Replace misuse of bufSize() with bufUsed().

bufSize() should only be used whem checking the total size of the buffer, not how much of it is currently used.

In these cases bufUsed() and bufSize() are returning the same value but benign-looking code changes could break this assumption.

src/common/crypto/cipherBlock.c

@@ -392,7 +392,7 @@ cipherBlockNew(CipherMode mode, CipherType cipherType, const Buffer *pass, const
     FUNCTION_LOG_END();
 
     ASSERT(pass != NULL);
-    ASSERT(bufSize(pass) > 0);
+    ASSERT(bufUsed(pass) > 0);
 
     // Init crypto subsystem
     cryptoInit();

src/common/io/read.c

@@ -282,7 +282,7 @@ ioReadLineParam(IoRead *this, bool allowEof)
 
             // If the buffer is full then the linefeed (if it exists) is outside the buffer
             if (bufFull(this->output))
-                THROW_FMT(FileReadError, "unable to find line in %zu byte buffer", bufSize(this->output));
+                THROW_FMT(FileReadError, "unable to find line in %zu byte buffer", bufUsed(this->output));
 
             if (ioReadEof(this))
             {

src/common/type/xml.c

@@ -451,7 +451,7 @@ xmlDocumentNewBuf(const Buffer *buffer)
     FUNCTION_TEST_END();
 
     ASSERT(buffer != NULL);
-    ASSERT(bufSize(buffer) > 0);
+    ASSERT(bufUsed(buffer) > 0);
 
     FUNCTION_TEST_RETURN(xmlDocumentNewC(bufPtrConst(buffer), bufUsed(buffer)));
 }

src/storage/s3/storage.c

@@ -804,7 +804,7 @@ storageS3PathRemoveInternal(StorageS3 *this, HttpRequest *request, XmlDocument *
         const Buffer *response = httpResponseContent(storageS3ResponseP(request));
 
         // Nothing is returned when there are no errors
-        if (bufSize(response) > 0)
+        if (bufUsed(response) > 0)
         {
             XmlNodeList *errorList = xmlNodeChildList(xmlDocumentRoot(xmlDocumentNewBuf(response)), S3_XML_TAG_ERROR_STR);