Use SSize_t/STRLEN in more places in regexp code

As part of getting the regexp engine to handle long strings, this com-
mit changes any variables, parameters and struct members that hold
lengths of the string being matched against (or parts thereof) to use
SSize_t or STRLEN instead of [IU]32.

To avoid having to change any logic, I kept the signedness the same.

I did not change anything that affects the length of the regular
expression itself, so regexps are still practically limited to
I32_MAX.  Changing that would involve changing the size of regnodes,
which would be a lot more involved.

These changes should fix bugs, but are very hard to test.  In most
cases, I don’t know the regexp engine well enough to come up with test
cases that test the paths in question with long strings.  In other
cases I don’t have a box with enough memory to test the fix.

Author: Father Chrysostomos

embed.fnc

@@ -1096,8 +1096,8 @@ EMsR	|SV*	|_new_invlist_C_array|NN const UV* const list
 : Not used currently: EXMs	|bool	|_invlistEQ	|NN SV* const a|NN SV* const b|const bool complement_b
 #endif
 Ap	|I32	|pregexec	|NN REGEXP * const prog|NN char* stringarg \
-				|NN char* strend|NN char* strbeg|I32 minend \
-				|NN SV* screamer|U32 nosave
+				|NN char* strend|NN char* strbeg \
+				|SSize_t minend |NN SV* screamer|U32 nosave
 Ap	|void	|pregfree	|NULLOK REGEXP* r
 Ap	|void	|pregfree2	|NN REGEXP *rx
 : FIXME - is anything in re using this now?
@@ -1128,8 +1128,9 @@ EiPR	|I32	|regcurly	|NN const char *s                   \
 				|const bool rbrace_must_be_escaped
 #endif
 Ap	|I32	|regexec_flags	|NN REGEXP *const rx|NN char *stringarg \
-				|NN char *strend|NN char *strbeg|I32 minend \
-				|NN SV *sv|NULLOK void *data|U32 flags
+				|NN char *strend|NN char *strbeg \
+				|SSize_t minend|NN SV *sv \
+				|NULLOK void *data|U32 flags
 ApR	|regnode*|regnext	|NULLOK regnode* p
 EXp |SV*|reg_named_buff          |NN REGEXP * const rx|NULLOK SV * const key \
                                  |NULLOK SV * const value|const U32 flags
@@ -2033,8 +2034,8 @@ Ei	|U8   |compute_EXACTish|NN struct RExC_state_t *pRExC_state
 Es	|char *	|nextchar	|NN struct RExC_state_t *pRExC_state
 Es	|bool	|reg_skipcomment|NN struct RExC_state_t *pRExC_state
 Es	|void	|scan_commit	|NN const struct RExC_state_t *pRExC_state \
-				|NN struct scan_data_t *data|NN I32 *minlenp \
-				|int is_inf
+				|NN struct scan_data_t *data \
+				|NN SSize_t *minlenp|int is_inf
 Esn	|void	|cl_anything	|NN const struct RExC_state_t *pRExC_state \
 				|NN struct regnode_charclass_class *cl
 EsRn	|int	|cl_is_anything	|NN const struct regnode_charclass_class *cl
@@ -2046,7 +2047,7 @@ Esn	|void	|cl_or		|NN const struct RExC_state_t *pRExC_state \
 				|NN struct regnode_charclass_class *cl \
 				|NN const struct regnode_charclass_class *or_with
 Es	|SSize_t|study_chunk	|NN struct RExC_state_t *pRExC_state \
-				|NN regnode **scanp|NN I32 *minlenp \
+				|NN regnode **scanp|NN SSize_t *minlenp \
 				|NN SSize_t *deltap|NN regnode *last \
 				|NULLOK struct scan_data_t *data \
 				|I32 stopparen|NULLOK U8* recursed \
@@ -2104,15 +2105,15 @@ Es	|CHECKPOINT|regcppush	|NN const regexp *rex|I32 parenfloor\
 				|U32 maxopenparen
 Es	|void	|regcppop	|NN regexp *rex\
 				|NN U32 *maxopenparen_p
-ERsn	|U8*	|reghop3	|NN U8 *s|I32 off|NN const U8 *lim
+ERsn	|U8*	|reghop3	|NN U8 *s|SSize_t off|NN const U8 *lim
 ERsM	|SV*	|core_regclass_swash|NULLOK const regexp *prog \
 				|NN const struct regnode *node|bool doinit \
 				|NULLOK SV **listsvp
 #ifdef XXX_dmq
-ERsn	|U8*	|reghop4	|NN U8 *s|I32 off|NN const U8 *llim \
+ERsn	|U8*	|reghop4	|NN U8 *s|SSize_t off|NN const U8 *llim \
 				|NN const U8 *rlim
 #endif
-ERsn	|U8*	|reghopmaybe3	|NN U8 *s|I32 off|NN const U8 *lim
+ERsn	|U8*	|reghopmaybe3	|NN U8 *s|SSize_t off|NN const U8 *lim
 ERs	|char*	|find_byclass	|NN regexp * prog|NN const regnode *c \
 				|NN char *s|NN const char *strend \
 				|NULLOK regmatch_info *reginfo

pod/perlreapi.pod

@@ -17,7 +17,7 @@ following format:
                          REGEXP * const rx,
                          char* stringarg,
                          char* strend, char* strbeg,
-                         I32 minend, SV* sv,
+                         SSize_t minend, SV* sv,
                          void* data, U32 flags);
         char*   (*intuit) (pTHX_
                            REGEXP * const rx, SV *sv,
@@ -238,7 +238,7 @@ certain optimisations when this is set.
 
     I32 exec(pTHX_ REGEXP * const rx,
              char *stringarg, char* strend, char* strbeg,
-             I32 minend, SV* sv,
+             SSize_t minend, SV* sv,
              void* data, U32 flags);
 
 Execute a regexp. The arguments are

proto.h

@@ -3187,7 +3187,7 @@ PERL_CALLCONV REGEXP*	Perl_pregcomp(pTHX_ SV * const pattern, const U32 flags)
 #define PERL_ARGS_ASSERT_PREGCOMP	\
 	assert(pattern)
 
-PERL_CALLCONV I32	Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, char* strend, char* strbeg, I32 minend, SV* screamer, U32 nosave)
+PERL_CALLCONV I32	Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, char* strend, char* strbeg, SSize_t minend, SV* screamer, U32 nosave)
 			__attribute__nonnull__(pTHX_1)
 			__attribute__nonnull__(pTHX_2)
 			__attribute__nonnull__(pTHX_3)
@@ -3409,7 +3409,7 @@ PERL_CALLCONV void	Perl_regdump(pTHX_ const regexp* r)
 #define PERL_ARGS_ASSERT_REGDUMP	\
 	assert(r)
 
-PERL_CALLCONV I32	Perl_regexec_flags(pTHX_ REGEXP *const rx, char *stringarg, char *strend, char *strbeg, I32 minend, SV *sv, void *data, U32 flags)
+PERL_CALLCONV I32	Perl_regexec_flags(pTHX_ REGEXP *const rx, char *stringarg, char *strend, char *strbeg, SSize_t minend, SV *sv, void *data, U32 flags)
 			__attribute__nonnull__(pTHX_1)
 			__attribute__nonnull__(pTHX_2)
 			__attribute__nonnull__(pTHX_3)
@@ -6766,14 +6766,14 @@ STATIC char *	S_regwhite(struct RExC_state_t *pRExC_state, char *p)
 #define PERL_ARGS_ASSERT_REGWHITE	\
 	assert(pRExC_state); assert(p)
 
-STATIC void	S_scan_commit(pTHX_ const struct RExC_state_t *pRExC_state, struct scan_data_t *data, I32 *minlenp, int is_inf)
+STATIC void	S_scan_commit(pTHX_ const struct RExC_state_t *pRExC_state, struct scan_data_t *data, SSize_t *minlenp, int is_inf)
 			__attribute__nonnull__(pTHX_1)
 			__attribute__nonnull__(pTHX_2)
 			__attribute__nonnull__(pTHX_3);
 #define PERL_ARGS_ASSERT_SCAN_COMMIT	\
 	assert(pRExC_state); assert(data); assert(minlenp)
 
-STATIC SSize_t	S_study_chunk(pTHX_ struct RExC_state_t *pRExC_state, regnode **scanp, I32 *minlenp, SSize_t *deltap, regnode *last, struct scan_data_t *data, I32 stopparen, U8* recursed, struct regnode_charclass_class *and_withp, U32 flags, U32 depth)
+STATIC SSize_t	S_study_chunk(pTHX_ struct RExC_state_t *pRExC_state, regnode **scanp, SSize_t *minlenp, SSize_t *deltap, regnode *last, struct scan_data_t *data, I32 stopparen, U8* recursed, struct regnode_charclass_class *and_withp, U32 flags, U32 depth)
 			__attribute__nonnull__(pTHX_1)
 			__attribute__nonnull__(pTHX_2)
 			__attribute__nonnull__(pTHX_3)
@@ -6979,14 +6979,14 @@ STATIC CHECKPOINT	S_regcppush(pTHX_ const regexp *rex, I32 parenfloor, U32 maxop
 #define PERL_ARGS_ASSERT_REGCPPUSH	\
 	assert(rex)
 
-STATIC U8*	S_reghop3(U8 *s, I32 off, const U8 *lim)
+STATIC U8*	S_reghop3(U8 *s, SSize_t off, const U8 *lim)
 			__attribute__warn_unused_result__
 			__attribute__nonnull__(1)
 			__attribute__nonnull__(3);
 #define PERL_ARGS_ASSERT_REGHOP3	\
 	assert(s); assert(lim)
 
-STATIC U8*	S_reghopmaybe3(U8 *s, I32 off, const U8 *lim)
+STATIC U8*	S_reghopmaybe3(U8 *s, SSize_t off, const U8 *lim)
 			__attribute__warn_unused_result__
 			__attribute__nonnull__(1)
 			__attribute__nonnull__(3);
@@ -7035,7 +7035,7 @@ STATIC void	S_to_utf8_substr(pTHX_ regexp * prog)
 	assert(prog)
 
 #  if defined(XXX_dmq)
-STATIC U8*	S_reghop4(U8 *s, I32 off, const U8 *llim, const U8 *rlim)
+STATIC U8*	S_reghop4(U8 *s, SSize_t off, const U8 *llim, const U8 *rlim)
 			__attribute__warn_unused_result__
 			__attribute__nonnull__(1)
 			__attribute__nonnull__(3)