Function unzOpenInternal

src/Setup/unzip.cpp:2924–2967

Open a Zip file. If the zipfile cannot be opened (file don't exist or in not valid), return NULL. Otherwise, the return value is a unzFile Handle, usable with other unzip functions

// If the zipfile cannot be opened (file don't exist or in not valid), return NULL.
// Otherwise, the return value is a unzFile Handle, usable with other unzip functions
unzFile unzOpenInternal(LUFILE *fin)
{ if (fin==NULL) return NULL;
  if (unz_copyright[0]!=' ') {lufclose(fin); return NULL;}

  int err=UNZ_OK;
  unz_s us;
  uLong central_pos,uL;
  central_pos = unzlocal_SearchCentralDir(fin);
  if (central_pos==0xFFFFFFFF) err=UNZ_ERRNO;
  if (lufseek(fin,central_pos,SEEK_SET)!=0) err=UNZ_ERRNO;
  // the signature, already checked
  if (unzlocal_getLong(fin,&uL)!=UNZ_OK) err=UNZ_ERRNO;
  // number of this disk
  uLong number_disk;          // number of the current dist, used for spanning ZIP, unsupported, always 0
  if (unzlocal_getShort(fin,&number_disk)!=UNZ_OK) err=UNZ_ERRNO;
  // number of the disk with the start of the central directory
  uLong number_disk_with_CD;  // number the the disk with central dir, used for spaning ZIP, unsupported, always 0
  if (unzlocal_getShort(fin,&number_disk_with_CD)!=UNZ_OK) err=UNZ_ERRNO;
  // total number of entries in the central dir on this disk
  if (unzlocal_getShort(fin,&us.gi.number_entry)!=UNZ_OK) err=UNZ_ERRNO;
  // total number of entries in the central dir
  uLong number_entry_CD;      // total number of entries in the central dir (same than number_entry on nospan)
  if (unzlocal_getShort(fin,&number_entry_CD)!=UNZ_OK) err=UNZ_ERRNO;
  if ((number_entry_CD!=us.gi.number_entry) || (number_disk_with_CD!=0) || (number_disk!=0)) err=UNZ_BADZIPFILE;
  // size of the central directory
  if (unzlocal_getLong(fin,&us.size_central_dir)!=UNZ_OK) err=UNZ_ERRNO;
  // offset of start of central directory with respect to the starting disk number
  if (unzlocal_getLong(fin,&us.offset_central_dir)!=UNZ_OK) err=UNZ_ERRNO;
  // zipfile comment length
  if (unzlocal_getShort(fin,&us.gi.size_comment)!=UNZ_OK) err=UNZ_ERRNO;
  if ((central_pos+fin->initial_offset<us.offset_central_dir+us.size_central_dir) && (err==UNZ_OK)) err=UNZ_BADZIPFILE;
  if (err!=UNZ_OK) {lufclose(fin);return NULL;}

  us.file=fin;
  us.byte_before_the_zipfile = central_pos+fin->initial_offset - (us.offset_central_dir+us.size_central_dir);
  us.central_pos = central_pos;
  us.pfile_in_zip_read = NULL;
  fin->initial_offset = 0; // since the zipfile itself is expected to handle this

  unz_s *s = (unz_s*)zmalloc(sizeof(unz_s));
  *s=us;
  unzGoToFirstFile((unzFile)s);
  return (unzFile)s;
}