file_magic_test()

Emagic_type datrw::util::file_magic_test	(	std::istream &	is,
		const char *const	cmagic,
		const bool &	fortranmode = false
	)

check magic number in file

Check for magic number in file.

,

Parameters

is	input stream to read from
cmagic	4-byte character sequence representing magic number (most restrictive: pass a const pointer to a const char) is pointer to character array of size sizeof(int)
fortranmode	use Fortran binary I/O if true

Returns

The return value tells whether the file matches

The function may have the following return values

• magic_match The file has the requested magic number and the bytesex of the data matches that of the system
• magic_swap The file has the requested magic number but byte swapping is required for input data
• magic_nomatch The requested magic number was not found in the file

Definition at line 105 of file bytesex.cc.

References datrw::util::IOUnion< T >::bytes, magic(), magic_match, magic_nomatch, magic_swap, swap(), and datrw::util::IOUnion< T >::value.

Referenced by datrw::binary::ibinstream::ibinstream().

    {
      Emagic_type result=magic_nomatch;
      IOUnion<int> req_magic, in_magic;
      // create requested magic number
      req_magic.value=magic(cmagic);
      // skip Fortran block size
      if (fortranmode) is.read(in_magic.bytes, sizeof(int));
      // read magic number and compare
      is.read(in_magic.bytes, sizeof(int));
      if (in_magic.value == req_magic.value)
      { result=magic_match; }
      else if (in_magic.value == swap(req_magic.value))
      { result=magic_swap; }
      // skip Fortran block size
      if (fortranmode) is.read(in_magic.bytes, sizeof(int));
      return(result);
    } // file_magic_test()

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