1 files changed, 150 insertions, 95 deletions
diff --git a/src/nix-worker/main.cc b/src/nix-worker/main.cc
index cf550895e4b2..17e892c648fc 100644
--- a/src/nix-worker/main.cc
+++ b/src/nix-worker/main.cc
@@ -10,7 +10,7 @@
 using namespace nix;
 
 
-Path readStorePath(Source & from)
+static Path readStorePath(Source & from)
 {
     Path path = readString(from);
     assertStorePath(path);
@@ -18,7 +18,7 @@ Path readStorePath(Source & from)
 }
 
 
-PathSet readStorePaths(Source & from)
+static PathSet readStorePaths(Source & from)
 {
     PathSet paths = readStringSet(from);
     for (PathSet::iterator i = paths.begin(); i != paths.end(); ++i)
@@ -27,123 +27,178 @@ PathSet readStorePaths(Source & from)
 }
 
 
-void processConnection(Source & from, Sink & to)
+static Sink * _to; /* !!! should make writeToStderr an object */
+bool canSendStderr;
+
+
+static void tunnelStderr(const unsigned char * buf, size_t count)
 {
-    store = boost::shared_ptr<StoreAPI>(new LocalStore(true));
+    writeFull(STDERR_FILENO, buf, count);
+    if (canSendStderr) {
+        try {
+            writeInt(STDERR_NEXT, *_to);
+            writeString(string((char *) buf, count), *_to);
+        } catch (...) {
+            /* Write failed; that means that the other side is
+               gone. */
+            canSendStderr = false;
+            throw;
+        }
+    }
+}
 
-    unsigned int magic = readInt(from);
-    if (magic != WORKER_MAGIC_1) throw Error("protocol mismatch");
 
-    writeInt(WORKER_MAGIC_2, to);
+/* startWork() means that we're starting an operation for which we
+   want to send out stderr to the client. */
+static void startWork()
+{
+    canSendStderr = true;
+}
 
-    debug("greeting exchanged");
 
-    bool quit = false;
+/* stopWork() means that we're done; stop sending stderr to the
+   client. */
+static void stopWork()
+{
+    canSendStderr = false;
+    writeInt(STDERR_LAST, *_to);
+}
 
-    unsigned int opCount = 0;
-    
-    do {
+
+static void performOp(Source & from, Sink & to, unsigned int op)
+{
+    switch (op) {
+
+#if 0        
+    case wopQuit: {
+        /* Close the database. */
+        store.reset((StoreAPI *) 0);
+        writeInt(1, to);
+        break;
+    }
+#endif
+
+    case wopIsValidPath: {
+        Path path = readStorePath(from);
+        writeInt(store->isValidPath(path), to);
+        break;
+    }
+
+    case wopHasSubstitutes: {
+        Path path = readStorePath(from);
+        writeInt(store->hasSubstitutes(path), to);
+        break;
+    }
+
+    case wopQueryPathHash: {
+        Path path = readStorePath(from);
+        writeString(printHash(store->queryPathHash(path)), to);
+        break;
+    }
+
+    case wopQueryReferences:
+    case wopQueryReferrers: {
+        Path path = readStorePath(from);
+        PathSet paths;
+        if (op == wopQueryReferences)
+            store->queryReferences(path, paths);
+        else
+            store->queryReferrers(path, paths);
+        writeStringSet(paths, to);
+        break;
+    }
+
+    case wopAddToStore: {
+        /* !!! uberquick hack */
+        string baseName = readString(from);
+        bool fixed = readInt(from) == 1;
+        bool recursive = readInt(from) == 1;
+        string hashAlgo = readString(from);
         
-        WorkerOp op = (WorkerOp) readInt(from);
+        Path tmp = createTempDir();
+        Path tmp2 = tmp + "/" + baseName;
+        restorePath(tmp2, from);
 
-        opCount++;
+        writeString(store->addToStore(tmp2, fixed, recursive, hashAlgo), to);
+            
+        deletePath(tmp);
+        break;
+    }
 
-        switch (op) {
+    case wopAddTextToStore: {
+        string suffix = readString(from);
+        string s = readString(from);
+        PathSet refs = readStorePaths(from);
+        writeString(store->addTextToStore(suffix, s, refs), to);
+        break;
+    }
 
-        case wopQuit: {
-            /* Close the database. */
-            store.reset((StoreAPI *) 0);
-            writeInt(1, to);
-            quit = true;
-            break;
-        }
+    case wopBuildDerivations: {
+        PathSet drvs = readStorePaths(from);
+        startWork();
+        store->buildDerivations(drvs);
+        stopWork();
+        writeInt(1, to);
+        break;
+    }
 
-        case wopIsValidPath: {
-            Path path = readStorePath(from);
-            writeInt(store->isValidPath(path), to);
-            break;
-        }
+    case wopEnsurePath: {
+        Path path = readStorePath(from);
+        store->ensurePath(path);
+        writeInt(1, to);
+        break;
+    }
 
-        case wopHasSubstitutes: {
-            Path path = readStorePath(from);
-            writeInt(store->hasSubstitutes(path), to);
-            break;
-        }
+    case wopAddTempRoot: {
+        Path path = readStorePath(from);
+        store->addTempRoot(path);
+        writeInt(1, to);
+        break;
+    }
 
-        case wopQueryPathHash: {
-            Path path = readStorePath(from);
-            writeString(printHash(store->queryPathHash(path)), to);
-            break;
-        }
+    case wopSyncWithGC: {
+        store->syncWithGC();
+        writeInt(1, to);
+        break;
+    }
 
-        case wopQueryReferences:
-        case wopQueryReferrers: {
-            Path path = readStorePath(from);
-            PathSet paths;
-            if (op == wopQueryReferences)
-                store->queryReferences(path, paths);
-            else
-                store->queryReferrers(path, paths);
-            writeStringSet(paths, to);
-            break;
-        }
+    default:
+        throw Error(format("invalid operation %1%") % op);
+    }
+}
 
-        case wopAddToStore: {
-            /* !!! uberquick hack */
-            string baseName = readString(from);
-            bool fixed = readInt(from) == 1;
-            bool recursive = readInt(from) == 1;
-            string hashAlgo = readString(from);
 
-            Path tmp = createTempDir();
-            Path tmp2 = tmp + "/" + baseName;
-            restorePath(tmp2, from);
+static void processConnection(Source & from, Sink & to)
+{
+    store = boost::shared_ptr<StoreAPI>(new LocalStore(true));
 
-            writeString(store->addToStore(tmp2, fixed, recursive, hashAlgo), to);
-            
-            deletePath(tmp);
-            break;
-        }
+    unsigned int magic = readInt(from);
+    if (magic != WORKER_MAGIC_1) throw Error("protocol mismatch");
 
-        case wopAddTextToStore: {
-            string suffix = readString(from);
-            string s = readString(from);
-            PathSet refs = readStorePaths(from);
-            writeString(store->addTextToStore(suffix, s, refs), to);
-            break;
-        }
+    writeInt(WORKER_MAGIC_2, to);
 
-        case wopBuildDerivations: {
-            PathSet drvs = readStorePaths(from);
-            store->buildDerivations(drvs);
-            writeInt(1, to);
-            break;
-        }
+    debug("greeting exchanged");
 
-        case wopEnsurePath: {
-            Path path = readStorePath(from);
-            store->ensurePath(path);
-            writeInt(1, to);
-            break;
-        }
+    _to = &to;
+    canSendStderr = false;
+    writeToStderr = tunnelStderr;
 
-        case wopAddTempRoot: {
-            Path path = readStorePath(from);
-            store->addTempRoot(path);
-            writeInt(1, to);
-            break;
-        }
+    bool quit = false;
 
-        case wopSyncWithGC: {
-            store->syncWithGC();
-            writeInt(1, to);
-            break;
-        }
+    unsigned int opCount = 0;
+    
+    do {
+        WorkerOp op = (WorkerOp) readInt(from);
 
-        default:
-            throw Error(format("invalid operation %1%") % op);
+        opCount++;
+
+        try {
+            performOp(from, to, op);
+        } catch (Error & e) {
+            writeInt(STDERR_ERROR, *_to);
+            writeString(e.msg(), to);
         }
-        
+
     } while (!quit);
 
     printMsg(lvlError, format("%1% worker operations") % opCount);