hwstub: Add completion and some pretty printing to the shell

This uses slightly hacked luaprompt to provide all the goodis.
See https://github.com/dpapavas/luaprompt for original.

Change-Id: Iedddb79abae5809299322bc215722dd928c35cca

5 files changed, 1724 insertions, 18 deletions

diff --git a/utils/hwstub/tools/Makefile b/utils/hwstub/tools/Makefile
index 6db0c709b1..f718300623 100644
--- a/utils/hwstub/tools/Makefile
+++ b/utils/hwstub/tools/Makefile
@@ -26,7 +26,7 @@ $(REGTOOLS_LIB_DIR)/libsocdesc.a:
 %.o: %.cpp
         $(CXX) $(CXXFLAGS) -c -o $@ $<
 
-hwstub_shell: hwstub_shell.o $(LIBS)
+hwstub_shell: hwstub_shell.o prompt.o $(LIBS)
         $(LD) -o $@ $^ $(LDFLAGS)
 
 hwstub_load: hwstub_load.o $(LIBS)
diff --git a/utils/hwstub/tools/hwstub_shell.cpp b/utils/hwstub/tools/hwstub_shell.cpp
index 8b7a8b9e80..f59ca8b82a 100644
--- a/utils/hwstub/tools/hwstub_shell.cpp
+++ b/utils/hwstub/tools/hwstub_shell.cpp
@@ -29,6 +29,9 @@
 #include <lua.hpp>
 #include <unistd.h>
 #include "soc_desc.hpp"
+extern "C" {
+#include "prompt.h"
+}
 
 #if LUA_VERSION_NUM < 502
 #warning You need at least lua 5.2
@@ -941,21 +944,8 @@ int main(int argc, char **argv)
             printf("error: %s\n", lua_tostring(g_lua, -1));
     }
 
-    // use readline to provide some history and completion
-    rl_bind_key('\t', rl_complete);
-    while(!g_exit)
-    {
-        char *input = readline("> ");
-        if(!input)
-            break;
-        add_history(input);
-        // evaluate string
-        if(luaL_dostring(g_lua, input))
-            printf("error: %s\n", lua_tostring(g_lua, -1));
-        // pop everything to start from a clean stack
-        lua_pop(g_lua, lua_gettop(g_lua));
-        free(input);
-    }
+    // start interactive shell
+    luap_enter(g_lua, &g_exit);
 
     Lerr:
     // display log if handled
diff --git a/utils/hwstub/tools/lua/hwlib.lua b/utils/hwstub/tools/lua/hwlib.lua
index 5bbd1e2668..02ab9718d4 100644
--- a/utils/hwstub/tools/lua/hwlib.lua
+++ b/utils/hwstub/tools/lua/hwlib.lua
@@ -22,6 +22,8 @@ function HWLIB.load_blob(filename, address)
     io.close(f)
 end
 
-function HWLIB.printf(s,...)
-    return io.write(s:format(...))
+function HWLIB.printf(...)
+   local function wrapper(...) io.write(string.format(...)) end
+   local status, result = pcall(wrapper, ...)
+   if not status then error(result, 2) end
 end
diff --git a/utils/hwstub/tools/prompt.c b/utils/hwstub/tools/prompt.c
new file mode 100644
index 0000000000..4674158df6
--- /dev/null
+++ b/utils/hwstub/tools/prompt.c
@@ -0,0 +1,1659 @@
+/* Copyright (C) 2012-2015 Papavasileiou Dimitris
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <stdbool.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include "prompt.h"
+
+#ifdef HAVE_IOCTL
+#include <sys/ioctl.h>
+#endif
+
+#include <glob.h>
+
+#include <lualib.h>
+#include <lauxlib.h>
+
+
+#if LUA_VERSION_NUM == 501
+#define lua_pushglobaltable(L) lua_pushvalue (L, LUA_GLOBALSINDEX)
+#define LUA_OK 0
+#define lua_rawlen lua_objlen
+#endif
+
+#ifdef HAVE_LIBREADLINE
+#include <readline/readline.h>
+#else
+
+/* This is a simple readline-like function in case readline is not
+ * available. */
+
+#define MAXINPUT 1024
+
+static char *readline(char *prompt)
+{
+    char *line = NULL;
+    int k;
+
+    line = malloc (MAXINPUT);
+
+    fputs(prompt, stdout);
+    fflush(stdout);
+
+    if (!fgets(line, MAXINPUT, stdin)) {
+        return NULL;
+    }
+
+    k = strlen (line);
+
+    if (line[k - 1] == '\n') {
+        line[k - 1] = '\0';
+    }
+
+    return line;
+}
+
+#endif /* HAVE_LIBREADLINE */
+
+#ifdef HAVE_READLINE_HISTORY
+#include <readline/history.h>
+#endif /* HAVE_READLINE_HISTORY */
+
+#if LUA_VERSION_NUM == 501
+#define EOF_MARKER "'<eof>'"
+#else
+#define EOF_MARKER "<eof>"
+#endif
+
+#define print_output(...) fprintf (stdout, __VA_ARGS__), fflush(stdout)
+#define print_error(...) fprintf (stderr, __VA_ARGS__), fflush(stderr)
+#define absolute(L, i) (i < 0 ? lua_gettop (L) + i + 1 : i)
+
+#define COLOR(i) (colorize ? colors[i] : "")
+
+static lua_State *M;
+static int initialized = 0;
+static char *logfile, *chunkname, *prompts[2][2], *buffer = NULL;
+
+#ifdef SAVE_RESULTS
+static int results = LUA_REFNIL, results_n = 0;
+#endif
+
+static int colorize = 1;
+static const char *colors[] = {"\033[0m",
+                               "\033[0;31m",
+                               "\033[1;31m",
+                               "\033[0;32m",
+                               "\033[1;32m",
+                               "\033[0;33m",
+                               "\033[1;33m",
+                               "\033[1m",
+                               "\033[22m"};
+
+#ifdef HAVE_LIBREADLINE
+
+static void display_matches (char **matches, int num_matches, int max_length)
+{
+    print_output ("%s", COLOR(7));
+    rl_display_match_list (matches, num_matches, max_length);
+    print_output ("%s", COLOR(0));
+    rl_on_new_line ();
+}
+
+#ifdef COMPLETE_KEYWORDS
+static char *keyword_completions (const char *text, int state)
+{
+    static const char **c, *keywords[] = {
+#if LUA_VERSION_NUM == 502
+        "goto",
+#endif
+        "and", "break", "do", "else", "elseif", "end", "false", "for",
+        "function", "if", "in", "local", "nil", "not", "or",
+        "repeat", "return", "then", "true", "until", "while", NULL
+    };
+
+    int s, t;
+
+    if (state == 0) {
+        c = keywords - 1;
+    }
+
+    /* Loop through the list of keywords and return the ones that
+     * match. */
+
+    for (c += 1 ; *c ; c += 1) {
+        s = strlen (*c);
+        t = strlen(text);
+
+        if (s >= t && !strncmp (*c, text, t)) {
+            return strdup (*c);
+        }
+    }
+
+    return NULL;
+}
+#endif
+
+#ifdef COMPLETE_TABLE_KEYS
+
+static int look_up_metatable;
+
+static char *table_key_completions (const char *text, int state)
+{
+    static const char *c, *token;
+    static char oper;
+    static int h;
+
+    if (state == 0) {
+        h = lua_gettop(M);
+
+        /* Scan to the beginning of the to-be-completed token. */
+
+        for (c = text + strlen (text) - 1;
+             c >= text && *c != '.' && *c != ':' && *c != '[';
+             c -= 1);
+
+        if (c > text) {
+            oper = *c;
+            token = c + 1;
+
+            /* Get the iterable value, the keys of which we wish to
+             * complete. */
+
+            lua_pushliteral (M, "return ");
+            lua_pushlstring (M, text, token - text - 1);
+            lua_concat (M, 2);
+
+            if (luaL_loadstring (M, lua_tostring (M, -1)) ||
+                lua_pcall (M, 0, 1, 0) ||
+                (lua_type (M, -1) != LUA_TUSERDATA &&
+                 lua_type (M, -1) != LUA_TTABLE)) {
+
+                lua_settop(M, h);
+                return NULL;
+            }
+        } else {
+            oper = 0;
+            token = text;
+
+            lua_pushglobaltable(M);
+        }
+
+        if (look_up_metatable) {
+            /* Replace the to-be-iterated value with it's metatable
+             * and set up a call to next. */
+
+            if (!luaL_getmetafield(M, -1, "__index") ||
+                (lua_type (M, -1) != LUA_TUSERDATA &&
+                 lua_type (M, -1) != LUA_TTABLE)) {
+                lua_settop(M, h);
+                return NULL;
+            }
+
+            lua_getglobal(M, "next");
+            lua_replace(M, -3);
+            lua_pushnil(M);
+        } else {
+            /* Call the standard pairs function. */
+
+            lua_getglobal (M, "pairs");
+            lua_insert (M, -2);
+
+            if(lua_type (M, -2) != LUA_TFUNCTION ||
+               lua_pcall (M, 1, 3, 0)) {
+
+                lua_settop(M, h);
+                return NULL;
+            }
+        }
+    }
+
+    /* Iterate the table/userdata and generate matches. */
+
+    while (lua_pushvalue(M, -3), lua_insert (M, -3),
+           lua_pushvalue(M, -2), lua_insert (M, -4),
+           lua_pcall (M, 2, 2, 0) == 0) {
+        char *candidate;
+        size_t l, m;
+        int suppress, type, keytype;
+
+        if (lua_isnil(M, -2)) {
+            lua_settop(M, h);
+            return NULL;
+        }
+
+        /* Make some notes about the value we're completing.  We'll
+         * make use of them later on. */
+
+        type = lua_type (M, -1);
+        suppress = (type == LUA_TTABLE || type == LUA_TUSERDATA ||
+                   type == LUA_TFUNCTION);
+
+        keytype = LUA_TNIL;
+        if (type == LUA_TTABLE) {
+            lua_pushnil(M);
+            if (lua_next(M, -2)) {
+                keytype = lua_type (M, -2);
+                lua_pop (M, 2);
+            } else {
+                /* There are no keys in the table so we won't want to
+                 * index it.  Add a space. */
+
+                suppress = 0;
+            }
+        }
+
+        /* Pop the value, keep the key. */
+
+        lua_pop (M, 1);
+
+        /* We're mainly interested in strings at this point but if
+         * we're completing for the table[key] syntax we consider
+         * numeric keys too. */
+
+        if (lua_type (M, -1) == LUA_TSTRING ||
+            (oper == '[' && lua_type (M, -1) == LUA_TNUMBER)) {
+            if (oper == '[') {
+                if (lua_type (M, -1) == LUA_TNUMBER) {
+                    lua_Number n;
+                    int i;
+
+                    n = lua_tonumber (M, -1);
+                    i = lua_tointeger (M, -1);
+
+                    /* If this isn't an integer key, we may as well
+                     * forget about it. */
+
+                    if ((lua_Number)i == n) {
+                        l = asprintf (&candidate, "%d]", i);
+                    } else {
+                        continue;
+                    }
+                } else {
+                    char q;
+
+                    q = token[0];
+                    if (q != '"' && q != '\'') {
+                        q = '"';
+                    }
+
+                    l = asprintf (&candidate, "%c%s%c]",
+                                  q, lua_tostring (M, -1), q);
+                }
+            } else {
+                candidate = strdup((char *)lua_tolstring (M, -1, &l));
+            }
+
+            m = strlen(token);
+
+            if (l >= m && !strncmp (token, candidate, m) &&
+                (oper != ':' || type == LUA_TFUNCTION)
+#ifdef HIDDEN_KEY_PREFIX
+                && strncmp(candidate, HIDDEN_KEY_PREFIX,
+                           sizeof(HIDDEN_KEY_PREFIX) - 1)
+#endif
+                ) {
+                char *match;
+
+                /* If the candidate has been fully typed (or
+                 * previously completed) consider adding certain
+                 * helpful suffixes. */
+#ifndef ALWAYS_APPEND_SUFFIXES
+                if (l == m) {
+#endif
+                    if (type == LUA_TFUNCTION) {
+                        rl_completion_append_character = '('; suppress = 0;
+                    } else if (type == LUA_TTABLE) {
+                        if (keytype == LUA_TSTRING) {
+                            rl_completion_append_character  = '.'; suppress = 0;
+                        } else if (keytype != LUA_TNIL) {
+                            rl_completion_append_character  = '['; suppress = 0;
+                        }
+                    }
+#ifndef ALWAYS_APPEND_SUFFIXES
+                };
+#endif
+
+                if (token > text) {
+                    /* Were not completing a global variable.  Put the
+                     * completed string together out of the table and
+                     * the key. */
+
+                    match = (char *)malloc ((token - text) + l + 1);
+                    strncpy (match, text, token - text);
+                    strcpy (match + (token - text), candidate);
+
+                    free(candidate);
+                } else {
+                    /* Return the whole candidate as is, to be freed
+                     * by Readline. */
+
+                    match = candidate;
+                }
+
+                /* Suppress the newline when completing a table
+                 * or other potentially complex value. */
+
+                if (suppress) {
+                    rl_completion_suppress_append = 1;
+                }
+
+                return match;
+            } else {
+                free(candidate);
+            }
+        }
+    }
+
+    lua_settop(M, h);
+    return NULL;
+}
+#endif
+
+#ifdef COMPLETE_MODULES
+static char *module_completions (const char *text, int state)
+{
+    char *match = NULL;
+    static int h;
+
+    if (state == 0) {
+        glob_t vector;
+        const char *b, *d, *q, *s, *t, *strings[3];
+        int i, n = 0, ondot, hasdot, quoted;
+
+        hasdot = strchr(text, '.') != NULL;
+        ondot = text[0] != '\0' && text[strlen(text) - 1] == '.';
+        quoted = text[0] == '\'' || text[0] == '"';
+
+#ifdef NO_MODULE_LOAD
+        if(!quoted) {
+            return NULL;
+        }
+#endif
+
+        lua_newtable(M);
+        h = lua_gettop(M);
+
+        /* Try to load the input as a module. */
+
+        lua_getglobal(M, "require");
+
+        if (!lua_isfunction (M, -1)) {
+            lua_settop(M, h - 1);
+            return NULL;
+        }
+
+        lua_pushliteral(M, "package");
+
+        if(lua_pcall(M, 1, 1, 0) != LUA_OK) {
+            lua_settop(M, h - 1);
+            return NULL;
+        }
+
+        if (!ondot && !quoted && text[0] != '\0') {
+            lua_getfield(M, -1, "loaded");
+            lua_pushstring(M, text);
+            lua_gettable(M, -2);
+
+            /* If it's not an already loaded module, check whether the
+             * input is an available module by searching for it and/or
+             * trying to load it. */
+
+            if (!lua_toboolean(M, -1)) {
+                int load = 1;
+
+                lua_pop(M, 2);
+
+#ifdef CONFIRM_MODULE_LOAD
+                /* Look for the module as require would and ask the
+                 * user whether it should be loaded or not. */
+
+#if LUA_VERSION_NUM == 501
+                lua_getfield(M, -1, "loaders");
+#else
+                lua_getfield(M, -1, "searchers");
+#endif
+                lua_pushnil(M);
+
+                while((load = lua_next(M, -2))) {
+                    lua_pushstring(M, text);
+                    lua_call(M, 1, 1);
+
+                    if (lua_isfunction(M, -1)) {
+                        char c;
+
+                        print_output ("\nLoad module '%s' (y or n)", text);
+
+                        while ((c = tolower(rl_read_key())) != 'y' && c != 'n');
+
+                        if (c == 'y') {
+                            lua_pop(M, 3);
+                            break;
+                        } else {
+                            print_output ("\n");
+                            rl_on_new_line ();
+
+                            /* If it was found but not loaded, return
+                             * the module name as a match to avoid
+                             * asking the user againg if the tab key
+                             * is pressed repeatedly. */
+
+                            lua_settop(M, h);
+                            return strdup(text);
+                        }
+                    }
+
+                    lua_pop(M, 1);
+                }
+#endif
+
+                /* Load the model if needed. */
+
+                if (load) {
+                    lua_pushfstring (M, "%s=require(\"%s\")", text, text);
+
+                    if (luaL_loadstring (M, lua_tostring (M, -1)) == LUA_OK &&
+                        lua_pcall (M, 0, 0, 0) == LUA_OK) {
+#ifdef CONFIRM_MODULE_LOAD
+                        print_output (" ...loaded\n");
+#else
+                        print_output ("\nLoaded module '%s'.\n", text);
+#endif
+
+                        rl_on_new_line ();
+
+                        lua_settop(M, h - 1);
+                        return NULL;
+                    }
+                }
+            } else {
+                lua_settop(M, h - 1);
+                return NULL;
+            }
+
+            /* Clean up but leave the package.table on the stack. */
+
+            lua_settop(M, h + 1);
+        }
+
+        /* Look for matches in package.preload. */
+
+        lua_getfield(M, -1, "preload");
+
+        lua_pushnil(M);
+        while(lua_next(M, -2)) {
+            lua_pop(M, 1);
+
+            if (lua_type(M, -1) == LUA_TSTRING &&
+                    !strncmp(text + quoted, lua_tostring(M, -1),
+                             strlen(text + quoted))) {
+
+                lua_pushstring(M, text);
+                lua_rawseti (M, h, (n += 1));
+            }
+        }
+
+        lua_pop(M, 1);
+
+        /* Get the configuration (directory, path separators, module
+         * name wildcard). */
+
+        lua_getfield(M, -1, "config");
+        for (s = (char *)lua_tostring(M, -1), i = 0;
+             i < 3;
+             s = t + 1, i += 1) {
+
+            t = strchr(s, '\n');
+            lua_pushlstring(M, s, t - s);
+            strings[i] = lua_tostring(M, -1);
+        }
+
+        lua_remove(M, -4);
+
+        /* Get the path and cpath */
+
+        lua_getfield(M, -4, "path");
+        lua_pushstring(M, strings[1]);
+        lua_getfield(M, -6, "cpath");
+        lua_pushstring(M, strings[1]);
+        lua_concat(M, 4);
+
+        /* Synthesize the pattern. */
+
+        if (hasdot) {
+            luaL_gsub(M, text + quoted, ".", strings[0]);
+        } else {
+            lua_pushstring(M, text + quoted);
+        }
+
+        lua_pushliteral(M, "*");
+        lua_concat(M, 2);
+
+        for (b = d = lua_tostring(M, -2) ; d ; b = d + 1)  {
+            size_t i;
+
+            d = strstr(b, strings[1]);
+            q = strstr(b, strings[2]);
+
+            if (!q || q > d) {
+                continue;
+            }
+
+            lua_pushlstring(M, b, d - b);
+            luaL_gsub(M, lua_tostring(M, -1), strings[2],
+                      lua_tostring(M, -2));
+
+            glob(lua_tostring(M, -1), 0, NULL, &vector);
+
+            lua_pop(M, 2);
+
+            for (i = 0 ; i < vector.gl_pathc ; i += 1) {
+                char *p = vector.gl_pathv[i];
+
+                if (quoted) {
+                    lua_pushlstring(M, text, 1);
+                }
+
+                lua_pushlstring(M, p + (q - b), strlen(p) - (d - b) + 1);
+
+                if (hasdot) {
+                    luaL_gsub(M, lua_tostring(M, -1), strings[0], ".");
+                    lua_replace(M, -2);
+                }
+
+                {
+                    const char *s;
+                    size_t l;
+
+                    s = lua_tolstring(M, -1, &l);
+
+                    /* Suppress submodules named init. */
+
+                    if (l < sizeof("init") - 1 ||
+                        strcmp(s + l - sizeof("init") + 1, "init")) {
+
+                        if (quoted) {
+                            lua_pushlstring(M, text, 1);
+
+                            lua_concat(M, 3);
+                        }
+
+                        lua_rawseti(M, h, (n += 1));
+                    } else {
+                        lua_pop(M, 1 + quoted);
+                    }
+                }
+            }
+
+            globfree(&vector);
+        }
+
+        lua_pop(M, 6);
+    }
+
+    /* Return the next match from the table of matches. */
+
+    lua_pushnil(M);
+    if (lua_next(M, -2)) {
+        match = strdup(lua_tostring(M, -1));
+
+        rl_completion_suppress_append = !(match[0] == '"' || match[0] == '\'');
+
+        /* Pop the match. */
+
+        lua_pushnil(M);
+        lua_rawseti(M, -4, lua_tointeger(M, -3));
+
+        /* Pop key/value. */
+
+        lua_pop(M, 2);
+    } else {
+        /* Pop the empty table. */
+
+        lua_pop(M, 1);
+    }
+
+    return match;
+}
+#endif
+
+static char *generator (const char *text, int state)
+{
+    static int which;
+    char *match = NULL;
+
+    if (state == 0) {
+        which = 0;
+    }
+
+    /* Try to complete a keyword. */
+
+    if (which == 0) {
+#ifdef COMPLETE_KEYWORDS
+        if ((match = keyword_completions (text, state))) {
+            return match;
+        }
+#endif
+        which += 1;
+        state = 0;
+    }
+
+    /* Try to complete a module name. */
+
+    if (which == 1) {
+#ifdef COMPLETE_MODULES
+        if ((match = module_completions (text, state))) {
+            return match;
+        }
+#endif
+        which += 1;
+        state = 0;
+    }
+
+    /* Try to complete a table access. */
+
+    if (which == 2) {
+#ifdef COMPLETE_TABLE_KEYS
+        look_up_metatable = 0;
+        if ((match = table_key_completions (text, state))) {
+            return match;
+        }
+#endif
+        which += 1;
+        state = 0;
+    }
+
+    /* Try to complete a metatable access. */
+
+    if (which == 3) {
+#ifdef COMPLETE_METATABLE_KEYS
+        look_up_metatable = 1;
+        if ((match = table_key_completions (text, state))) {
+            return match;
+        }
+#endif
+        which += 1;
+        state = 0;
+    }
+
+#ifdef COMPLETE_FILE_NAMES
+    /* Try to complete a file name. */
+
+    if (which == 4) {
+        if (text[0] == '\'' || text[0] == '"') {
+            match = rl_filename_completion_function (text + 1, state);
+
+            if (match) {
+                struct stat s;
+                int n;
+
+                n = strlen (match);
+                stat(match, &s);
+
+                /* If a match was produced, add the quote
+                 * characters. */
+
+                match = (char *)realloc (match, n + 3);
+                memmove (match + 1, match, n);
+                match[0] = text[0];
+
+                /* If the file's a directory, add a trailing backslash
+                 * and suppress the space, otherwise add the closing
+                 * quote. */
+
+                if (S_ISDIR(s.st_mode)) {
+                    match[n + 1] = '/';
+
+                    rl_completion_suppress_append = 1;
+                } else {
+                    match[n + 1] = text[0];
+                }
+
+                match[n + 2] = '\0';
+            }
+        }
+    }
+#endif
+
+    return match;
+}
+#endif
+
+static void finish ()
+{
+#ifdef HAVE_READLINE_HISTORY
+    /* Save the command history on exit. */
+
+    if (logfile) {
+        write_history (logfile);
+    }
+#endif
+}
+
+static int traceback(lua_State *L)
+{
+    lua_Debug ar;
+    int i;
+
+    if (lua_isnoneornil (L, 1) ||
+        (!lua_isstring (L, 1) &&
+         !luaL_callmeta(L, 1, "__tostring"))) {
+        lua_pushliteral(L, "(no error message)");
+    }
+
+    if (lua_gettop (L) > 1) {
+        lua_replace (L, 1);
+        lua_settop (L, 1);
+    }
+
+    /* Print the Lua stack. */
+
+    lua_pushstring(L, "\n\nStack trace:\n");
+
+    for (i = 0 ; lua_getstack (L, i, &ar) ; i += 1) {
+#if LUA_VERSION_NUM == 501
+        lua_getinfo(M, "Snl", &ar);
+#else
+        lua_getinfo(M, "Snlt", &ar);
+
+        if (ar.istailcall) {
+            lua_pushfstring(L, "\t... tail calls\n");
+        }
+#endif
+
+        if (!strcmp (ar.what, "C")) {
+            lua_pushfstring(L, "\t#%d %s[C]:%s in function ",
+                            i, COLOR(7), COLOR(8));
+
+            if (ar.name) {
+                lua_pushfstring(L, "'%s%s%s'\n",
+                                COLOR(7), ar.name, COLOR(8));
+            } else {
+                lua_pushfstring(L, "%s?%s\n", COLOR(7), COLOR(8));
+            }
+        } else if (!strcmp (ar.what, "main")) {
+            lua_pushfstring(L, "\t#%d %s%s:%d:%s in the main chunk\n",
+                            i, COLOR(7), ar.short_src, ar.currentline,
+                            COLOR(8));
+        } else if (!strcmp (ar.what, "Lua")) {
+            lua_pushfstring(L, "\t#%d %s%s:%d:%s in function ",
+                            i, COLOR(7), ar.short_src, ar.currentline,
+                            COLOR(8));
+
+            if (ar.name) {
+                lua_pushfstring(L, "'%s%s%s'\n",
+                                COLOR(7), ar.name, COLOR(8));
+            } else {
+                lua_pushfstring(L, "%s?%s\n", COLOR(7), COLOR(8));
+            }
+        }
+    }
+
+    if (i == 0) {
+        lua_pushstring (L, "No activation records.\n");
+    }
+
+    lua_concat (L, lua_gettop(L));
+
+    return 1;
+}
+
+static int execute ()
+{
+    int i, h_0, h, status;
+
+#ifdef SAVE_RESULTS
+    /* Get the results table, and stash it behind the to-be-executed
+     * chunk. */
+
+    lua_rawgeti(M, LUA_REGISTRYINDEX, results);
+    lua_insert(M, -2);
+#endif
+
+    h_0 = lua_gettop(M);
+    status = luap_call (M, 0);
+    h = lua_gettop (M) - h_0 + 1;
+
+    for (i = h ; i > 0 ; i -= 1) {
+        const char *result;
+
+        result = luap_describe (M, -i);
+
+#ifdef SAVE_RESULTS
+        lua_pushvalue (M, -i);
+        lua_rawseti(M, h_0 - 1, (results_n += 1));
+
+        print_output ("%s%s[%d]%s = %s%s\n",
+                      COLOR(4), RESULTS_TABLE_NAME, results_n,
+                      COLOR(3), result, COLOR(0));
+#else
+        if (h == 1) {
+            print_output ("%s%s%s\n", COLOR(3), result, COLOR(0));
+        } else {
+            print_output ("%s%d%s: %s%s\n", COLOR(4), h - i + 1,
+                          COLOR(3), result, COLOR(0));
+        }
+#endif
+    }
+
+    /* Clean up.  We need to remove the results table as well if we
+     * track results. */
+
+#ifdef SAVE_RESULTS
+    lua_settop (M, h_0 - 2);
+#else
+    lua_settop (M, h_0 - 1);
+#endif
+
+    return status;
+}
+
+/* This is the pretty-printing related stuff. */
+
+static char *dump;
+static int length, offset, indent, column, linewidth, ancestors;
+
+#define dump_literal(s) (check_fit(sizeof(s) - 1), \
+                         strcpy (dump + offset, s), \
+                         offset += sizeof(s) - 1, \
+                         column += width(s))
+
+#define dump_character(c) (check_fit(1), \
+                           dump[offset] = c, \
+                           offset += 1, \
+                           column += 1)
+
+static int width (const char *s)
+{
+    const char *c;
+    int n, discard = 0;
+
+    /* Calculate the printed width of the chunk s ignoring escape
+     * sequences. */
+
+    for (c = s, n = 0 ; *c ; c += 1) {
+        if (!discard && *c == '\033') {
+            discard = 1;
+        }
+
+        if (!discard) {
+            n+= 1;
+        }
+
+        if (discard && *c == 'm') {
+            discard = 0;
+        }
+    }
+
+    return n;
+}
+
+static void check_fit (int size)
+{
+    /* Check if a chunk fits in the buffer and expand as necessary. */
+
+    if (offset + size + 1 > length) {
+        length = offset + size + 1;
+        dump = (char *)realloc (dump, length * sizeof (char));
+    }
+}
+
+static int is_identifier (const char *s, int n)
+{
+    int i;
+
+    /* Check whether a string can be used as a key without quotes and
+     * braces. */
+
+    for (i = 0 ; i < n ; i += 1) {
+        if (!isalpha(s[i]) &&
+            (i == 0 || !isalnum(s[i])) &&
+            s[i] != '_') {
+            return 0;
+        }
+    }
+
+    return 1;
+}
+
+static void break_line ()
+{
+    int i;
+
+    check_fit (indent + 1);
+
+    /* Add a line break. */
+
+    dump[offset] = '\n';
+
+    /* And indent to the current level. */
+
+    for (i = 1 ; i <= indent ; i += 1) {
+        dump[offset + i] = ' ';
+    }
+
+    offset += indent + 1;
+    column = indent;
+}
+
+static void dump_string (const char *s, int n)
+{
+    int l;
+
+    /* Break the line if the current chunk doesn't fit but it would
+     * fit if we started on a fresh line at the current indent. */
+
+    l = width(s);
+
+    if (column + l > linewidth && indent + l <= linewidth) {
+        break_line();
+    }
+
+    check_fit (n);
+
+    /* Copy the string to the buffer. */
+
+    memcpy (dump + offset, s, n);
+    dump[offset + n] = '\0';
+
+    offset += n;
+    column += l;
+}
+
+static void describe (lua_State *L, int index)
+{
+    char *s;
+    size_t n;
+    int type;
+
+    index = absolute (L, index);
+    type = lua_type (L, index);
+
+    if (luaL_getmetafield (L, index, "__tostring")) {
+        lua_pushvalue (L, index);
+        lua_pcall (L, 1, 1, 0);
+        s = (char *)lua_tolstring (L, -1, &n);
+        lua_pop (L, 1);
+
+        dump_string (s, n);
+    } else if (type == LUA_TNUMBER) {
+        /* Copy the value to avoid mutating it. */
+
+        lua_pushvalue (L, index);
+        s = (char *)lua_tolstring (L, -1, &n);
+        lua_pop (L, 1);
+
+        dump_string (s, n);
+    } else if (type == LUA_TSTRING) {
+        int i, started, score, level, uselevel = 0;
+
+        s = (char *)lua_tolstring (L, index, &n);
+
+        /* Scan the string to decide how to print it. */
+
+        for (i = 0, score = n, started = 0 ; i < (int)n ; i += 1) {
+            if (s[i] == '\n' || s[i] == '\t' ||
+                s[i] == '\v' || s[i] == '\r') {
+                /* These characters show up better in a long sting so
+                 * bias towards that. */
+
+                score += linewidth / 2;
+            } else if (s[i] == '\a' || s[i] == '\b' ||
+                       s[i] == '\f' || !isprint(s[i])) {
+                /* These however go better with an escaped short
+                 * string (unless you like the bell or weird
+                 * characters). */
+
+                score -= linewidth / 4;
+            }
+
+            /* Check what long string delimeter level to use so that
+             * the string won't be closed prematurely. */
+
+            if (!started) {
+                if (s[i] == ']') {
+                    started = 1;
+                    level = 0;
+                }
+            } else {
+                if (s[i] == '=') {
+                    level += 1;
+                } else if (s[i] == ']') {
+                    if (level >= uselevel) {
+                        uselevel = level + 1;
+                    }
+                } else {
+                    started = 0;
+                }
+            }
+        }
+
+        if (score > linewidth) {
+            /* Dump the string as a long string. */
+
+            dump_character ('[');
+            for (i = 0 ; i < uselevel ; i += 1) {
+                dump_character ('=');
+            }
+            dump_literal ("[\n");
+
+            dump_string (s, n);
+
+            dump_character (']');
+            for (i = 0 ; i < uselevel ; i += 1) {
+                dump_character ('=');
+            }
+            dump_literal ("]");
+        } else {
+            /* Escape the string as needed and print it as a normal
+             * string. */
+
+            dump_literal ("\"");
+
+            for (i = 0 ; i < (int)n ; i += 1) {
+                if (s[i] == '"' || s[i] == '\\') {
+                    dump_literal ("\\");
+                    dump_character (s[i]);
+                } else if (s[i] == '\a') {
+                    dump_literal ("\\a");
+                } else if (s[i] == '\b') {
+                    dump_literal ("\\b");
+                } else if (s[i] == '\f') {
+                    dump_literal ("\\f");
+                } else if (s[i] == '\n') {
+                    dump_literal ("\\n");
+                } else if (s[i] == '\r') {
+                    dump_literal ("\\r");
+                } else if (s[i] == '\t') {
+                    dump_literal ("\\t");
+                } else if (s[i] == '\v') {
+                    dump_literal ("\\v");
+                } else if (isprint(s[i])) {
+                    dump_character (s[i]);
+                } else {
+                    char t[5];
+                    size_t n;
+
+                    n = sprintf (t, "\\%03u", ((unsigned char *)s)[i]);
+                    dump_string (t, n);
+                }
+            }
+
+            dump_literal ("\"");
+        }
+    } else if (type == LUA_TNIL) {
+        n = asprintf (&s, "%snil%s", COLOR(7), COLOR(8));
+        dump_string (s, n);
+        free(s);
+    } else if (type == LUA_TBOOLEAN) {
+        n = asprintf (&s, "%s%s%s",
+                      COLOR(7),
+                      lua_toboolean (L, index) ? "true" : "false",
+                      COLOR(8));
+        dump_string (s, n);
+        free(s);
+    } else if (type == LUA_TFUNCTION) {
+        n = asprintf (&s, "<%sfunction:%s %p>",
+                      COLOR(7), COLOR(8), lua_topointer (L, index));
+        dump_string (s, n);
+        free(s);
+    } else if (type == LUA_TUSERDATA) {
+        n = asprintf (&s, "<%suserdata:%s %p>",
+                      COLOR(7), COLOR(8), lua_topointer (L, index));
+
+        dump_string (s, n);
+        free(s);
+    } else if (type == LUA_TTHREAD) {
+        n = asprintf (&s, "<%sthread:%s %p>",
+                      COLOR(7), COLOR(8), lua_topointer (L, index));
+        dump_string (s, n);
+        free(s);
+    } else if (type == LUA_TTABLE) {
+        int i, l, n, oldindent, multiline, nobreak;
+
+        /* Check if table is too deeply nested. */
+
+        if (indent > 8 * linewidth / 10) {
+            char *s;
+            size_t n;
+
+            n = asprintf (&s, "{ %s...%s }", COLOR(7), COLOR(8));
+            dump_string (s, n);
+            free(s);
+
+            return;
+        }
+
+        /* Check if the table introduces a cycle by checking whether
+         * it is a back-edge (that is equal to an ancestor table. */
+
+        lua_rawgeti (L, LUA_REGISTRYINDEX, ancestors);
+        n = lua_rawlen(L, -1);
+
+        for (i = 0 ; i < n ; i += 1) {
+            lua_rawgeti (L, -1, n - i);
+#if LUA_VERSION_NUM == 501
+            if(lua_equal (L, -1, -3)) {
+#else
+            if(lua_compare (L, -1, -3, LUA_OPEQ)) {
+#endif
+                char *s;
+                size_t n;
+
+                n = asprintf (&s, "{ %s[%d]...%s }",
+                              COLOR(7), -(i + 1), COLOR(8));
+                dump_string (s, n);
+                free(s);
+                lua_pop (L, 2);
+
+                return;
+            }
+
+            lua_pop (L, 1);
+        }
+
+        /* Add the table to the ancestor list and pop the ancestor
+         * list table. */
+
+        lua_pushvalue (L, index);
+        lua_rawseti (L, -2, n + 1);
+        lua_pop (L, 1);
+
+        /* Open the table and update the indentation level to the
+         * current column. */
+
+        dump_literal ("{ ");
+        oldindent = indent;
+        indent = column;
+        multiline = 0;
+        nobreak = 0;
+
+        l = lua_rawlen (L, index);
+
+        /* Traverse the array part first. */
+
+        for (i = 0 ; i < l ; i += 1) {
+            lua_pushinteger (L, i + 1);
+            lua_gettable (L, index);
+
+            /* Start a fresh line when dumping tables to make sure
+             * there's plenty of room. */
+
+            if (lua_istable (L, -1)) {
+                if (!nobreak) {
+                    break_line();
+                }
+
+                multiline = 1;
+            }
+
+            nobreak = 0;
+
+            /* Dump the value and separating comma. */
+
+            describe (L, -1);
+            dump_literal (", ");
+
+            if (lua_istable (L, -1) && i != l - 1) {
+                break_line();
+                nobreak = 1;
+            }
+
+            lua_pop (L, 1);
+        }
+
+        /* Now for the hash part. */
+
+        lua_pushnil (L);
+        while (lua_next (L, index) != 0) {
+            if (lua_type (L, -2) != LUA_TNUMBER ||
+                lua_tonumber (L, -2) != lua_tointeger (L, -2) ||
+                lua_tointeger (L, -2) < 1 ||
+                lua_tointeger (L, -2) > l) {
+
+                /* Keep each key-value pair on a separate line. */
+
+                break_line ();
+                multiline  = 1;
+
+                /* Dump the key and value. */
+
+                if (lua_type (L, -2) == LUA_TSTRING) {
+                    char *s;
+                    size_t n;
+
+                    s = (char *)lua_tolstring (L, -2, &n);
+
+                    if(is_identifier (s, n)) {
+                        dump_string (COLOR(7), strlen(COLOR(7)));
+                        dump_string (s, n);
+                        dump_string (COLOR(8), strlen(COLOR(8)));
+                    } else {
+                        dump_literal ("[");
+                        describe (L, -2);
+                        dump_literal ("]");
+                    }
+                } else {
+                    dump_literal ("[");
+                    describe (L, -2);
+                    dump_literal ("]");
+                }
+
+                dump_literal (" = ");
+                describe (L, -1);
+                dump_literal (",");
+            }
+
+            lua_pop (L, 1);
+        }
+
+        /* Remove the table from the ancestor list. */
+
+        lua_rawgeti (L, LUA_REGISTRYINDEX, ancestors);
+        lua_pushnil (L);
+        lua_rawseti (L, -2, n + 1);
+        lua_pop (L, 1);
+
+        /* Pop the indentation level. */
+
+        indent = oldindent;
+
+        if (multiline) {
+            break_line();
+            dump_literal ("}");
+        } else {
+            dump_literal (" }");
+        }
+    }
+}
+
+char *luap_describe (lua_State *L, int index)
+{
+    int oldcolorize;
+
+#ifdef HAVE_IOCTL
+    struct winsize w;
+
+    /* Initialize the state. */
+
+    if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &w) < 0) {
+        linewidth = 80;
+    } else {
+        linewidth = w.ws_col;
+    }
+#else
+    linewidth = 80;
+#endif
+
+    index = absolute (L, index);
+    offset = 0;
+    indent = 0;
+    column = 0;
+
+    /* Suppress colorization, to avoid escape sequences in the
+     * returned strings. */
+
+    oldcolorize = colorize;
+    colorize = 0;
+
+    /* Create a table to hold the ancestors for checking for cycles
+     * when printing table hierarchies. */
+
+    lua_newtable (L);
+    ancestors = luaL_ref (L, LUA_REGISTRYINDEX);
+
+    describe (L, index);
+
+    luaL_unref (L, LUA_REGISTRYINDEX, ancestors);
+    colorize = oldcolorize;
+
+    return dump;
+}
+
+/* These are custom commands. */
+
+#ifdef HAVE_LIBREADLINE
+static int describe_stack (int count, int key)
+{
+    int i, h;
+
+    print_output ("%s", COLOR(7));
+
+    h = lua_gettop (M);
+
+    if (count < 0) {
+        i = h + count + 1;
+
+        if (i > 0 && i <= h) {
+            print_output ("\nValue at stack index %d(%d):\n%s%s",
+                          i, -h + i - 1, COLOR(3), luap_describe (M, i));
+        } else {
+            print_error ("Invalid stack index.\n");
+        }
+    } else {
+        if (h > 0) {
+            print_output ("\nThe stack contains %d values.\n", h);
+            for (i = 1 ; i <= h ; i += 1) {
+                print_output ("\n%d(%d):\t%s", i, -h + i - 1, lua_typename(M, lua_type(M, i)));
+            }
+        } else {
+            print_output ("\nThe stack is empty.");
+        }
+    }
+
+    print_output ("%s\n", COLOR(0));
+
+    rl_on_new_line ();
+
+    return 0;
+}
+#endif
+
+int luap_call (lua_State *L, int n) {
+    int h, status;
+
+    /* We can wind up here before reaching luap_enter, so this is
+     * needed. */
+
+    M = L;
+
+    /* Push the error handler onto the stack. */
+
+    h = lua_gettop(L) - n;
+    lua_pushcfunction (L, traceback);
+    lua_insert (L, h);
+
+    /* Try to execute the supplied chunk and keep note of any return
+     * values. */
+
+    status = lua_pcall(L, n, LUA_MULTRET, h);
+
+    /* Print any errors. */
+
+    if (status != LUA_OK) {
+        print_error ("%s%s%s\n", COLOR(1), lua_tostring (L, -1), COLOR(0));
+        lua_pop (L, 1);
+    }
+
+    /* Remove the error handler. */
+
+    lua_remove (L, h);
+
+    return status;
+}
+
+void luap_setprompts(lua_State *L, const char *single, const char *multi)
+{
+    /* Plain, uncolored prompts. */
+
+    prompts[0][0] = (char *)realloc (prompts[0][0], strlen (single) + 1);
+    prompts[0][1] = (char *)realloc (prompts[0][1], strlen (multi) + 1);
+    strcpy(prompts[0][0], single);
+    strcpy(prompts[0][1], multi);
+
+    /* Colored prompts. */
+
+    prompts[1][0] = (char *)realloc (prompts[1][0], strlen (single) + 16);
+    prompts[1][1] = (char *)realloc (prompts[1][1], strlen (multi) + 16);
+#ifdef HAVE_LIBREADLINE
+    sprintf (prompts[1][0], "\001%s\002%s\001%s\002",
+             COLOR(6), single, COLOR(0));
+    sprintf (prompts[1][1], "\001%s\002%s\001%s\002",
+             COLOR(6), multi, COLOR(0));
+#else
+    sprintf (prompts[1][0], "%s%s%s", COLOR(6), single, COLOR(0));
+    sprintf (prompts[1][1], "%s%s%s", COLOR(6), multi, COLOR(0));
+#endif
+}
+
+void luap_sethistory(lua_State *L, const char *file)
+{
+    if (file) {
+        logfile = realloc (logfile, strlen(file) + 1);
+        strcpy (logfile, file);
+    } else if (logfile) {
+        free(logfile);
+        logfile = NULL;
+    }
+}
+
+void luap_setcolor(lua_State *L, int enable)
+{
+    /* Don't allow color if we're not writing to a terminal. */
+
+    if (!isatty (STDOUT_FILENO) || !isatty (STDERR_FILENO)) {
+        colorize = 0;
+    } else {
+        colorize = enable;
+    }
+}
+
+void luap_setname(lua_State *L, const char *name)
+{
+    chunkname = (char *)realloc (chunkname, strlen(name) + 2);
+    chunkname[0] = '=';
+    strcpy (chunkname + 1, name);
+}
+
+void luap_getprompts(lua_State *L, const char **single, const char **multi)
+{
+    *single = prompts[0][0];
+    *multi = prompts[0][1];
+}
+
+void luap_gethistory(lua_State *L, const char **file)
+{
+    *file = logfile;
+}
+
+void luap_getcolor(lua_State *L, int *enabled)
+{
+    *enabled = colorize;
+}
+
+void luap_getname(lua_State *L, const char **name)
+{
+    *name = chunkname + 1;
+}
+
+void luap_enter(lua_State *L, bool *terminate)
+{
+    int incomplete = 0, s = 0, t = 0, l;
+    char *line, *prepended;
+#ifdef SAVE_RESULTS
+    int cleanup = 0;
+#endif
+
+    /* Save the state since it needs to be passed to some readline
+     * callbacks. */
+
+    M = L;
+
+    if (!initialized) {
+#ifdef HAVE_LIBREADLINE
+        rl_basic_word_break_characters = " \t\n`@$><=;|&{(";
+        rl_completion_entry_function = generator;
+        rl_completion_display_matches_hook = display_matches;
+
+        rl_add_defun ("lua-describe-stack", describe_stack, META('s'));
+#endif
+
+#ifdef HAVE_READLINE_HISTORY
+        /* Load the command history if there is one. */
+
+        if (logfile) {
+            read_history (logfile);
+        }
+#endif
+        if (!chunkname) {
+            luap_setname (L, "lua");
+        }
+
+        if (!prompts[0][0]) {
+            luap_setprompts (L, ">  ", ">> ");
+        }
+
+        atexit (finish);
+
+        initialized = 1;
+    }
+
+#ifdef SAVE_RESULTS
+    if (results == LUA_REFNIL) {
+        lua_newtable(L);
+
+#ifdef WEAK_RESULTS
+        lua_newtable(L);
+        lua_pushliteral(L, "v");
+        lua_setfield(L, -2, "__mode");
+        lua_setmetatable(L, -2);
+#endif
+
+        results = luaL_ref(L, LUA_REGISTRYINDEX);
+    }
+
+    lua_getglobal(L, RESULTS_TABLE_NAME);
+    if (lua_isnil(L, -1)) {
+        lua_rawgeti(L, LUA_REGISTRYINDEX, results);
+        lua_setglobal(L, RESULTS_TABLE_NAME);
+
+        cleanup = 1;
+    }
+    lua_pop(L, 1);
+#endif
+
+    while (!(*terminate) &&
+           (line = readline (incomplete ?
+                             prompts[colorize][1] : prompts[colorize][0]))) {
+        int status;
+
+        if (*line == '\0') {
+            free(line);
+            continue;
+        }
+
+        /* Add/copy the line to the buffer. */
+
+        if (incomplete) {
+            s += strlen (line) + 1;
+
+            if (s > t) {
+                buffer = (char *)realloc (buffer, s + 1);
+                t = s;
+            }
+
+            strcat (buffer, "\n");
+            strcat (buffer, line);
+        } else {
+            s = strlen (line);
+
+            if (s > t) {
+                buffer = (char *)realloc (buffer, s + 1);
+                t = s;
+            }
+
+            strcpy (buffer, line);
+        }
+
+        /* Try to execute the line with a return prepended first.  If
+         * this works we can show returned values. */
+
+        l = asprintf (&prepended, "return %s", buffer);
+
+        if (luaL_loadbuffer(L, prepended, l, chunkname) == LUA_OK) {
+            execute();
+
+            incomplete = 0;
+        } else {
+            lua_pop (L, 1);
+
+            /* Try to execute the line as-is. */
+
+            status = luaL_loadbuffer(L, buffer, s, chunkname);
+
+            incomplete = 0;
+
+            if (status == LUA_ERRSYNTAX) {
+                const char *message;
+                const int k = sizeof(EOF_MARKER) / sizeof(char) - 1;
+                size_t n;
+
+                message = lua_tolstring (L, -1, &n);
+
+                /* If the error message mentions an unexpected eof
+                 * then consider this a multi-line statement and wait
+                 * for more input.  If not then just print the error
+                 * message.*/
+
+                if ((int)n > k &&
+                    !strncmp (message + n - k, EOF_MARKER, k)) {
+                    incomplete = 1;
+                } else {
+                    print_error ("%s%s%s\n", COLOR(1), lua_tostring (L, -1),
+                                 COLOR(0));
+                }
+
+                lua_pop (L, 1);
+            } else if (status == LUA_ERRMEM) {
+                print_error ("%s%s%s\n", COLOR(1), lua_tostring (L, -1),
+                             COLOR(0));
+                lua_pop (L, 1);
+            } else {
+                /* Try to execute the loaded chunk. */
+
+                execute ();
+                incomplete = 0;
+            }
+        }
+
+#ifdef HAVE_READLINE_HISTORY
+        /* Add the line to the history if non-empty. */
+
+        if (!incomplete) {
+            add_history (buffer);
+        }
+#endif
+
+        free (prepended);
+        free (line);
+    }
+
+#ifdef SAVE_RESULTS
+    if (cleanup) {
+        lua_pushnil(L);
+        lua_setglobal(L, RESULTS_TABLE_NAME);
+    }
+#endif
+
+    print_output ("\n");
+}
diff --git a/utils/hwstub/tools/prompt.h b/utils/hwstub/tools/prompt.h
new file mode 100644
index 0000000000..0ad044b934
--- /dev/null
+++ b/utils/hwstub/tools/prompt.h
@@ -0,0 +1,55 @@
+/* Copyright (C) 2012-2015 Papavasileiou Dimitris
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef _PROMPT_H_
+#define _PROMPT_H_
+
+#include <lualib.h>
+#include <lauxlib.h>
+
+#define HAVE_LIBREADLINE
+#define HAVE_READLINE_HISTORY
+#define HAVE_IOCTL
+#define COMPLETE_KEYWORDS
+#define COMPLETE_MODULES
+#define COMPLETE_TABLE_KEYS
+#define COMPLETE_METATABLE_KEYS
+#define COMPLETE_FILE_NAMES
+
+#define LUAP_VERSION "0.6"
+
+void luap_setprompts(lua_State *L, const char *single, const char *multi);
+void luap_sethistory(lua_State *L, const char *file);
+void luap_setname(lua_State *L, const char *name);
+void luap_setcolor(lua_State *L, int enable);
+
+void luap_getprompts(lua_State *L, const char **single, const char **multi);
+void luap_gethistory(lua_State *L, const char **file);
+void luap_getcolor(lua_State *L, int *enabled);
+void luap_getname(lua_State *L, const char **name);
+
+void luap_enter(lua_State *L, bool *terminate);
+char *luap_describe (lua_State *L, int index);
+int luap_call (lua_State *L, int n);
+
+#endif