Add a basic logging implementation

include/olm/logging.hh

+/* Copyright 2016 OpenMarket Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef OLM_LOGGING_HH_
+#define OLM_LOGGING_HH_
+
+namespace olm {
+
+const unsigned int LOG_FATAL   = 1;
+const unsigned int LOG_ERROR   = 2;
+const unsigned int LOG_WARNING = 3;
+const unsigned int LOG_INFO    = 4;
+const unsigned int LOG_DEBUG   = 5;
+
+void set_log_level(unsigned int log_level);
+
+__attribute__((__format__ (__printf__, 3, 4)))
+void logf(unsigned int level, const char *category,
+          const char *format, ...);
+
+} // namespace olm
+
+#endif /* OLM_LOGGING_HH_ */

include/olm/olm.hh

-/* Copyright 2015 OpenMarket Ltd
+/* Copyright 2015, 2016 OpenMarket Ltd
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,7 +51,7 @@ OlmSession * olm_session(
 );
 
 /** Initialise a utility object using the supplied memory
- *  The supplied memory must be at least olm_session_size() bytes */
+ *  The supplied memory must be at least olm_utility_size() bytes */
 OlmUtility * olm_utility(
     void * memory
 );
@@ -415,6 +415,13 @@ size_t olm_ed25519_verify(
     void * signature, size_t signature_length
 );
 
+/**
+ * Set the log level. By default, 1, which logs only FATAL messages.
+ */
+void olm_set_log_level(
+    unsigned int level
+);
+
 #ifdef __cplusplus
 }
 #endif

javascript/olm_post.js

@@ -383,4 +383,5 @@ olm_exports["Account"] = Account;
 olm_exports["Session"] = Session;
 olm_exports["Utility"] = Utility;
 
+olm_exports['set_log_level'] = Module['_olm_set_log_level'];
 }();

src/logging.cpp

+/* Copyright 2016 OpenMarket Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "olm/logging.hh"
+
+#include <cstdarg>
+#include <cstdio>
+
+namespace olm {
+
+static unsigned int log_level = 1;
+
+void set_log_level(unsigned int level) {
+    log_level = level;
+}
+
+void logf(unsigned int level, const char *category,
+          const char *format, ...) {
+    if (level > log_level) {
+        return;
+    }
+
+    fputs(category, stdout);
+    fputs(": ", stdout);
+
+    va_list ap;
+    va_start(ap, format);
+    vprintf(format, ap);
+    va_end(ap);
+
+    putchar('\n');
+}
+
+} // namespace olm

src/olm.cpp

@@ -19,6 +19,7 @@
 #include "olm/base64.hh"
 #include "olm/cipher.hh"
 #include "olm/memory.hh"
+#include "olm/logging.hh"
 
 #include <new>
 #include <cstring>
@@ -818,4 +819,10 @@ size_t olm_ed25519_verify(
     );
 }
 
+void olm_set_log_level(
+    unsigned int level
+) {
+    olm::set_log_level(level);
+}
+
 }