Merge pull request #10111 from obsidiansystems/git-objects

Support symlinks properly with `git-hashing` experimental feature
This commit is contained in:
Eelco Dolstra 2024-03-01 15:00:43 +01:00 committed by GitHub
commit ba9b6b29b7
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6 changed files with 110 additions and 26 deletions

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@ -56,31 +56,63 @@ void parseBlob(
FileSystemObjectSink & sink,
const Path & sinkPath,
Source & source,
bool executable,
BlobMode blobMode,
const ExperimentalFeatureSettings & xpSettings)
{
xpSettings.require(Xp::GitHashing);
sink.createRegularFile(sinkPath, [&](auto & crf) {
if (executable)
crf.isExecutable();
unsigned long long size = std::stoi(getStringUntil(source, 0));
unsigned long long size = std::stoi(getStringUntil(source, 0));
auto doRegularFile = [&](bool executable) {
sink.createRegularFile(sinkPath, [&](auto & crf) {
if (executable)
crf.isExecutable();
crf.preallocateContents(size);
crf.preallocateContents(size);
unsigned long long left = size;
std::string buf;
buf.reserve(65536);
unsigned long long left = size;
std::string buf;
buf.reserve(65536);
while (left) {
while (left) {
checkInterrupt();
buf.resize(std::min((unsigned long long)buf.capacity(), left));
source(buf);
crf(buf);
left -= buf.size();
}
});
};
switch (blobMode) {
case BlobMode::Regular:
doRegularFile(false);
break;
case BlobMode::Executable:
doRegularFile(true);
break;
case BlobMode::Symlink:
{
std::string target;
target.resize(size, '0');
target.reserve(size);
for (size_t n = 0; n < target.size();) {
checkInterrupt();
buf.resize(std::min((unsigned long long)buf.capacity(), left));
source(buf);
crf(buf);
left -= buf.size();
n += source.read(
const_cast<char *>(target.c_str()) + n,
target.size() - n);
}
});
sink.createSymlink(sinkPath, target);
break;
}
default:
assert(false);
}
}
void parseTree(
@ -142,7 +174,7 @@ void parse(
FileSystemObjectSink & sink,
const Path & sinkPath,
Source & source,
bool executable,
BlobMode rootModeIfBlob,
std::function<SinkHook> hook,
const ExperimentalFeatureSettings & xpSettings)
{
@ -152,7 +184,7 @@ void parse(
switch (type) {
case ObjectType::Blob:
parseBlob(sink, sinkPath, source, executable, xpSettings);
parseBlob(sink, sinkPath, source, rootModeIfBlob, xpSettings);
break;
case ObjectType::Tree:
parseTree(sink, sinkPath, source, hook, xpSettings);
@ -177,7 +209,7 @@ std::optional<Mode> convertMode(SourceAccessor::Type type)
void restore(FileSystemObjectSink & sink, Source & source, std::function<RestoreHook> hook)
{
parse(sink, "", source, false, [&](Path name, TreeEntry entry) {
parse(sink, "", source, BlobMode::Regular, [&](Path name, TreeEntry entry) {
auto [accessor, from] = hook(entry.hash);
auto stat = accessor->lstat(from);
auto gotOpt = convertMode(stat.type);
@ -275,6 +307,13 @@ Mode dump(
}
case SourceAccessor::tSymlink:
{
auto target = accessor.readLink(path);
dumpBlobPrefix(target.size(), sink, xpSettings);
sink(target);
return Mode::Symlink;
}
case SourceAccessor::tMisc:
default:
throw Error("file '%1%' has an unsupported type", path);

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@ -75,10 +75,23 @@ ObjectType parseObjectType(
Source & source,
const ExperimentalFeatureSettings & xpSettings = experimentalFeatureSettings);
/**
* These 3 modes are represented by blob objects.
*
* Sometimes we need this information to disambiguate how a blob is
* being used to better match our own "file system object" data model.
*/
enum struct BlobMode : RawMode
{
Regular = static_cast<RawMode>(Mode::Regular),
Executable = static_cast<RawMode>(Mode::Executable),
Symlink = static_cast<RawMode>(Mode::Symlink),
};
void parseBlob(
FileSystemObjectSink & sink, const Path & sinkPath,
Source & source,
bool executable,
BlobMode blobMode,
const ExperimentalFeatureSettings & xpSettings = experimentalFeatureSettings);
void parseTree(
@ -89,11 +102,15 @@ void parseTree(
/**
* Helper putting the previous three `parse*` functions together.
*
* @rootModeIfBlob How to interpret a root blob, for which there is no
* disambiguating dir entry to answer that questino. If the root it not
* a blob, this is ignored.
*/
void parse(
FileSystemObjectSink & sink, const Path & sinkPath,
Source & source,
bool executable,
BlobMode rootModeIfBlob,
std::function<SinkHook> hook,
const ExperimentalFeatureSettings & xpSettings = experimentalFeatureSettings);

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@ -56,3 +56,12 @@ echo Run Hello World! > $TEST_ROOT/dummy3/dir/executable
path3=$(nix store add --mode git --hash-algo sha1 $TEST_ROOT/dummy3)
hash3=$(nix-store -q --hash $path3)
test "$hash3" = "sha256:08y3nm3mvn9qvskqnf13lfgax5lh73krxz4fcjd5cp202ggpw9nv"
rm -rf $TEST_ROOT/dummy3
mkdir -p $TEST_ROOT/dummy3
mkdir -p $TEST_ROOT/dummy3/dir
touch $TEST_ROOT/dummy3/dir/file
ln -s './hello/world.txt' $TEST_ROOT/dummy3/dir/symlink
path3=$(nix store add --mode git --hash-algo sha1 $TEST_ROOT/dummy3)
hash3=$(nix-store -q --hash $path3)
test "$hash3" = "sha256:1dwazas8irzpar89s8k2bnp72imfw7kgg4aflhhsfnicg8h428f3"

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@ -1,3 +1,4 @@
100644 blob 63ddb340119baf8492d2da53af47e8c7cfcd5eb2 Foo
100755 blob 63ddb340119baf8492d2da53af47e8c7cfcd5eb2 bAr
040000 tree 4b825dc642cb6eb9a060e54bf8d69288fbee4904 baZ
120000 blob 63ddb340119baf8492d2da53af47e8c7cfcd5eb2 quuX

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@ -67,7 +67,7 @@ TEST_F(GitTest, blob_read) {
StringSink out;
RegularFileSink out2 { out };
ASSERT_EQ(parseObjectType(in, mockXpSettings), ObjectType::Blob);
parseBlob(out2, "", in, false, mockXpSettings);
parseBlob(out2, "", in, BlobMode::Regular, mockXpSettings);
auto expected = readFile(goldenMaster("hello-world.bin"));
@ -115,6 +115,15 @@ const static Tree tree = {
.hash = Hash::parseAny("4b825dc642cb6eb9a060e54bf8d69288fbee4904", HashAlgorithm::SHA1),
},
},
{
"quuX",
{
.mode = Mode::Symlink,
// hello world with special chars from above (symlink target
// can be anything)
.hash = Hash::parseAny("63ddb340119baf8492d2da53af47e8c7cfcd5eb2", HashAlgorithm::SHA1),
},
},
};
TEST_F(GitTest, tree_read) {
@ -165,6 +174,12 @@ TEST_F(GitTest, both_roundrip) {
.contents = "good day,\n\0\n\tworld!",
},
},
{
"quux",
File::Symlink {
.target = "/over/there",
},
},
},
},
},
@ -195,21 +210,24 @@ TEST_F(GitTest, both_roundrip) {
MemorySink sinkFiles2 { files2 };
std::function<void(const Path, const Hash &, bool)> mkSinkHook;
mkSinkHook = [&](auto prefix, auto & hash, auto executable) {
std::function<void(const Path, const Hash &, BlobMode)> mkSinkHook;
mkSinkHook = [&](auto prefix, auto & hash, auto blobMode) {
StringSource in { cas[hash] };
parse(
sinkFiles2, prefix, in, executable,
sinkFiles2, prefix, in, blobMode,
[&](const Path & name, const auto & entry) {
mkSinkHook(
prefix + "/" + name,
entry.hash,
entry.mode == Mode::Executable);
// N.B. this cast would not be acceptable in real
// code, because it would make an assert reachable,
// but it should harmless in this test.
static_cast<BlobMode>(entry.mode));
},
mockXpSettings);
};
mkSinkHook("", root.hash, false);
mkSinkHook("", root.hash, BlobMode::Regular);
ASSERT_EQ(files, files2);
}