C++ gsoap mime/dime for binary files in windows

Question

Hello,

I'm pretty close to losing my head here ;)

I'm developing a service that uses gsoap. I would like to return a mime response. I have everything working, but when reading binary files, all kind of files like jpeg, pdf, etc... contains the \0 char several times over the data (if opened with notepad can see a lot of NUL).

So any code for reading a raw file fails miserably once it finds the end-of-file char. I have tried to replace the \0 but the file becomes incorrect to display.

I have also tried several methods including the example that comes with gsoap.

So resuming,

fstream generic code doesn't work.

for (i = 0; i < MAX_FILE_SIZE; i++)
    { if ((c = fgetc(fd)) == EOF)
        break;
      image.__ptr[i] = c;
    } 

doesn't work also

QFile::ReadAll works but when converting QString to char* the array is trimmed in the first NUL.

So, which is the best aproach to read an entire binary file? Its crazy how sometimes C++ at the basic.

Thanks in advance.

I have tried this as retnick suggested below

    UrlToPdf urlToPdf;  
urlToPdf.getUrl(&input, &result);  

QByteArray raw = urlToPdf.getPdf(QString(result.data.c_str()));  

int   size      = raw.toBase64().size();  
char* arraydata = new char[size];  
strcpy(arraydata, raw.toBase64().data());  

soap_set_mime(this, "MIME_boundary", NULL);  
if(soap_set_mime_attachment(this, arraydata, size, SOAP_MIME_BASE64, "application/pdf", NULL, NULL, NULL))  
{  
    soap_clr_mime(this);  

    soapMessage = this->error;  
}  

but no luck... the mime response is bigger than the actual file...

David G Ortega

Answer 1

to read binary files use fread() Once you read it treat it as an array of bytes not as a string. No string functions allowed.

EDIT: The gSOAP documentation section 14.1 explains how to send MIME attachments. I only refer to the relevant function (please read it all).

  int soap_set_mime_attachment(struct soap *soap, char *buf_ptr, size_t buf_size, 
        enum soap_mime_encoding encoding, 
        const char *type, const char *id, 
        const char *location, const char *description);

char *buf_ptr is your buffer. size_t buf_size is the length of your buffer.

So just do your QFile::ReadAll.

this gives you back a QByteArray. The QByteArray has the method

QByteArray QByteArray::toBase64 () const

this will return a

 QByteArray base64image = QByteArray::toBase64(rawImage);    

so now just do

soap_set_mime(soap, "MIME_boundary", "<[email protected]>"); 
/* add a base64 encoded image (base64image points to base64 data) */ 
soap_set_mime_attachment(soap, 
        base64image.data(), base64image.size(), 
        SOAP_MIME_BASE64, "image/jpeg", 
        "<[email protected]>", NULL, NULL); 

I have not tested this but should be close to finished.

Answer 2

QFile::ReadAll works but when converting QString to char* the array is trimmed in the first NUL.

Are you sure it's actually trimmed or you just can't print/view the array in the debugger [since C-style strings are 0 terminated]?

If the QString itself is not enough for your needs you may want to convert it to a std::vector or similar using the range constructor or range assign, you'll have lots less grief towards the how much data the container holds.

EDIT: Here's some sample code for fstream reading from a binary file:

std::ifstream image( <image_file_name>, std::ios_base::in | std::ios_base::binary );
std::istream_iterator< char > image_begin( image ), image_end;
std::vector< char > vctImage( image_begin, image_end ); 

The std::ios_base::binary is the most important part of the thing (similar to fopen/fread ["rb"] & probably QFile has something similar)

Also posting some sample code usually helps in getting the right answer.

HIH

Answer 3

Hi!!

I have the solution for this... As renick suggested I tried his idea but it failed without undestanding it so much... From a logical point of view recnick was right... bat the truth is that any king of string manipulation using QT QByteArray, std or mem is going to stop when findind the first \0 char, Qt QString can do it without problems but when converting it to c string (char*) the data will be again trimmed with the first \0

I found that using QDataStream::readRawData reads the file into a char* given the size to read. So thats how I accomplished the deal...

QFile file("test.pdf");
file.open(QIODevice::ReadOnly);

int         size   = file.size();
char*       buffer = new char[size];    
QDataStream stream(&file);
stream.readRawData(buffer, size);

soap_set_mime(this, "MIME_boundary", NULL);
if(soap_set_mime_attachment(this, buffer, size, SOAP_MIME_BINARY, "application/pdf", NULL, NULL, NULL))
{
    soap_clr_mime(this);

    soapMessage = this->error;
}

Note that in the line

if(soap_set_mime_attachment(this, buffer, size, SOAP_MIME_BINARY, "application/pdf", NULL, NULL, NULL))

I'm still using the size var instead of doing sizeof(buffer) or any other aproach since this one is going to trimm again the data qhen finding the first \0...

Hope this helps...

David G Ortega