xC: nuke Readline and libedit

Replace them with a custom frontend making use of the termo library. It's a bit rough at the edges, yet thoroughly functional. The original libraries have carried us far, but they've become more trouble than what they're worth: - It's much easier to make this change than to keep fixing both frontends. That has become particularly difficult as of late. - It's also a much smaller undertaking than rewriting the client in more radical ways, such as: - Going for headless operation (also note that we currently lack a terminal relay client). - Rewriting the entire user interface to use curses. - Abandoning GNU Readline clears up licencing. - The old interface code was full of odd hacks and wild adapters. While this commit adds some fresh ugly areas, in sum it's a cleanup. - Purging the dependencies simplifies an eventual automated rewrite in another language. Some freshly invalidated issues: - Readline 8.3 has reworked history, and our method of circumventing a memory leak in history handling stopped working reliably. Very tough to trace. - Editline could block waiting on input. - Editline refresh.c revision 1.61 seems to have completely broken the prompt hiding mechanism, with no obvious means of circumventing.
2026-07-18 01:23:55 +02:00
parent e52501a1df
commit 67d044a426
9 changed files with 1270 additions and 1743 deletions
@@ -1,3 +1,6 @@
 [submodule "liberty"]
 	path = liberty
 	url = https://git.janouch.name/p/liberty.git
+[submodule "termo"]
+	path = termo
+	url = https://git.janouch.name/p/termo.git
@@ -9,8 +9,6 @@ project (xK VERSION "${project_version}"
 	DESCRIPTION "IRC daemon, bot, TUI client and its web frontend" LANGUAGES C)

 # Options
-option (WANT_READLINE "Use GNU Readline for the UI (better)" ON)
-option (WANT_LIBEDIT "Use BSD libedit for the UI" OFF)
 option (WANT_XF "Build xF" OFF)

 # Moar warnings
@@ -88,10 +86,28 @@ CHECK_C_SOURCE_RUNS ("#include <iconv.h>
 		== (iconv_t) -1; }" ICONV_ACCEPTS_TRANSLIT)

 # Dependencies for xC
-pkg_check_modules (libffi REQUIRED libffi)
-list (APPEND xC_libraries ${libffi_LIBRARIES})
-include_directories (${libffi_INCLUDE_DIRS})
-link_directories (${libffi_LIBRARY_DIRS})
+find_package (Termo QUIET NO_MODULE)
+option (USE_SYSTEM_TERMO
+	"Don't compile our own termo library, use the system one" "${Termo_FOUND}")
+if (USE_SYSTEM_TERMO)
+	if (NOT Termo_FOUND)
+		message (FATAL_ERROR "System termo library not found")
+	endif ()
+else ()
+	# We don't want the library to install, but EXCLUDE_FROM_ALL ignores tests
+	add_subdirectory (termo EXCLUDE_FROM_ALL)
+	file (WRITE ${PROJECT_BINARY_DIR}/CTestCustom.cmake
+		"execute_process (COMMAND ${CMAKE_COMMAND} --build termo)")
+
+	# We don't have many good choices; this is a relatively clean approach
+	# (other possibilities: setting a variable in the parent scope, using
+	# a cache variable, writing a special config file with build paths in it
+	# and including it here, or setting a custom property on the targets)
+	get_directory_property (Termo_INCLUDE_DIRS
+		DIRECTORY termo INCLUDE_DIRECTORIES)
+	set (Termo_LIBRARIES termo-static)
+endif ()
+list (APPEND xC_libraries ${Termo_LIBRARIES})

 # XXX: other Lua versions may be acceptable, don't know yet
 pkg_search_module (lua
@@ -120,32 +136,8 @@ else ()
 	message (SEND_ERROR "Curses not found")
 endif ()

-if ((WANT_READLINE AND WANT_LIBEDIT) OR (NOT WANT_READLINE AND NOT WANT_LIBEDIT))
-	message (SEND_ERROR "You have to choose either GNU Readline or libedit")
-elseif (WANT_READLINE)
-	pkg_check_modules (readline readline)
-
-	# OpenBSD's default readline is too old
-	if ("${CMAKE_SYSTEM_NAME}" MATCHES "OpenBSD")
-		include_directories (${OPENBSD_LOCALBASE}/include/ereadline)
-		list (APPEND xC_libraries ereadline)
-	elseif (readline_FOUND)
-		list (APPEND xC_libraries ${readline_LIBRARIES})
-		include_directories (${readline_INCLUDE_DIRS})
-		link_directories (${readline_LIBRARY_DIRS})
-	else ()
-		list (APPEND xC_libraries readline)
-	endif ()
-elseif (WANT_LIBEDIT)
-	pkg_check_modules (libedit REQUIRED libedit)
-	list (APPEND xC_libraries ${libedit_LIBRARIES})
-	include_directories (${libedit_INCLUDE_DIRS})
-endif ()
-
 # Generate a configuration file
-set (HAVE_READLINE "${WANT_READLINE}")
-set (HAVE_EDITLINE "${WANT_LIBEDIT}")
-set (HAVE_LUA      "${WITH_LUA}")
+set (HAVE_LUA "${WITH_LUA}")

 include (GNUInstallDirs)
 set (project_config ${PROJECT_BINARY_DIR}/config.h)
@@ -186,6 +178,7 @@ endforeach ()
 add_dependencies (xD replies)
 add_dependencies (xC replies xC-proto)
 target_link_libraries (xC ${xC_libraries})
+target_include_directories (xC PRIVATE ${Termo_INCLUDE_DIRS})

 if (WANT_XF)
 	pkg_check_modules (x11 REQUIRED x11 xrender xft fontconfig)
@@ -203,7 +196,10 @@ include (CTest)
 if (BUILD_TESTING)
 	add_executable (test-xC $<TARGET_PROPERTY:xC,SOURCES>)
 	set_target_properties (test-xC PROPERTIES COMPILE_DEFINITIONS TESTING)
-	target_link_libraries (test-xC $<TARGET_PROPERTY:xC,LINK_LIBRARIES>)
+	target_include_directories (test-xC
+		PUBLIC $<TARGET_PROPERTY:xC,INCLUDE_DIRECTORIES>)
+	target_link_libraries (test-xC
+		PUBLIC $<TARGET_PROPERTY:xC,LINK_LIBRARIES>)
 	add_threads (test-xC)
 	add_dependencies (test-xC replies)

@@ -1,5 +1,9 @@
 Unreleased

+ * xC: nuked broken Readline and editline support, added a custom frontend
+
+ * xC: added a /bindings command
+
 * xC: added support for Lua 5.5

 * prime.lua: prevented a DoS opportunity on excessively large numbers
@@ -10,9 +10,10 @@ They're all lean on dependencies, and offer a maximally permissive licence.

 xC
 --
-The IRC client, and the core of 'xK'.  It is largely defined by building on top
-of GNU Readline or BSD Editline that have been hacked to death.  Its interface
-should feel somewhat familiar for weechat or irssi users.
+The IRC client, and the core of 'xK'.  Its interface should feel somewhat
+familiar for weechat or irssi users.  Currently the terminal interface
+experience deserves some polishing, because we've just got rid of
+Readline/Editline dependencies, which kept breaking in exciting ways.

 image::xC.webp[align="center"]

@@ -88,8 +89,7 @@ Building
 Build-only dependencies: CMake, pkg-config, awk, liberty (included),
 asciidoctor or asciidoc (recommended but optional) +
 Common runtime dependencies: openssl +
-Additionally for 'xC': curses, libffi, readline >= 6.0 or libedit >= 2013-07-12,
- lua >= 5.3 (optional) +
+Additionally for 'xC': curses, lua >= 5.3 (optional), termo (included) +

 $ git clone --recursive https://git.janouch.name/p/xK.git
 $ mkdir xK/build
@@ -191,26 +191,6 @@ in the required form, use:

 $ openssl x509 -in public.pem -outform DER | sha256sum

-Custom Key Bindings in xC
-------------------------
-The default and preferred frontend used in 'xC' is GNU Readline.  This means
-that you can change your bindings by editing '~/.inputrc'.  For example:
-
-....
-# Preload with system-wide settings
-$include /etc/inputrc
-
-# Make M-left and M-right reorder buffers
-$if xC
-"\e\e[C": move-buffer-right
-"\e\e[D": move-buffer-left
-$endif
-....
-
-Consult the source code and the GNU Readline manual for a list of available
-functions.  Also refer to the latter for the exact syntax of this file.
-Beware that you can easily break the program if you're not careful.
-
 How do I make xC look like the screenshot?
 ------------------------------------------
 With the defaults, 'xC' doesn't look too fancy because I don't want to have
@@ -255,6 +235,3 @@ License
 -------
 This software is released under the terms of the 0BSD license, the text of which
 is included within the package along with the list of authors.
-
-Note that 'xC' becomes GPL-licensed when you link it against GNU Readline,
-but that is not a concern of this source package.  The licenses are compatible.
@@ -134,6 +134,31 @@ xerr_describe_error (void)
 	return reason;
 }

+static bool
+str_append_c_utf8 (struct str *s, uint32_t ucs4)
+{
+	if (ucs4 < 0x80)
+		str_append_c (s, ucs4);
+	else if (ucs4 < 0x7FF)
+		str_append_data (s, (char[]) {
+			0xc0 | (ucs4 >> 6),
+			0x80 | (ucs4 & 0x3f) }, 2);
+	else if (ucs4 < 0xFFFF)
+		str_append_data (s, (char[]) {
+			0xe0 | (ucs4 >> 12),
+			0x80 | ((ucs4 >> 6) & 0x3f),
+			0x80 | (ucs4 & 0x3f) }, 3);
+	else if (ucs4 < 0x10FFFF)
+		str_append_data (s, (char[]) {
+			0xf0 | (ucs4 >> 18),
+			0x80 | ((ucs4 >> 12) & 0x3f),
+			0x80 | ((ucs4 >> 6) & 0x3f),
+			0x80 | (ucs4 & 0x3f) }, 4);
+	else
+		return false;
+	return true;
+}
+
 static struct str
 str_from_cstr (const char *cstr)
 {
@@ -6,8 +6,6 @@
 // We use the XDG Base Directory Specification, but may be installed anywhere.
 #define PROJECT_DATADIR "${CMAKE_INSTALL_FULL_DATADIR}"

-#cmakedefine HAVE_READLINE
-#cmakedefine HAVE_EDITLINE
 #cmakedefine HAVE_LUA

 #cmakedefine01 ICONV_ACCEPTS_TRANSLIT
@@ -39,10 +39,9 @@ This feature may be used to preview server MOTD files.

 Key bindings
 ------------
-Most key bindings are inherited from the frontend in use, which is either GNU
-Readline or BSD editline.  A few of them, however, are special to the IRC client
-or assume a different function.  This is a list of all local overrides and
-their respective function names:
+The basic key bindings are inspired by GNU Readline.  On top of that, there are
+some which are special to the IRC client or assume a different function.
+This is a list of all local specialties and their respective function names:

 *M-p*::
 	Go up in history for this buffer (normally mapped to *C-p*).
@@ -83,13 +82,20 @@ their respective function names:
 	Should there be any issues with the display, this will clear the terminal
 	screen and redraw all information.

-Additionally, *C-w* and *C-u* in editline behave the same as they would in
-Readline or the "vi" command mode, even though the "emacs" mode is enabled
-by default.
+Custom bindings
+---------------
+Edit the configuration file manually.  For example, to make buffer reordering
+functions accessible:

-Bindings can be customized in your _.inputrc_ or _.editrc_ file.  Both libraries
-support conditional execution based on the program name.  Beware that it is easy
-to make breaking changes.
+....
+bindings = {
+	"M-Left" = "move-buffer-left"
+	"M-Right" = "move-buffer-right"
+}
+....
+
+You may bind any function you see in the */bindings* listing, though beware that
+you can easily break the program if you're not careful.

 Lua plugin API
 --------------
@@ -313,10 +319,6 @@ _/usr/local/share/xC/plugins/_::
 _/usr/share/xC/plugins/_::
 	Plugins are searched for in these directories, in order.

-Bugs
----
-The editline (libedit) frontend may exhibit some unexpected behaviour.
-
 Reporting bugs
 --------------
 Use https://git.janouch.name/p/xK to report bugs, request features,
@@ -324,4 +326,4 @@ or submit pull requests.

 See also
 --------
-*less*(1), *readline*(3) or *editline*(7)
+*less*(1)