fix issue with internally quoting multibyte characters; the let builtin now suppresses additional array subscript expansion; small change to how readline export-completions displays filenames; new loadable builtin to do floating-point arithmetic

CHANGES

@@ -1885,7 +1885,7 @@ n. The `test -N' operator uses nanosecond timestamp granularity if it's
    available.
 
 o. Bash posix mode now treats assignment statements preceding shell function
-   definitions the same as in its default mode, since POSIX has changed and
+   calls the same as in its default mode, since POSIX has changed and
    no longer requires those assignments to persist after the function returns
    (POSIX interp 654).
 

CWRU/CWRU.chlog

@@ -10796,3 +10796,41 @@ tests/printf7.sub,tests/cond-regexp2.sub
 tests/run-all, tests/run-minimal
 	- BASHOPTS: unset or unexport as appropriate, same as SHELLOPTS
 	  From a report by Martin D Kealey <martin@kurahaupo.gen.nz>
+
+				    1/9
+				    ---
+subst.c
+	- string_extract_verbatim: take into account the fact that CTLESC can
+	  quote multibyte characters; use ADVANCE_CHAR instead of increment
+	  Fixes bug reported by jktseug@gmail.com
+
+				   1/10
+				   ----
+expr.c
+	- expr_bind_variable,expr_streval: suppress additional expansion if
+	  called by the `let' builtin, whether or not array_expand_once is set
+	- expr_skipsubscript: suppress expansion while parsing subscripts
+	  whether array_expand_once is set or not
+	  Still have to change tests if this goes final
+	  These are all conditional on shell_compatibility_level > 51
+	  From a bug-bash post by Greg Wooledge <greg@wooledge.org>
+
+				   1/14
+				   ----
+lib/readline/complete.c
+	- _rl_export_completions: use print_filename instead of fprintf to
+	  display the possible completions so slashes and file types can
+	  be included
+	  From a patch from Matthew Tromp <matthewktromp@gmail.com>
+
+				   1/15
+				   ----
+examples/loadables/fltexpr.c
+	- fltexpr: new loadable builtin to do floating-point arithmetic
+	  expression evaluation and optionally print the result
+
+				   1/16
+				   ----
+builtins/printf.def
+	- getarg(), advancearg(): cosmetic changes to make it easier to
+	  implement %N$ format specifiers in the future

MANIFEST

@@ -784,6 +784,7 @@ examples/loadables/getconf.h	f
 examples/loadables/getconf.c	f
 examples/loadables/fdflags.c	f
 examples/loadables/finfo.c	f
+examples/loadables/fltexpr.c	f
 examples/loadables/cat.c	f
 examples/loadables/csv.c	f
 examples/loadables/dsv.c	f

builtins/printf.def

@@ -242,6 +242,12 @@ static char *vbuf, *vname;
 static size_t vbsize;
 static size_t vblen;
 
+/* printf format numbered argument support */
+static char **narg_argv;
+static int narg_argc;
+static int narg_maxind;
+static int narg_curind;
+
 static intmax_t tw;
 
 static char *conv_buf;
@@ -1329,16 +1335,32 @@ mklong (char *str, char *modifiers, size_t mlen)
   return (conv_buf);
 }
 
+static inline char *
+getarg (void)
+{
+  return (garglist ? garglist->word->word : 0);
+}
+
+static inline void
+advancearg (void)
+{
+  garglist = garglist->next;
+}
+
 static int
 getchr (void)
 {
   int ret;
+  char *arg;
 
-  if (garglist == 0)
+  arg = getarg ();
+
+  if (arg == 0)
     return ('\0');
 
-  ret = (int)garglist->word->word[0];
-  garglist = garglist->next;
+  ret = (int)arg[0];
+
+  advancearg ();
   return ret;
 }
 
@@ -1347,11 +1369,11 @@ getstr (void)
 {
   char *ret;
 
-  if (garglist == 0)
+  ret = getarg ();
+  if (ret == 0)
     return ("");
 
-  ret = garglist->word->word;
-  garglist = garglist->next;
+  advancearg ();
   return ret;
 }
 
@@ -1379,23 +1401,25 @@ static int
 getint (int overflow_retval)
 {
   intmax_t ret;
-  char *ep;
+  char *ep, *arg;
   int overflow;
 
-  if (garglist == 0)
+  arg = getarg ();
+
+  if (arg == 0)
     return (0);
 
-  if (garglist->word->word[0] == '\'' || garglist->word->word[0] == '"')
+  if (arg[0] == '\'' || arg[0] == '"')
     return asciicode ();
 
   errno = 0;
-  ret = strtoimax (garglist->word->word, &ep, 0);
+  ret = strtoimax (arg, &ep, 0);
   if (overflow = (errno == ERANGE) || (ret < INT_MIN || ret > INT_MAX))
     errno = ERANGE;	/* force errno */
 
-  chk_converror (garglist->word->word, ep);
+  chk_converror (arg, ep);
 
-  garglist = garglist->next;
+  advancearg ();
   return (overflow ? overflow_retval : (int)ret);
 }
 
@@ -1403,20 +1427,22 @@ static intmax_t
 getintmax (void)
 {
   intmax_t ret;
-  char *ep;
+  char *ep, *arg;
 
-  if (garglist == 0)
+  arg = getarg ();
+
+  if (arg == 0)
     return (0);
 
-  if (garglist->word->word[0] == '\'' || garglist->word->word[0] == '"')
+  if (arg[0] == '\'' || arg[0] == '"')
     return asciicode ();
 
   errno = 0;
-  ret = strtoimax (garglist->word->word, &ep, 0);
+  ret = strtoimax (arg, &ep, 0);
 
-  chk_converror (garglist->word->word, ep);
+  chk_converror (arg, ep);
 
-  garglist = garglist->next;
+  advancearg ();
   return (ret);
 }
 
@@ -1424,20 +1450,22 @@ static uintmax_t
 getuintmax (void)
 {
   uintmax_t ret;
-  char *ep;
+  char *ep, *arg;
 
-  if (garglist == 0)
+  arg = getarg ();
+
+  if (arg == 0)
     return (0);
 
-  if (garglist->word->word[0] == '\'' || garglist->word->word[0] == '"')
+  if (arg[0] == '\'' || arg[0] == '"')
     return asciicode ();
 
   errno = 0;
-  ret = strtoumax (garglist->word->word, &ep, 0);
+  ret = strtoumax (arg, &ep, 0);
 
-  chk_converror (garglist->word->word, ep);  
+  chk_converror (arg, ep);  
 
-  garglist = garglist->next;
+  advancearg ();
   return (ret);
 }
 
@@ -1445,20 +1473,22 @@ static double
 getdouble (void)
 {
   double ret;
-  char *ep;
+  char *ep, *arg;
 
-  if (garglist == 0)
+  arg = getarg ();
+
+  if (arg == 0)
     return (0);
 
-  if (garglist->word->word[0] == '\'' || garglist->word->word[0] == '"')
+  if (arg[0] == '\'' || arg[0] == '"')
     return asciicode ();
 
   errno = 0;
-  ret = strtod (garglist->word->word, &ep);
+  ret = strtod (arg, &ep);
 
-  chk_converror (garglist->word->word, ep);
+  chk_converror (arg, ep);
 
-  garglist = garglist->next;
+  advancearg ();
   return (ret);
 }
 
@@ -1466,20 +1496,22 @@ static floatmax_t
 getfloatmax (void)
 {
   floatmax_t ret;
-  char *ep;
+  char *ep, *arg;
 
-  if (garglist == 0)
+  arg = getarg ();
+
+  if (arg == 0)
     return (0);
 
-  if (garglist->word->word[0] == '\'' || garglist->word->word[0] == '"')
+  if (arg[0] == '\'' || arg[0] == '"')
     return asciicode ();
 
   errno = 0;
-  ret = strtofltmax (garglist->word->word, &ep);
+  ret = strtofltmax (arg, &ep);
 
-  chk_converror (garglist->word->word, ep);
+  chk_converror (arg, ep);
 
-  garglist = garglist->next;
+  advancearg ();
   return (ret);
 }
 
@@ -1488,23 +1520,25 @@ static intmax_t
 asciicode (void)
 {
   register intmax_t ch;
+  char *arg;
 #if defined (HANDLE_MULTIBYTE)
   wchar_t wc;
   size_t slen, mblength;
 #endif
   DECLARE_MBSTATE;
 
+  arg = getarg ();
 #if defined (HANDLE_MULTIBYTE)
-  slen = strlen (garglist->word->word+1);
+  slen = strlen (arg+1);
   wc = 0;
-  mblength = mbrtowc (&wc, garglist->word->word+1, slen, &state);
+  mblength = mbrtowc (&wc, arg+1, slen, &state);
   if (MB_INVALIDCH (mblength) == 0)
     ch = wc;		/* XXX */
   else
 #endif
-    ch = (unsigned char)garglist->word->word[1];
+    ch = (unsigned char)arg[1];
 
-  garglist = garglist->next;
+  advancearg ();
   return (ch);
 }
 
@@ -1515,16 +1549,18 @@ getwidestr (size_t *lenp)
   wchar_t *ws;
   const char *mbs;
   size_t slen, mblength;
+  char *arg;
   DECLARE_MBSTATE;
 
-  if (garglist == 0)
+  arg = getarg ();
+  if (arg == 0)
     {
       if (lenp)
 	*lenp = 0;
       return NULL;
     }
 
-  mbs = garglist->word->word;
+  mbs = arg;
   slen = strlen (mbs);
   ws = (wchar_t *)xmalloc ((slen + 1) * sizeof (wchar_t));
   mblength = mbsrtowcs (ws, &mbs, slen + 1, &state);
@@ -1535,13 +1571,13 @@ getwidestr (size_t *lenp)
     {
       int i;
       for (i = 0; i < slen; i++)
-	ws[i] = (wchar_t)garglist->word->word[i];
+	ws[i] = (wchar_t)arg[i];
       ws[slen] = L'\0';
       if (lenp)
 	*lenp = slen;
     }
 
-  garglist = garglist->next;
+  advancearg ();
   return (ws);
 }
 
@@ -1550,17 +1586,19 @@ getwidechar (void)
 {
   wchar_t wc;
   size_t slen, mblength;
+  char *arg;
   DECLARE_MBSTATE;
 
-  if (garglist == 0)
+  arg = getarg ();
+  if (arg == 0)
     return L'\0';
 
   wc = 0;
-  mblength = mbrtowc (&wc, garglist->word->word, locale_mb_cur_max, &state);
+  mblength = mbrtowc (&wc, arg, locale_mb_cur_max, &state);
   if (MB_INVALIDCH (mblength))
-    wc = (wchar_t)garglist->word->word[0];
+    wc = (wchar_t)arg[0];
 
-  garglist = garglist->next;
+  advancearg ();
   return (wc);
 }
 

doc/bash.1

@@ -1673,6 +1673,8 @@ If this variable is in the environment when
 .B bash
 starts up, the shell enables each option in the list before
 reading any startup files.
+If this variable is exported, child shells will enable each option
+in the list.
 This variable is read-only.
 .TP
 .B BASHPID
@@ -13259,7 +13261,10 @@ builtin command.
 .IP \(bu
 Importing function definitions from the shell environment at startup.
 .IP \(bu
-Parsing the value of
+Parsing the values of
+.SM
+.B BASHOPTS
+and
 .SM
 .B SHELLOPTS
 from the shell environment at startup.

doc/bashref.texi

@@ -6715,6 +6715,8 @@ as @samp{on} by @samp{shopt}.
 If this variable is in the environment when Bash
 starts up, the shell enables each option in the list before
 reading any startup files.
+If this variable is exported, child shells will enable each option
+in the list.
 This variable is readonly.
 
 @item BASHPID

examples/loadables/Makefile.in

@@ -104,7 +104,7 @@ ALLPROG = print truefalse sleep finfo logname basename dirname fdflags \
 	  tty pathchk tee head mkdir rmdir mkfifo mktemp printenv id whoami \
 	  uname sync push ln unlink realpath strftime mypid setpgid seq rm \
 	  accept csv dsv cut stat getconf kv strptime
-OTHERPROG = necho hello cat pushd asort
+OTHERPROG = necho hello cat pushd asort fltexpr
 
 SUBDIRS = perl
 
@@ -250,6 +250,10 @@ stat:	stat.o
 asort:	asort.o
 	$(SHOBJ_LD) $(SHOBJ_LDFLAGS) $(SHOBJ_XLDFLAGS) -o $@ asort.o $(SHOBJ_LIBS)
 
+fltexpr:	fltexpr.o
+	$(SHOBJ_LD) $(SHOBJ_LDFLAGS) $(SHOBJ_XLDFLAGS) -o $@ fltexpr.o $(SHOBJ_LIBS) -lm
+
+
 # pushd is a special case.  We use the same source that the builtin version
 # uses, with special compilation options.
 #

expr.c

@@ -88,6 +88,9 @@
 #include "subst.h"
 #include "typemax.h"		/* INTMAX_MAX, INTMAX_MIN */
 
+#include "builtins/common.h"	/* this_shell_builtin */
+#include "builtins/builtext.h"	/* let_builtin */
+
 /* Because of the $((...)) construct, expressions may include newlines.
    Here is a macro which accepts newlines, tabs and spaces as whitespace. */
 #define cr_whitespace(c) (whitespace(c) || ((c) == '\n'))
@@ -194,6 +197,10 @@ static intmax_t	expr_streval (char *, int, struct lvalue *);
 static intmax_t	strlong (char *);
 static void	evalerror (const char *);
 
+#if defined (ARRAYS)
+static int	expr_skipsubscript (char *, char *);
+#endif
+
 static void	pushexp (void);
 static void	popexp (void);
 static void	expr_unwind (void);
@@ -330,7 +337,9 @@ expr_bind_variable (const char *lhs, const char *rhs)
     return;		/* XXX */
 
 #if defined (ARRAY_VARS)
-  aflags = (array_expand_once && already_expanded) ? ASS_NOEXPAND : 0;
+  aflags = (array_expand_once && already_expanded) ? ASS_NOEXPAND : 0;	/* XXX */
+  if (this_shell_builtin == let_builtin && shell_compatibility_level > 51)
+    aflags |= ASS_NOEXPAND;		/* we didn't quote subscripts */
   aflags |= ASS_ALLOWALLSUB;		/* allow assoc[@]=value */
 #else
   aflags = 0;
@@ -347,18 +356,21 @@ expr_bind_variable (const char *lhs, const char *rhs)
 static int
 expr_skipsubscript (char *vp, char *cp)
 {
-  int flags, isassoc;
+  int flags, isassoc, noexp;
   SHELL_VAR *entry;
 
-  isassoc = 0;
+  isassoc = noexp = 0;
   entry = 0;
-  if (array_expand_once & already_expanded)
+  /* We're not doing any evaluation here, we should suppress expansion when
+     skipping over the subscript */
+  noexp = already_expanded && (shell_compatibility_level > 51 || array_expand_once);
+  if (noexp)
     {
       *cp = '\0';
       isassoc = valid_identifier (vp) && (entry = find_variable (vp)) && assoc_p (entry);
       *cp = '[';	/* ] */
     }
-  flags = (isassoc && array_expand_once && already_expanded) ? VA_NOEXPAND : 0;
+  flags = (isassoc && noexp) ? VA_NOEXPAND : 0;
   return (skipsubscript (cp, 0, flags));
 }
 
@@ -881,9 +893,7 @@ expmuldiv (void)
 
   val1 = exppower ();
 
-  while ((curtok == MUL) ||
-	 (curtok == DIV) ||
-	 (curtok == MOD))
+  while ((curtok == MUL) || (curtok == DIV) || (curtok == MOD))
     {
       int op = curtok;
       char *stp, *sltp;
@@ -1057,47 +1067,49 @@ exp0 (void)
       /* Skip over closing paren. */
       readtok ();
     }
-  else if ((curtok == NUM) || (curtok == STR))
+  else if (curtok == NUM)
     {
       val = tokval;
-      if (curtok == STR)
+      readtok ();
+    }
+  else if (curtok == STR)
+    {
+      val = tokval;
+      SAVETOK (&ec);
+      tokstr = (char *)NULL;	/* keep it from being freed */
+      noeval = 1;
+      readtok ();
+      stok = curtok;
+
+      /* post-increment or post-decrement */
+      if (stok == POSTINC || stok == POSTDEC)
 	{
-	  SAVETOK (&ec);
-	  tokstr = (char *)NULL;	/* keep it from being freed */
-          noeval = 1;
-          readtok ();
-          stok = curtok;
+ 	  /* restore certain portions of EC */
+ 	  tokstr = ec.tokstr;
+ 	  noeval = ec.noeval;
+ 	  curlval = ec.lval;
+ 	  lasttok = STR;	/* ec.curtok */
 
-	  /* post-increment or post-decrement */
- 	  if (stok == POSTINC || stok == POSTDEC)
- 	    {
- 	      /* restore certain portions of EC */
- 	      tokstr = ec.tokstr;
- 	      noeval = ec.noeval;
- 	      curlval = ec.lval;
- 	      lasttok = STR;	/* ec.curtok */
-
-	      v2 = val + ((stok == POSTINC) ? 1 : -1);
-	      vincdec = itos (v2);
-	      if (noeval == 0)
-		{
+	  v2 = val + ((stok == POSTINC) ? 1 : -1);
+	  vincdec = itos (v2);
+	  if (noeval == 0)
+	    {
 #if defined (ARRAY_VARS)
-		  if (curlval.ind != -1)
-		    expr_bind_array_element (curlval.tokstr, curlval.ind, vincdec);
-		  else
+	      if (curlval.ind != -1)
+		expr_bind_array_element (curlval.tokstr, curlval.ind, vincdec);
+	      else
 #endif
-		    expr_bind_variable (tokstr, vincdec);
-		}
-	      free (vincdec);
-	      curtok = NUM;	/* make sure x++=7 is flagged as an error */
- 	    }
- 	  else
- 	    {
-	      /* XXX - watch out for pointer aliasing issues here */
-	      if (stok == STR)	/* free new tokstr before old one is restored */
-		FREE (tokstr);
-	      RESTORETOK (&ec);
- 	    }
+		expr_bind_variable (tokstr, vincdec);
+	    }
+	  free (vincdec);
+	  curtok = NUM;	/* make sure x++=7 is flagged as an error */
+	}
+      else
+	{
+	  /* XXX - watch out for pointer aliasing issues here */
+	  if (stok == STR)	/* free new tokstr before old one is restored */
+	    FREE (tokstr);
+	  RESTORETOK (&ec);
 	}
 	  
       readtok ();
@@ -1155,6 +1167,8 @@ expr_streval (char *tok, int e, struct lvalue *lvalue)
 
 #if defined (ARRAY_VARS)
   tflag = (array_expand_once && already_expanded) ? AV_NOEXPAND : 0;	/* for a start */
+  if (this_shell_builtin == let_builtin && shell_compatibility_level > 51)
+    tflag |= AV_NOEXPAND;	/* we didn't quote subscripts */
 #endif
 
   /* [[[[[ */

lib/readline/complete.c

@@ -3066,7 +3066,10 @@ _rl_export_completions (char **matches, char *text, int start, int end)
   fprintf (rl_outstream, "%s\n", text);
   fprintf (rl_outstream, "%d:%d\n", start, end);	/* : because it's not a radix character */
   for (i = 0; i < len; i++)
-    fprintf (rl_outstream, "%s\n", matches[i]);
+    {
+      print_filename (matches[i], matches[i], 0);
+      fprintf (rl_outstream, "\n");
+    }
   fflush (rl_outstream);
 }
 

lib/readline/doc/history.3

@@ -79,8 +79,8 @@
 .SH NAME
 history \- GNU History Library
 .SH COPYRIGHT
-.if t The GNU History Library is Copyright \(co 1989-2024 by the Free Software Foundation, Inc.
-.if n The GNU History Library is Copyright (C) 1989-2024 by the Free Software Foundation, Inc.
+.if t The GNU History Library is Copyright \(co 1989-2025 by the Free Software Foundation, Inc.
+.if n The GNU History Library is Copyright (C) 1989-2025 by the Free Software Foundation, Inc.
 .SH DESCRIPTION
 Many programs read input from the user a line at a time.
 The GNU

lib/readline/doc/history.texi

@@ -1,4 +1,4 @@
-\input texinfo    @c -*-texinfo-*-
+c\input texinfo    @c -*-texinfo-*-
 @c %**start of header (This is for running Texinfo on a region.)
 @setfilename history.info
 @settitle GNU History Library
@@ -12,7 +12,7 @@ This document describes the GNU History library
 a programming tool that provides a consistent user interface for
 recalling lines of previously typed input.
 
-Copyright @copyright{} 1988--2024 Free Software Foundation, Inc.
+Copyright @copyright{} 1988--2025 Free Software Foundation, Inc.
 
 @quotation
 Permission is granted to copy, distribute and/or modify this document

lib/readline/doc/hstech.texi

@@ -1,7 +1,7 @@
 @ignore
 This file documents the user interface to the GNU History library.
 
-Copyright (C) 1988-2024 Free Software Foundation, Inc.
+Copyright (C) 1988-2025 Free Software Foundation, Inc.
 Authored by Brian Fox and Chet Ramey.
 
 Permission is granted to make and distribute verbatim copies of this manual

lib/readline/doc/hsuser.texi

@@ -1,7 +1,7 @@
 @ignore
 This file documents the user interface to the GNU History library.
 
-Copyright (C) 1988--2024 Free Software Foundation, Inc.
+Copyright (C) 1988--2025 Free Software Foundation, Inc.
 Authored by Brian Fox and Chet Ramey.
 
 Permission is granted to make and distribute verbatim copies of this manual

lib/readline/doc/readline.3

@@ -60,8 +60,8 @@ readline \- get a line from a user with editing
 \fBreadline\fP (\fIconst char *prompt\fP);
 .fi
 .SH COPYRIGHT
-.if n Readline is Copyright (C) 1989\-2024 Free Software Foundation,  Inc.
-.if t Readline is Copyright \(co 1989\-2024 Free Software Foundation, Inc.
+.if n Readline is Copyright (C) 1989\-2025 Free Software Foundation,  Inc.
+.if t Readline is Copyright \(co 1989\-2025 Free Software Foundation, Inc.
 .SH DESCRIPTION
 .LP
 .B readline

lib/readline/doc/rlman.texi

@@ -13,7 +13,7 @@ This manual describes the GNU Readline Library
 consistency of user interface across discrete programs which provide
 a command line interface.
 
-Copyright @copyright{} 1988--2024 Free Software Foundation, Inc.
+Copyright @copyright{} 1988--2025 Free Software Foundation, Inc.
 
 @quotation
 Permission is granted to copy, distribute and/or modify this document

lib/readline/doc/rltech.texi

@@ -7,7 +7,7 @@ This document describes the GNU Readline Library, a utility for aiding
 in the consistency of user interface across discrete programs that need
 to provide a command line interface.
 
-Copyright (C) 1988--2024 Free Software Foundation, Inc.
+Copyright (C) 1988--2025 Free Software Foundation, Inc.
 
 Permission is granted to make and distribute verbatim copies of
 this manual provided the copyright notice and this permission notice

lib/readline/doc/rluser.texi

@@ -11,7 +11,7 @@ use these features.  There is a document entitled "readline.texinfo"
 which contains both end-user and programmer documentation for the
 GNU Readline Library.
 
-Copyright (C) 1988--2024 Free Software Foundation, Inc.
+Copyright (C) 1988--2025 Free Software Foundation, Inc.
 
 Authored by Brian Fox and Chet Ramey.
 

lib/readline/doc/rluserman.texi

@@ -12,7 +12,7 @@ This manual describes the end user interface of the GNU Readline Library
 consistency of user interface across discrete programs which provide
 a command line interface.
 
-Copyright @copyright{} 1988--2024 Free Software Foundation, Inc.
+Copyright @copyright{} 1988--2025 Free Software Foundation, Inc.
 
 @quotation
 Permission is granted to copy, distribute and/or modify this document

lib/readline/doc/version.texi

@@ -1,5 +1,5 @@
 @ignore
-Copyright (C) 1988-2024 Free Software Foundation, Inc. 
+Copyright (C) 1988-2025 Free Software Foundation, Inc. 
 @end ignore
 
 @set EDITION 8.3

shell.c

@@ -1,6 +1,6 @@
 /* shell.c -- GNU's idea of the POSIX shell specification. */
 
-/* Copyright (C) 1987-2024 Free Software Foundation, Inc.
+/* Copyright (C) 1987-2025 Free Software Foundation, Inc.
 
    This file is part of GNU Bash, the Bourne Again SHell.
 

subst.c

@@ -4,7 +4,7 @@
 /* ``Have a little faith, there's magic in the night.  You ain't a
      beauty, but, hey, you're alright.'' */
 
-/* Copyright (C) 1987-2024 Free Software Foundation, Inc.
+/* Copyright (C) 1987-2025 Free Software Foundation, Inc.
 
    This file is part of GNU Bash, the Bourne Again SHell.
 
@@ -1184,7 +1184,9 @@ string_extract_verbatim (const char *string, size_t slen, size_t *sindex, char *
 #endif
       if ((flags & SX_NOCTLESC) == 0 && c == CTLESC)
 	{
-	  i += 2;
+	  i++;
+	  CHECK_STRING_OVERRUN (i, i, slen, c);
+	  ADVANCE_CHAR (string, slen, i);	/* CTLESC can quote mbchars */
 	  CHECK_STRING_OVERRUN (i, i, slen, c);
 	  continue;
 	}