines removed on success.  Returns -1 on failure.
 */
int owl_util_file_deleteline(const char *filename, const char *line, int backup)
{
  char *backupfile, *newfile, *buf = NULL;
  gchar *actual_filename; /* gchar; we need to g_free it */
  FILE *old, *new;
  struct stat st;
  int numremoved = 0;

  if ((old = fopen(filename, "r")) == NULL) {
    owl_function_error("Cannot open %s (for reading): %s",
		       filename, strerror(errno));
    return -1;
  }

  if (fstat(fileno(old), &st) != 0) {
    owl_function_error("Cannot stat %s: %s", filename, strerror(errno));
    fclose(old);
    return -1;
  }

  /* resolve symlinks, because link() fails on symlinks, at least on AFS */
  actual_filename = owl_util_recursive_resolve_link(filename);
  if (actual_filename == NULL) {
    fclose(old);
    return -1; /* resolving the symlink failed, but we already logged this error */
  }

  newfile = g_strdup_printf("%s.new", actual_filename);
  if ((new = fopen(newfile, "w")) == NULL) {
    owl_function_error("Cannot open %s (for writing): %s",
		       actual_filename, strerror(errno));
    g_free(newfile);
    fclose(old);
    g_free(actual_filename);
    return -1;
  }

  if (fchmod(fileno(new), st.st_mode & 0777) != 0) {
    owl_function_error("Cannot set permissions on %s: %s",
		       actual_filename, strerror(errno));
    unlink(newfile);
    fclose(new);
    g_free(newfile);
    fclose(old);
    g_free(actual_filename);
    return -1;
  }

  while (owl_getline_chomp(&buf, old))
    if (strcasecmp(buf, line) != 0)
      fprintf(new, "%s\n", buf);
    else
      numremoved++;
  g_free(buf);

  fclose(new);
  fclose(old);

  if (backup) {
    backupfile = g_strdup_printf("%s.backup", actual_filename);
    unlink(backupfile);
    if (link(actual_filename, backupfile) != 0) {
      owl_function_error("Cannot link %s: %s", backupfile, strerror(errno));
      g_free(backupfile);
      unlink(newfile);
      g_free(newfile);
      return -1;
    }
    g_free(backupfile);
  }

  if (rename(newfile, actual_filename) != 0) {
    owl_function_error("Cannot move %s to %s: %s",
		       newfile, actual_filename, strerror(errno));
    numremoved = -1;
  }

  unlink(newfile);
  g_free(newfile);

  g_free(actual_filename);

  return numremoved;
}

/* Return the base class or instance from a zephyr class, by removing
   leading `un' or trailing `.d'.
   The caller is responsible for freeing the allocated string.
*/
CALLER_OWN char *owl_util_baseclass(const char *class)
{
  char *start, *end;

  while(!strncmp(class, "un", 2)) {
    class += 2;
  }

  start = g_strdup(class);
  end = start + strlen(start) - 1;
  while(end > start && *end == 'd' && *(end-1) == '.') {
    end -= 2;
  }
  *(end + 1) = 0;

  return start;
}

const char * owl_get_datadir(void)
{
  const char * datadir = getenv("BARNOWL_DATA_DIR");
  if(datadir != NULL)
    return datadir;
  return DATADIR;
}

const char * owl_get_bindir(void)
{
  const char * bindir = getenv("BARNOWL_BIN_DIR");
  if(bindir != NULL)
    return bindir;
  return BINDIR;
}

/* Strips format characters from a valid utf-8 string. Returns the
   empty string if 'in' does not validate.  Caller must free the return. */
CALLER_OWN char *owl_strip_format_chars(const char *in)
{
  char *r;
  if (g_utf8_validate(in, -1, NULL)) {
    const char *s, *p;
    r = g_new(char, strlen(in)+1);
    r[0] = '\0';
    s = in;
    p = strchr(s, OWL_FMTEXT_UC_STARTBYTE_UTF8);
    while(p) {
      /* If it's a format character, copy up to it, and skip all
	 immediately following format characters. */
      if (owl_fmtext_is_format_char(g_utf8_get_char(p))) {
	strncat(r, s, p-s);
	p = g_utf8_next_char(p);
	while (owl_fmtext_is_format_char(g_utf8_get_char(p))) {
	  p = g_utf8_next_char(p);
	}
	s = p;
	p = strchr(s, OWL_FMTEXT_UC_STARTBYTE_UTF8);
      }
      else {
	p = strchr(p+1, OWL_FMTEXT_UC_STARTBYTE_UTF8);
      }
    }
    if (s) strcat(r,s);
  }
  else {
    r = g_strdup("");
  }
  return r;
}

/* If in is not UTF-8, convert from ISO-8859-1. We may want to allow
 * the caller to specify an alternative in the future. We also strip
 * out characters in Unicode Plane 16, as we use that plane internally
 * for formatting.
 * Caller must free the return.
 */
CALLER_OWN char *owl_validate_or_convert(const char *in)
{
  if (g_utf8_validate(in, -1, NULL)) {
    return owl_strip_format_chars(in);
  }
  else {
    return g_convert(in, -1,
		     "UTF-8", "ISO-8859-1",
		     NULL, NULL, NULL);
  }
}
/*
 * Validate 'in' as UTF-8, and either return a copy of it, or an empty
 * string if it is invalid utf-8.
 * Caller must free the return.
 */
CALLER_OWN char *owl_validate_utf8(const char *in)
{
  char *out;
  if (g_utf8_validate(in, -1, NULL)) {
    out = g_strdup(in);
  } else {
    out = g_strdup("");
  }
  return out;
}

CALLER_OWN char *owl_util_compat_casefold(const char *str)
{
  /*
   * Quoting Anders Kaseorg at https://github.com/barnowl/barnowl/pull/54#issuecomment-31452543:
   *
   * The Unicode specification calls this compatibility caseless matching, and
   * the correct transformation actually has five calls:
   * NFKC(toCasefold(NFKD(toCasefold(NFD(string))))) Zephyr’s current
   * implementation incorrectly omits the innermost NFD, but that difference
   * only matters for characters including U+0345 ◌ͅ COMBINING GREEK
   * YPOGEGRAMMENI. I think we should just write the correct version and get
   * Zephyr fixed.
   *
   * Neither of these operations should be called toNFKC_Casefold, because that
   * has slightly different behavior regarding Default_Ignorable_Code_Point. I
   * propose compat_casefold. And I guess if Jabber wants it too, we should
   * move it to util.c.
   */
  char *tmp0 = g_utf8_normalize(str, -1, G_NORMALIZE_NFD);
  char *tmp1 = g_utf8_casefold(tmp0, -1);
  char *tmp2 = g_utf8_normalize(tmp1, -1, G_NORMALIZE_NFKD);
  char *tmp3 = g_utf8_casefold(tmp2, -1);
  char *out = g_utf8_normalize(tmp3, -1, G_NORMALIZE_NFKC);
  g_free(tmp0);
  g_free(tmp1);
  g_free(tmp2);
  g_free(tmp3);

  return out;
}

/* This is based on _extract() and _isCJ() from perl's Text::WrapI18N */
int owl_util_can_break_after(gunichar c)
{
  
  if (c == ' ') return 1;
  if (c >= 0x3000 && c <= 0x312f) {
    /* CJK punctuations, Hiragana, Katakana, Bopomofo */
    if (c == 0x300a || c == 0x300c || c == 0x300e ||
        c == 0x3010 || c == 0x3014 || c == 0x3016 ||
        c == 0x3018 || c == 0x301a)
      return 0;
    return 1;
  }
  if (c >= 0x31a0 && c <= 0x31bf) {return 1;}  /* Bopomofo */
  if (c >= 0x31f0 && c <= 0x31ff) {return 1;}  /* Katakana extension */
  if (c >= 0x3400 && c <= 0x9fff) {return 1;}  /* Han Ideogram */
  if (c >= 0xf900 && c <= 0xfaff) {return 1;}  /* Han Ideogram */
  if (c >= 0x20000 && c <= 0x2ffff) {return 1;}  /* Han Ideogram */
  return 0;
}

/* caller must free the return */
CALLER_OWN char *owl_escape_highbit(const char *str)
{
  GString *out = g_string_new("");
  unsigned char c;
  while((c = (*str++))) {
    if(c == '\\') {
      g_string_append(out, "\\\\");
    } else if(c & 0x80) {
      g_string_append_printf(out, "\\x%02x", (int)c);
    } else {
      g_string_append_c(out, c);
    }
  }
  return g_string_free(out, 0);
}

/* innards of owl_getline{,_chomp} below */
static int owl_getline_internal(char **s, FILE *fp, int newline)
{
  int size = 0;
  int target = 0;
  int count = 0;
  int c;

  while (1) {
    c = getc(fp);
    if ((target + 1) > size) {
      size += BUFSIZ;
      *s = g_renew(char, *s, size);
    }
    if (c == EOF)
      break;
    count++;
    if (c != '\n' || newline)
	(*s)[target++] = c;
    if (c == '\n')
      break;
  }
  (*s)[target] = 0;

  return count;
}

/* Read a line from fp, allocating memory to hold it, returning the number of
 * byte read.  *s should either be NULL or a pointer to memory allocated with
 * g_malloc; it will be g_renew'd as appropriate.  The caller must
 * eventually free it.  (This is roughly the interface of getline in the gnu
 * libc).
 *
 * The final newline will be included if it's there.
 */
int owl_getline(char **s, FILE *fp)
{
  return owl_getline_internal(s, fp, 1);
}

/* As above, but omitting the final newline */
int owl_getline_chomp(char **s, FILE *fp)
{
  return owl_getline_internal(s, fp, 0);
}

/* Read the rest of the input available in fp into a string. */
CALLER_OWN char *owl_slurp(FILE *fp)
{
  char *buf = NULL;
  char *p;
  int size = 0;
  int count;

  while (1) {
    buf = g_renew(char, buf, size + BUFSIZ);
    p = &buf[size];
    size += BUFSIZ;

    if ((count = fread(p, 1, BUFSIZ, fp)) < BUFSIZ)
      break;
  }
  p[count] = 0;

  return buf;
}

int owl_util_get_colorpairs(void) {
#ifndef NCURSES_EXT_COLORS
  /* Without ext-color support (an ABI change), ncurses only supports 256
   * different color pairs. However, it gives us a larger number even if your
   * ncurses is compiled without ext-color. */
  return MIN(COLOR_PAIRS, 256);
#else
  return COLOR_PAIRS;
#endif
}

gulong owl_dirty_window_on_signal(owl_window *w, gpointer sender, const gchar *detailed_signal)
{
  return owl_signal_connect_object(sender, detailed_signal, G_CALLBACK(owl_window_dirty), w, G_CONNECT_SWAPPED);
}

typedef struct { /*noproto*/
  GObject  *sender;
  gulong    signal_id;
} SignalData;

static void _closure_invalidated(gpointer data, GClosure *closure);

/*
 * GObject's g_signal_connect_object has a documented bug. This function is
 * identical except it does not leak the signal handler.
 */
gulong owl_signal_connect_object(gpointer sender, const gchar *detailed_signal, GCallback c_handler, gpointer receiver, GConnectFlags connect_flags)
{
  g_return_val_if_fail (G_TYPE_CHECK_INSTANCE (sender), 0);
  g_return_val_if_fail (detailed_signal != NULL, 0);
  g_return_val_if_fail (c_handler != NULL, 0);

  if (receiver) {
    SignalData *sdata;
    GClosure *closure;
    gulong signal_id;

    g_return_val_if_fail (G_IS_OBJECT (receiver), 0);

    closure = ((connect_flags & G_CONNECT_SWAPPED) ? g_cclosure_new_object_swap : g_cclosure_new_object) (c_handler, receiver);
    signal_id = g_signal_connect_closure (sender, detailed_signal, closure, connect_flags & G_CONNECT_AFTER);

    /* Register the missing hooks */
    sdata = g_slice_new0(SignalData);
    sdata->sender = sender;
    sdata->signal_id = signal_id;

    g_closure_add_invalidate_notifier(closure, sdata, _closure_invalidated);

    return signal_id;
  } else {
    return g_signal_connect_data(sender, detailed_signal, c_handler, NULL, NULL, connect_flags);
  }
}

/*
 * There are three ways the signal could come to an end:
 * 
 * 1. The user explicitly disconnects it with the returned signal_id.
 *    - In that case, the disconnection unref's the closure, causing it
 *      to first be invalidated. The handler's already disconnected, so
 *      we have no work to do.
 * 2. The sender gets destroyed.
 *    - GObject will disconnect each signal which then goes into the above
 *      case. Our handler does no work.
 * 3. The receiver gets destroyed.
 *    - The GClosure was created by g_cclosure_new_object_{,swap} which gets
 *      invalidated when the receiver is destroyed. We then follow through case 1
 *      again, but *this* time, the handler has not been disconnected. We then
 *      clean up ourselves.
 *
 * We can't actually hook into this process earlier with weakrefs as GObject
 * will, on object dispose, first disconnect signals, then invalidate closures,
 * and notify weakrefs last.
 */
static void _closure_invalidated(gpointer data, GClosure *closure)
{
  SignalData *sdata = data;
  if (g_signal_handler_is_connected(sdata->sender, sdata->signal_id)) {
    g_signal_handler_disconnect(sdata->sender, sdata->signal_id);
  }
  g_slice_free(SignalData, sdata);
}