Examples of errors detected by the V555 diagnostic

V555. Expression of the 'A - B > 0' kind will work as 'A != B'.

Trans-Proteomic Pipeline

V555 The expression 'ppw_ref.size() - have_cluster > 0' will work as 'ppw_ref.size() != have_cluster'. proteinprophet.cpp 6767

size_type size() const;

void computeDegenWts()
{
  ....
  int have_cluster = 0;
  ....
  if ( have_cluster > 0 && ppw_ref.size() - have_cluster > 0 )
  ....
}

Scilab

V555 The expression 'wcslen(dir) - wcslen(DirTmp) > 0' will work as 'wcslen(dir) != wcslen(DirTmp)'. getscilabdirectory.c 44

size_t wcslen(const wchar_t * _Str);

char *getScilabDirectory(BOOL UnixStyle)
{
  ....
  if (wcslen(dir) - wcslen(DirTmp)>0)
  {
    dir[wcslen(dir) - wcslen(DirTmp)] = L'\0';
  }
  else return NULL;
  ....
}

Similar errors can be found in some other places:

• V555 The expression 'nbcharacters - 1 > 0' will work as 'nbcharacters != 1'. checkcsvwriteformat.c 85

OpenSSL

V555 The expression of the 'A - B > 0' kind will work as 'A != B'. bio_ok.c 243

typedef struct ok_struct
{
  ....
  size_t buf_len_save;
  size_t buf_off_save;
  ....
} BIO_OK_CTX;

static int ok_read(BIO *b, char *out, int outl)
{
  ....
  BIO_OK_CTX *ctx;
  ....
  /* copy start of the next block into proper place */
  if(ctx->buf_len_save - ctx->buf_off_save > 0)
  ....
}

Wine Is Not an Emulator

V555 The expression 'This->nStreams - nr > 0' will work as 'This->nStreams != nr'. editstream.c 172

static HRESULT
AVIFILE_RemoveStream(IAVIEditStreamImpl* const This, DWORD nr)
{
  ....
  This->nStreams--;
  if (This->nStreams - nr > 0) {   // <=
    memmove(This->pStreams + nr, This->pStreams + nr + 1,
            (This->nStreams - nr) * sizeof(EditStreamTable));
  }
  ....
}

Similar errors can be found in some other places:

• V555 The expression 'This->fInfo.dwStreams - nStream > 0' will work as 'This->fInfo.dwStreams != nStream'. avifile.c 469

PHP:Hypertext Preprocessor

V555 The expression 'out_buf_size - ocnt > 0' will work as 'out_buf_size != ocnt'. filters.c 1702

static int strfilter_convert_append_bucket(
{
  size_t out_buf_size;
  ....
  size_t ocnt, icnt, tcnt;
  ....
  if (out_buf_size - ocnt > 0) { // <=
    ....
    php_stream_bucket_append(buckets_out, new_bucket TSRMLS_CC);
  } else {
    pefree(out_buf, persistent);
  }
  ....
}

OpenJPEG

V555 The expression of the 'A - B > 0' kind will work as 'A != B'. itkopenjpeg j2k.c 3421

typedef struct opj_stepsize
{
  OPJ_UINT32 expn;
  OPJ_UINT32 mant;
};

bool j2k_read_SQcd_SQcc(
  opj_j2k_t *p_j2k,
  OPJ_UINT32 p_comp_no,
  OPJ_BYTE* p_header_data,
  OPJ_UINT32 * p_header_size,
  struct opj_event_mgr * p_manager
  )
{
  ....
  OPJ_UINT32 l_band_no;
  ....
  l_tccp->stepsizes[l_band_no].expn =
    ((l_tccp->stepsizes[0].expn) - ((l_band_no - 1) / 3) > 0) ?
      (l_tccp->stepsizes[0].expn) - ((l_band_no - 1) / 3) : 0;
  ....
}

K Desktop Environment

V555 The expression 'm_pos - backOffset > 0' will work as 'm_pos != backOffset'. pp-stream.cpp 225

unsigned int rpp::Stream::peekLastOutput(uint backOffset) const {
  if(m_pos - backOffset > 0)
    return m_string->at(m_pos - backOffset - 1);
  return 0;
}

Similar errors can be found in some other places:

• V555 The expression 'nextOffset - currentOffset > 0' will work as 'nextOffset != currentOffset'. pp-location.cpp 211

FreeSWITCH

V555 The expression 'parser->maxlen - parser->minlen > 0' will work as 'parser->maxlen != parser->minlen'. switch_ivr.c 2342

typedef uintptr_t switch_size_t;

switch_size_t maxlen;
switch_size_t buflen;
switch_size_t minlen;

SWITCH_DECLARE(void *) switch_ivr_digit_stream_parser_feed(....)
{
  ....
  if (parser->maxlen - parser->minlen > 0 && ....) {
    len = 0;
  }
  ....
}

PHP:Hypertext Preprocessor

V555 The expression of the 'A - B > 0' kind will work as 'A != B'. ZendAccelerator.c 3915

typedef union _znode_op {
  uint32_t      num;
  ....
}
struct _zend_op {
  _znode_op op2;
  ....
}

struct _zend_op_array {
  uint32_t num_dynamic_func_defs;
  ....
}

typedef struct _zend_op_array zend_op_array;

static void preload_remove_declares(zend_op_array *op_array)
{
  zend_op *opline = op_array->opcodes;
  ....
  while (opline != end) {
    switch (opline->opcode) {
      ....
      case ZEND_DECLARE_FUNCTION:
        ....
        if (func && func == op_array->dynamic_func_defs[opline->op2.num]) {
          ....
          if (op_array->num_dynamic_func_defs == 0) {
            dynamic_func_defs = NULL;
          } else {
            ....
            if (op_array->num_dynamic_func_defs - opline->op2.num > 0) {  // <=
              memcpy(
                dynamic_func_defs + opline->op2.num,
                op_array->dynamic_func_defs + (opline->op2.num + 1),
                sizeof(zend_op_array*)
                * (op_array->num_dynamic_func_defs - opline->op2.num));
            }
  // the rest of the code
}

It's a subtraction of two unsigned values. If the minuend is less than the subtrahend, the result will be a value less than zero. However, since there are unsigned values, we get the modulo arithmetic. This expression should be replaced with the following: 'if (op_array->num_dynamic_func_defs > opline->op2.num)'.