5 files changed, 32 insertions, 19 deletions

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 706f646a6..ba89230b0 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1950,8 +1950,11 @@ void linkOrCopy(const Path & from, const Path & to)
         /* Hard-linking fails if we exceed the maximum link count on a
            file (e.g. 32000 of ext3), which is quite possible after a
            'nix-store --optimise'. FIXME: actually, why don't we just
-           bind-mount in this case? */
-        if (errno != EMLINK)
+           bind-mount in this case?
+           
+           It can also fail with EPERM in BeegFS v7 and earlier versions
+           which don't allow hard-links to other directories */
+        if (errno != EMLINK && errno != EPERM)
             throw SysError("linking '%s' to '%s'", to, from);
         copyPath(from, to);
     }
diff --git a/src/libstore/builtins/fetchurl.cc b/src/libstore/builtins/fetchurl.cc
index f3827684b..84c7d2082 100644
--- a/src/libstore/builtins/fetchurl.cc
+++ b/src/libstore/builtins/fetchurl.cc
@@ -58,13 +58,16 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
         }
     };
 
+    /* We always have one output, and if it's a fixed-output derivation (as
+       checked below) it must be the only output */
+    auto & output = drv.outputs.begin()->second;
+
     /* Try the hashed mirrors first. */
-    if (getAttr("outputHashMode") == "flat")
+    if (output.hash && output.hash->method == FileIngestionMethod::Flat)
         for (auto hashedMirror : settings.hashedMirrors.get())
             try {
                 if (!hasSuffix(hashedMirror, "/")) hashedMirror += '/';
-                auto ht = parseHashTypeOpt(getAttr("outputHashAlgo"));
-                auto h = Hash(getAttr("outputHash"), ht);
+                auto & h = output.hash->hash;
                 fetch(hashedMirror + printHashType(h.type) + "/" + h.to_string(Base16, false));
                 return;
             } catch (Error & e) {
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 6c49075ba..42551ef6b 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -404,7 +404,7 @@ static DerivationOutput readDerivationOutput(Source & in, const Store & store)
 {
     auto path = store.parseStorePath(readString(in));
     auto hashAlgo = readString(in);
-    const auto hash = readString(in);
+    auto hash = readString(in);
 
     std::optional<FixedOutputHash> fsh;
     if (hashAlgo != "") {
@@ -413,7 +413,7 @@ static DerivationOutput readDerivationOutput(Source & in, const Store & store)
             method = FileIngestionMethod::Recursive;
             hashAlgo = string(hashAlgo, 2);
         }
-        const HashType hashType = parseHashType(hashAlgo);
+        auto hashType = parseHashType(hashAlgo);
         fsh = FixedOutputHash {
             .method = std::move(method),
             .hash = Hash(hash, hashType),
@@ -463,11 +463,16 @@ Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv)
 void writeDerivation(Sink & out, const Store & store, const BasicDerivation & drv)
 {
     out << drv.outputs.size();
-    for (auto & i : drv.outputs)
+    for (auto & i : drv.outputs) {
         out << i.first
-            << store.printStorePath(i.second.path)
-            << i.second.hash->printMethodAlgo()
-            << i.second.hash->hash.to_string(Base16, false);
+            << store.printStorePath(i.second.path);
+        if (i.second.hash) {
+            out << i.second.hash->printMethodAlgo()
+                << i.second.hash->hash.to_string(Base16, false);
+        } else {
+            out << "" << "";
+        }
+    }
     writeStorePaths(store, out, drv.inputSrcs);
     out << drv.platform << drv.builder << drv.args;
     out << drv.env.size();
diff --git a/src/libutil/hash.cc b/src/libutil/hash.cc
index 70a18f9a0..e060700d9 100644
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@@ -104,6 +104,7 @@ static string printHash32(const Hash & hash)
 
 string printHash16or32(const Hash & hash)
 {
+    assert(hash.type);
     return hash.to_string(hash.type == htMD5 ? Base16 : Base32, false);
 }
 
@@ -365,14 +366,15 @@ HashType parseHashType(std::string_view s)
 string printHashType(HashType ht)
 {
     switch (ht) {
-    case htMD5: return "md5"; break;
-    case htSHA1: return "sha1"; break;
-    case htSHA256: return "sha256"; break;
-    case htSHA512: return "sha512"; break;
+    case htMD5: return "md5";
+    case htSHA1: return "sha1";
+    case htSHA256: return "sha256";
+    case htSHA512: return "sha512";
+    default:
+        // illegal hash type enum value internally, as opposed to external input
+        // which should be validated with nice error message.
+        abort();
     }
-    // illegal hash type enum value internally, as opposed to external input
-    // which should be validated with nice error message.
-    abort();
 }
 
 }
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index b51850ccf..a55295912 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -10,7 +10,7 @@ namespace nix {
 MakeError(BadHash, Error);
 
 
-enum HashType : char { htMD5, htSHA1, htSHA256, htSHA512 };
+enum HashType : char { htMD5 = 42, htSHA1, htSHA256, htSHA512 };
 
 
 const int md5HashSize = 16;