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2020-07-19

2020-07-19 22:45:53 by Stephen R. van den Berg <srb@cuci.nl>

Stdio.Buffer: Protect against calls in destructed Buffer objects.

887:    }    }    +  static Buffer* already_destructed() { +  Pike_error("Stdio.Buffer already destructed.\n"); +  return 0; +  } +    #undef THIS   #define THIS (&(((struct Buffer_struct *)Pike_fp->current_storage)->b))    -  + #define CHECK_DESTRUCTED(io) ((io)->this ? (io) : already_destructed())       /* pike functions */   
907:    */    PIKEFUN int(-1..) input_from( object f, int|void _nbytes, int|void _once )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    size_t sz = io_len( io );    size_t bread = 0, nbytes = (size_t)-1;    struct my_file *fd;
983:    */    PIKEFUN void __set_on_write( zero|function f )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);       if (f)    assign_svalue(&io->output, f);
1031:    PIKEFUN int(-1..) output_to( object|function(string(8bit):int) f,    int|void nbytes )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    ptrdiff_t written = 0;    ptrdiff_t sz = io_len( io );    int write_fun_num = -1;
1119:    */    PIKEFUN int read_sint( int nbytes )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    struct pike_string *tmp;    Pike_sp--;    if( !io_avail( io, nbytes ) )
1152:       PIKEFUN int(0..) _size_object( )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    if (io->malloced)    {    push_ulongest(THIS->allocated);
1171:    */    PIKEFUN Buffer add_padding( int(0..) nbytes, int|void _byte )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    int byte = 0;    if( _byte ) byte = _byte->u.integer;   
1218:    */    PIKEFUN Buffer add( object|string(8bit)|int|array(object|string(8bit)|int) ... argp)    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    int i; -  Buffer *io = THIS; +        for(i=0; i<args; i++ )    io_append_svalue( io, argp+i );
1233:    */    PIKEFUN Buffer add_int8( int i )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    *io_add_space(io,1,0)=i;    io->len++;    Pike_sp--;
1246:    */    PIKEFUN Buffer add_int8( object mpz )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    INT64 i = 0; -  Buffer *io = THIS; +     unsigned char *p = io_add_space(io,1,0);    if (!low_int64_from_bignum(&i, mpz)) {    SIMPLE_ARG_TYPE_ERROR("add_int8", 1, "int|Gmp.mpz");
1263:    */    PIKEFUN Buffer add_int16( int i )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    unsigned char *p = io_add_space(io,2,0);    p[0] = i>>8;    p[1] = i;
1278:    */    PIKEFUN Buffer add_int16( object mpz )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    INT64 i = 0; -  Buffer *io = THIS; +     unsigned char *p = io_add_space(io,2,0);    if (!low_int64_from_bignum(&i, mpz)) {    SIMPLE_ARG_TYPE_ERROR("add_int16", 1, "int|Gmp.mpz");
1295:    */    PIKEFUN Buffer add_int32( int i )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    unsigned char *p = io_add_space(io,4,0);    p[0] = i>>24;    p[1] = i>>16;
1311:    */    PIKEFUN Buffer add_int32( object mpz )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    INT64 i = 0; -  Buffer *io = THIS; +     unsigned char *p = io_add_space(io,4,0);    if (!low_int64_from_bignum(&i, mpz)) {    SIMPLE_ARG_TYPE_ERROR("add_int32", 1, "int|Gmp.mpz");
1376:    int|string(8bit)|object|array(int|string(8bit)|Buffer|array) str,    int size_size, void|int offset )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    size_t len = io_svalue_len(io, str);       if( offset )
1402:    */    PIKEFUN Buffer add_int( object|int i, int width )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    pop_stack(); /* width */    if( TYPEOF(*i) == PIKE_T_INT )    { -  io_add_int( THIS, i->u.integer, width ); +  io_add_int( io, i->u.integer, width );    Pike_sp--;    }    else    {    convert_stack_top_to_bignum(); -  io_add_bignum( THIS, i->u.object, width ); +  io_add_bignum( io, i->u.object, width );    pop_stack(); /* o. */    }    ref_push_object(Pike_fp->current_object);
1428:    */    PIKEFUN Buffer add_hint( object|int i, int len_width )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    int width;    pop_stack(); /* width */    if( TYPEOF(*i) == PIKE_T_INT )    {    INT_TYPE ui = i->u.integer;    if (!ui) { -  io_add_int( THIS, 0, len_width ); +  io_add_int( io, 0, len_width );    } else {    for( width=1; width<SIZEOF_INT_TYPE; width++ )    if( ui < (((INT_TYPE)1)<<(width*8)) &&    ui >= -(((INT_TYPE)1)<<(width*8-1)) )    break; -  io_add_int( THIS, width, len_width ); -  io_add_int( THIS, i->u.integer, width ); +  io_add_int( io, width, len_width ); +  io_add_int( io, i->u.integer, width );    }    Pike_sp--;    }
1449:    {    convert_stack_top_to_bignum();    width = (mpz_sizeinbase( (void*)i->u.object->storage, 2)+7)/8; -  io_add_int( THIS, width, len_width ); -  io_add_bignum( THIS, i->u.object, width ); +  io_add_int( io, width, len_width ); +  io_add_bignum( io, i->u.object, width );    pop_stack(); /* o. */    }    ref_push_object(Pike_fp->current_object);
1470:    */    PIKEFUN Buffer add_ints( array(int) a, int bpi )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    int i,l = a->size;    struct svalue *it = a->item;    unsigned char *ptr;    ptrdiff_t n=0;    ONERROR e; -  Buffer *io = THIS; +        io_unwrite_on_error(io, &e);   
1544:    PIKEFUN int(8bit) `[]( int off )    flags ID_PROTECTED;    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    if( off < 0 )    off = io_len(io)-off;   
1561:    PIKEFUN void `[]=( int off, int val )    flags ID_PROTECTED;    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);       io_ensure_malloced( io, 0 );   
1588:    PIKEFUN int(0..) _sizeof()    flags ID_PROTECTED;    { -  push_ulongest(io_len(THIS)); +  Buffer *io = CHECK_DESTRUCTED(THIS); +  push_ulongest(io_len(io));    }       /*! @decl string(8bit) cast("string")
1601:    PIKEFUN string(8bit) cast(string to)    flags ID_PROTECTED;    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    if( to != literal_string_string )    {    push_undefined();    return;    } -  if( io_len(THIS) > 0x7fffffff ) +  if( io_len(io) > 0x7fffffff )    Pike_error("This buffer is too large to convert to a string.\n"); -  push_string(make_shared_binary_string((void*)io_read_pointer(THIS), -  (INT32)io_len(THIS))); +  push_string(make_shared_binary_string((void*)io_read_pointer(io), +  (INT32)io_len(io)));    }      
1665:    */    PIKEFUN Buffer set_error_mode( int|program m )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    if( TYPEOF(*m) == PIKE_T_INT ) -  io_set_error_mode( THIS, m->u.integer ? buffer_error_program : 0 ); +  io_set_error_mode( io, m->u.integer ? buffer_error_program : 0 );    else -  io_set_error_mode( THIS, program_from_svalue(m)); +  io_set_error_mode( io, program_from_svalue(m));       pop_stack();    ref_push_object(Pike_fp->current_object);
1683:    */    PIKEFUN Buffer lock()    { -  push_object( io_read_buffer( THIS, 0, 0 ) ); +  Buffer *io = CHECK_DESTRUCTED(THIS); +  push_object( io_read_buffer( io, 0, 0 ) );    }       PIKEFUN string(8bit) _sprintf(int o, mapping|void UNUSED)    flags ID_PROTECTED;    { -  +  Buffer *io = CHECK_DESTRUCTED(THIS);    size_t bytes;    pop_n_elems(args-1);    Pike_sp--;
1699:    push_static_text("%O(%d bytes, read=[..%d] data=[%d..%d] free=[%d..%d] %s%s)");    ref_push_program(Pike_fp->current_object->prog);    /* io_len [..offset] [offset..len] [..allocated] */ -  push_int(io_len(THIS)); -  push_int(THIS->offset-1); -  push_int(THIS->offset); +  push_int(io_len(io)); +  push_int(io->offset-1); +  push_int(io->offset);    -  push_int(THIS->len-1); -  push_int(THIS->len); -  push_int(THIS->allocated); -  push_static_text( (THIS->str ? "string" : THIS->malloced ? "allocated" : "subbuffer" ) ); -  if( THIS->locked ) +  push_int(io->len-1); +  push_int(io->len); +  push_int(io->allocated); +  push_static_text( (io->str ? "string" : io->malloced ? "allocated" : "subbuffer" ) ); +  if( io->locked )    push_static_text(" (read only)");    else    push_static_text("");
1716:    break;       case 's': -  bytes = io_len(THIS); -  THIS->locked_move++; -  push_string( io_read_string(THIS, bytes) ); -  io_rewind(THIS, bytes); -  THIS->locked_move--; +  bytes = io_len(io); +  io->locked_move++; +  push_string( io_read_string(io, bytes) ); +  io_rewind(io, bytes); +  io->locked_move--;    break;       case 'q':    push_static_text("%q"); -  bytes = io_len(THIS); -  THIS->locked_move++; -  push_string( io_read_string(THIS, bytes) ); -  io_rewind(THIS, bytes); -  THIS->locked_move--; +  bytes = io_len(io); +  io->locked_move++; +  push_string( io_read_string(io, bytes) ); +  io_rewind(io, bytes); +  io->locked_move--;    f_sprintf(2);    break;    default:
1755:    */    PIKEFUN string(8bit) read_hstring( int bytes, void|int offset )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    INT64 len; -  Buffer *io = THIS; +     struct pike_string *s;    ONERROR e;   
1813:    PIKEFUN string(8bit) read_cstring(void|int(8bit) sentinel,    void|int(8bit) escape)    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    int csentinel = sentinel ? sentinel->u.integer : 0;       if (!escape || (escape->u.integer == csentinel)) {
1901:    rawtype tFunc(tInt8bit tOr(tInt, tVoid) tOr(tIntPos, tVoid),    tOr(tInt_10, tIntPos));    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    unsigned char *buf = io_read_pointer(io);    unsigned char *buf_end = buf + io_len(io);   
1971:    PIKEFUN int _search(string(8bit) substring, int|void start, int|void end)    flags ID_PROTECTED;    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    unsigned char *buf = io_read_pointer(io);    unsigned char *buf_end = buf + io_len(io);    SearchMojt mojt;
2046:    */    PIKEFUN Buffer read_hbuffer( int bytes, int|void copy )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    INT64 len;    int do_copy = 0; -  Buffer *io = THIS; +     ONERROR e;       io_rewind_on_error( io, &e );
2084:    */    PIKEFUN Buffer read_buffer( int bytes, int|void copy )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    int do_copy = 0;    struct object *o;    if( copy )    do_copy = copy->u.integer;    Pike_sp-=args; -  if( (o = io_read_buffer( THIS, bytes, do_copy )) ) +  if( (o = io_read_buffer( io, bytes, do_copy )) )    push_object(o);    else    push_int(0);
2106:    rawtype tFuncV(tAttr("strict_sprintf_format", tOr(tStr, tObj)),    tAttr("sprintf_args", tMix), tObjIs_BUFFER);    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    ONERROR _e;    struct string_builder tmp;    init_string_builder(&tmp,0);
2113:    low_f_sprintf(args, &tmp);    if( tmp.s->size_shift )    Pike_error("Buffer only handles 8bit data.\n"); -  io_append( THIS, tmp.s->str, tmp.s->len ); +  io_append( io, tmp.s->str, tmp.s->len );    pop_n_elems(args);    CALL_AND_UNSET_ONERROR(_e);    ref_push_object(Pike_fp->current_object);
2130:    */    PIKEFUN array sscanf( string(8bit) format )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    INT32 i;    ptrdiff_t num_used;    struct svalue *start = Pike_sp;    retry:    i = low_sscanf_pcharp( -  MKPCHARP(io_read_pointer(THIS), 0), io_len(THIS), +  MKPCHARP(io_read_pointer(io), 0), io_len(io),    MKPCHARP(format->str,format->size_shift), format->len,    &num_used);       if( !num_used )    { -  if( io_range_error(THIS,0) ) +  if( io_range_error(io,0) )    goto retry;    pop_n_elems(Pike_sp-start);    push_int(0);    }    else    { -  io_consume( THIS, num_used ); +  io_consume( io, num_used );    f_aggregate(Pike_sp-start);    }    }
2176:    */    PIKEFUN mixed read_json(int|void require_whitespace)    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    INT_TYPE whites = 0;    ptrdiff_t stop;    static ptrdiff_t(*parse_json_pcharp)(PCHARP,size_t,int,char**);
2187:    if( !parse_json_pcharp )    parse_json_pcharp = PIKE_MODULE_IMPORT(Standards.JSON, parse_json_pcharp );    retry: -  stop = parse_json_pcharp( MKPCHARP(io_read_pointer(THIS),0), -  io_len(THIS), 1|8, &err ); /* json_utf8 */ +  stop = parse_json_pcharp( MKPCHARP(io_read_pointer(io),0), +  io_len(io), 1|8, &err ); /* json_utf8 */       if( stop < 0 )    { -  if( -stop == (ptrdiff_t)io_len(THIS) || (err && !strncmp(err,"Unterminated",12))) +  if( -stop == (ptrdiff_t)io_len(io) || (err && !strncmp(err,"Unterminated",12)))    { -  if( io_range_error(THIS,0) ) +  if( io_range_error(io,0) )    goto retry;    push_undefined();    }
2210:    else    {    if( whites && -  (io_is_whitespace(THIS,stop)<=0 && io_is_whitespace(THIS,stop-1)<=0)) +  (io_is_whitespace(io,stop)<=0 && io_is_whitespace(io,stop-1)<=0))    { -  if( stop == (ptrdiff_t)io_len(THIS) ) +  if( stop == (ptrdiff_t)io_len(io) )    { -  if( io_range_error(THIS,0) ) +  if( io_range_error(io,0) )    goto retry;    pop_stack();    push_undefined();
2225:    else    {    if( whites ) -  while( io_is_whitespace( THIS, stop ) ) +  while( io_is_whitespace( io, stop ) )    stop++; -  io_consume( THIS, stop ); +  io_consume( io, stop );    }    }    }
2251:    */    PIKEFUN string(8bit)|int|float|array match( string(8bit) format )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    INT32 i;    ptrdiff_t num_used;    struct svalue *start = Pike_sp;    retry:    i = low_sscanf_pcharp( -  MKPCHARP(io_read_pointer(THIS), 0), io_len(THIS), +  MKPCHARP(io_read_pointer(io), 0), io_len(io),    MKPCHARP(format->str,format->size_shift), format->len,    &num_used);       if( !num_used )    { -  if( io_range_error(THIS,0) ) +  if( io_range_error(io,0) )    goto retry;    pop_n_elems(Pike_sp-start);    push_int(0);    }    else    { -  io_consume( THIS, num_used ); +  io_consume( io, num_used );    if( Pike_sp-start > 1 )    f_add(Pike_sp-start);    }
2281:    */    PIKEFUN void clear( )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    io->offset = io->len = 0;    }   
2295:    */    PIKEFUN void set_max_waste(float howmuch)    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    io->max_waste = howmuch;    io_add_space( io, 0, 1 );    io_trim_waste( io );
2314:    */    PIKEFUN void trim( )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);       io_add_space( io, 0, 1 );    io_trim(io);
2326:    */    PIKEFUN void allocate( int n )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    Pike_sp--;    if (!n) return;    if (n < 0)
2342:    */    PIKEFUN int(-1..) consume( int n )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    Pike_sp--; -  if( !io_avail( THIS, n ) ) +  if( !io_avail( io, n ) )    push_int(-1);    else -  push_int64( io_consume( THIS, n ) ); +  push_int64( io_consume( io, n ) );    }       /*! @decl int(0..)|int(-1..-1) truncate( int(0..) n )
2357:    */    PIKEFUN int(-1..) truncate( int(0..) n )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    ptrdiff_t diff = io_len(io) - n;    Pike_sp--;   
2387:    */    PIKEFUN int(-1..) unread( int bytes )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    Pike_sp--; -  push_int64( io_rewind( THIS, bytes ) ); +  push_int64( io_rewind( io, bytes ) );    }       /*! @decl string(8bit) read( int n )
2402:    */    PIKEFUN string(8bit) read( int bytes )    { +  Buffer *io = CHECK_DESTRUCTED(THIS);    struct pike_string *s;    Pike_sp--; -  s = io_read_string(THIS, bytes ); +  s = io_read_string(io, bytes );    if( s )    push_string( s );    else
2425:    */    PIKEFUN string(8bit) read()    { -  push_string( io_read_string(THIS, io_len(THIS)) ); +  Buffer *io = CHECK_DESTRUCTED(THIS); +  push_string( io_read_string(io, io_len(io)) );    }       /*! @decl string(8bit) try_read(int len)
2445:    */    PIKEFUN string(8bit) try_read( int bytes )    { -  Buffer *this = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    struct pike_string *s;    Pike_sp--;    /* Hm. signed/unsigned comparisons abound. */ -  if( bytes > 0 && (size_t)bytes > io_len(this) ) -  bytes = io_len(this); -  push_string( io_read_string(this, bytes ) ); +  if( bytes > 0 && (size_t)bytes > io_len(io) ) +  bytes = io_len(io); +  push_string( io_read_string(io, bytes ) );    }       /*! @decl int(8bit) read_int8()    */    PIKEFUN int(8bit) read_int8( )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    if( LIKELY(io_avail( io, 1 )) )    push_int( io_read_byte_uc(io) );    else
2469:    */    PIKEFUN int(0..65535) read_int16( )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    if( LIKELY(io_avail( io, 2 )) )    push_int( io_read_number_uc(io,2) );    else
2480:    */    PIKEFUN int(0..16777215) read_int24( )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    if( LIKELY(io_avail( io, 3 )) )    push_int( io_read_number_uc(io,3) );    else
2491:    */    PIKEFUN int(0..4294967295) read_int32( )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    if( LIKELY(io_avail( io, 4 )) )    {    push_int( io_read_number_uc(io,4) );
2521:    */    PIKEFUN int(0..) read_int( int len )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    struct object *o;       Pike_sp--;
2554:    */    PIKEFUN int(0..) read_le_int( int len )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    struct object *o;       Pike_sp--;
2585:    */    PIKEFUN int(0..) read_hint( int size_len )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    ONERROR e;    INT_TYPE len;    struct object *o;
2626:    */    PIKEFUN array(int(0..)) read_ints( int num, int len )    { -  Buffer *io = THIS; +  Buffer *io = CHECK_DESTRUCTED(THIS);    INT_TYPE i;    struct object *o;    struct array *a;
2663:    */    PIKEFUN string _encode()    { -  push_string(io_read_string(THIS, io_len(THIS))); +  Buffer *io = CHECK_DESTRUCTED(THIS); +  push_string(io_read_string(io, io_len(io)));    }       PIKEFUN void _decode(string(8bit) x)    { -  Buffer *this = THIS; -  if( this->buffer ) +  Buffer *io = CHECK_DESTRUCTED(THIS); +  if( io->buffer )    Pike_error("Can not initialize twice.\n");    if( x->size_shift )    Pike_error("Can not handle non-8bit data.\n"); -  this->buffer = (unsigned char*)x->str; -  this->len = x->len; -  this->malloced = 0; -  this->str = x; +  io->buffer = (unsigned char*)x->str; +  io->len = x->len; +  io->malloced = 0; +  io->str = x;    add_ref(x);    }   
2688:    */    PIKEFUN void read_only()    { -  io_lock( THIS ); +  Buffer *io = CHECK_DESTRUCTED(THIS); +  io_lock( io );    }      
2754:    */    PIKEFUN object(Buffer.RewindKey) rewind_on_error()    { -  push_object( io_create_rewind_key( THIS, 1 ) ); +  Buffer *io = CHECK_DESTRUCTED(THIS); +  push_object( io_create_rewind_key( io, 1 ) );    }       PIKEFUN object(Buffer.RewindKey) rewind_key()    { -  push_object( io_create_rewind_key( THIS, 0 ) ); +  Buffer *io = CHECK_DESTRUCTED(THIS); +  push_object( io_create_rewind_key( io, 0 ) );    }       /*! @decl void create( int|void len )
2793:    PIKEFUN void create( int|void|string(8bit)|object|array x )    flags ID_PROTECTED;    { -  Buffer *this = THIS; -  if( this->buffer ) +  Buffer *io = CHECK_DESTRUCTED(THIS); +  if( io->buffer )    Pike_error("Can not initialize twice.\n");    if( !x )    { -  this->buffer = xalloc(256-32); -  this->allocated = 256-32; -  this->malloced = 1; +  io->buffer = xalloc(256-32); +  io->allocated = 256-32; +  io->malloced = 1;    }    else if( TYPEOF(*x) == PIKE_T_INT )    {    INT_TYPE len = x->u.integer;    if( len <= 0 ) -  this->buffer = xalloc(1); +  io->buffer = xalloc(1);    else -  this->buffer = xalloc(len); -  this->allocated = MAXIMUM(len,1); -  this->malloced = 1; +  io->buffer = xalloc(len); +  io->allocated = MAXIMUM(len,1); +  io->malloced = 1;    pop_stack();    }    else    { -  io_append_svalue( THIS, x ); +  io_append_svalue( io, x );    pop_stack();    }    }       INIT { -  Buffer *this = THIS; -  this->max_waste = 0.615; -  this->this = Pike_fp->current_object; +  Buffer *io = THIS; +  io->max_waste = 0.615; +  io->this = Pike_fp->current_object;    }       EXIT { -  Buffer *this = THIS; -  io_unlink_external_storage( this ); -  if( this->error_mode ) -  free_program( this->error_mode ); -  if( this->malloced ) -  free( this->buffer ); +  Buffer *io = THIS; +  io_unlink_external_storage( io ); +  if( io->error_mode ) +  free_program( io->error_mode ); +  if( io->malloced ) +  free( io->buffer );    }