xs - Perl SV value from pointer without copy -

how create sv value null terminated string without copy? newsvpv(const char*, strlen) without copy , moving ownership perl (so perl must release string memory). need avoid huge memory allocation , copy.

i found following example:

sv *r = sv_newmortal(); svpok_on(r); sv_usepvn_mg(r, string, strlen(string) + 1); 

but don't have deep knowledge of xs internals , have doubts.

if want perl manage memory block, needs know how reallocate , deallocate it. memory knows how reallocate , deallocate memory allocated using allocator, newx. (otherwise, have associate reallocator , deallocator each memory block.)

if can't allocate memory block using newx, best option might create read-only sv svlen set zero. tells perl doesn't own memory. sv blessed class has destructor deallocate memory using appropriate deallocator.

if can allocate memory block using newx, can use following:

sv* newsvpvn_steal_flags(pthx_ const char* ptr, strlen len, const u32 flags) { #define newsvpvn_steal_flags(a,b,c) newsvpvn_steal_flags(athx_ a,b,c)     sv* sv;      assert(!(flags & ~(svf_utf8|svs_temp|sv_has_trailing_nul)));      sv = newsv(0);     sv_usepvn_flags(sv, ptr, len, flags & sv_has_trailing_nul);     if ((flags & svf_utf8) && svok(sv)) {         svutf8_on(sv);     }      svtaint(sv);      if (flags & svs_temp) {         sv_2mortal(sv);     }      return sv; } 

note: ptr should point memory allocated newx, , must point start of block returned newx.

note: accepts flags svf_utf8 (to specify ptr utf-8 encoding of string seen in perl), svs_temp (to have sv_2mortal called on sv) , sv_has_trailing_nul (see below).

note: code expects string buffer of scalars have trailing nul (even though length of buffer known , though buffer can contain nuls). if memory block allocated has trailing nul beyond end of data (e.g. c-style nul-terminated string), pass sv_has_trailing_nul flag. if not, function attempt extend buffer , add nul.