Merge pull request #9024 from obsidiansystems/git-objects-prep

Shuffle `ParseSink` code in preparation for git hashing support

src/libutil/archive.cc

@@ -27,8 +27,6 @@ struct ArchiveSettings : Config
         #endif
         "use-case-hack",
         "Whether to enable a Darwin-specific hack for dealing with file name collisions."};
-    Setting<bool> preallocateContents{this, false, "preallocate-contents",
-        "Whether to preallocate files when writing objects with known size."};
 };
 
 static ArchiveSettings archiveSettings;
@@ -302,71 +300,6 @@ void parseDump(ParseSink & sink, Source & source)
 }
 
 
-struct RestoreSink : ParseSink
-{
-    Path dstPath;
-    AutoCloseFD fd;
-
-    void createDirectory(const Path & path) override
-    {
-        Path p = dstPath + path;
-        if (mkdir(p.c_str(), 0777) == -1)
-            throw SysError("creating directory '%1%'", p);
-    };
-
-    void createRegularFile(const Path & path) override
-    {
-        Path p = dstPath + path;
-        fd = open(p.c_str(), O_CREAT | O_EXCL | O_WRONLY | O_CLOEXEC, 0666);
-        if (!fd) throw SysError("creating file '%1%'", p);
-    }
-
-    void closeRegularFile() override
-    {
-        /* Call close explicitly to make sure the error is checked */
-        fd.close();
-    }
-
-    void isExecutable() override
-    {
-        struct stat st;
-        if (fstat(fd.get(), &st) == -1)
-            throw SysError("fstat");
-        if (fchmod(fd.get(), st.st_mode | (S_IXUSR | S_IXGRP | S_IXOTH)) == -1)
-            throw SysError("fchmod");
-    }
-
-    void preallocateContents(uint64_t len) override
-    {
-        if (!archiveSettings.preallocateContents)
-            return;
-
-#if HAVE_POSIX_FALLOCATE
-        if (len) {
-            errno = posix_fallocate(fd.get(), 0, len);
-            /* Note that EINVAL may indicate that the underlying
-               filesystem doesn't support preallocation (e.g. on
-               OpenSolaris).  Since preallocation is just an
-               optimisation, ignore it. */
-            if (errno && errno != EINVAL && errno != EOPNOTSUPP && errno != ENOSYS)
-                throw SysError("preallocating file of %1% bytes", len);
-        }
-#endif
-    }
-
-    void receiveContents(std::string_view data) override
-    {
-        writeFull(fd.get(), data);
-    }
-
-    void createSymlink(const Path & path, const std::string & target) override
-    {
-        Path p = dstPath + path;
-        nix::createSymlink(target, p);
-    }
-};
-
-
 void restorePath(const Path & path, Source & source)
 {
     RestoreSink sink;

src/libutil/archive.hh

@@ -3,6 +3,7 @@
 
 #include "types.hh"
 #include "serialise.hh"
+#include "fs-sink.hh"
 
 
 namespace nix {
@@ -72,22 +73,6 @@ time_t dumpPathAndGetMtime(const Path & path, Sink & sink,
  */
 void dumpString(std::string_view s, Sink & sink);
 
-/**
- * \todo Fix this API, it sucks.
- */
-struct ParseSink
-{
-    virtual void createDirectory(const Path & path) { };
-
-    virtual void createRegularFile(const Path & path) { };
-    virtual void closeRegularFile() { };
-    virtual void isExecutable() { };
-    virtual void preallocateContents(uint64_t size) { };
-    virtual void receiveContents(std::string_view data) { };
-
-    virtual void createSymlink(const Path & path, const std::string & target) { };
-};
-
 /**
  * If the NAR archive contains a single file at top-level, then save
  * the contents of the file to `s`.  Otherwise barf.

src/libutil/fs-sink.cc

@@ -0,0 +1,77 @@
+#include <fcntl.h>
+
+#include "config.hh"
+#include "fs-sink.hh"
+
+namespace nix {
+
+struct RestoreSinkSettings : Config
+{
+    Setting<bool> preallocateContents{this, false, "preallocate-contents",
+        "Whether to preallocate files when writing objects with known size."};
+};
+
+static RestoreSinkSettings restoreSinkSettings;
+
+static GlobalConfig::Register r1(&restoreSinkSettings);
+
+
+void RestoreSink::createDirectory(const Path & path)
+{
+    Path p = dstPath + path;
+    if (mkdir(p.c_str(), 0777) == -1)
+        throw SysError("creating directory '%1%'", p);
+};
+
+void RestoreSink::createRegularFile(const Path & path)
+{
+    Path p = dstPath + path;
+    fd = open(p.c_str(), O_CREAT | O_EXCL | O_WRONLY | O_CLOEXEC, 0666);
+    if (!fd) throw SysError("creating file '%1%'", p);
+}
+
+void RestoreSink::closeRegularFile()
+{
+    /* Call close explicitly to make sure the error is checked */
+    fd.close();
+}
+
+void RestoreSink::isExecutable()
+{
+    struct stat st;
+    if (fstat(fd.get(), &st) == -1)
+        throw SysError("fstat");
+    if (fchmod(fd.get(), st.st_mode | (S_IXUSR | S_IXGRP | S_IXOTH)) == -1)
+        throw SysError("fchmod");
+}
+
+void RestoreSink::preallocateContents(uint64_t len)
+{
+    if (!restoreSinkSettings.preallocateContents)
+        return;
+
+#if HAVE_POSIX_FALLOCATE
+    if (len) {
+        errno = posix_fallocate(fd.get(), 0, len);
+        /* Note that EINVAL may indicate that the underlying
+           filesystem doesn't support preallocation (e.g. on
+           OpenSolaris).  Since preallocation is just an
+           optimisation, ignore it. */
+        if (errno && errno != EINVAL && errno != EOPNOTSUPP && errno != ENOSYS)
+            throw SysError("preallocating file of %1% bytes", len);
+    }
+#endif
+}
+
+void RestoreSink::receiveContents(std::string_view data)
+{
+    writeFull(fd.get(), data);
+}
+
+void RestoreSink::createSymlink(const Path & path, const std::string & target)
+{
+    Path p = dstPath + path;
+    nix::createSymlink(target, p);
+}
+
+}

src/libutil/fs-sink.hh

@@ -0,0 +1,42 @@
+#pragma once
+///@file
+
+#include "types.hh"
+#include "serialise.hh"
+
+namespace nix {
+
+/**
+ * \todo Fix this API, it sucks.
+ */
+struct ParseSink
+{
+    virtual void createDirectory(const Path & path) { };
+
+    virtual void createRegularFile(const Path & path) { };
+    virtual void closeRegularFile() { };
+    virtual void isExecutable() { };
+    virtual void preallocateContents(uint64_t size) { };
+    virtual void receiveContents(std::string_view data) { };
+
+    virtual void createSymlink(const Path & path, const std::string & target) { };
+};
+
+struct RestoreSink : ParseSink
+{
+    Path dstPath;
+    AutoCloseFD fd;
+
+
+    void createDirectory(const Path & path) override;
+
+    void createRegularFile(const Path & path) override;
+    void closeRegularFile() override;
+    void isExecutable() override;
+    void preallocateContents(uint64_t size) override;
+    void receiveContents(std::string_view data) override;
+
+    void createSymlink(const Path & path, const std::string & target) override;
+};
+
+}

src/libutil/hash.hh

@@ -145,13 +145,17 @@ std::string printHash16or32(const Hash & hash);
 Hash hashString(HashType ht, std::string_view s);
 
 /**
- * Compute the hash of the given file.
+ * Compute the hash of the given file, hashing its contents directly.
+ *
+ * (Metadata, such as the executable permission bit, is ignored.)
  */
 Hash hashFile(HashType ht, const Path & path);
 
 /**
- * Compute the hash of the given path.  The hash is defined as
- * (essentially) hashString(ht, dumpPath(path)).
+ * Compute the hash of the given path, serializing as a Nix Archive and
+ * then hashing that.
+ *
+ * The hash is defined as (essentially) hashString(ht, dumpPath(path)).
  */
 typedef std::pair<Hash, uint64_t> HashResult;
 HashResult hashPath(HashType ht, const Path & path,