(C) Get a Google Drive Access Token using a JSON Private Key

Demonstrates how to get a Google Drive API access token using a JSON service account private key.

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#include <C_CkFileAccess.h>
#include <C_CkAuthGoogle.h>
#include <C_CkSocket.h>

void ChilkatSample(void)
    {
    HCkFileAccess fac;
    const char *jsonKey;
    HCkAuthGoogle gAuth;
    HCkSocket tlsSock;
    BOOL success;

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

    // First load the JSON key into a string.
    fac = CkFileAccess_Create();
    jsonKey = CkFileAccess_readEntireTextFile(fac,"qa_data/googleApi/chilkatcloud-b8826e030499.json","utf-8");
    if (CkFileAccess_getLastMethodSuccess(fac) != TRUE) {
        printf("%s\n",CkFileAccess_lastErrorText(fac));
        CkFileAccess_Dispose(fac);
        return;
    }

    gAuth = CkAuthGoogle_Create();
    CkAuthGoogle_putJsonKey(gAuth,jsonKey);

    // Choose a scope.
    CkAuthGoogle_putScope(gAuth,"https://www.googleapis.com/auth/drive");

    // Request an access token that is valid for this many seconds.
    CkAuthGoogle_putExpireNumSeconds(gAuth,3600);

    // If the application is requesting delegated access:
    // The email address of the user for which the application is requesting delegated access,
    // then set the email address here. (Otherwise leave it empty.)
    CkAuthGoogle_putSubEmailAddress(gAuth,"");

    // Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
    // The Chilkat socket object is used so that the connection can be established
    // through proxies or an SSH tunnel if desired.
    tlsSock = CkSocket_Create();
    success = CkSocket_Connect(tlsSock,"www.googleapis.com",443,TRUE,5000);
    if (success != TRUE) {
        printf("%s\n",CkSocket_lastErrorText(tlsSock));
        CkFileAccess_Dispose(fac);
        CkAuthGoogle_Dispose(gAuth);
        CkSocket_Dispose(tlsSock);
        return;
    }

    // Send the request to obtain the access token.
    success = CkAuthGoogle_ObtainAccessToken(gAuth,tlsSock);
    if (success != TRUE) {
        printf("%s\n",CkAuthGoogle_lastErrorText(gAuth));
        CkFileAccess_Dispose(fac);
        CkAuthGoogle_Dispose(gAuth);
        CkSocket_Dispose(tlsSock);
        return;
    }

    // Examine the access token:
    printf("Access Token: %s\n",CkAuthGoogle_accessToken(gAuth));


    CkFileAccess_Dispose(fac);
    CkAuthGoogle_Dispose(gAuth);
    CkSocket_Dispose(tlsSock);

    }