* Skeleton of the privileged worker program.

* Some refactoring: put the NAR archive integer/string serialisation
  code in a separate file so it can be reused by the worker protocol
  implementation.

src/libutil/serialise.cc

@@ -0,0 +1,87 @@
+#include "serialise.hh"
+#include "util.hh"
+
+
+namespace nix {
+
+
+void FdSink::operator () (const unsigned char * data, unsigned int len)
+{
+    writeFull(fd, data, len);
+}
+
+
+void FdSource::operator () (unsigned char * data, unsigned int len)
+{
+    readFull(fd, data, len);
+}
+
+
+void writePadding(unsigned int len, Sink & sink)
+{
+    if (len % 8) {
+        unsigned char zero[8];
+        memset(zero, 0, sizeof(zero));
+        sink(zero, 8 - (len % 8));
+    }
+}
+
+
+void writeInt(unsigned int n, Sink & sink)
+{
+    unsigned char buf[8];
+    memset(buf, 0, sizeof(buf));
+    buf[0] = n & 0xff;
+    buf[1] = (n >> 8) & 0xff;
+    buf[2] = (n >> 16) & 0xff;
+    buf[3] = (n >> 24) & 0xff;
+    sink(buf, sizeof(buf));
+}
+
+
+void writeString(const string & s, Sink & sink)
+{
+    unsigned int len = s.length();
+    writeInt(len, sink);
+    sink((const unsigned char *) s.c_str(), len);
+    writePadding(len, sink);
+}
+
+
+void readPadding(unsigned int len, Source & source)
+{
+    if (len % 8) {
+        unsigned char zero[8];
+        unsigned int n = 8 - (len % 8);
+        source(zero, n);
+        for (unsigned int i = 0; i < n; i++)
+            if (zero[i]) throw Error("non-zero padding");
+    }
+}
+
+
+unsigned int readInt(Source & source)
+{
+    unsigned char buf[8];
+    source(buf, sizeof(buf));
+    if (buf[4] || buf[5] || buf[6] || buf[7])
+        throw Error("implementation cannot deal with > 32-bit integers");
+    return
+        buf[0] |
+        (buf[1] << 8) |
+        (buf[2] << 16) |
+        (buf[3] << 24);
+}
+
+
+string readString(Source & source)
+{
+    unsigned int len = readInt(source);
+    char buf[len];
+    source((unsigned char *) buf, len);
+    readPadding(len, source);
+    return string(buf, len);
+}
+
+ 
+}