Cpp: Handle empty recipients consistently

* lang/cpp/src/context.cpp (Context::getKeysFromRecipients):
New helper.
(Context::encrypt, Context::startEncryption, Context::signAndEncrypt)
(Context::startCombinedSigningAndEncryption): Use new helper.
* lang/cpp/src/context.h (Context::getKeysFromRecipients): Add
as private helper.

--
bf776ce was incomplete as the code to handle recpients
was duplicated four times. This is now unified and constently
uses a nullptr instead of an empty array.

lang/cpp/src/context.cpp

@@ -1109,6 +1109,22 @@ static gpgme_encrypt_flags_t encryptflags2encryptflags(Context::EncryptionFlags
     return static_cast<gpgme_encrypt_flags_t>(result);
 }
 
+gpgme_key_t *const Context::getKeysFromRecipients(const std::vector<Key> &recipients)
+{
+    if (recipients.empty()) {
+        return nullptr;
+    }
+    gpgme_key_t *ret = new gpgme_key_t[ recipients.size() + 1 ];
+    gpgme_key_t *keys_it = ret;
+    for (std::vector<Key>::const_iterator it = recipients.begin() ; it != recipients.end() ; ++it) {
+        if (it->impl()) {
+            *keys_it++ = it->impl();
+        }
+    }
+    *keys_it++ = 0;
+    return ret;
+}
+
 EncryptionResult Context::encrypt(const std::vector<Key> &recipients, const Data &plainText, Data &cipherText, EncryptionFlags flags)
 {
     d->lastop = Private::Encrypt;
@@ -1117,18 +1133,12 @@ EncryptionResult Context::encrypt(const std::vector<Key> &recipients, const Data
     }
     const Data::Private *const pdp = plainText.impl();
     Data::Private *const cdp = cipherText.impl();
-    gpgme_key_t *const keys = new gpgme_key_t[ recipients.size() + 1 ];
+    gpgme_key_t *const keys = getKeysFromRecipients(recipients);
-    gpgme_key_t *keys_it = keys;
+    d->lasterr = gpgme_op_encrypt(d->ctx, keys, encryptflags2encryptflags(flags),
-    for (std::vector<Key>::const_iterator it = recipients.begin() ; it != recipients.end() ; ++it) {
-        if (it->impl()) {
-            *keys_it++ = it->impl();
-        }
-    }
-    *keys_it++ = 0;
-    d->lasterr = gpgme_op_encrypt(d->ctx, recipients.empty() ? nullptr : keys,
-                                  encryptflags2encryptflags(flags),
                                   pdp ? pdp->data : 0, cdp ? cdp->data : 0);
+    if (keys) {
         delete[] keys;
+    }
     return EncryptionResult(d->ctx, Error(d->lasterr));
 }
 
@@ -1149,17 +1159,12 @@ Error Context::startEncryption(const std::vector<Key> &recipients, const Data &p
     }
     const Data::Private *const pdp = plainText.impl();
     Data::Private *const cdp = cipherText.impl();
-    gpgme_key_t *const keys = new gpgme_key_t[ recipients.size() + 1 ];
+    gpgme_key_t *const keys = getKeysFromRecipients(recipients);
-    gpgme_key_t *keys_it = keys;
-    for (std::vector<Key>::const_iterator it = recipients.begin() ; it != recipients.end() ; ++it) {
-        if (it->impl()) {
-            *keys_it++ = it->impl();
-        }
-    }
-    *keys_it++ = 0;
     d->lasterr = gpgme_op_encrypt_start(d->ctx, keys, encryptflags2encryptflags(flags),
                                         pdp ? pdp->data : 0, cdp ? cdp->data : 0);
+    if (keys) {
         delete[] keys;
+    }
     return Error(d->lasterr);
 }
 
@@ -1177,17 +1182,12 @@ std::pair<SigningResult, EncryptionResult> Context::signAndEncrypt(const std::ve
     d->lastop = Private::SignAndEncrypt;
     const Data::Private *const pdp = plainText.impl();
     Data::Private *const cdp = cipherText.impl();
-    gpgme_key_t *const keys = new gpgme_key_t[ recipients.size() + 1 ];
+    gpgme_key_t *const keys = getKeysFromRecipients(recipients);
-    gpgme_key_t *keys_it = keys;
-    for (std::vector<Key>::const_iterator it = recipients.begin() ; it != recipients.end() ; ++it) {
-        if (it->impl()) {
-            *keys_it++ = it->impl();
-        }
-    }
-    *keys_it++ = 0;
     d->lasterr = gpgme_op_encrypt_sign(d->ctx, keys, encryptflags2encryptflags(flags),
                                        pdp ? pdp->data : 0, cdp ? cdp->data : 0);
+    if (keys) {
         delete[] keys;
+    }
     return std::make_pair(SigningResult(d->ctx, Error(d->lasterr)),
                           EncryptionResult(d->ctx, Error(d->lasterr)));
 }
@@ -1197,17 +1197,12 @@ Error Context::startCombinedSigningAndEncryption(const std::vector<Key> &recipie
     d->lastop = Private::SignAndEncrypt;
     const Data::Private *const pdp = plainText.impl();
     Data::Private *const cdp = cipherText.impl();
-    gpgme_key_t *const keys = new gpgme_key_t[ recipients.size() + 1 ];
+    gpgme_key_t *const keys = getKeysFromRecipients(recipients);
-    gpgme_key_t *keys_it = keys;
-    for (std::vector<Key>::const_iterator it = recipients.begin() ; it != recipients.end() ; ++it) {
-        if (it->impl()) {
-            *keys_it++ = it->impl();
-        }
-    }
-    *keys_it++ = 0;
     d->lasterr = gpgme_op_encrypt_sign_start(d->ctx, keys, encryptflags2encryptflags(flags),
                  pdp ? pdp->data : 0, cdp ? cdp->data : 0);
+    if (keys) {
         delete[] keys;
+    }
     return Error(d->lasterr);
 }
 

lang/cpp/src/context.h

@@ -368,6 +368,11 @@ public:
     {
         return d;
     }
+private:
+    // Helper functions that need to be context because they rely
+    // on the "Friendlyness" of context to access the gpgme types.
+    gpgme_key_t *const getKeysFromRecipients(const std::vector<Key> &recipients);
+
 private:
     Private *const d;