Add hash-git command

src/libutil/git.cc

@@ -0,0 +1,65 @@
+#include "archive.hh"
+#include "hash.hh"
+#include "util.hh"
+#include "config.hh"
+
+using namespace std::string_literals;
+
+namespace nix {
+
+void dumpGit(const Path & path, Sink & sink, PathFilter & filter)
+{
+    struct stat st;
+    if (lstat(path.c_str(), &st))
+        throw SysError(format("getting attributes of path '%1%'") % path);
+
+    if (S_ISREG(st.st_mode)) {
+        auto s = (format("blob %d\0%s"s) % std::to_string(st.st_size) % readFile(path)).str();
+
+        vector<unsigned char> v;
+        std::copy(s.begin(), s.end(), std::back_inserter(v));
+        sink(v.data(), v.size());
+    }
+
+    else if (S_ISDIR(st.st_mode)) {
+        std::string s1 = "";
+
+        std::map<string, string> entries;
+        for (auto & i : readDirectory(path))
+            entries[i.name] = i.name;
+
+        for (auto & i : entries)
+            if (filter(path + "/" + i.first)) {
+                HashSink hashSink(htSHA1);
+                dumpGit(path + "/" + i.first, hashSink, filter);
+                auto hash = hashSink.finish().first;
+
+                struct stat st2;
+                if (lstat((path + "/" + i.first).c_str(), &st2))
+                    throw SysError(format("getting attributes of path '%1%'") % (path + "/" + i.first));
+
+                unsigned int perm;
+                if (S_ISDIR(st2.st_mode))
+                    perm = 40000;
+                else if (S_ISREG(st2.st_mode)) {
+                    if (st2.st_mode & S_IXUSR)
+                        perm = 100755;
+                    else
+                        perm = 100644;
+                } else
+                    throw Error(format("file '%1%' has an unsupported type") % (path + "/" + i.first));
+
+                s1 += (format("%6d %s\0%s"s) % perm % i.first % hash.hash).str();
+            }
+
+        std::string s2 = (format("tree %d\0%s"s) % s1.size() % s1).str();
+
+        vector<unsigned char> v;
+        std::copy(s2.begin(), s2.end(), std::back_inserter(v));
+        sink(v.data(), v.size());
+    }
+
+    else throw Error(format("file '%1%' has an unsupported type") % path);
+}
+
+}

src/libutil/git.hh

@@ -0,0 +1,10 @@
+#pragma once
+
+#include "types.hh"
+#include "serialise.hh"
+
+namespace nix {
+
+void dumpGit(const Path & path, Sink & sink, PathFilter & filter = defaultPathFilter);
+
+}

src/nix/hash.cc

@@ -4,12 +4,13 @@
 #include "shared.hh"
 #include "references.hh"
 #include "archive.hh"
+#include "git.hh"
 
 using namespace nix;
 
 struct CmdHash : Command
 {
-    enum Mode { mFile, mPath };
+    enum Mode { mFile, mPath, mGit };
     Mode mode;
     Base base = SRI;
     bool truncate = false;
@@ -36,9 +37,12 @@ struct CmdHash : Command
 
     std::string description() override
     {
-        return mode == mFile
-            ? "print cryptographic hash of a regular file"
-            : "print cryptographic hash of the NAR serialisation of a path";
+        switch (mode) {
+        case mFile: return "print cryptographic hash of a regular file";
+        case mPath: return "print cryptographic hash of the NAR serialisation of a path";
+        case mGit: return "print cryptographic hash of the Git serialisation of a path";
+        }
+        throw;
     }
 
     Category category() override { return catUtility; }
@@ -55,6 +59,8 @@ struct CmdHash : Command
 
             if (mode == mFile)
                 readFile(path, *hashSink);
+            else if (mode == mGit)
+                dumpGit(path, *hashSink);
             else
                 dumpPath(path, *hashSink);
 
@@ -67,6 +73,7 @@ struct CmdHash : Command
 
 static RegisterCommand r1("hash-file", [](){ return make_ref<CmdHash>(CmdHash::mFile); });
 static RegisterCommand r2("hash-path", [](){ return make_ref<CmdHash>(CmdHash::mPath); });
+static RegisterCommand r3("hash-git", [](){ return make_ref<CmdHash>(CmdHash::mGit); });
 
 struct CmdToBase : Command
 {
@@ -98,10 +105,10 @@ struct CmdToBase : Command
     }
 };
 
-static RegisterCommand r3("to-base16", [](){ return make_ref<CmdToBase>(Base16); });
-static RegisterCommand r4("to-base32", [](){ return make_ref<CmdToBase>(Base32); });
-static RegisterCommand r5("to-base64", [](){ return make_ref<CmdToBase>(Base64); });
-static RegisterCommand r6("to-sri", [](){ return make_ref<CmdToBase>(SRI); });
+static RegisterCommand r4("to-base16", [](){ return make_ref<CmdToBase>(Base16); });
+static RegisterCommand r5("to-base32", [](){ return make_ref<CmdToBase>(Base32); });
+static RegisterCommand r6("to-base64", [](){ return make_ref<CmdToBase>(Base64); });
+static RegisterCommand r7("to-sri", [](){ return make_ref<CmdToBase>(SRI); });
 
 /* Legacy nix-hash command. */
 static int compatNixHash(int argc, char * * argv)

tests/hash.sh

@@ -85,3 +85,18 @@ try3() {
 try3 sha1 "800d59cfcd3c05e900cb4e214be48f6b886a08df" "vw46m23bizj4n8afrc0fj19wrp7mj3c0" "gA1Zz808BekAy04hS+SPa4hqCN8="
 try3 sha256 "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad" "1b8m03r63zqhnjf7l5wnldhh7c134ap5vpj0850ymkq1iyzicy5s" "ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0="
 try3 sha512 "204a8fc6dda82f0a0ced7beb8e08a41657c16ef468b228a8279be331a703c33596fd15c13b1b07f9aa1d3bea57789ca031ad85c7a71dd70354ec631238ca3445" "12k9jiq29iyqm03swfsgiw5mlqs173qazm3n7daz43infy12pyrcdf30fkk3qwv4yl2ick8yipc2mqnlh48xsvvxl60lbx8vp38yji0" "IEqPxt2oLwoM7XvrjgikFlfBbvRosiioJ5vjMacDwzWW/RXBOxsH+aodO+pXeJygMa2Fx6cd1wNU7GMSOMo0RQ=="
+
+# Git.
+try4 () {
+    hash=$(nix hash-git --base16 --type sha1 $TEST_ROOT/hash-path)
+    if test "$hash" != "$1"; then
+        echo "git hash, expected $1, got $hash"
+        exit 1
+    fi
+}
+
+rm -rf $TEST_ROOT/hash-path
+mkdir $TEST_ROOT/hash-path
+echo "Hello World" > $TEST_ROOT/hash-path/hello
+
+try4 "117c62a8c5e01758bd284126a6af69deab9dbbe2"