Making progress on util::dprintf

luprex/cpp/core/util.cpp

@@ -720,6 +720,63 @@ eng::string XYZ::debug_string() const {
     return oss.str();
 }
 
+
+void (*dprintf_hook)(const char *oneline);
+
+void hook_dprintf(void (*func)(const char *oneline)) {
+    dprintf_hook = func;
+}
+
+static void chop_up_dprintf(char *buffer, int size) {
+    // Drop the final newline, if any.  We're going
+    // to automatically end with a newline and we don't
+    // want to double up.
+    if ((size > 0) && (buffer[size-1] == '\n')) {
+        size -= 1;
+    }
+
+    // Chop it up into lines and call the hook one line
+    // at a time.  Replace control characters as we go.
+    const char *base = buffer;
+    for (int i = 0; i <= size; i++) {
+        if (buffer[i] < ' ') {
+            if ((buffer[i] == '\n') || (buffer[i] == 0)) {
+                buffer[i] = 0;
+                if (dprintf_hook == nullptr) {
+                    fprintf(stderr, "%s\n", base);
+                } else {
+                    dprintf_hook(base);
+                }
+                base = buffer + i + 1;
+            } else {
+                buffer[i] = ' ';
+            }
+        }
+    }
+    
+    // If we're sending to stderr, flush.  If not, then
+    // the hook routine is responsible for flushing its own
+    // output.
+    if (dprintf_hook == nullptr) {
+        fflush(stderr);
+    }
+}
+
+void dprintf(const char *format, ...) {
+    char buffer[256];
+    va_list args;
+    va_start (args, format);
+    int n = vsnprintf(buffer, 256, format, args);
+    if (n <= 255) {
+        chop_up_dprintf(buffer, n);
+    } else {
+        char *lbuffer = (char *)malloc(n + 1);
+        vsnprintf(lbuffer, n+1, format, args);
+        chop_up_dprintf(lbuffer, n);
+        free(lbuffer);
+    }
+}
+
 } // namespace util