diff -r 21274e5950af -r a1f4cb076d2f src/server/util/writer.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/server/util/writer.c	Sat Sep 24 16:26:10 2022 +0200
@@ -0,0 +1,124 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 2018 Olaf Wintermann. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *
+ *   2. Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in the
+ *      documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "writer.h"
+
+void writer_init(Writer *w, SYS_NETFD fd, char *buf, size_t len) {
+    w->fd = fd;
+    w->write = (wr_writefunc)net_write;
+    w->buffer = buf;
+    w->size = len;
+    w->pos = 0;
+    w->error = 0;
+}
+
+void writer_init_with_stream(Writer *w, void *stream, wr_writefunc writefunc, char *buf, size_t len) {
+    w->fd = stream;
+    w->write = writefunc;
+    w->buffer = buf;
+    w->size = len;
+    w->pos = 0;
+    w->error = 0;
+}
+
+int writer_flush(Writer *w) {
+    if(w->error) {
+        return w->error;
+    }
+    
+    size_t pos = 0;
+    size_t len = w->pos;
+    
+    while(len > 0) {
+        //fwrite(w->buffer+pos, 1, len, stdout);
+        //fflush(stdout);
+        ssize_t r = w->write(w->fd, w->buffer + pos, len);
+        if(r <= 0) {
+            break;
+        }
+        len -= r;
+        pos += r;
+    }
+    
+    if(pos != w->pos) {
+        w->error = 1;
+        return 1;
+    }
+    
+    w->pos = 0;
+    return 0;
+}
+
+int writer_put(Writer *w, const char *s, size_t len) {
+    if(w->error) {
+        return w->error;
+    }
+    
+    // available bytes
+    size_t a = w->size - w->pos;
+    if(a == 0) {
+        if(writer_flush(w)) {
+            return 1;
+        }
+    }
+    
+    size_t cplen = len > a ? a : len; // number of bytes we can copy
+    memcpy(w->buffer+w->pos, s, cplen);
+    w->pos += cplen;
+    
+    if(cplen < len) {
+        // not all bytes copied -> call writer_put again
+        // the number of available bytes is 0 then, therefore flush is called
+        return writer_put(w, s + cplen, len - cplen);
+    } else {
+        return 0;
+    }
+}
+
+int writer_puts(Writer *w, sstr_t s) {
+    return writer_put(w, s.ptr, s.length);
+}
+
+int writer_putc(Writer *w, char c) {
+    if(w->pos == w->size) {
+        if(writer_flush(w)) {
+            return 1;
+        }
+    }
+    w->buffer[w->pos++] = c;
+    return 0;
+}
+
+int writer_fwrite(const void *s, size_t size, size_t nelem, Writer *out) {
+    int w = writer_put(out, s, size*nelem);
+    return w/size;
+}