Add an Expect-like tool

This is to provide an Expect utility with a minimal dependency tree
for C-based projects.  It also addresses some Tcl Expect design issues,
as perceived by me.

README.adoc

@@ -68,6 +68,9 @@ lxdrgen-mjs.awk::
 lxdrgen-swift.awk::
 	LibertyXDR backend for the Swift programming language.
 
+wdye::
+	Compiled Lua-based Expect-like utility, intended purely for build checks.
+
 Contributing and Support
 ------------------------
 Use https://git.janouch.name/p/liberty to report any bugs, request features,

tools/wdye/CMakeLists.txt

@@ -0,0 +1,39 @@
+cmake_minimum_required (VERSION 3.18)
+project (wdye VERSION 1 DESCRIPTION "What did you expect?" LANGUAGES C)
+
+set (CMAKE_C_STANDARD 99)
+set (CMAKE_C_STANDARD_REQUIRED ON)
+set (CMAKE_C_EXTENSIONS OFF)
+
+# -Wunused-function is pretty annoying here, as everything is static
+set (options -Wall -Wextra -Wno-unused-function)
+add_compile_options ("$<$<CXX_COMPILER_ID:GNU>:${options}>")
+add_compile_options ("$<$<CXX_COMPILER_ID:Clang>:${options}>")
+
+set (CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/../../cmake")
+
+find_package (Curses)
+find_package (PkgConfig REQUIRED)
+pkg_search_module (lua REQUIRED
+	lua53 lua5.3 lua-5.3 lua54 lua5.4 lua-5.4 lua>=5.3)
+
+option (WITH_CURSES "Offer terminal sequences using Curses" "${CURSES_FOUND}")
+
+include_directories ("${PROJECT_BINARY_DIR}")
+file (CONFIGURE OUTPUT "${PROJECT_BINARY_DIR}/config.h" CONTENT [[
+#define PROGRAM_NAME "${PROJECT_NAME}"
+#define PROGRAM_VERSION "${PROJECT_VERSION}"
+#cmakedefine WITH_CURSES
+]])
+
+add_executable (wdye wdye.c)
+target_include_directories (wdye PUBLIC ${lua_INCLUDE_DIRS})
+target_link_directories (wdye PUBLIC ${lua_LIBRARY_DIRS})
+target_link_libraries (wdye PUBLIC ${lua_LIBRARIES})
+if (WITH_CURSES)
+	target_include_directories (wdye PUBLIC ${CURSES_INCLUDE_DIRS})
+	target_link_libraries (wdye PUBLIC ${CURSES_LIBRARIES})
+endif ()
+
+add_test (NAME simple COMMAND wdye "${PROJECT_SOURCE_DIR}/test.lua")
+include (CTest)

tools/wdye/test.lua

@@ -0,0 +1,24 @@
+for k, v in pairs(wdye) do _G[k] = v end
+
+-- The terminal echoes back, we don't want to read the same stuff twice.
+local cat = spawn {"sh", "-c", "cat > /dev/null", environ={TERM="xterm"}}
+assert(cat, "failed to spawn process")
+assert(cat.term.key_left, "bad terminfo")
+
+cat:send("Hello\r")
+local m = expect(cat:exact {"Hello\r", function (p) return p[0] end})
+assert(m == "Hello\r", "exact match failed, or value expansion mismatch")
+
+local t = table.pack(expect(timeout {.5, 42}))
+assert(#t == 1 and t[1] == 42, "timeout match failed, or value mismatch")
+
+cat:send("abc123\r")
+expect(cat:regex {"A(.*)3", nocase=true, function (p)
+	assert(p[0] == "abc123", "wrong regex group #0")
+	assert(p[1] == "bc12", "wrong regex group #1")
+end})
+
+-- Send EOF (^D), test method chaining.
+cat:send("Closing...\r"):send("\004")
+local v = expect(cat:eof {true},
+	cat:default {.5, function (p) error "expected EOF, got a timeout" end})

tools/wdye/wdye.adoc

@@ -0,0 +1,126 @@
+wdye(1)
+=======
+:doctype: manpage
+:manmanual: wdye Manual
+:mansource: wdye {release-version}
+
+Name
+----
+wdye - what did you expect: Lua-based Expect tool
+
+Synopsis
+--------
+*wdye* _program.lua_
+
+Description
+-----------
+*wdye* executes a Lua script, providing an *expect*(1)-like API targeted
+at application testing.
+
+API
+---
+This list is logically ordered.  Uppercase names represent object types.
+
+wdye.spawn {file [, arg1, ...] [, environ=env]}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Creates a new pseudoterminal, spawns the given program in it,
+and returns a _process_ object.  When *file* doesn't contain slashes,
+the program will be searched for in _PATH_.
+
+The *env* map may be used to override environment variables, notably _TERM_.
+Variables evaluating to _false_ will be removed from the environment.
+
+The program's whole process group receives SIGKILL when the _process_
+is garbage-collected.
+
+wdye.expect ([pattern1, ...])
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Waits until any pattern is ready, in order.
+When no *timeout* (or *default*) patterns are included, one is added implicitly.
+
+The function returns the matching _pattern_'s values, while replacing
+any included functions with the results of their immediate evaluation,
+passing the matching _pattern_ as their sole argument.
+
+wdye.timeout {[timeout, ] [value1, ...]}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Returns a new timeout _pattern_.  When no *timeout* is given, which is specified
+in seconds, a default timeout value is assumed.  Any further values
+are remembered to be later processed by *expect*.
+
+wdye.continue ()
+~~~~~~~~~~~~~~~~
+Raises a _nil_ error, which is interpreted by *expect* as a signal to restart
+all processing.
+
+PROCESS.buffer
+~~~~~~~~~~~~~~
+A string with the _process_' current read buffer contents.
+
+PROCESS.term
+~~~~~~~~~~~~
+A table with the _process_' *terminfo*(5) capabilities,
+notably containing all **key_...** codes.
+This functionality may not be enabled, then this table will always be empty.
+
+PROCESS:send ([string, ...])
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Writes the given strings to the _process_' terminal slave,
+and returns the _process_ for method chaining.
+
+Beware of echoing and deadlocks, as only *expect* can read from the _process_,
+and thus consume the terminal slave's output queue.
+
+PROCESS:regex {pattern [, nocase=true] [, notransfer=true] [, value1, ...]}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Returns a new regular expression _pattern_.  The *pattern* is a POSIX
+Extended Regular Expression.  Whether it can match NUL bytes depends on your
+system C library.
+
+When the *nocase* option is _true_, the expression will be matched
+case-insensitively.
+
+Unless the *notransfer* option is _true_, all data up until the end of the match
+will be erased from the _process_' read buffer upon a successful match.
+
+PROCESS:exact {literal [, nocase=true] [, notransfer=true] [, value1, ...]}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Returns a new literal string _pattern_.  This behaves as if the *literal*
+had its ERE special characters quoted, and was then passed to *regex*.
+This _pattern_ can always match NUL bytes.
+
+PROCESS:eof {[notransfer=true, ] [value1, ...]}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Returns a new end-of-file _pattern_, which matches the entire read buffer
+contents once the child process closes the terminal.
+
+PROCESS:default {[timeout, ] [notransfer=true, ] [value1, ...]}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Returns a new _pattern_ combining *wdye.timeout* with *eof*.
+
+PATTERN.process
+~~~~~~~~~~~~~~~
+A reference to the _pattern_'s respective process, or _nil_.
+
+PATTERN[group]
+~~~~~~~~~~~~~~
+For patterns that can match data, the zeroth group will be the whole matched
+input sequence.
+For *regex* patterns, positive groups relate to regular expression subgroups.
+Missing groups evaluate to _nil_.
+
+Example
+-------
+ for k, v in pairs(wdye) do _G[k] = v end
+ local rot13 = spawn {"tr", "A-Za-z", "N-ZA-Mn-za-m", environ={TERM="dumb"}}
+ rot13:send "Hello\r"
+ expect(rot13:exact {"Uryyb\r"})
+
+Reporting bugs
+--------------
+Use https://git.janouch.name/p/liberty to report bugs, request features,
+or submit pull requests.
+
+See also
+--------
+*expect*(1), *terminfo*(5), *regex*(7)