libutil: convert readFileSource to a generator

Change-Id: I5f92b15fd367d46eb047d74ab6e317b4f51a46d3

src/libstore/binary-cache-store.cc

@@ -385,7 +385,7 @@ StorePath BinaryCacheStore::addToStore(
     if (method == FileIngestionMethod::Recursive) {
         sink << dumpPath(srcPath, filter);
     } else {
-        readFileSource(srcPath)->drainInto(sink);
+        sink << readFileSource(srcPath);
     }
     auto h = sink.finish().first;
 

src/libstore/build/local-derivation-goal.cc

@@ -2219,7 +2219,7 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
             HashModuloSink caSink { outputHash.hashType, oldHashPart };
             std::visit(overloaded {
                 [&](const TextIngestionMethod &) {
-                    readFileSource(actualPath)->drainInto(caSink);
+                    caSink << readFileSource(actualPath);
                 },
                 [&](const FileIngestionMethod & m2) {
                     switch (m2) {
@@ -2227,7 +2227,7 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
                         caSink << dumpPath(actualPath);
                         break;
                     case FileIngestionMethod::Flat:
-                        readFileSource(actualPath)->drainInto(caSink);
+                        caSink << readFileSource(actualPath);
                         break;
                     }
                 },

src/libstore/local-binary-cache-store.cc

@@ -71,7 +71,7 @@ protected:
     void getFile(const std::string & path, Sink & sink) override
     {
         try {
-            readFileSource(binaryCacheDir + "/" + path)->drainInto(sink);
+            sink << readFileSource(binaryCacheDir + "/" + path);
         } catch (SysError & e) {
             if (e.errNo == ENOENT)
                 throw NoSuchBinaryCacheFile("file '%s' does not exist in binary cache", path);

src/libstore/local-store.cc

@@ -1890,7 +1890,7 @@ ContentAddress LocalStore::hashCAPath(
     HashModuloSink caSink ( hashType, std::string(pathHash) );
     std::visit(overloaded {
         [&](const TextIngestionMethod &) {
-            readFileSource(path)->drainInto(caSink);
+            caSink << readFileSource(path);
         },
         [&](const FileIngestionMethod & m2) {
             switch (m2) {
@@ -1898,7 +1898,7 @@ ContentAddress LocalStore::hashCAPath(
                 caSink << dumpPath(path);
                 break;
             case FileIngestionMethod::Flat:
-                readFileSource(path)->drainInto(caSink);
+                caSink << readFileSource(path);
                 break;
             }
         },

src/libstore/store-api.cc

@@ -275,13 +275,11 @@ StorePath Store::addToStore(
     const StorePathSet & references)
 {
     Path srcPath(absPath(_srcPath));
-    auto source = sinkToSource([&](Sink & sink) {
-        if (method == FileIngestionMethod::Recursive)
-            sink << dumpPath(srcPath, filter);
-        else
-            readFileSource(srcPath)->drainInto(sink);
-    });
-    return addToStoreFromDump(*source, name, method, hashAlgo, repair, references);
+    auto source = GeneratorSource{
+        method == FileIngestionMethod::Recursive ? dumpPath(srcPath, filter).decay()
+                                                 : readFileSource(srcPath)
+    };
+    return addToStoreFromDump(source, name, method, hashAlgo, repair, references);
 }
 
 void Store::addMultipleToStore(

src/libutil/file-system.cc

@@ -289,17 +289,12 @@ std::string readFile(const Path & path)
 }
 
 
-box_ptr<Source> readFileSource(const Path & path)
+Generator<Bytes> readFileSource(const Path & path)
 {
     AutoCloseFD fd{open(path.c_str(), O_RDONLY | O_CLOEXEC)};
     if (!fd)
         throw SysError("opening file '%s'", path);
-
-    struct FileSource : FdSource {
-        AutoCloseFD fd;
-        explicit FileSource(AutoCloseFD fd) : FdSource(fd.get()), fd(std::move(fd)) {}
-    };
-    return make_box_ptr<FileSource>(std::move(fd));
+    co_yield drainFDSource(fd.get());
 }
 
 

src/libutil/file-system.hh

@@ -143,7 +143,7 @@ unsigned char getFileType(const Path & path);
  * Read the contents of a file into a string.
  */
 std::string readFile(const Path & path);
-box_ptr<Source> readFileSource(const Path & path);
+Generator<Bytes> readFileSource(const Path & path);
 
 /**
  * Write a string to a file.

src/libutil/hash.cc

@@ -324,7 +324,7 @@ Hash hashString(HashType ht, std::string_view s)
 Hash hashFile(HashType ht, const Path & path)
 {
     HashSink sink(ht);
-    readFileSource(path)->drainInto(sink);
+    sink << readFileSource(path);
     return sink.finish().first;
 }
 

src/nix/add-to-store.cc

@@ -37,7 +37,7 @@ struct CmdAddToStore : MixDryRun, StoreCommand
         Hash hash = narHash;
         if (ingestionMethod == FileIngestionMethod::Flat) {
             HashSink hsink(htSHA256);
-            readFileSource(path)->drainInto(hsink);
+            hsink << readFileSource(path);
             hash = hsink.finish().first;
         }
 

src/nix/hash.cc

@@ -85,7 +85,7 @@ struct CmdHashBase : Command
 
             switch (mode) {
             case FileIngestionMethod::Flat:
-                readFileSource(path)->drainInto(*hashSink);
+                *hashSink << readFileSource(path);
                 break;
             case FileIngestionMethod::Recursive:
                 *hashSink << dumpPath(path);