degesch: allow launching an editor for input

Useful for editing multiline text (such as making it single-line).

Some refactoring and cleanup.

3 files changed, 250 insertions, 47 deletions

diff --git a/NEWS b/NEWS
index 97de82a..8c4fb3b 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,8 @@
 
  * degesch: libedit backend works again
  
+ * degesch: added capability to edit the input line using VISUAL/EDITOR
+
  * degesch: correctly respond to stopping and resuming (SIGTSTP)
 
  * degesch: fixed decoding of text formatting
diff --git a/common.c b/common.c
index 8470171..0d34591 100644
--- a/common.c
+++ b/common.c
@@ -54,6 +54,49 @@ str_vector_find (const struct str_vector *v, const char *s)
 	return -1;
 }
 
+/// This differs from the non-unique version in that we expect the filename
+/// to be something like a pattern for mkstemp(), so the resulting path can
+/// reside in a system-wide directory with no risk of a conflict.
+static char *
+resolve_relative_runtime_unique_filename (const char *filename)
+{
+	struct str path;
+	str_init (&path);
+
+	const char *runtime_dir = getenv ("XDG_RUNTIME_DIR");
+	if (runtime_dir && *runtime_dir == '/')
+		str_append (&path, runtime_dir);
+	else
+		str_append (&path, "/tmp");
+	str_append_printf (&path, "/%s/%s", PROGRAM_NAME, filename);
+
+	// Try to create the file's ancestors;
+	// typically the user will want to immediately create a file in there
+	const char *last_slash = strrchr (path.str, '/');
+	if (last_slash && last_slash != path.str)
+	{
+		char *copy = xstrndup (path.str, last_slash - path.str);
+		(void) mkdir_with_parents (copy, NULL);
+		free (copy);
+	}
+	return str_steal (&path);
+}
+
+static bool
+xwrite (int fd, const char *data, size_t len, struct error **e)
+{
+	size_t written = 0;
+	while (written < len)
+	{
+		ssize_t res = write (fd, data + written, len - written);
+		if (res >= 0)
+			written += res;
+		else if (errno != EINTR)
+			FAIL ("%s", strerror (errno));
+	}
+	return true;
+}
+
 // --- Logging -----------------------------------------------------------------
 
 static void
diff --git a/degesch.c b/degesch.c
index 287a60d..09f5d69 100644
--- a/degesch.c
+++ b/degesch.c
@@ -149,8 +149,6 @@ struct input
 	int saved_mark;                     ///< Saved mark
 #elif defined HAVE_EDITLINE
 	EditLine *editline;                 ///< The EditLine object
-	char *(*saved_prompt) (EditLine *); ///< Saved prompt function
-	char saved_char;                    ///< Saved char for the prompt
 #endif // HAVE_EDITLINE
 
 	char *prompt;                       ///< The prompt we use
@@ -221,16 +219,24 @@ input_set_prompt (struct input *self, char *prompt)
 }
 
 static void
-input_erase (struct input *self)
+input_erase_content (struct input *self)
 {
 	(void) self;
 
-	rl_set_prompt ("");
 	rl_replace_line ("", false);
 	rl_redisplay ();
 }
 
 static void
+input_erase (struct input *self)
+{
+	(void) self;
+
+	rl_set_prompt ("");
+	input_erase_content (self);
+}
+
+static void
 input_bind (struct input *self, const char *seq, const char *function_name)
 {
 	(void) self;
@@ -269,6 +275,13 @@ input_insert (struct input *self, const char *s)
 	return true;
 }
 
+static char *
+input_get_content (struct input *self)
+{
+	(void) self;
+	return rl_copy_text (0, rl_end);
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
 static int app_readline_init (void);
@@ -560,29 +573,39 @@ input_make_empty_prompt (EditLine *editline)
 }
 
 static void
-input_erase (struct input *self)
+input_erase_content (struct input *self)
 {
 	const LineInfoW *info = el_wline (self->editline);
 	int len = info->lastchar - info->buffer;
 	int point = info->cursor - info->buffer;
 	el_cursor (self->editline, len - point);
 	el_wdeletestr (self->editline, len);
+	input_redisplay (self);
+}
 
-	// XXX: this doesn't seem to save the escape character
-	el_get (self->editline, EL_PROMPT, &self->saved_prompt, &self->saved_char);
+static void
+input_erase (struct input *self)
+{
 	el_set (self->editline, EL_PROMPT, input_make_empty_prompt);
-	input_redisplay (self);
+	input_erase_content (self);
 }
 
 static bool
 input_insert (struct input *self, const char *s)
 {
-	bool success = !el_insertstr (self->editline, s);
+	bool success = !*s || !el_insertstr (self->editline, s);
 	if (self->prompt_shown > 0)
 		input_redisplay (self);
 	return success;
 }
 
+static char *
+input_get_content (struct input *self)
+{
+	const LineInfo *info = el_line (self->editline);
+	return xstrndup (info->buffer, info->lastchar - info->buffer);
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
 static void
@@ -699,8 +722,7 @@ input_show (struct input *self)
 		return;
 
 	input_restore (self);
-	// Would have used "saved_char" but it doesn't seem to work.
-	// And it doesn't even when it does anyway (it seems to just strip it).
+	// XXX: the ignore doesn't quite work, see https://gnats.netbsd.org/47539
 	el_set (self->editline,
 		EL_PROMPT_ESC, input_make_prompt, INPUT_START_IGNORE);
 	input_redisplay (self);
@@ -1518,6 +1540,8 @@ struct app_context
 	struct str input_buffer;            ///< Buffered pasted content
 
 	bool running_backlog_helper;        ///< Running a backlog helper
+	bool running_editor;                ///< Running editor for the input
+	char *editor_filename;              ///< The file being edited by user
 	int terminal_suspended;             ///< Terminal suspension level
 
 	struct plugin *plugins;             ///< Loaded plugins
@@ -1624,6 +1648,8 @@ app_context_free (struct app_context *self)
 
 	input_free (&self->input);
 	str_free (&self->input_buffer);
+
+	free (self->editor_filename);
 }
 
 static void refresh_prompt (struct app_context *ctx);
@@ -10107,47 +10133,52 @@ jump_to_buffer (struct app_context *ctx, int n)
 	return true;
 }
 
-static void
-exec_backlog_helper (const char *command, FILE *backlog)
-{
-	dup2 (fileno (backlog), STDIN_FILENO);
-
-	// Put the child into a new foreground process group
-	hard_assert (setpgid (0, 0)!= -1);
-	hard_assert (tcsetpgrp (STDOUT_FILENO, getpgid (0)) != -1);
-
-	execl ("/bin/sh", "/bin/sh", "-c", command, NULL);
-	print_error ("%s: %s", "Failed to launch backlog helper", strerror (errno));
-	_exit (EXIT_FAILURE);
-}
-
-static void
-launch_backlog_helper (struct app_context *ctx, FILE *backlog)
+static pid_t
+spawn_helper_child (struct app_context *ctx)
 {
-	hard_assert (!ctx->running_backlog_helper);
 	suspend_terminal (ctx);
-
 	pid_t child = fork ();
-	if (child == 0)
-		exec_backlog_helper (get_config_string
-			(ctx->config.root, "behaviour.backlog_helper"), backlog);
-
-	if (child == -1)
+	switch (child)
+	{
+	case -1:
 	{
 		int saved_errno = errno;
 		resume_terminal (ctx);
-		log_global_error (ctx, "#s: #s",
-			"Failed to launch backlog helper", strerror (saved_errno));
+		errno = saved_errno;
+		break;
 	}
-	else
-	{
-		// Make sure the child has its own process group
+	case 0:
+		// Put the child in a new foreground process group
+		hard_assert (setpgid (0, 0) != -1);
+		hard_assert (tcsetpgrp (STDOUT_FILENO, getpgid (0)) != -1);
+		break;
+	default:
+		// Make sure of it in the parent as well before continuing
 		(void) setpgid (child, child);
+	}
+	return child;
+}
 
+static void
+launch_backlog_helper (struct app_context *ctx, FILE *backlog)
+{
+	hard_assert (!ctx->running_backlog_helper);
+	switch (spawn_helper_child (ctx))
+	{
+	case 0:
+		dup2 (fileno (backlog), STDIN_FILENO);
+		execl ("/bin/sh", "/bin/sh", "-c", get_config_string
+			(ctx->config.root, "behaviour.backlog_helper"), NULL);
+		print_error ("%s: %s",
+			"Failed to launch backlog helper", strerror (errno));
+		_exit (EXIT_FAILURE);
+	case -1:
+		log_global_error (ctx, "#s: #s",
+			"Failed to launch backlog helper", strerror (errno));
+		break;
+	default:
 		ctx->running_backlog_helper = true;
 	}
-
-	fclose (backlog);
 }
 
 static void
@@ -10168,6 +10199,7 @@ display_backlog (struct app_context *ctx)
 	rewind (backlog);
 	set_cloexec (fileno (backlog));
 	launch_backlog_helper (ctx, backlog);
+	fclose (backlog);
 }
 
 static void
@@ -10189,6 +10221,103 @@ display_full_log (struct app_context *ctx)
 
 	set_cloexec (fileno (full_log));
 	launch_backlog_helper (ctx, full_log);
+	fclose (full_log);
+}
+
+static bool
+dump_input_to_file (struct app_context *ctx, char *template, struct error **e)
+{
+	int fd = mkstemp (template);
+	if (fd < 0)
+		FAIL ("%s", strerror (errno));
+
+	char *input = input_get_content (&ctx->input);
+	bool success = xwrite (fd, input, strlen (input), e);
+	free (input);
+
+	if (!success)
+		(void) unlink (template);
+
+	xclose (fd);
+	return success;
+}
+
+static char *
+try_dump_input_to_file (struct app_context *ctx)
+{
+	char *template = resolve_filename
+		("input.XXXXXX", resolve_relative_runtime_unique_filename);
+
+	struct error *e = NULL;
+	if (dump_input_to_file (ctx, template, &e))
+		return template;
+
+	log_global_error (ctx, "#s: #s",
+		"Failed to create a temporary file for editing", e->message);
+	error_free (e);
+	free (template);
+	return NULL;
+}
+
+static void
+launch_input_editor (struct app_context *ctx)
+{
+	char *filename;
+	if (!(filename = try_dump_input_to_file (ctx)))
+		return;
+
+	const char *command;
+	if (!(command = getenv ("VISUAL"))
+	 && !(command = getenv ("EDITOR")))
+		command = "vi";
+
+	hard_assert (!ctx->running_editor);
+	switch (spawn_helper_child (ctx))
+	{
+	case 0:
+		execlp (command, command, filename, NULL);
+		print_error ("%s: %s",
+			"Failed to launch editor", strerror (errno));
+		_exit (EXIT_FAILURE);
+	case -1:
+		log_global_error (ctx, "#s: #s",
+			"Failed to launch editor", strerror (errno));
+		free (filename);
+		break;
+	default:
+		ctx->running_editor = true;
+		ctx->editor_filename = filename;
+	}
+}
+
+static void
+process_edited_input (struct app_context *ctx)
+{
+	struct str input;
+	str_init (&input);
+
+	struct error *e = NULL;
+	if (!read_file (ctx->editor_filename, &input, &e))
+	{
+		log_global_error (ctx, "#s: #s", "Input editing failed", e->message);
+		error_free (e);
+	}
+	else
+		input_erase_content (&ctx->input);
+
+	if (!input_insert (&ctx->input, input.str))
+		log_global_error (ctx, "#s: #s", "Input editing failed",
+			"could not re-insert the modified text");
+
+	if (unlink (ctx->editor_filename))
+		log_global_error (ctx, "Could not unlink `#s': #s",
+			ctx->editor_filename, strerror (errno));
+
+	free (ctx->editor_filename);
+	ctx->editor_filename = NULL;
+	str_free (&input);
+
+	ctx->running_editor = false;
 }
 
 static void
@@ -10204,6 +10333,7 @@ bind_common_keys (struct app_context *ctx)
 
 	input_bind_meta (self, 'm', "insert-attribute");
 	input_bind_meta (self, 'h', "display-full-log");
+	input_bind_meta (self, 'e', "edit-input");
 
 	if (key_f5)
 		input_bind (self, key_f5, "previous-buffer");
@@ -10276,6 +10406,17 @@ on_readline_display_full_log (int count, int key)
 }
 
 static int
+on_readline_edit_input (int count, int key)
+{
+	(void) count;
+	(void) key;
+
+	struct app_context *ctx = g_ctx;
+	launch_input_editor (ctx);
+	return 0;
+}
+
+static int
 on_readline_redraw_screen (int count, int key)
 {
 	(void) count;
@@ -10380,6 +10521,7 @@ app_readline_init (void)
 	rl_add_defun ("goto-buffer",      on_readline_goto_buffer,      -1);
 	rl_add_defun ("display-backlog",  on_readline_display_backlog,  -1);
 	rl_add_defun ("display-full-log", on_readline_display_full_log, -1);
+	rl_add_defun ("edit-input",       on_readline_edit_input,       -1);
 	rl_add_defun ("redraw-screen",    on_readline_redraw_screen,    -1);
 	rl_add_defun ("insert-attribute", on_readline_insert_attribute, -1);
 	rl_add_defun ("start-paste-mode", on_readline_start_paste_mode, -1);
@@ -10461,6 +10603,16 @@ on_editline_display_full_log (EditLine *editline, int key)
 }
 
 static unsigned char
+on_editline_edit_input (EditLine *editline, int key)
+{
+	(void) editline;
+	(void) key;
+
+	launch_input_editor (g_ctx);
+	return CC_NORM;
+}
+
+static unsigned char
 on_editline_redraw_screen (EditLine *editline, int key)
 {
 	(void) editline;
@@ -10588,6 +10740,7 @@ app_editline_init (struct input *self)
 		{ "next-buffer",      "Next buffer",     on_editline_next_buffer      },
 		{ "display-backlog",  "Show backlog",    on_editline_display_backlog  },
 		{ "display-full-log", "Show full log",   on_editline_display_full_log },
+		{ "edit-input",       "Edit input",      on_editline_edit_input       },
 		{ "redraw-screen",    "Redraw screen",   on_editline_redraw_screen    },
 		{ "insert-attribute", "mIRC formatting", on_editline_insert_attribute },
 		{ "start-paste-mode", "Bracketed paste", on_editline_start_paste_mode },
@@ -10846,19 +10999,22 @@ try_reap_child (struct app_context *ctx)
 	if (!zombie)
 		return false;
 
-	if (!ctx->running_backlog_helper)
-	{
-		print_debug ("an unknown child has died");
-		return true;
-	}
 	if (WIFSTOPPED (status))
 	{
 		// We could also send SIGCONT but what's the point
+		print_debug ("a child has been stopped, killing its process group");
 		kill (-zombie, SIGKILL);
 		return true;
 	}
 
-	ctx->running_backlog_helper = false;
+	if (ctx->running_backlog_helper)
+		ctx->running_backlog_helper = false;
+	else if (!ctx->running_editor)
+	{
+		print_debug ("an unknown child has died");
+		return true;
+	}
+
 	hard_assert (tcsetpgrp (STDOUT_FILENO, getpgid (0)) != -1);
 	resume_terminal (ctx);
 
@@ -10868,6 +11024,8 @@ try_reap_child (struct app_context *ctx)
 	else if (WIFEXITED (status) && WEXITSTATUS (status) != 0)
 		log_global_error (ctx,
 			"Child returned status #d", WEXITSTATUS (status));
+	else if (ctx->running_editor)
+		process_edited_input (ctx);
 	return true;
 }