creating/opening file on disk returns EAGAIN - c++

Question

As title says I'm getting this error while trying to open file for binary writing(mode doesnt seem matter).
My app uses libev to handle sockets(non blocking/epoll backend) and while parsing client packets i want at some point where i receive fileupload message to start writing down to disk data i get from server.
I couldn't google anything about EAGAIN(Resource temporarily unavailable) message and file opening..
These are methods I've tried:
fopen( ... ) returns EAGAIN
using ofstream/fstream's open(...) by creating them on heap(new) returns EAGAIN
using ofstream/fstream's open(...) staticly as class member (ofstream m_ofFile;) works, but strangly compiler generates code which calls ofstream destructor and closes file before exiting class method im calling .open from. Now that contradicts with my C++ knowledge where for class members which are class types, destructors are called right before class owner's..
edit:
#Joachim
You're right, I'm not acually getting this error..(method #1. gonna test method #2 again soon). File opens regulary and i get regular FILE*. That happens in Init(...) function of my class, but then when I call OnFileChunk later on m_hFile is 0 and therefor i cant write to it. Here is complete class code:
class CFileTransferCS
{
wstring m_wszfile;
wstring m_wszLocalUserFolderPath;
int m_nChunkIndex;
int m_nWrittenBytes;
int m_nFileSize;
FILE* m_hFile;
CFileTransferCS( const CFileTransferCS& c ){}
CFileTransferCS& operator=( const CFileTransferCS& c ){}
public:
CFileTransferCS( );
CFileTransferCS( wstring file, uint32_t size );
void OnFileChunk( char* FileChunk, int size );
void Init( wstring file, uint32_t size );
void SetLocalUserLocalPath( wstring path );
};
CFileTransferCS::CFileTransferCS( )
{
m_hFile = NULL;
m_wszLocalUserFolderPath = L"";
m_nChunkIndex = 0;
m_nWrittenBytes = 0;
}
CFileTransferCS::CFileTransferCS( wstring file, uint32_t size )
{
m_nChunkIndex = 0;
m_nWrittenBytes = 0;
m_wszfile = file;
m_nFileSize = size;
wstring wszFullFilePath = m_wszLocalUserFolderPath + m_wszfile.substr( m_wszfile.find_last_of(L"\\") + 1 );
// string fp = string( file.begin(),file.end() );
string fp ="test.bin"; //for testing purposes
this->m_hFile = fopen(fp.c_str(),"wb");
printf("fp: %s hFile %d\n",fp.c_str(),this->m_hFile); //everything's fine here...
if(!this->m_hFile)
{
perror ("cant open file ");
}
}
void CFileTransferCS::SetLocalUserLocalPath( wstring path )
{
m_wszLocalUserFolderPath = path;
}
void CFileTransferCS::Init( wstring file, uint32_t size )
{
// If previous transfer session got interrupted for whatever reason
// close and delete old file and open new one
if( this->m_hFile )
{
printf("init CS transfer: deleting old file///\n");
fclose( this->m_hFile );
string fp = string( file.begin(),file.end() );
if( remove( fp.c_str() ))
{
//cant delete file...
}
}
CFileTransferCS( file, size );
}
void CFileTransferCS::OnFileChunk( char* FileChunk, int size )
{
for (;;)
{
printf("ofc: hFile %d\n",this->m_hFile); //m_hFile is 0 here...
if( !this->m_hFile )
{
// m_pofFile->open("kurac.txt",fstream::out);
printf("file not opened!\n");
break;
}
int nBytesWritten = fwrite( FileChunk, 1, size, this->m_hFile );
if( !nBytesWritten )
{
perror("file write!!\n");
break;
}
m_nWrittenBytes+=size;
if( m_nWrittenBytes == m_nFileSize )
{
fclose( m_hFile );
printf("file uplaod transfer finished!!!\n");
}
break;
}
printf("CFileTransferCS::OnFileChunk size: %d m_nWrittenBytes: %d m_nFileSize: %d\n",size,m_nWrittenBytes,m_nFileSize);
}
final edit:
I got it.. Calling explicitly CFileTransferCS( wstring file, uint32_t size ) constructor made problems.. Calling constructor like this explicitly caused that this pointer in it wasnt original one(that Init function was using) so when i was opening file from it and saving handle to m_hFile, i was doing it in some other object(now im not sure if CFileTransferCS(..) call allocated memory for CFileTransferCS object or it corrupted some other part of memory randomly.. will check it out with IDA later on )
Thanks to everyone and my apologies.
Regards, Mike –

Answer 1

#MikeJacksons answer:
Calling explicitly CFileTransferCS( wstring file, uint32_t size ) constructor made problems. Calling constructor like this explicitly caused that this pointer in it wasnt original one(that Init function was using) so when i was opening file from it and saving handle to m_hFile, i was doing it in some other object(now im not sure if CFileTransferCS(..) call allocated memory for CFileTransferCS object or it corrupted some other part of memory randomly.. will check it out with IDA later on ) Thanks everyone and my apologies.
Removed: CFileTransferCS( file, size );
(No need to appologize Mike, looks like you did a great job hunting down the bug).