Re: Handling conflicts caused by command-line editing, revisited
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- Subject: Re: Handling conflicts caused by command-line editing, revisited
- From: Andrew Gierth <andrew@...>
- Date: 2018年7月20日 00:40:44 +0100
>>>>> "Andrew" == Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
Andrew> 2) patch lua.c to make it load libedit/libreadline dynamically
Andrew> rather than explicitly linking it, and not load it until it's
Andrew> needed (and maybe add an option to disable it even then)
So I did a proof-of-concept patch for this, and tested that it (a) seems
to work and (b) resolves the issue.
Here's the patch against lua 5.3.5 (as a bonus, it also backpatches the
rl_readline_name / rl_inhibit_completion settings). This is intended for
FreeBSD, but nothing in it is OS-dependent except the pathname for
libedit or readline.
Open questions:
- stealing an option letter (currently -N) to disable editing might
cause conflicts in future, and obviously isn't portable to unpatched
systems; I _think_ that it should be unnecessary, since loading
libedit with RTLD_LOCAL should prevent it interfering with lua
modules, and some preliminary testing suggests that this is so
- currently it silently falls back to no editing if dlopen fails,
should there be a warning saying why?
--
Andrew.
--- src/lua.c.orig 2017年04月19日 17:29:57 UTC
+++ src/lua.c
@@ -77,16 +77,69 @@
*/
#if !defined(lua_readline) /* { */
-#if defined(LUA_USE_READLINE) /* { */
+#if defined(LUA_USE_READLINE_DL)/* { */
+
+#include <dlfcn.h>
+
+#ifndef LUA_READLINE_LIBPATH
+#define LUA_READLINE_LIBPATH "/usr/local/lib/libedit.so"
+#endif
+
+typedef char *readline_functype(const char *);
+typedef int add_history_functype(const char *);
+
+static readline_functype *lua_readline_p = NULL;
+static add_history_functype *lua_saveline_p = NULL;
+static int disable_readline = 0;
+
+static void lua_initreadline(lua_State *L)
+{
+ void *editlib = NULL;
+ union dl_func_hack {
+ void *ptr;
+ readline_functype *rlfunc;
+ add_history_functype *ahfunc;
+ char **rlnamevar;
+ int *icompvar;
+ } u;
+ (void) L;
+ if (disable_readline)
+ return;
+ if ((editlib = dlopen(LUA_READLINE_LIBPATH, RTLD_LAZY | RTLD_LOCAL))) {
+ u.ptr = dlsym(editlib, "readline");
+ lua_readline_p = u.rlfunc;
+ u.ptr = dlsym(editlib, "add_history");
+ lua_saveline_p = u.ahfunc;
+ if ((u.ptr = dlsym(editlib, "rl_readline_name")))
+ *u.rlnamevar = "lua";
+ if ((u.ptr = dlsym(editlib, "rl_inhibit_completion")))
+ *u.icompvar = 1;
+ }
+}
+
+#define lua_readline(L,b,p) \
+ ((void)L, \
+ (lua_readline_p) \
+ ? (((b)=lua_readline_p(p)) != NULL) \
+ : (fputs(p, stdout), fflush(stdout), fgets(b, LUA_MAXINPUT, stdin) != NULL))
+#define lua_saveline(L,line) \
+ do { (void)L; if (lua_saveline_p) lua_saveline_p(line); } while(0)
+#define lua_freeline(L,b) \
+ do { (void)L; if (lua_readline_p) free(b); } while(0)
+
+#elif defined(LUA_USE_READLINE) /* { */
#include <readline/readline.h>
#include <readline/history.h>
+#define lua_initreadline(L) \
+ ((void)L, rl_readline_name="lua", rl_inhibit_completion=1)
#define lua_readline(L,b,p) ((void)L, ((b)=readline(p)) != NULL)
#define lua_saveline(L,line) ((void)L, add_history(line))
#define lua_freeline(L,b) ((void)L, free(b))
#else /* }{ */
+#define lua_initreadline(L) ((void) L)
#define lua_readline(L,b,p) \
((void)L, fputs(p, stdout), fflush(stdout), /* show prompt */ \
fgets(b, LUA_MAXINPUT, stdin) != NULL) /* get line */
@@ -141,6 +194,9 @@ static void print_usage (const char *bad
" -l name require library 'name' into global 'name'\n"
" -v show version information\n"
" -E ignore environment variables\n"
+#if defined(LUA_USE_READLINE_DL)
+ " -N disable command-line editing\n"
+#endif
" -- stop handling options\n"
" - stop handling options and execute stdin\n"
,
@@ -406,6 +462,7 @@ static void doREPL (lua_State *L) {
int status;
const char *oldprogname = progname;
progname = NULL; /* no 'progname' on errors in interactive mode */
+ lua_initreadline(L);
while ((status = loadline(L)) != -1) {
if (status == LUA_OK)
status = docall(L, 0, LUA_MULTRET);
@@ -455,6 +512,7 @@ static int handle_script (lua_State *L,
#define has_v 4 /* -v */
#define has_e 8 /* -e */
#define has_E 16 /* -E */
+#define has_N 32 /* -N */
/*
** Traverses all arguments from 'argv', returning a mask with those
@@ -482,6 +540,13 @@ static int collectargs (char **argv, int
return has_error; /* invalid option */
args |= has_E;
break;
+#if defined(LUA_USE_READLINE_DL)
+ case 'N':
+ if (argv[i][2] != '0円') /* extra characters after 1st? */
+ return has_error; /* invalid option */
+ args |= has_N;
+ break;
+#endif
case 'i':
args |= has_i; /* (-i implies -v) *//* FALLTHROUGH */
case 'v':
@@ -579,6 +644,10 @@ static int pmain (lua_State *L) {
if (script < argc && /* execute main script (if there is one) */
handle_script(L, argv + script) != LUA_OK)
return 0;
+#if defined(LUA_USE_READLINE_DL)
+ if (args & has_N)
+ disable_readline = 1;
+#endif
if (args & has_i) /* -i option? */
doREPL(L); /* do read-eval-print loop */
else if (script == argc && !(args & (has_e | has_v))) { /* no arguments? */