Control: tags -1 + patch
This is caused by a non-printable character (meant to be interpreted by
the terminal) stuffed in the prompt string given to GNU readline.
It should have been enclosed in RL_PROMPT_START_IGNORE/RL_PROMPT_END_IGNORE
pairs. "fix-readline-related-bug.patch" does that. It is a Scheme-only
fix, but it's not ideal because it hardcodes libreadline constants.
Ideally, "Iedline.scm" would get eval-ed in an environment where C code
has made the constants (from <readline/readline.h>) available. This way
the constants are not hardcoded in the source code and the Scheme
namespace is not polluted with implementation details. Alas, I could
not figure out how to try-load some Scheme code from C with a prepared
environment.
While reading some of the code I found what *might* be 2 other
(unrelated) bugs. See "add-missing-edit-line-feature.patch" and
"fix-argument-imm-being-ignored-in-m_letstar1.patch".
Cheers.
Description: Fix readline-related bug
Non-printable character (meant to be interpreted by the terminal) in the
prompt string was not enclosed in RL_PROMPT_START_IGNORE/RL_PROMPT_END_IGNORE
pairs, resulting in improper behaviour by GNU readline.
.
This is a Scheme-only fix, but it's not ideal because it hardcodes
libreadline constants. Ideally, "Iedline.scm" would get eval-ed in an
environment where C code has made the constants (from <readline/readline.h>)
available. This way the constants are not hardcoded in the source code and
the Scheme namespace is not polluted with implementation details.
Author: astian <ast...@elude.in>
Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=831017
Forwarded: no
Last-Update: 2018-03-03
--- scm-5f2.orig/Iedline.scm
+++ scm-5f2/Iedline.scm
@@ -23,7 +23,17 @@
;; lines, i.e. lines unterminated by a newline.
(define (make-edited-line-port)
- (let ((prompt "")
+ (let ; The prompt string we receive.
+ ((prompt "")
+ ; Hack to make readline overwrite the prompt we manually write.
+ ; Notice that #\cr is being wrapped in #\soh and #\stx, respectively
+ ; RL_PROMPT_START_IGNORE and RL_PROMPT_END_IGNORE (defined in
+ ; <readline/readline.h>), to signal to readline that #\cr is
+ ; invisible.
+ (prompt-hack (string #\soh #\cr #\stx))
+ ; Concatenation of "prompt-hack" and "prompt", this is the actual
+ ; prompt we send to readline.
+ (prompt-real "")
(outp (default-output-port))
(inp (default-input-port))
(strp (call-with-input-string "" identity)))
@@ -31,18 +41,40 @@
(vector (lambda (c)
(write-char c outp))
(lambda (s)
+ ; Reverse-engineered assumption: string-write to this port will
+ ; only be done in the following cases:
+ ;
+ ; - Empty string.
+ ;
+ ; - Printing repl results, in which case the string will
+ ; always come linefeed-terminated.
+ ;
+ ; - Prompt printing, which will never be linefeed-terminated.
+ ; The prompt string is immediately printed (manually),
+ ; later, when GNU readline is called, a carriage return
+ ; prepended to the same prompt string will cause it to
+ ; write its prompt on top of the one we printed ourselves
+ ; (therefore only one instance of the prompt string is
+ ; actually visible to the interactive user). Presumably
+ ; this is the result of kluging optional readline support
+ ; on top of an existing prompting mechanism.
+ ;
+ ; -- astian
(display s outp)
(or (zero? (string-length s))
(eq? #\newline (string-ref s (- (string-length s) 1)))
(begin
- (set! prompt (string-append "\r" s))
- (force-output outp))))
+ (or (string=? s prompt)
+ (begin
+ (set! prompt s)
+ (set! prompt-real (string-append prompt-hack prompt)))))
+ (force-output outp)))
(lambda ()
(force-output outp))
(lambda ()
(let tail ((c (read-char strp)))
(if (char? c) c
- (let ((str (read-edited-line prompt)))
+ (let ((str (read-edited-line prompt-real)))
(if (string? str)
(let ((n (string-length str)))
(add-history str)
Description: Add missing "edit-line" feature
Don't know why it was missing.
Author: astian <ast...@elude.in>
Forwarded: no
Last-Update: 2018-03-03
--- scm-5f2.orig/edline.c
+++ scm-5f2/edline.c
@@ -65,6 +65,9 @@ void init_edline()
make_subr(s_def_outport, tc7_subr_0, def_outport);
make_subr(s_readline, tc7_subr_1, lreadline);
make_subr(s_add_history, tc7_subr_1, ladd_history);
+
+ add_feature("edit-line");
+
if (scm_ldprog(s_Iedline))
wta(*loc_errobj, "couldn't init", s_Iedline);
}
Description: Fix argument "imm" being ignored in "m_letstar1"
Like "m_letrec1", "m_letstar1" is used in the implementation of various
syntactic elements. Like in "m_letrec1", argument "imm" in "m_letstar1"
is supposed to indicate (methinks) what syntactic element is being
implemented.
Author: astian <ast...@elude.in>
Forwarded: no
Last-Update: 2018-03-03
--- scm-5f2.orig/eval.c
+++ scm-5f2/eval.c
@@ -1274,6 +1274,7 @@ int scm_nullenv_p(env)
static SCM m_letstar1(imm, vars, inits, body, env, ctxt)
SCM imm, vars, inits, body, env, ctxt;
{
+ SCM op = MAKSPCSYM2(IM_LETSTAR, imm);
SCM init, bdgs = cons(env, EOL); /* initial env is for debug printing. */
SCM *loc = &CDR(bdgs);
while (NIMP(vars)) {
@@ -1284,7 +1285,7 @@ static SCM m_letstar1(imm, vars, inits,
vars = CDR(vars);
inits = CDR(inits);
}
- return cons2(IM_LETSTAR, bdgs, m_body(body, env, ctxt));
+ return cons2(op, bdgs, m_body(body, env, ctxt));
}
SCM m_letstar(xorig, env, ctxt)
