From d892bbfd0e53c860823f1bdf98e0a6a4172351d3 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Wed, 4 Apr 2018 23:00:49 -0700
Subject: regex: read/print bug: escaped double quote.

Because the regex printer wrongly uses out_str_char (for the
sake of borrowing its semicolon-notation processing) when
a regex prints, all characters that require escaping in a
string literal get escaped, which includes the " character.
Unfortunately the \" sequence which results is rejected
by the regex parser.

* lib.c (out_str_char): Kludge: add extra argument to
distinguish regex use versus string use, and treat the double
quote accordingly.
(out_str_readable): Give 0 arg to new param of out_str_char.

* lib.h (out_str_char): Declaration updated.

* regex.c (print_class_char, print_rec): Pass 1 to new param
of out_str_char.
---
 lib.c   | 11 ++++++++---
 lib.h   |  2 +-
 regex.c |  4 ++--
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/lib.c b/lib.c
index f089ee90..cf800c52 100644
--- a/lib.c
+++ b/lib.c
@@ -10849,7 +10849,7 @@ static val simple_qref_args_p(val args, val pos)
   }
 }
 
-void out_str_char(wchar_t ch, val out, int *semi_flag)
+void out_str_char(wchar_t ch, val out, int *semi_flag, int regex)
 {
   if (*semi_flag && (iswxdigit(ch) || ch == ';'))
     put_char(chr(';'), out);
@@ -10864,9 +10864,14 @@ void out_str_char(wchar_t ch, val out, int *semi_flag)
   case '\v': put_string(lit("\\v"), out); break;
   case '\f': put_string(lit("\\f"), out); break;
   case '\r': put_string(lit("\\r"), out); break;
-  case '"': put_string(lit("\\\""), out); break;
   case '\\': put_string(lit("\\\\"), out); break;
   case 27: put_string(lit("\\e"), out); break;
+  case '"':
+    if (regex)
+      put_char(chr(ch), out);
+    else
+      put_string(lit("\\\""), out);
+    break;
   default:
     {
       val fmt = nil;
@@ -10891,7 +10896,7 @@ void out_str_char(wchar_t ch, val out, int *semi_flag)
 static void out_str_readable(const wchar_t *ptr, val out, int *semi_flag)
 {
   for (; *ptr; ptr++)
-    out_str_char(*ptr, out, semi_flag);
+    out_str_char(*ptr, out, semi_flag, 0);
 }
 
 static void out_lazy_str(val lstr, val out)
diff --git a/lib.h b/lib.h
index 6fe29fe2..b473b4dd 100644
--- a/lib.h
+++ b/lib.h
@@ -1069,7 +1069,7 @@ val to(val range);
 val set_from(val range, val from);
 val set_to(val range, val to);
 val env(void);
-void out_str_char(wchar_t ch, val out, int *semi_flag);
+void out_str_char(wchar_t ch, val out, int *semi_flag, int regex);
 val obj_print_impl(val obj, val out, val pretty, struct strm_ctx *);
 val obj_print(val obj, val stream, val pretty);
 val print(val obj, val stream, val pretty);
diff --git a/regex.c b/regex.c
index 47693e97..3fb6b42c 100644
--- a/regex.c
+++ b/regex.c
@@ -2272,7 +2272,7 @@ static void print_class_char(val ch, val first_p, val stream, int *semi_flag)
     put_char(ch, stream);
     return;
   }
-  out_str_char(c_chr(ch), stream, semi_flag);
+  out_str_char(c_chr(ch), stream, semi_flag, 1);
 }
 
 static void print_rec(val exp, val stream, int *semi_flag);
@@ -2311,7 +2311,7 @@ static void print_rec(val exp, val stream, int *semi_flag)
       put_char(exp, stream);
       break;
     default:
-      out_str_char(ch, stream, semi_flag);
+      out_str_char(ch, stream, semi_flag, 1);
     }
   } else if (stringp(exp)) {
     cnum i;
-- 
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