add support for case-insensitive incremental and non-incremental history searches; controlled by new bindable variable `search-ignore-case'

18 files changed, 346 insertions, 157 deletions

diff --git a/aclocal.m4 b/aclocal.m4
index cc97bd4..37546c6 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -1758,8 +1758,9 @@ AC_CHECK_HEADERS(langinfo.h)
 AC_CHECK_HEADERS(mbstr.h)
 
 AC_CHECK_FUNC(mbrlen, AC_DEFINE(HAVE_MBRLEN))
-AC_CHECK_FUNC(mbscasecmp, AC_DEFINE(HAVE_MBSCMP))
+AC_CHECK_FUNC(mbscasecmp, AC_DEFINE(HAVE_MBSCASECMP))
 AC_CHECK_FUNC(mbscmp, AC_DEFINE(HAVE_MBSCMP))
+AC_CHECK_FUNC(mbsncmp, AC_DEFINE(HAVE_MBSNCMP))
 AC_CHECK_FUNC(mbsnrtowcs, AC_DEFINE(HAVE_MBSNRTOWCS))
 AC_CHECK_FUNC(mbsrtowcs, AC_DEFINE(HAVE_MBSRTOWCS))
 
@@ -1770,6 +1771,7 @@ AC_CHECK_FUNC(wcscoll, AC_DEFINE(HAVE_WCSCOLL))
 AC_CHECK_FUNC(wcsdup, AC_DEFINE(HAVE_WCSDUP))
 AC_CHECK_FUNC(wcwidth, AC_DEFINE(HAVE_WCWIDTH))
 AC_CHECK_FUNC(wctype, AC_DEFINE(HAVE_WCTYPE))
+AC_CHECK_FUNC(wcsnrtombs, AC_DEFINE(HAVE_WCSNRTOMBS))
 
 AC_REPLACE_FUNCS(wcswidth)
 
diff --git a/bind.c b/bind.c
index 9677893..54ee5cd 100644
--- a/bind.c
+++ b/bind.c
@@ -1916,6 +1916,7 @@ static const struct {
   { "prefer-visible-bell",	&_rl_prefer_visible_bell,	V_SPECIAL },
   { "print-completions-horizontally", &_rl_print_completions_horizontally, 0 },
   { "revert-all-at-newline",	&_rl_revert_all_at_newline,	0 },
+  { "search-ignore-case",	&_rl_search_case_fold,		0 },
   { "show-all-if-ambiguous",	&_rl_complete_show_all,		0 },
   { "show-all-if-unmodified",	&_rl_complete_show_unmodified,	0 },
   { "show-mode-in-prompt",	&_rl_show_mode_in_prompt,	0 },
diff --git a/complete.c b/complete.c
index fe0b879..2016d39 100644
--- a/complete.c
+++ b/complete.c
@@ -1,6 +1,6 @@
 /* complete.c -- filename completion for readline. */
 
-/* Copyright (C) 1987-2022 Free Software Foundation, Inc.
+/* Copyright (C) 1987-2022,2023 Free Software Foundation, Inc.
 
    This file is part of the GNU Readline Library (Readline), a library
    for reading lines of text with interactive input and history editing.
@@ -2349,18 +2349,7 @@ rl_username_completion_function (const char *text, int state)
 static int
 complete_fncmp (const char *convfn, int convlen, const char *filename, int filename_len)
 {
-  register char *s1, *s2;
-  int d, len;
-#if defined (HANDLE_MULTIBYTE)
-  size_t v1, v2;
-  mbstate_t ps1, ps2;
-  WCHAR_T wc1, wc2;
-#endif
-
-#if defined (HANDLE_MULTIBYTE)
-  memset (&ps1, 0, sizeof (mbstate_t));
-  memset (&ps2, 0, sizeof (mbstate_t));
-#endif
+  size_t len;
 
   if (filename_len == 0)
     return 1;
@@ -2368,100 +2357,26 @@ complete_fncmp (const char *convfn, int convlen, const char *filename, int filen
     return 0;
 
   len = filename_len;
-  s1 = (char *)convfn;
-  s2 = (char *)filename;
 
   /* Otherwise, if these match up to the length of filename, then
      it is a match. */
-  if (_rl_completion_case_fold && _rl_completion_case_map)
-    {
-      /* Case-insensitive comparison treating _ and - as equivalent */
-#if defined (HANDLE_MULTIBYTE)
-      if (MB_CUR_MAX > 1 && rl_byte_oriented == 0)
-	{
-	  do
-	    {
-	      v1 = MBRTOWC (&wc1, s1, convlen, &ps1);
-	      v2 = MBRTOWC (&wc2, s2, filename_len, &ps2);
-	      if (v1 == 0 && v2 == 0)
-		return 1;
-	      else if (MB_INVALIDCH (v1) || MB_INVALIDCH (v2))
-		{
-		  if (*s1 != *s2)		/* do byte comparison */
-		    return 0;
-		  else if ((*s1 == '-' || *s1 == '_') && (*s2 == '-' || *s2 == '_'))
-		    return 0;
-		  s1++; s2++; len--;
-		  continue;
-		}
-	      wc1 = towlower (wc1);
-	      wc2 = towlower (wc2);
-	      s1 += v1;
-	      s2 += v1;
-	      len -= v1;
-	      if ((wc1 == L'-' || wc1 == L'_') && (wc2 == L'-' || wc2 == L'_'))
-	        continue;
-	      if (wc1 != wc2)
-		return 0;
-	    }
-	  while (len != 0);
-	}
-      else
-#endif
-	{
-	do
-	  {
-	    d = _rl_to_lower (*s1) - _rl_to_lower (*s2);
-	    /* *s1 == [-_] && *s2 == [-_] */
-	    if ((*s1 == '-' || *s1 == '_') && (*s2 == '-' || *s2 == '_'))
-	      d = 0;
-	    if (d != 0)
-	      return 0;
-	    s1++; s2++;	/* already checked convlen >= filename_len */
-	  }
-	while (--len != 0);
-	}
-
-      return 1;
-    }
-  else if (_rl_completion_case_fold)
+  if (_rl_completion_case_fold)
     {
+      /* Case-insensitive comparison treating _ and - as equivalent if
+	 _rl_completion_case_map is non-zero */
 #if defined (HANDLE_MULTIBYTE)
       if (MB_CUR_MAX > 1 && rl_byte_oriented == 0)
-	{
-	  do
-	    {
-	      v1 = MBRTOWC (&wc1, s1, convlen, &ps1);
-	      v2 = MBRTOWC (&wc2, s2, filename_len, &ps2);
-	      if (v1 == 0 && v2 == 0)
-		return 1;
-	      else if (MB_INVALIDCH (v1) || MB_INVALIDCH (v2))
-		{
-		  if (*s1 != *s2)		/* do byte comparison */
-		    return 0;
-		  s1++; s2++; len--;
-		  continue;
-		}
-	      wc1 = towlower (wc1);
-	      wc2 = towlower (wc2);
-	      if (wc1 != wc2)
-		return 0;
-	      s1 += v1;
-	      s2 += v1;
-	      len -= v1;
-	    }
-	  while (len != 0);
-	  return 1;
-	}
+	return (_rl_mb_strcaseeqn (convfn, convlen, filename, filename_len, len, _rl_completion_case_map));
       else
 #endif
       if ((_rl_to_lower (convfn[0]) == _rl_to_lower (filename[0])) &&
-	  (convlen >= filename_len) &&
-	  (_rl_strnicmp (filename, convfn, filename_len) == 0))
-	return 1;
+	  (convlen >= filename_len))
+	return (_rl_strcaseeqn (convfn, filename, len, _rl_completion_case_map));
     }
   else
     {
+      /* XXX - add new _rl_mb_streqn function (like mbsncmp) instead of
+	 relying on byte equivalence? */
       if ((convfn[0] == filename[0]) &&
 	  (convlen >= filename_len) &&
 	  (strncmp (filename, convfn, filename_len) == 0))
diff --git a/config.h.in b/config.h.in
index 521e778..ede3722 100644
--- a/config.h.in
+++ b/config.h.in
@@ -87,6 +87,12 @@
 /* Define if you have the mbrtowc function. */
 #undef HAVE_MBRTOWC
 
+/* Define if you have the mbscmp function. */
+#undef HAVE_MBSCMP
+
+/* Define if you have the mbsncmp function. */
+#undef HAVE_MBSNCMP
+
 /* Define if you have the mbsrtowcs function. */
 #undef HAVE_MBSRTOWCS
 
diff --git a/configure b/configure
index cb4e07a..72ec539 100755
--- a/configure
+++ b/configure
@@ -7421,7 +7421,7 @@ fi
 ac_fn_c_check_func "$LINENO" "mbscasecmp" "ac_cv_func_mbscasecmp"
 if test "x$ac_cv_func_mbscasecmp" = xyes
 then :
-  printf "%s\n" "#define HAVE_MBSCMP 1" >>confdefs.h
+  printf "%s\n" "#define HAVE_MBSCASECMP 1" >>confdefs.h
 
 fi
 
@@ -7432,6 +7432,13 @@ then :
 
 fi
 
+ac_fn_c_check_func "$LINENO" "mbsncmp" "ac_cv_func_mbsncmp"
+if test "x$ac_cv_func_mbsncmp" = xyes
+then :
+  printf "%s\n" "#define HAVE_MBSNCMP 1" >>confdefs.h
+
+fi
+
 ac_fn_c_check_func "$LINENO" "mbsnrtowcs" "ac_cv_func_mbsnrtowcs"
 if test "x$ac_cv_func_mbsnrtowcs" = xyes
 then :
@@ -7497,6 +7504,13 @@ then :
 
 fi
 
+ac_fn_c_check_func "$LINENO" "wcsnrtombs" "ac_cv_func_wcsnrtombs"
+if test "x$ac_cv_func_wcsnrtombs" = xyes
+then :
+  printf "%s\n" "#define HAVE_WCSNRTOMBS 1" >>confdefs.h
+
+fi
+
 
 ac_fn_c_check_func "$LINENO" "wcswidth" "ac_cv_func_wcswidth"
 if test "x$ac_cv_func_wcswidth" = xyes
diff --git a/doc/readline.3 b/doc/readline.3
index 77ef02a..9a63e09 100644
--- a/doc/readline.3
+++ b/doc/readline.3
@@ -6,9 +6,9 @@
 .\"	Case Western Reserve University
 .\"	chet.ramey@case.edu
 .\"
-.\"	Last Change: Mon Sep 19 11:11:22 EDT 2022
+.\"	Last Change: Fri Feb 17 10:59:58 EST 2023
 .\"
-.TH READLINE 3 "2022 September 19" "GNU Readline 8.2"
+.TH READLINE 3 "2023 February 17" "GNU Readline 8.2"
 .\"
 .\" File Name macro.  This used to be `.PN', for Path Name,
 .\" but Sun doesn't seem to like that very much.
@@ -34,8 +34,8 @@ 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\-2020 Free Software Foundation,  Inc.
-.if t Readline is Copyright \(co 1989\-2020 Free Software Foundation, Inc.
+.if n Readline is Copyright (C) 1989\-2023 Free Software Foundation,  Inc.
+.if t Readline is Copyright \(co 1989\-2023 Free Software Foundation, Inc.
 .SH DESCRIPTION
 .LP
 .B readline
@@ -622,6 +622,10 @@ before returning when \fBaccept\-line\fP is executed.  By default,
 history lines may be modified and retain individual undo lists across
 calls to \fBreadline\fP.
 .TP
+.B search\-ignore\-case (Off)
+If set to \fBOn\fP, readline performs incremental and non-incremental
+history list searches in a case\-insensitive fashion.
+.TP
 .B show\-all\-if\-ambiguous (Off)
 This alters the default behavior of the completion functions.  If
 set to
diff --git a/doc/rluser.texi b/doc/rluser.texi
index cbcbb45..f68a4d7 100644
--- a/doc/rluser.texi
+++ b/doc/rluser.texi
@@ -9,7 +9,7 @@ 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--2022 Free Software Foundation, Inc.
+Copyright (C) 1988--2023 Free Software Foundation, Inc.
 
 Authored by Brian Fox and Chet Ramey.
 
@@ -757,6 +757,12 @@ before returning when @code{accept-line} is executed.  By default,
 history lines may be modified and retain individual undo lists across
 calls to @code{readline()}.  The default is @samp{off}.
 
+@item search-ignore-case
+@vindex search-ignore-case
+If set to @samp{on}, Readline performs incremental and non-incremental
+history list searches in a case-insensitive fashion.
+The default value is @samp{off}.
+
 @item show-all-if-ambiguous
 @vindex show-all-if-ambiguous
 This alters the default behavior of the completion functions.  If
diff --git a/doc/version.texi b/doc/version.texi
index 2b80d34..a72ee26 100644
--- a/doc/version.texi
+++ b/doc/version.texi
@@ -5,7 +5,7 @@ Copyright (C) 1988-2023 Free Software Foundation, Inc.
 @set EDITION 8.2
 @set VERSION 8.2
 
-@set UPDATED 21 January 2023
-@set UPDATED-MONTH January 2023
+@set UPDATED 17 February 2023
+@set UPDATED-MONTH February 2023
 
-@set LASTCHANGE Sat Jan 21 17:10:44 EST 2023
+@set LASTCHANGE Fri Feb 17 11:03:17 EST 2023
diff --git a/histfile.c b/histfile.c
index d299b5e..a3c8d9b 100644
--- a/histfile.c
+++ b/histfile.c
@@ -630,10 +630,10 @@ history_truncate_file (const char *fname, int lines)
       if (write (file, bp, chars_read - (bp - buffer)) < 0)
 	rv = errno;
 
-      if (fstat (file, &nfinfo) < 0 && rv == 0)
+      if (rv == 0 && fstat (file, &nfinfo) < 0)
 	rv = errno;
 
-      if (close (file) < 0 && rv == 0)
+      if (rv == 0 && close (file) < 0)
 	rv = errno;
     }
   else
@@ -670,6 +670,38 @@ history_truncate_file (const char *fname, int lines)
   return rv;
 }
 
+/* Use stdio to write the history file after mmap or malloc fails, on the
+   assumption that the stdio library can allocate the smaller buffers it uses. */
+static int
+history_write_slow (int fd, HIST_ENTRY **the_history, int nelements, int overwrite)
+{
+  FILE *fp;
+  int i, j, e;
+
+  fp = fdopen (fd, overwrite ? "w" : "a");
+  if (fp == 0)
+    return -1;
+
+  for (j = 0, i = history_length - nelements; i < history_length; i++)
+    {
+      if (history_write_timestamps && the_history[i]->timestamp && the_history[i]->timestamp[0])
+	fprintf (fp, "%s\n", the_history[i]->timestamp);
+      if (fprintf (fp, "%s\n", the_history[i]->line) < 0)
+	goto slow_write_error;
+    }
+  if (fflush (fp) < 0)
+    {
+slow_write_error:
+      e = errno;
+      fclose (fp);
+      errno = e;
+      return -1;
+    }
+  if (fclose (fp) < 0)
+    return -1;
+  return 0;
+}
+
 /* Workhorse function for writing history.  Writes the last NELEMENT entries
    from the history list to FILENAME.  OVERWRITE is non-zero if you
    wish to replace FILENAME with the entries. */
@@ -738,6 +770,8 @@ history_do_write (const char *filename, int nelements, int overwrite)
     if ((void *)buffer == MAP_FAILED)
       {
 mmap_error:
+	if ((rv = history_write_slow (file, the_history, nelements, overwrite)) == 0)
+	  goto write_success;
 	rv = errno;
 	close (file);
 	if (tempname)
@@ -750,6 +784,8 @@ mmap_error:
     buffer = (char *)malloc (buffer_size);
     if (buffer == 0)
       {
+	if ((rv = history_write_slow (file, the_history, nelements, overwrite)) == 0)
+	  goto write_success;
       	rv = errno;
 	close (file);
 	if (tempname)
@@ -788,6 +824,7 @@ mmap_error:
   if (close (file) < 0 && rv == 0)
     rv = errno;
 
+write_success:
   if (rv == 0 && histname && tempname)
     rv = histfile_restore (tempname, histname);
 
diff --git a/histlib.h b/histlib.h
index 29fc4d2..ca698ac 100644
--- a/histlib.h
+++ b/histlib.h
@@ -34,6 +34,11 @@
 				    : ((a)[0] == (b)[0]) && (strncmp ((a), (b), (n)) == 0))
 #endif
 
+#if !defined (HAVE_STRCASECMP)
+#define strcasecmp(a,b)	strcmp ((a), (b))
+#define strncasecmp(a, b, n)	strncmp ((a), (b), (n))
+#endif
+
 #ifndef savestring
 #define savestring(x) strcpy (xmalloc (1 + strlen (x)), (x))
 #endif
@@ -72,6 +77,7 @@ extern char *strchr ();
 #define NON_ANCHORED_SEARCH	0
 #define ANCHORED_SEARCH		0x01
 #define PATTERN_SEARCH		0x02
+#define CASEFOLD_SEARCH		0x04
 
 /* Possible definitions for what style of writing the history file we want. */
 #define HISTORY_APPEND 0
@@ -81,6 +87,7 @@ extern char *strchr ();
 
 /* histsearch.c */
 extern int _hs_history_patsearch (const char *, int, int);
+extern int _hs_history_search (const char *, int, int);
 
 /* history.c */
 extern void _hs_replace_history_data (int, histdata_t *, histdata_t *);
diff --git a/histsearch.c b/histsearch.c
index 7e5b250..b43ead1 100644
--- a/histsearch.c
+++ b/histsearch.c
@@ -1,6 +1,6 @@
 /* histsearch.c -- searching the history list. */
 
-/* Copyright (C) 1989, 1992-2009,2017,2021 Free Software Foundation, Inc.
+/* Copyright (C) 1989, 1992-2009,2017,2021,2023 Free Software Foundation, Inc.
 
    This file contains the GNU History Library (History), a set of
    routines for managing the text of previously typed lines.
@@ -47,6 +47,8 @@
 #include "histlib.h"
 #include "xmalloc.h"
 
+#include "rlmbutil.h"
+
 /* The list of alternate characters that can delimit a history search
    string. */
 char *history_search_delimiter_chars = (char *)NULL;
@@ -57,7 +59,10 @@ static int history_search_internal (const char *, int, int);
    If DIRECTION < 0, then the search is through previous entries, else
    through subsequent.  If ANCHORED is non-zero, the string must
    appear at the beginning of a history line, otherwise, the string
-   may appear anywhere in the line.  If the string is found, then
+   may appear anywhere in the line.  If PATSEARCH is non-zero, and fnmatch(3)
+   is available, fnmatch is used to match the string instead of a simple
+   string comparison. If IGNORECASE is set, the string comparison is
+   performed case-insensitively. If the string is found, then
    current_history () is the history entry, and the value of this
    function is the offset in the line of that history entry that the
    string was found in.  Otherwise, nothing is changed, and a -1 is
@@ -68,9 +73,10 @@ history_search_internal (const char *string, int direction, int flags)
 {
   int i, reverse;
   char *line;
-  int line_index;
-  size_t string_len;
-  int anchored, patsearch;
+  size_t string_len, line_len;
+  int line_index;		/* can't be unsigned */
+  int anchored, patsearch, igncase;
+  int found, mb_cur_max;
   HIST_ENTRY **the_history; 	/* local */
 
   i = history_offset;
@@ -81,6 +87,7 @@ history_search_internal (const char *string, int direction, int flags)
 #else
   patsearch = 0;
 #endif
+  igncase = (flags & CASEFOLD_SEARCH);
 
   /* Take care of trivial cases first. */
   if (string == 0 || *string == '\0')
@@ -92,6 +99,8 @@ history_search_internal (const char *string, int direction, int flags)
   if (reverse && (i >= history_length))
     i = history_length - 1;
 
+  mb_cur_max = MB_CUR_MAX;
+
 #define NEXT_LINE() do { if (reverse) i--; else i++; } while (0)
 
   the_history = history_list ();
@@ -105,7 +114,7 @@ history_search_internal (const char *string, int direction, int flags)
 	return (-1);
 
       line = the_history[i]->line;
-      line_index = strlen (line);
+      line_len = line_index = strlen (line);
 
       /* If STRING is longer than line, no match. */
       if (patsearch == 0 && (string_len > line_index))
@@ -117,18 +126,27 @@ history_search_internal (const char *string, int direction, int flags)
       /* Handle anchored searches first. */
       if (anchored == ANCHORED_SEARCH)
 	{
+	  found = 0;
 #if defined (HAVE_FNMATCH)
 	  if (patsearch)
+	    found = fnmatch (string, line, 0) == 0;
+	  else
+#endif
+	  if (igncase)
 	    {
-	      if (fnmatch (string, line, 0) == 0)
-		{
-		  history_offset = i;
-		  return (0);
-		}
+#if defined (HANDLE_MULTIBYTE)
+	      if (mb_cur_max > 1)	/* no rl_byte_oriented equivalent */
+		found = _rl_mb_strcaseeqn (string, string_len,
+					   line, line_len,
+					   string_len, 0);
+	      else
+#endif
+		found = strncasecmp (string, line, string_len) == 0;
 	    }
 	  else
-#endif
-	  if (STREQN (string, line, string_len))
+	    found = STREQN (string, line, string_len);
+
+	  if (found)
 	    {
 	      history_offset = i;
 	      return (0);
@@ -141,55 +159,80 @@ history_search_internal (const char *string, int direction, int flags)
       /* Do substring search. */
       if (reverse)
 	{
-	  line_index -= (patsearch == 0) ? string_len : 1;
+	  size_t ll;
+
+	  ll = (patsearch == 0) ? string_len : 1;
+	  line_index -= ll;
+	  found = 0;
 
 	  while (line_index >= 0)
 	    {
 #if defined (HAVE_FNMATCH)
 	      if (patsearch)
+		found = fnmatch (string, line + line_index, 0) == 0;
+	      else
+#endif
+	      if (igncase)
 		{
-		  if (fnmatch (string, line + line_index, 0) == 0)
-		    {
-		      history_offset = i;
-		      return (line_index);
-		    }
+#if defined (HANDLE_MULTIBYTE)
+		  if (mb_cur_max > 1)	/* no rl_byte_oriented equivalent */
+		    found = _rl_mb_strcaseeqn (string, string_len,
+					       line + line_index, ll,
+					       string_len, 0);
+		  else
+#endif
+		  found = strncasecmp (string, line + line_index, string_len) == 0;
 		}
 	      else
-#endif
-	      if (STREQN (string, line + line_index, string_len))
+	        found = STREQN (string, line + line_index, string_len);
+
+	      if (found)
 		{
 		  history_offset = i;
 		  return (line_index);
 		}
 	      line_index--;
+	      ll++;
 	    }
 	}
       else
 	{
 	  register int limit;
+	  size_t ll;
 
+	  ll = line_len;
 	  limit = line_index - string_len + 1;
 	  line_index = 0;
+	  found = 0;
 
 	  while (line_index < limit)
 	    {
 #if defined (HAVE_FNMATCH)
 	      if (patsearch)
+		found = fnmatch (string, line + line_index, 0) == 0;
+	      else
+#endif
+	      if (igncase)
 		{
-		  if (fnmatch (string, line + line_index, 0) == 0)
-		    {
-		      history_offset = i;
-		      return (line_index);
-		    }
+#if defined (HANDLE_MULTIBYTE)
+		  if (mb_cur_max > 1)	/* no rl_byte_oriented equivalent */
+		    found = _rl_mb_strcaseeqn (string, string_len,
+					       line + line_index, ll,
+					       string_len, 0);
+		  else
+#endif
+		  found = strncasecmp (string, line + line_index, string_len) == 0;
 		}
 	      else
-#endif
-	      if (STREQN (string, line + line_index, string_len))
+		found = STREQN (string, line + line_index, string_len);
+
+	      if (found)
 		{
 		  history_offset = i;
 		  return (line_index);
 		}
 	      line_index++;
+	      ll--;
 	    }
 	}
       NEXT_LINE ();
@@ -267,6 +310,13 @@ history_search_prefix (const char *string, int direction)
   return (history_search_internal (string, direction, ANCHORED_SEARCH));
 }
 
+/* At some point, make this public for users of the history library. */
+int
+_hs_history_search (const char *string, int direction, int flags)
+{
+  return (history_search_internal (string, direction, flags));
+}
+
 /* Search for STRING in the history list.  DIR is < 0 for searching
    backwards.  POS is an absolute index into the history list at
    which point to begin searching. */
diff --git a/isearch.c b/isearch.c
index 3756181..89c9338 100644
--- a/isearch.c
+++ b/isearch.c
@@ -59,6 +59,8 @@ char *_rl_isearch_terminators = (char *)NULL;
 
 _rl_search_cxt *_rl_iscxt = 0;
 
+int _rl_search_case_fold = 0;
+
 static int rl_search_history (int, int);
 
 static _rl_search_cxt *_rl_isearch_init (int);
@@ -753,7 +755,27 @@ opcode_dispatch:
       /* Search the current line. */
       while ((cxt->sflags & SF_REVERSE) ? (cxt->sline_index >= 0) : (cxt->sline_index < limit))
 	{
-	  if (STREQN (cxt->search_string, cxt->sline + cxt->sline_index, cxt->search_string_index))
+	  int found;
+
+	  if (_rl_search_case_fold)
+	    {
+#if defined (HANDLE_MULTIBYTE)
+	      if (MB_CUR_MAX > 1 && rl_byte_oriented == 0)
+		found = _rl_mb_strcaseeqn (cxt->search_string,
+					   cxt->search_string_index,
+					   cxt->sline + cxt->sline_index,
+					   limit,
+					   cxt->search_string_index, 0);
+	      else
+		found = _rl_strnicmp (cxt->search_string,
+				      cxt->sline + cxt->sline_index,
+				      cxt->search_string_index) == 0;
+#endif
+	    }
+	  else
+	    found = STREQN (cxt->search_string, cxt->sline + cxt->sline_index, cxt->search_string_index);
+
+	  if (found)
 	    {
 	      cxt->sflags |= SF_FOUND;
 	      break;
diff --git a/mbutil.c b/mbutil.c
index 11cf229..0844e28 100644
--- a/mbutil.c
+++ b/mbutil.c
@@ -521,3 +521,78 @@ _rl_find_prev_mbchar (const char *string, int seed, int flags)
   return ((seed == 0) ? seed : seed - 1);
 #endif
 }
+
+/* Compare the first N characters of S1 and S2 without regard to case. If
+   FLAGS&1, apply the mapping specified by completion-map-case and make
+   `-' and `_' equivalent. Returns 1 if the strings are equal. */
+int
+_rl_mb_strcaseeqn (const char *s1, size_t l1, const char *s2, size_t l2, size_t n, int flags)
+{
+  size_t v1, v2;
+  mbstate_t ps1, ps2;
+  WCHAR_T wc1, wc2;
+
+  memset (&ps1, 0, sizeof (mbstate_t));
+  memset (&ps2, 0, sizeof (mbstate_t));
+
+  do
+    {
+      v1 = MBRTOWC(&wc1, s1, l1, &ps1);
+      v2 = MBRTOWC(&wc2, s2, l2, &ps2);
+      if (v1 == 0 && v2 == 0)
+	return 1;
+      else if (MB_INVALIDCH(v1) || MB_INVALIDCH(v2))
+ 	{
+ 	  int d;
+ 	  d = _rl_to_lower (*s1) - _rl_to_lower (*s2);	/* do byte comparison */
+	  if ((flags & 1) && (*s1 == '-' || *s1 == '_') && (*s2 == '-' || *s2 == '_'))
+	    d = 0;		/* case insensitive character mapping */
+	  if (d != 0)
+	    return 0;
+	  s1++;
+	  s2++;
+	  n--;
+	  continue;
+ 	}
+      wc1 = towlower(wc1);
+      wc2 = towlower(wc2);
+      s1 += v1;
+      s2 += v1;
+      n -= v1;
+      if ((flags & 1) && (wc1 == L'-' || wc1 == L'_') && (wc2 == L'-' || wc2 == L'_'))
+        continue;
+      if (wc1 != wc2)
+	return 0;
+    }
+  while (n != 0);
+
+  return 1;
+}
+
+/* Return 1 if the multibyte characters pointed to by S1 and S2 are equal
+   without regard to case. If FLAGS&1, apply the mapping specified by
+   completion-map-case and make `-' and `_' equivalent. */
+int
+_rl_mb_charcasecmp (const char *s1, mbstate_t *ps1, const char *s2, mbstate_t *ps2, int flags)
+{
+  int d;
+  size_t v1, v2;
+  wchar_t wc1, wc2;
+
+  d = MB_CUR_MAX;
+  v1 = MBRTOWC(&wc1, s1, d, ps1);
+  v2 = MBRTOWC(&wc2, s2, d, ps2);
+  if (v1 == 0 && v2 == 0)
+    return 1;
+  else if (MB_INVALIDCH(v1) || MB_INVALIDCH(v2))
+    {
+      if ((flags & 1) && (*s1 == '-' || *s1 == '_') && (*s2 == '-' || *s2 == '_'))
+	return 1;
+      return (_rl_to_lower (*s1) == _rl_to_lower (*s2));
+    }
+  wc1 = towlower(wc1);
+  wc2 = towlower(wc2);
+  if ((flags & 1) && (wc1 == L'-' || wc1 == L'_') && (wc2 == L'-' || wc2 == L'_'))
+    return 1;
+  return (wc1 == wc2);
+}
diff --git a/rlmbutil.h b/rlmbutil.h
index 42d47c3..92ce05b 100644
--- a/rlmbutil.h
+++ b/rlmbutil.h
@@ -1,6 +1,6 @@
 /* rlmbutil.h -- utility functions for multibyte characters. */
 
-/* Copyright (C) 2001-2021 Free Software Foundation, Inc.
+/* Copyright (C) 2001-2021,2023 Free Software Foundation, Inc.
 
    This file is part of the GNU Readline Library (Readline), a library
    for reading lines of text with interactive input and history editing.      
@@ -121,6 +121,9 @@ extern int _rl_is_mbchar_matched (const char *, int, int, char *, int);
 extern WCHAR_T _rl_char_value (const char *, int);
 extern int _rl_walphabetic (WCHAR_T);
 
+extern int _rl_mb_strcaseeqn (const char *, size_t, const char *, size_t, size_t, int);
+extern int _rl_mb_charcasecmp (const char *, mbstate_t *, const char *, mbstate_t *, int);
+
 #define _rl_to_wupper(wc)	(iswlower (wc) ? towupper (wc) : (wc))
 #define _rl_to_wlower(wc)	(iswupper (wc) ? towlower (wc) : (wc))
 
diff --git a/rlprivate.h b/rlprivate.h
index 77a4d8c..e97ea90 100644
--- a/rlprivate.h
+++ b/rlprivate.h
@@ -475,6 +475,8 @@ extern int _rl_tropen (void);
 extern int _rl_abort_internal (void);
 extern int _rl_null_function (int, int);
 extern char *_rl_strindex (const char *, const char *);
+extern int _rl_strcaseeqn (const char *, const char *, size_t, int);
+extern int _rl_charcasecmp (int, int, int);
 extern int _rl_qsort_string_compare (char **, char **);
 extern int (_rl_uppercase_p) (int);
 extern int (_rl_lowercase_p) (int);
@@ -544,6 +546,7 @@ extern int _rl_vi_cmd_modestr_len;
 extern char *_rl_isearch_terminators;
 
 extern _rl_search_cxt *_rl_iscxt;
+extern int _rl_search_case_fold;
 
 /* macro.c */
 extern char *_rl_executing_macro;
diff --git a/search.c b/search.c
index 43c66b1..b7be876 100644
--- a/search.c
+++ b/search.c
@@ -135,21 +135,23 @@ noninc_search_from_pos (char *string, int pos, int dir, int flags, int *ncp)
   RL_SETSTATE(RL_STATE_SEARCH);
   /* These functions return the match offset in the line; history_offset gives
      the matching line in the history list */
-  if (flags & SF_PATTERN)
+
+  sflags = 0;		/* Non-anchored search */
+  s = string;
+  if (*s == '^')
     {
-      s = string;
-      sflags = 0;		/* Non-anchored search */
-      if (*s == '^')
-	{
-	  sflags |= ANCHORED_SEARCH;
-	  s++;
-	}
-      ret = _hs_history_patsearch (s, dir, sflags);
+      sflags |= ANCHORED_SEARCH;
+      s++;
     }
-  else if (*string == '^')
-    ret = history_search_prefix (string + 1, dir);
+
+  if (flags & SF_PATTERN)
+    ret = _hs_history_patsearch (s, dir, sflags);
   else
-    ret = history_search (string, dir);
+    {
+      if (_rl_search_case_fold)
+	sflags |= CASEFOLD_SEARCH;
+      ret = _hs_history_search (s, dir, sflags);
+    }
   RL_UNSETSTATE(RL_STATE_SEARCH);
 
   if (ncp)
@@ -201,7 +203,7 @@ noninc_dosearch (char *string, int dir, int flags)
 
   make_history_line_current (entry);
 
-  if (_rl_enable_active_region && ((flags & SF_PATTERN) == 0) && ind > 0 && ind < rl_end)
+  if (_rl_enable_active_region && ((flags & SF_PATTERN) == 0) && ind >= 0 && ind < rl_end)
     {
       rl_point = ind;
       rl_mark = ind + strlen (string);
diff --git a/tcap.h b/tcap.h
index 1121061..467ea60 100644
--- a/tcap.h
+++ b/tcap.h
@@ -1,6 +1,6 @@
 /* tcap.h -- termcap library functions and variables. */
 
-/* Copyright (C) 1996-2015 Free Software Foundation, Inc.
+/* Copyright (C) 1996-2015,2023 Free Software Foundation, Inc.
 
    This file is part of the GNU Readline Library (Readline), a library
    for reading lines of text with interactive input and history editing.      
@@ -46,14 +46,14 @@ extern char *UP, *BC;
 
 extern short ospeed;
 
-extern int tgetent PARAMS((char *, const char *));
-extern int tgetflag PARAMS((const char *));
-extern int tgetnum PARAMS((const char *));
-extern char *tgetstr PARAMS((const char *, char **));
+extern int tgetent (char *, const char *);
+extern int tgetflag (const char *);
+extern int tgetnum (const char *);
+extern char *tgetstr (const char *, char **);
 
-extern int tputs PARAMS((const char *, int, int (*)(int));
+extern int tputs (const char *, int, int (*)(int));
 
-extern char *tgoto PARAMS((const char *, int, int));
+extern char *tgoto (const char *, int, int);
 
 #endif /* HAVE_TERMCAP_H */
 
diff --git a/util.c b/util.c
index d481b85..b68abdc 100644
--- a/util.c
+++ b/util.c
@@ -418,6 +418,48 @@ _rl_stricmp (const char *string1, const char *string2)
 }
 #endif /* !HAVE_STRCASECMP */
 
+/* Compare the first N characters of S1 and S2 without regard to case. If
+   FLAGS&1, apply the mapping specified by completion-map-case and make
+   `-' and `_' equivalent. Returns 1 if the strings are equal. */
+int
+_rl_strcaseeqn(const char *s1, const char *s2, size_t n, int flags)
+{
+  int c1, c2;
+  int d;
+
+  if ((flags & 1) == 0)
+    return (_rl_strnicmp (s1, s2, n) == 0);
+
+  do
+    {
+      c1 = _rl_to_lower (*s1);
+      c2 = _rl_to_lower (*s2);
+
+      d = c1 - c2;
+      if ((*s1 == '-' || *s1 == '_') && (*s2 == '-' || *s2 == '_'))
+	d = 0;		/* case insensitive character mapping */
+      if (d != 0)
+	return 0;
+      s1++;
+      s2++;
+      n--;
+    }
+  while (n != 0);
+
+  return 1;
+}
+
+/* Return 1 if the characters C1 and C2 are equal without regard to case.
+   If FLAGS&1, apply the mapping specified by completion-map-case and make
+   `-' and `_' equivalent. */
+int
+_rl_charcasecmp (int c1, int c2, int flags)
+{
+  if ((flags & 1) && (c1 == '-' || c1 == '_') && (c2 == '-' || c2 == '_'))
+    return 1;
+  return ( _rl_to_lower (c1) == _rl_to_lower (c2));
+}
+
 /* Stupid comparison routine for qsort () ing strings. */
 int
 _rl_qsort_string_compare (char **s1, char **s2)