(MFC) Azure File Service: Upload Large File

Sample code to upload a large file to a directory in a share in the Azure File Service. A file is uploaded by first creating the file in the Azure share and then writing ranges of bytes to the file. Azure imposes a 4MB limit for each PUT to write a range. Files larger than 4MB need to be uploaded by making multiple "Put Range" calls. This example uploads a large file requiring multiple "Put Range" calls.

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See Also: Using MFC CString in Chilkat

#include <CkRest.h>
#include <CkFileAccess.h>
#include <CkAuthAzureStorage.h>
#include <CkStringBuilder.h>
#include <CkBinData.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // Azure File Service Example: Upload a large file.  
    // See:  https://docs.microsoft.com/en-us/rest/api/storageservices/create-share
    // also see: https://docs.microsoft.com/en-us/rest/api/storageservices/put-range

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkRest rest;

    // Connect to the Azure Storage Blob Service
    bool bTls = true;
    int port = 443;
    bool bAutoReconnect = true;
    // In this example, the storage account name is "chilkat".
    bool success = rest.Connect("chilkat.file.core.windows.net",port,bTls,bAutoReconnect);
    if (success != true) {
        strOut.append(rest.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // This example will upload a larger file.
    const char *localFilePath = "qa_data/zips/somethingBig.zip";
    CkFileAccess fac;
    // Note: The FileSize method returns a signed 32-bit integer.  If the file is potentially larger than 2GB, call FileSizeStr instead to return
    // the size of the file as a string, then convert to an integer value.
    int szLocalFile = fac.FileSize(localFilePath);
    if (szLocalFile < 0) {
        strOut.append(fac.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Provide Azure Cloud credentials for the REST calls.
    CkAuthAzureStorage azAuth;
    azAuth.put_AccessKey("AZURE_ACCESS_KEY");
    // The account name used here should match the 1st part of the domain passed in the call to Connect (above).
    azAuth.put_Account("chilkat");
    azAuth.put_Scheme("SharedKey");
    azAuth.put_Service("File");
    // This causes the "x-ms-version: 2020-08-04" header to be automatically added.
    azAuth.put_XMsVersion("2020-08-04");
    success = rest.SetAuthAzureStorage(azAuth);

    // Note: The application does not need to explicitly set the following
    // headers: x-ms-date, Authorization.  These headers
    // are automatically set by Chilkat.

    // However, a few additional headers are required for the "Create File" operation:
    rest.AddHeader("x-ms-type","file");

    // This required header specifies the final size of the file (or the maximum size it can be).
    CkStringBuilder sbFileSize;
    sbFileSize.AppendInt(szLocalFile);
    rest.AddHeader("x-ms-content-length",sbFileSize.getAsString());

    // Send a PUT request to create the file (or replace the file if it already exists).
    // This will initialize the file in the Azure file storage.  To upload content, we'll need
    // to do the "Put Range" operation one or more times.

    // The following will create the file "somethingBig.zip" in the share "pip"
    const char *responseStr = rest.fullRequestNoBody("PUT","/pip/somethingBig.zip");
    if (rest.get_LastMethodSuccess() != true) {
        strOut.append(rest.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // When successful, the Azure File Service will respond with a 201 (Created) response status code,
    // with no XML response body.  If an error response is returned, there will be an XML response body.

    if (rest.get_ResponseStatusCode() != 201) {
        // Examine the request/response to see what happened.
        strOut.append("response status code = ");
        strOut.appendInt(rest.get_ResponseStatusCode());
        strOut.append("\r\n");
        strOut.append("response status text = ");
        strOut.append(rest.responseStatusText());
        strOut.append("\r\n");
        strOut.append("response header: ");
        strOut.append(rest.responseHeader());
        strOut.append("\r\n");
        strOut.append("response body (if any): ");
        strOut.append(responseStr);
        strOut.append("\r\n");
        strOut.append("---");
        strOut.append("\r\n");
        strOut.append("LastRequestStartLine: ");
        strOut.append(rest.lastRequestStartLine());
        strOut.append("\r\n");
        strOut.append("LastRequestHeader: ");
        strOut.append(rest.lastRequestHeader());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    strOut.append("Successfully created somethingBig.zip");
    strOut.append("\r\n");

    // --------------------------------------------------------------------------------
    // Upload the file data...

    // Make sure the headers from the "Create File" operation are removed.
    rest.ClearAllHeaders();

    // The x-ms-write header is required for each "Put Range" request.
    rest.AddHeader("x-ms-write","update");

    CkStringBuilder sbRange;
    CkStringBuilder sbResponseBody;
    CkBinData bdFileData;

    // Open the file.  We'll be reading and uploading in chunks..
    success = fac.OpenForRead(localFilePath);
    if (success != true) {
        strOut.append(fac.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    int numBytesLeft = szLocalFile;
    int curIndex = 0;
    while (numBytesLeft > 0) {

        int chunkSize = numBytesLeft;
        // Azure allows for 4MB max chunks  (4 x 1024 x 1024 = 4194304)
        if (chunkSize > 4194304) {
            chunkSize = 4194304;
        }

        // The only tricky part here is to correctly add the x-ms-range header.
        // It will be formatted like this:
        // x-ms-range: bytes=0-759623
        sbRange.Clear();
        sbRange.Append("bytes=");
        sbRange.AppendInt(curIndex);
        sbRange.Append("-");
        sbRange.AppendInt(curIndex + chunkSize - 1);

        // This replaces the header if it already exists..
        rest.AddHeader("x-ms-range",sbRange.getAsString());

        // Read the next chunk from the local file.
        bdFileData.Clear();
        success = fac.FileReadBd(chunkSize,bdFileData);

        success = rest.FullRequestBd("PUT","/pip/somethingBig.zip?comp=range",bdFileData,sbResponseBody);
        if (success != true) {
            // This would indicate a failure where no response was received.
            strOut.append(rest.lastErrorText());
            strOut.append("\r\n");
            SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
            return;
        }

        // A 201 response indicates the chunk was uploaded.
        if (rest.get_ResponseStatusCode() != 201) {
            // Examine the request/response to see what happened.
            strOut.append("response status code = ");
            strOut.appendInt(rest.get_ResponseStatusCode());
            strOut.append("\r\n");
            strOut.append("response status text = ");
            strOut.append(rest.responseStatusText());
            strOut.append("\r\n");
            strOut.append("response header: ");
            strOut.append(rest.responseHeader());
            strOut.append("\r\n");
            strOut.append("response body (if any): ");
            strOut.append(responseStr);
            strOut.append("\r\n");
            strOut.append("---");
            strOut.append("\r\n");
            strOut.append("LastRequestStartLine: ");
            strOut.append(rest.lastRequestStartLine());
            strOut.append("\r\n");
            strOut.append("LastRequestHeader: ");
            strOut.append(rest.lastRequestHeader());
            strOut.append("\r\n");
            SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
            return;
        }

        strOut.append("Uploaded chunk from ");
        strOut.appendInt(curIndex);
        strOut.append(" to ");
        strOut.appendInt(curIndex + chunkSize - 1);
        strOut.append("\r\n");

        curIndex = curIndex + chunkSize;
        numBytesLeft = numBytesLeft - chunkSize;
    }

    fac.FileClose();

    strOut.append("success.");
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }