Fix GH-10648: add check function pointer into mbfl_encoding

Previously, mbstring used the same logic for encoding validation as for
encoding conversion.

However, there are cases where we want to use different logic for validation
and conversion. For example, if a string ends up with missing input
required by the encoding, or if a character is input that is invalid
as an encoding but can be converted, the conversion should succeed and
the validation should fail.

To achieve this, a function pointer mb_check_fn has been added to
struct mbfl_encoding to implement the logic used for validation.
Also, added implementation of validation logic for UTF-7, UTF7-IMAP,
ISO-2022-JP and JIS.

(The same change has already been made to PHP 8.2 and 8.3; see
6fc8d01. This commit is backporting the change to PHP 8.1.)

Author: pakutoma

UPGRADING

@@ -489,6 +489,16 @@ PHP 8.1 UPGRADE NOTES
   . All GMP function now accept octal string with the leading octal prefix ("0o"/"0O")
     RFC: https://wiki.php.net/rfc/explicit_octal_notation
 
+- MBString
+  . mb_check_encoding() now checks input encoding more strictly.
+  . mb_detect_encoding() now checks input encoding more strictly
+    when strict detection is enabled.
+  . mb_convert_encoding() checks the input encoding more strictly
+    if multiple encodings are passed to from_encoding
+    and the mbstring.strict_detection INI directive is set to 1.
+    This change only affects the encoding selection,
+    not the result of the conversion.
+
 - PDO ODBC:
   . PDO::getAttributes() with PDO::ATTR_SERVER_INFO and PDO::ATTR_SERVER_VERSION
     now return values instead of throwing PDOException.

ext/mbstring/libmbfl/filters/mbfilter_7bit.c

@@ -39,6 +39,7 @@ const mbfl_encoding mbfl_encoding_7bit = {
 	NULL,
 	MBFL_ENCTYPE_SBCS,
 	NULL,
+	NULL,
 	NULL
 };
 

ext/mbstring/libmbfl/filters/mbfilter_base64.c

@@ -39,6 +39,7 @@ const mbfl_encoding mbfl_encoding_base64 = {
 	NULL,
 	MBFL_ENCTYPE_GL_UNSAFE,
 	NULL,
+	NULL,
 	NULL
 };
 

ext/mbstring/libmbfl/filters/mbfilter_big5.c

@@ -63,7 +63,8 @@ const mbfl_encoding mbfl_encoding_big5 = {
 	mblen_table_big5,
 	MBFL_ENCTYPE_GL_UNSAFE,
 	&vtbl_big5_wchar,
-	&vtbl_wchar_big5
+	&vtbl_wchar_big5,
+	NULL
 };
 
 const mbfl_encoding mbfl_encoding_cp950 = {
@@ -74,7 +75,8 @@ const mbfl_encoding mbfl_encoding_cp950 = {
 	mblen_table_big5,
 	MBFL_ENCTYPE_GL_UNSAFE,
 	&vtbl_cp950_wchar,
-	&vtbl_wchar_cp950
+	&vtbl_wchar_cp950,
+	NULL
 };
 
 const struct mbfl_convert_vtbl vtbl_big5_wchar = {

ext/mbstring/libmbfl/filters/mbfilter_cp5022x.c

@@ -54,7 +54,8 @@ const mbfl_encoding mbfl_encoding_cp50220 = {
 	NULL,
 	MBFL_ENCTYPE_GL_UNSAFE,
 	&vtbl_cp50220_wchar,
-	&vtbl_wchar_cp50220
+	&vtbl_wchar_cp50220,
+	NULL
 };
 
 const mbfl_encoding mbfl_encoding_cp50221 = {
@@ -65,7 +66,8 @@ const mbfl_encoding mbfl_encoding_cp50221 = {
 	NULL,
 	MBFL_ENCTYPE_GL_UNSAFE,
 	&vtbl_cp50221_wchar,
-	&vtbl_wchar_cp50221
+	&vtbl_wchar_cp50221,
+	NULL
 };
 
 const mbfl_encoding mbfl_encoding_cp50222 = {
@@ -76,7 +78,8 @@ const mbfl_encoding mbfl_encoding_cp50222 = {
 	NULL,
 	MBFL_ENCTYPE_GL_UNSAFE,
 	&vtbl_cp50222_wchar,
-	&vtbl_wchar_cp50222
+	&vtbl_wchar_cp50222,
+	NULL
 };
 
 const struct mbfl_convert_vtbl vtbl_cp50220_wchar = {

ext/mbstring/libmbfl/filters/mbfilter_cp51932.c

@@ -65,7 +65,8 @@ const mbfl_encoding mbfl_encoding_cp51932 = {
 	mblen_table_eucjp,
 	0,
 	&vtbl_cp51932_wchar,
-	&vtbl_wchar_cp51932
+	&vtbl_wchar_cp51932,
+	NULL
 };
 
 const struct mbfl_convert_vtbl vtbl_cp51932_wchar = {

ext/mbstring/libmbfl/filters/mbfilter_cp932.c

@@ -95,7 +95,8 @@ const mbfl_encoding mbfl_encoding_cp932 = {
 	mblen_table_sjis,
 	MBFL_ENCTYPE_GL_UNSAFE,
 	&vtbl_cp932_wchar,
-	&vtbl_wchar_cp932
+	&vtbl_wchar_cp932,
+	NULL
 };
 
 const struct mbfl_convert_vtbl vtbl_cp932_wchar = {
@@ -126,7 +127,8 @@ const mbfl_encoding mbfl_encoding_sjiswin = {
 	mblen_table_sjis,
 	MBFL_ENCTYPE_GL_UNSAFE,
 	&vtbl_sjiswin_wchar,
-	&vtbl_wchar_sjiswin
+	&vtbl_wchar_sjiswin,
+	NULL
 };
 
 const struct mbfl_convert_vtbl vtbl_sjiswin_wchar = {

ext/mbstring/libmbfl/filters/mbfilter_cp936.c

@@ -63,7 +63,8 @@ const mbfl_encoding mbfl_encoding_cp936 = {
 	mblen_table_cp936,
 	MBFL_ENCTYPE_GL_UNSAFE,
 	&vtbl_cp936_wchar,
-	&vtbl_wchar_cp936
+	&vtbl_wchar_cp936,
+	NULL
 };
 
 const struct mbfl_convert_vtbl vtbl_cp936_wchar = {

ext/mbstring/libmbfl/filters/mbfilter_euc_cn.c

@@ -63,7 +63,8 @@ const mbfl_encoding mbfl_encoding_euc_cn = {
 	mblen_table_euccn,
 	0,
 	&vtbl_euccn_wchar,
-	&vtbl_wchar_euccn
+	&vtbl_wchar_euccn,
+	NULL
 };
 
 const struct mbfl_convert_vtbl vtbl_euccn_wchar = {

ext/mbstring/libmbfl/filters/mbfilter_euc_jp.c

@@ -64,7 +64,8 @@ const mbfl_encoding mbfl_encoding_euc_jp = {
 	mblen_table_eucjp,
 	0,
 	&vtbl_eucjp_wchar,
-	&vtbl_wchar_eucjp
+	&vtbl_wchar_eucjp,
+	NULL
 };
 
 const struct mbfl_convert_vtbl vtbl_eucjp_wchar = {