From 8d3e96ceae6e5931444d461b6acea47ee1a8bed6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Carlo=20Marcelo=20Arenas=20Bel=C3=B3n?= <carenas@gmail.com>
Date: Sun, 22 Oct 2023 06:07:32 -0700
Subject: [PATCH] maketables: avoid misleading values in case flipping table
 (#313)
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The tables generated by pcre2_maketables() include one that maps
all lowercase characters on the first 255 code points to their
corresponding upper case code point, but fails to notice that
toupper() could return a larger code point and therefore result
in the store of a truncated and unrelated code instead.

Restrict all values to what is valid for uint8_t and document
in the test case the failure for character 'ÎĽ'[1] (U+00B5) and
that was incorrectly getting back 924 (U+039C) from macOS fr_FR,
and resulting in an incorrect case equivalent with the truncated
value of 159.

[1] https://en.wikipedia.org/wiki/Mu_(letter)
---
 src/pcre2_maketables.c | 8 +++++---
 testdata/testinput3    | 5 +++++
 testdata/testoutput3   | 7 +++++++
 testdata/testoutput3A  | 7 +++++++
 testdata/testoutput3B  | 7 +++++++
 5 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/src/pcre2_maketables.c b/src/pcre2_maketables.c
index 56d249402..ac8b63b80 100644
--- a/src/pcre2_maketables.c
+++ b/src/pcre2_maketables.c
@@ -52,8 +52,6 @@ PCRE2_DFTABLES is defined. */
 #  include "pcre2_internal.h"
 #endif
 
-
-
 /*************************************************
 *           Create PCRE2 character tables        *
 *************************************************/
@@ -98,7 +96,11 @@ for (i = 0; i < 256; i++) *p++ = tolower(i);
 
 /* Next the case-flipping table */
 
-for (i = 0; i < 256; i++) *p++ = islower(i)? toupper(i) : tolower(i);
+for (i = 0; i < 256; i++)
+  {
+  int c = islower(i)? toupper(i) : tolower(i);
+  *p++ = (c < 256)? c : i;
+  }
 
 /* Then the character class tables. Don't try to be clever and save effort on
 exclusive ones - in some locales things may be different.
diff --git a/testdata/testinput3 b/testdata/testinput3
index 71e95fec4..20f8d4c23 100644
--- a/testdata/testinput3
+++ b/testdata/testinput3
@@ -75,6 +75,11 @@
 \= Expect no match
     école
 
+/\xb5/i
+    µ
+\= Expect no match
+    \x9c
+
 /\W+/
     >>>\xaa<<<
     >>>\xba<<< 
diff --git a/testdata/testoutput3 b/testdata/testoutput3
index 801966a98..717fa4569 100644
--- a/testdata/testoutput3
+++ b/testdata/testoutput3
@@ -108,6 +108,13 @@ Subject length lower bound = 1
     école
 No match
 
+/\xb5/i
+    µ
+ 0: µ
+\= Expect no match
+    \x9c
+No match
+
 /\W+/
     >>>\xaa<<<
  0: >>>
diff --git a/testdata/testoutput3A b/testdata/testoutput3A
index d7a223ab1..53f6894fc 100644
--- a/testdata/testoutput3A
+++ b/testdata/testoutput3A
@@ -108,6 +108,13 @@ Subject length lower bound = 1
     école
 No match
 
+/\xb5/i
+    µ
+ 0: µ
+\= Expect no match
+    \x9c
+No match
+
 /\W+/
     >>>\xaa<<<
  0: >>>
diff --git a/testdata/testoutput3B b/testdata/testoutput3B
index b18d441b4..1e22efe46 100644
--- a/testdata/testoutput3B
+++ b/testdata/testoutput3B
@@ -108,6 +108,13 @@ Subject length lower bound = 1
     école
 No match
 
+/\xb5/i
+    µ
+ 0: µ
+\= Expect no match
+    \x9c
+No match
+
 /\W+/
     >>>\xaa<<<
  0: >>>