6 files changed, 40 insertions, 0 deletions
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index cf0e2ad1b13b..29817df9d6e8 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -820,6 +820,28 @@ PathSet LocalStore::queryDerivationOutputs(const Path & path)
 }
 
 
+StringSet LocalStore::queryDerivationOutputNames(const Path & path)
+{
+    SQLiteTxn txn(db);
+    
+    SQLiteStmtUse use(stmtQueryDerivationOutputs);
+    stmtQueryDerivationOutputs.bind(queryValidPathId(path));
+    
+    StringSet outputNames;
+    int r;
+    while ((r = sqlite3_step(stmtQueryDerivationOutputs)) == SQLITE_ROW) {
+        const char * s = (const char *) sqlite3_column_text(stmtQueryDerivationOutputs, 0);
+        assert(s);
+        outputNames.insert(s);
+    }
+    
+    if (r != SQLITE_DONE)
+        throwSQLiteError(db, format("error getting output names of `%1%'") % path);
+
+    return outputNames;
+}
+
+
 void LocalStore::startSubstituter(const Path & substituter, RunningSubstituter & run)
 {
     if (run.pid != -1) return;
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 4cb905f67231..2739c4eea69d 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -118,6 +118,8 @@ public:
     PathSet queryValidDerivers(const Path & path);
 
     PathSet queryDerivationOutputs(const Path & path);
+
+    StringSet queryDerivationOutputNames(const Path & path);
     
     PathSet querySubstitutablePaths();
     
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 942c5bcf1c7c..6e9921ede79f 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -326,6 +326,16 @@ PathSet RemoteStore::queryDerivationOutputs(const Path & path)
 }
 
 
+PathSet RemoteStore::queryDerivationOutputNames(const Path & path)
+{
+    openConnection();
+    writeInt(wopQueryDerivationOutputNames, to);
+    writeString(path, to);
+    processStderr();
+    return readStrings<PathSet>(from);
+}
+
+
 Path RemoteStore::addToStore(const Path & _srcPath,
     bool recursive, HashType hashAlgo, PathFilter & filter)
 {
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index 34a2d91dfcd1..c5853ef53646 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -41,6 +41,8 @@ public:
     
     PathSet queryDerivationOutputs(const Path & path);
     
+    StringSet queryDerivationOutputNames(const Path & path);
+
     bool hasSubstitutes(const Path & path);
     
     bool querySubstitutablePathInfo(const Path & path,
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index d4997c886207..14890f5225ad 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -140,6 +140,9 @@ public:
 
     /* Query the outputs of the derivation denoted by `path'. */
     virtual PathSet queryDerivationOutputs(const Path & path) = 0;
+
+    /* Query the output names of the derivation denoted by `path'. */
+    virtual StringSet queryDerivationOutputNames(const Path & path) = 0;
     
     /* Query whether a path has substitutes. */
     virtual bool hasSubstitutes(const Path & path) = 0;
diff --git a/src/libstore/worker-protocol.hh b/src/libstore/worker-protocol.hh
index 760d08a747ae..ef1e0993df28 100644
--- a/src/libstore/worker-protocol.hh
+++ b/src/libstore/worker-protocol.hh
@@ -39,6 +39,7 @@ typedef enum {
     wopClearFailedPaths = 25,
     wopQueryPathInfo = 26,
     wopImportPaths = 27,
+    wopQueryDerivationOutputNames = 28,
 } WorkerOp;