register unsigned int c;   /* Character values not kept over RMATCH() calls */register BOOL utf8;        /* Local copy of UTF-8 flag for speed */BOOL minimize, possessive; /* Quantifier options *//* When recursion is not being used, all "local" variables that have to bepreserved over calls to RMATCH() are part of a "frame" which is obtained fromheap storage. Set up the top-level frame here; others are obtained from theheap whenever RMATCH() does a "recursion". See the macro definitions above. */#ifdef NO_RECURSEheapframe *frame = (pcre_stack_malloc)(sizeof(heapframe));frame->Xprevframe = NULL;            /* Marks the top level *//* Copy in the original argument variables */frame->Xeptr = eptr;frame->Xecode = ecode;frame->Xmstart = mstart;frame->Xoffset_top = offset_top;frame->Xims = ims;frame->Xeptrb = eptrb;frame->Xflags = flags;frame->Xrdepth = rdepth;/* This is where control jumps back to to effect "recursion" */HEAP_RECURSE:/* Macros make the argument variables come from the current frame */#define eptr               frame->Xeptr#define ecode              frame->Xecode#define mstart             frame->Xmstart#define offset_top         frame->Xoffset_top#define ims                frame->Xims#define eptrb              frame->Xeptrb#define flags              frame->Xflags#define rdepth             frame->Xrdepth/* Ditto for the local variables */#ifdef SUPPORT_UTF8#define charptr            frame->Xcharptr#endif#define callpat            frame->Xcallpat#define data               frame->Xdata#define next               frame->Xnext#define pp                 frame->Xpp#define prev               frame->Xprev#define saved_eptr         frame->Xsaved_eptr#define new_recursive      frame->Xnew_recursive#define cur_is_word        frame->Xcur_is_word#define condition          frame->Xcondition#define prev_is_word       frame->Xprev_is_word#define original_ims       frame->Xoriginal_ims#ifdef SUPPORT_UCP#define prop_type          frame->Xprop_type#define prop_value         frame->Xprop_value#define prop_fail_result   frame->Xprop_fail_result#define prop_category      frame->Xprop_category#define prop_chartype      frame->Xprop_chartype#define prop_script        frame->Xprop_script#define oclength           frame->Xoclength#define occhars            frame->Xocchars#endif#define ctype              frame->Xctype#define fc                 frame->Xfc#define fi                 frame->Xfi#define length             frame->Xlength#define max                frame->Xmax#define min                frame->Xmin#define number             frame->Xnumber#define offset             frame->Xoffset#define op                 frame->Xop#define save_capture_last  frame->Xsave_capture_last#define save_offset1       frame->Xsave_offset1#define save_offset2       frame->Xsave_offset2#define save_offset3       frame->Xsave_offset3#define stacksave          frame->Xstacksave#define newptrb            frame->Xnewptrb/* When recursion is being used, local variables are allocated on the stack andget preserved during recursion in the normal way. In this environment, fi andi, and fc and c, can be the same variables. */#else         /* NO_RECURSE not defined */#define fi i#define fc c#ifdef SUPPORT_UTF8                /* Many of these variables are used only  */const uschar *charptr;             /* in small blocks of the code. My normal */#endif                             /* style of coding would have declared    */const uschar *callpat;             /* them within each of those blocks.      */const uschar *data;                /* However, in order to accommodate the   */const uschar *next;                /* version of this code that uses an      */USPTR         pp;                  /* external "stack" implemented on the    */const uschar *prev;                /* heap, it is easier to declare them all */USPTR         saved_eptr;          /* here, so the declarations can be cut   */                                   /* out in a block. The only declarations  */recursion_info new_recursive;      /* within blocks below are for variables  */                                   /* that do not have to be preserved over  */BOOL cur_is_word;                  /* a recursive call to RMATCH().          */BOOL condition;BOOL prev_is_word;unsigned long int original_ims;#ifdef SUPPORT_UCPint prop_type;int prop_value;int prop_fail_result;int prop_category;int prop_chartype;int prop_script;int oclength;uschar occhars[8];#endifint ctype;int length;int max;int min;int number;int offset;int op;int save_capture_last;int save_offset1, save_offset2, save_offset3;int stacksave[REC_STACK_SAVE_MAX];eptrblock newptrb;#endif     /* NO_RECURSE *//* These statements are here to stop the compiler complaining about unitializedvariables. */#ifdef SUPPORT_UCPprop_value = 0;prop_fail_result = 0;#endif/* This label is used for tail recursion, which is used in a few cases evenwhen NO_RECURSE is not defined, in order to reduce the amount of stack that isused. Thanks to Ian Taylor for noticing this possibility and sending theoriginal patch. */TAIL_RECURSE:/* OK, now we can get on with the real code of the function. Recursive callsare specified by the macro RMATCH and RRETURN is used to return. WhenNO_RECURSE is *not* defined, these just turn into a recursive call to match()and a "return", respectively (possibly with some debugging if DEBUG isdefined). However, RMATCH isn't like a function call because it's quite acomplicated macro. It has to be used in one particular way. This shouldn't,however, impact performance when true recursion is being used. */#ifdef SUPPORT_UTF8utf8 = md->utf8;       /* Local copy of the flag */#elseutf8 = FALSE;#endif/* First check that we haven't called match() too many times, or that wehaven't exceeded the recursive call limit. */if (md->match_call_count++ >= md->match_limit) RRETURN(PCRE_ERROR_MATCHLIMIT);if (rdepth >= md->match_limit_recursion) RRETURN(PCRE_ERROR_RECURSIONLIMIT);original_ims = ims;    /* Save for resetting on ')' *//* At the start of a group with an unlimited repeat that may match an emptystring, the match_cbegroup flag is set. When this is the case, add the currentsubject pointer to the chain of such remembered pointers, to be checked when wehit the closing ket, in order to break infinite loops that match no characters.When match() is called in other circumstances, don't add to the chain. Thematch_cbegroup flag must NOT be used with tail recursion, because the memoryblock that is used is on the stack, so a new one may be required for eachmatch(). */if ((flags & match_cbegroup) != 0)  {  newptrb.epb_saved_eptr = eptr;  newptrb.epb_prev = eptrb;  eptrb = &newptrb;  }/* Now start processing the opcodes. */for (;;)  {  minimize = possessive = FALSE;  op = *ecode;  /* For partial matching, remember if we ever hit the end of the subject after  matching at least one subject character. */  if (md->partial &&      eptr >= md->end_subject &&      eptr > mstart)    md->hitend = TRUE;  switch(op)    {    case OP_FAIL:    RRETURN(MATCH_NOMATCH);    case OP_PRUNE:    RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md,      ims, eptrb, flags, RM51);    if (rrc != MATCH_NOMATCH) RRETURN(rrc);    RRETURN(MATCH_PRUNE);    case OP_COMMIT:    RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md,      ims, eptrb, flags, RM52);    if (rrc != MATCH_NOMATCH) RRETURN(rrc);    RRETURN(MATCH_COMMIT);    case OP_SKIP:    RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md,      ims, eptrb, flags, RM53);    if (rrc != MATCH_NOMATCH) RRETURN(rrc);    md->start_match_ptr = eptr;   /* Pass back current position */    RRETURN(MATCH_SKIP);    case OP_THEN:    RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md,      ims, eptrb, flags, RM54);    if (rrc != MATCH_NOMATCH) RRETURN(rrc);    RRETURN(MATCH_THEN);    /* Handle a capturing bracket. If there is space in the offset vector, save    the current subject position in the working slot at the top of the vector.    We mustn't change the current values of the data slot, because they may be    set from a previous iteration of this group, and be referred to by a    reference inside the group.    If the bracket fails to match, we need to restore this value and also the    values of the final offsets, in case they were set by a previous iteration    of the same bracket.    If there isn't enough space in the offset vector, treat this as if it were    a non-capturing bracket. Don't worry about setting the flag for the error    case here; that is handled in the code for KET. */    case OP_CBRA:    case OP_SCBRA:    number = GET2(ecode, 1+LINK_SIZE);    offset = number << 1;#ifdef DEBUG    printf("start bracket %d\n", number);    printf("subject=");    pchars(eptr, 16, TRUE, md);    printf("\n");#endif    if (offset < md->offset_max)      {      save_offset1 = md->offset_vector[offset];      save_offset2 = md->offset_vector[offset+1];      save_offset3 = md->offset_vector[md->offset_end - number];      save_capture_last = md->capture_last;      DPRINTF(("saving %d %d %d\n", save_offset1, save_offset2, save_offset3));      md->offset_vector[md->offset_end - number] = eptr - md->start_subject;      flags = (op == OP_SCBRA)? match_cbegroup : 0;      do        {        RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md,          ims, eptrb, flags, RM1);        if (rrc != MATCH_NOMATCH && rrc != MATCH_THEN) RRETURN(rrc);        md->capture_last = save_capture_last;        ecode += GET(ecode, 1);        }      while (*ecode == OP_ALT);      DPRINTF(("bracket %d failed\n", number));      md->offset_vector[offset] = save_offset1;      md->offset_vector[offset+1] = save_offset2;      md->offset_vector[md->offset_end - number] = save_offset3;      RRETURN(MATCH_NOMATCH);      }    /* FALL THROUGH ... Insufficient room for saving captured contents. Treat    as a non-capturing bracket. */    /* VVVVVVVVVVVVVVVVVVVVVVVVV */    /* VVVVVVVVVVVVVVVVVVVVVVVVV */    DPRINTF(("insufficient capture room: treat as non-capturing\n"));    /* VVVVVVVVVVVVVVVVVVVVVVVVV */    /* VVVVVVVVVVVVVVVVVVVVVVVVV */    /* Non-capturing bracket. Loop for all the alternatives. When we get to the    final alternative within the brackets, we would return the result of a    recursive call to match() whatever happened. We can reduce stack usage by    turning this into a tail recursion, except in the case when match_cbegroup    is set.*/    case OP_BRA:    case OP_SBRA:    DPRINTF(("start non-capturing bracket\n"));    flags = (op >= OP_SBRA)? match_cbegroup : 0;    for (;;)      {      if (ecode[GET(ecode, 1)] != OP_ALT)   /* Final alternative */        {        if (flags == 0)    /* Not a possibly empty group */          {          ecode += _pcre_OP_lengths[*ecode];          DPRINTF(("bracket 0 tail recursion\n"));          goto TAIL_RECURSE;          }        /* Possibly empty group; can't use tail recursion. */        RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md, ims,          eptrb, flags, RM48);        RRETURN(rrc);        }      /* For non-final alternatives, continue the loop for a NOMATCH result;      otherwise return. */      RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md, ims,        eptrb, flags, RM2);      if (rrc != MATCH_NOMATCH && rrc != MATCH_THEN) RRETURN(rrc);      ecode += GET(ecode, 1);      }    /* Control never reaches here. */    /* Conditional group: compilation checked that there are no more than    two branches. If the condition is false, skipping the first branch takes us    past the end if there is only one branch, but that's OK because that is    exactly what going to the ket would do. As there is only one branch to be    obeyed, we can use tail recursion to avoid using another stack frame. */    case OP_COND:    case OP_SCOND:    if (ecode[LINK_SIZE+1] == OP_RREF)         /* Recursion test */      {      offset = GET2(ecode, LINK_SIZE + 2);     /* Recursion group number*/      condition = md->recursive != NULL &&        (offset == RREF_ANY || offset == md->recursive->group_num);      ecode += condition? 3 : GET(ecode, 1);      }    else if (ecode[LINK_SIZE+1] == OP_CREF)    /* Group used test */      {      offset = GET2(ecode, LINK_SIZE+2) << 1;  /* Doubled ref number */      condition = offset < offset_top && md->offset_vector[offset] >= 0;      ecode += condition? 3 : GET(ecode, 1);      }    else if (ecode[LINK_SIZE+1] == OP_DEF)     /* DEFINE - always false */      {      condition = FALSE;      ecode += GET(ecode, 1);      }    /* The condition is an assertion. Call match() to evaluate it - setting    the final argument match_condassert causes it to stop at the end of an    assertion. */    else      {      RMATCH(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL,          match_condassert, RM3);      if (rrc == MATCH_MATCH)        {        condition = TRUE;        ecode += 1 + LINK_SIZE + GET(ecode, LINK_SIZE + 2);        while (*ecode == OP_ALT) ecode += GET(ecode, 1);        }      else if (rrc != MATCH_NOMATCH && rrc != MATCH_THEN)        {        RRETURN(rrc);         /* Need braces because of following else */        }      else        {        condition = FALSE;        ecode += GET(ecode, 1);        }      }    /* We are now at the branch that is to be obeyed. As there is only one,    we can use tail recursion to avoid using another stack frame, except when    match_cbegroup is required for an unlimited repeat of a possibly empty    group. If the second alternative doesn't exist, we can just plough on. */    if (condition || *ecode == OP_ALT)      {      ecode += 1 + LINK_SIZE;      if (op == OP_SCOND)        /* Possibly empty group */        {        RMATCH(eptr, ecode, offset_top, md, ims, eptrb, match_cbegroup, RM49);        RRETURN(rrc);        }