«0xC0000005: нарушение прав доступа» При использовании fstream

Question

Я знаю, что существует множество вопросов, касающихся нарушений прав доступа, но я много читал и все еще не могу понять, что это взломало. Я переводил этот код с java на C++ и гораздо менее опытным с C++, поэтому этот код может быть немного (aka very) wonky.

Мой код разбивает на этой линии (в setup_next_buff_reader):

this->buff_reader = new fstream(file_path,fstream::in|fstream::out); 

И прыгает в функции закрытия() в fstream.

Я понимаю, что, возможно, что-то не так с тем, как я обрабатываю указатели, выделяя/де-выделяя память и т. Д., Но я не знаю, где. Любая помощь по этому поводу очень ценится.

bool TabDelimitedSource::setup_next_buff_reader() { 

     // Sets up the lucene analyzer and tries to load the next file in 
     // this->data_source_files, resetting counters/flags as needed 

     this->current_source_file += 1; 
     bool no_more_files = false; // assume we have no more files by default 

     if(this->current_source_file < sizeof(this->data_source_files)){    
      const char* file_path = (this->data_source_files[this->current_source_file]).c_str(); 
      cout << "File Path: " <<file_path <<"\n"; 
      this->buff_reader = new fstream(file_path,fstream::in|fstream::out);     
     } 
     else{ 
       no_more_files = true; 
     } 

     return no_more_files; // let the caller know whether there was another file or not 
} 


TabDelimitedSource::TabDelimitedSource(){} 

TabDelimitedSource::TabDelimitedSource(const char* dir_path) { 
    // Load all of the files in the directory using the file name filter provided 
    //fstream * data_source_dir = new fstream("path.txt"); 
    // NOTE: To change what files are loaded, use a different Filter here 
    vector<string> files; 
    this->getdir(dir_path, files); 
    this->data_source_files = files; 
    open(); 
    cout << "Went through the TDSource constructor.\n"; 
} 

void TabDelimitedSource::setColumnHoldingDoc(int column){ 
    // Allow the user to specify which column then want to extract 
    this->column_holding_doc = column; 
} 

void TabDelimitedSource::open() { 
    this->current_row = -1; 
    this->current_source_file = -1; 
    this->setup_next_buff_reader(); // setup first data source 
} 

void TabDelimitedSource::close() { 
    try{ 
      this->buff_reader->close(); 
      this->buff_reader->clear(); 
    } 
    catch (ifstream::failure e){ 
      ; // ignore this exception 
    } 
} 

void TabDelimitedSource::reset(){ 
    this->close(); 
    this->open(); 
} 

vector<string> TabDelimitedSource::getNext() { 
    // Returns the next document (a given cell) from the file(s) 
    char row[256]; // Return NULL if no more documents/rows 
    vector<string> document; 

    try{ 
      this->buff_reader->getline(row, 256); 
      cout <<"Row: "<< row << "\n"; 
    }catch (ifstream::failure e){ 
      ; // Ignore and fall through 
    } 

    if (buff_reader->eof()){ 
      this->current_row += 1; 
      vector<string> cells; 
      this->split(row, "\t", cells); // Split the row on tabs 
      // Split the cell into individual words using the lucene analyzer 
      try{ 
       string original_document = cells.at(this->column_holding_doc); 
      }catch (ifstream::failure e){ 
        cout<<"Row " << this->current_row << " did not have column " << this->column_holding_doc; 
      } 
    } 
    else{ 
      // We're at the end of the current file, try loading the next one 
      bool no_more_files = this->setup_next_buff_reader(); 
      // If there was another file to load, recurse to get its first document 
      if (!no_more_files){ 
        // Don't waste time doing Array->ArrayList->Array conversion 
        return this->getNext(); 
      }   
    } 

    // Return our arrayList as an array... there has to be a better way to do this 
    vector<string> return_val ; 
    if(!document.empty()){ // return NULL by default     
      for(int i=0; i<(int)document.size(); i++){ 
        return_val.push_back(document[i]); 
      } 
    } 

    return return_val; 
} 

void TabDelimitedSource::split(const string& str, const string& delim, vector<string>& result){ 
size_t start_pos = 0; 
size_t match_pos; 
size_t substr_length; 

while((match_pos = str.find(delim, start_pos)) != string::npos){ 
    substr_length = match_pos - start_pos; 

    if (substr_length > 0){ 
     result.push_back(str.substr(start_pos, substr_length)); 
    } 
    start_pos = match_pos + delim.length(); 
} 

substr_length = str.length() - start_pos; 

if (substr_length > 0){ 
    result.push_back(str.substr(start_pos, substr_length)); 
}  
} 

int TabDelimitedSource::getdir(string dir, vector<string> &files){ 
    DIR *dp; 
    struct dirent *dirp; 
    if((dp = opendir(dir.c_str())) == NULL) { 
     cout << "Error(" << errno << ") opening " << dir << endl; 
     return errno; 
    } 

    while ((dirp = readdir(dp)) != NULL) { 
     files.push_back((const char*)(dirp->d_name)); 
    } 
    closedir(dp); 
    return 0; 
} 

TabDelimitedSource::~TabDelimitedSource(){} 

Вот стек вызовов:

msvcp90d.dll!std::basic_filebuf<char,std::char_traits<char> >::close() Line 232 + 0x3 bytes C++ 
msvcp90d.dll!std::basic_fstream<char,std::char_traits<char> >::close() Line 971 + 0xb bytes C++ 
Testing.exe!TabDelimitedSource::close() Line 98 + 0xe bytes C++ 
Testing.exe!TabDelimitedSource::setup_next_buff_reader() Line 26 C++ 
Testing.exe!TabDelimitedSource::open() Line 94 C++ 
Testing.exe!TabDelimitedSource::TabDelimitedSource(const char * dir_path=0x09800fa8) Line 76 C++ 
Testing.exe!Query::load_data_source(const char * data_path=0x09800fa8, std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_database="c:/Users/dfink.LISSARD2/Documents/Visual Studio 2008/Projects/Testing/jieddo.mdb", std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_dbtable="jieddo_v2", std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_field_id="report_id", std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_field_text="summary", std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_field_date="occured_when", std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_filter="event_type='Explosive Hazard' ", int tab_delim_column=1) Line 144 + 0x38 bytes C++ 
Testing.exe!Query::model(const char * path=0x09800fa8, std::basic_string<char,std::char_traits<char>,std::allocator<char> > database="c:/Users/dfink.LISSARD2/Documents/Visual Studio 2008/Projects/Testing/jieddo.mdb", std::basic_string<char,std::char_traits<char>,std::allocator<char> > dbtable="jieddo_v2", std::basic_string<char,std::char_traits<char>,std::allocator<char> > field_id="report_id", std::basic_string<char,std::char_traits<char>,std::allocator<char> > field_text="summary", std::basic_string<char,std::char_traits<char>,std::allocator<char> > field_date="occured_when", std::basic_string<char,std::char_traits<char>,std::allocator<char> > filter="event_type='Explosive Hazard' ", int tab_delim_column=1) Line 72 C++ 
Testing.exe!Query::Query(bool run_batch_job=true, std::basic_string<char,std::char_traits<char>,std::allocator<char> > datasource="tab-delimited-source", char * data_path=0x09800fa8, std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_database="c:/Users/dfink.LISSARD2/Documents/Visual Studio 2008/Projects/Testing/jieddo.mdb", std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_dbtable="jieddo_v2", std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_field_id="report_id", std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_field_text="summary", std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_field_date="occured_when", std::basic_string<char,std::char_traits<char>,std::allocator<char> > jdo_filter="event_type='Explosive Hazard' ", int tab_delim_column=1) Line 55 C++ 
Testing.exe!main() Line 209 + 0x1c3 bytes C++ 
Testing.exe!__tmainCRTStartup() Line 582 + 0x19 bytes C 
Testing.exe!mainCRTStartup() Line 399 C 
kernel32.dll!762e3677()  
[Frames below may be incorrect and/or missing, no symbols loaded for kernel32.dll] 
ntdll.dll!77399f02()  
ntdll.dll!77399ed5()  

Место, где я звоню TabDelimitedSource:

bool Query::load_data_source(const char* data_path, string jdo_database, 
        string jdo_dbtable, string jdo_field_id, 
        string jdo_field_text, string jdo_field_date, 
        string jdo_filter, int tab_delim_column){ 
    // Attempts to load the data source (to this.ds) based on the datasource name 
    // NOTE: This will write over the old data source if it exists! 
    // data_path:  Where the source files are located 
    // jdo_*:   Argument specific to Jieddo data source 
    // tab_delim_colum: Which column to extract from a tab delimited source file 
    bool load_successful = true; 
    try{ 
      if (this->datasource.compare("tab-delimited-source") == 0) { 
        this->ds = new TabDelimitedSource(data_path); 
        this->ds->setColumnHoldingDoc(tab_delim_column); 
        string pref_text_analyzer; 
        this->ds->setColumnHoldingDoc(tab_delim_column); 
      } 
      else {      
        load_successful = false; 
      } 
    } 
    catch(ifstream::failure e){ 
      cout<<"FAIL."<<"n"; 
      load_successful = false; 
    } 
    return load_successful; 
} 

EDIT: Извините, я забыл, что я добавил в две строки кода (Я взял их обратно). Код действительно разбивается на ту же линию, что упоминалось выше, но он выполняет шаги в mlock.h, в функции разблокировки.

Answer 1

Предполагая, что data_source_files вектор строк, этот тест

if(this->current_source_file < sizeof(this->data_source_files)){   

проверяет, является ли текущий индекс меньше, чем число байтов в станд :: векторный объект, а не если он меньше, чем число строк, содержащихся в векторе. Это будет

data_source_files.size() 

Это, скорее всего, вызовет доступ за пределы диапазона.