Backwards search not respecting range

[sorbits]

Summary

If I call onig_search with a start/range of 3-0 then it may still return a match outside this range.

Steps to Reproduce

Build the following source:

#include <string.h>
#include <stdio.h>
#include "oniguruma.h"

int main (int argc, char const* argv[])
{
    char const* ptrn = "\\h+";
    char const* data = "abcdef";

    OnigErrorInfo einfo;
    OnigRegex regex = NULL;
    if(ONIG_NORMAL == onig_new(&regex, (OnigUChar const*)ptrn, (OnigUChar const*)ptrn + strlen(ptrn), ONIG_OPTION_CAPTURE_GROUP, ONIG_ENCODING_UTF8, ONIG_SYNTAX_RUBY, &einfo))
    {
        OnigRegion* res = onig_region_new();
        if(ONIG_MISMATCH != onig_search(regex, (OnigUChar const*)data, (OnigUChar const*)data + strlen(data), (OnigUChar const*)data + 3, (OnigUChar const*)data, res, 0))
            fprintf(stderr, "%td-%td\n", res->beg[0], res->end[0]);
    }
    return 0;
}

Expected Result

I would expect the output to be 0-3.

Actual Result

The program outputs 3-4.

Notes

This was tested with current master (9cd4fa1) but problem has existed for as long as I know.

[k-takata]

It seems to be caused by this #ifdef block:

Onigmo/regexec.c

Line 4176 in 754f936

#ifdef USE_MATCH_RANGE_MUST_BE_INSIDE_OF_SPECIFIED_RANGE

I don't know why this block is needed. I'll look into it more closely.

BTW, I think the expected result is 2-3.

[k-takata]

Hmm, the #ifdef block was added with Oniguruma 5.7.0.

Copied from the HISTORY:

2007/04/27: Version 5.7.0

2007/04/20: [spec] add config USE_MATCH_RANGE_IS_COMPLETE_RANGE.
2007/04/20: [impl] refactoring in match_at().

Note: USE_MATCH_RANGE_IS_COMPLETE_RANGE was changed to USE_MATCH_RANGE_MUST_BE_INSIDE_OF_SPECIFIED_RANGE with Oniguruma 5.9.0.

[sorbits]

Thanks for looking into this.

Does this mean that defining USE_MATCH_RANGE_MUST_BE_INSIDE_OF_SPECIFIED_RANGE should return a match of 2-3?

I tried to define it in regexec.c:33 but got unchanged result.

[k-takata]

Does this mean that defining USE_MATCH_RANGE_MUST_BE_INSIDE_OF_SPECIFIED_RANGE should return a match of 2-3?

Yes, I think so. But currently the result is 3-4 as you reported.

After applying the following patch, the result becomes 2-3 when USE_MATCH_RANGE_MUST_BE_INSIDE_OF_SPECIFIED_RANGE is defined.
(If it is not defined, the result becomes 3-6.)

--- a/regexec.c
+++ b/regexec.c
@@ -4173,11 +4173,6 @@ onig_search_gpos(regex_t* reg, const UChar* str, const UChar* end,
     }
   }
   else {  /* backward search */
-#ifdef USE_MATCH_RANGE_MUST_BE_INSIDE_OF_SPECIFIED_RANGE
-    if (orig_start < end)
-      orig_start += enclen(reg->enc, orig_start); /* is upper range */
-#endif
-
     if (reg->optimize != ONIG_OPTIMIZE_NONE) {
       UChar *low, *high, *adjrange, *sch_start;

I'm concerning about side effects caused by this patch. More tests are needed.