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Merge "libfetchers/git: restore compat with builtins.fetchGit from 2.3" into main

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Maximilian Bosch 2024-09-29 08:56:16 +00:00 committed by Gerrit Code Review
commit 289e7a6b5a
4 changed files with 157 additions and 21 deletions
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23
doc/manual/rl-next/fetchGit-regression.md Normal file
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@ -0,0 +1,23 @@
---
synopsis: restore backwards-compatibility of `builtins.fetchGit` with Nix 2.3
issues: [5291, 5128]
credits: [ma27]
category: Fixes
---
Compatibility with `builtins.fetchGit` from Nix 2.3 has been restored as follows:
* Until now, each `ref` was prefixed with `refs/heads` unless it starts with `refs/` itself.
Now, this is not done if the `ref` looks like a commit hash.
* Specifying `builtins.fetchGit { ref = "a-tag"; /* … */ }` was broken because `refs/heads` was appended.
Now, the fetcher doesn't turn a ref into `refs/heads/ref`, but into `refs/*/ref`. That way,
the value in `ref` can be either a tag or a branch.
* The ref resolution happens the same way as in git:
* If `refs/ref` exists, it's used.
* If a tag `refs/tags/ref` exists, it's used.
* If a branch `refs/heads/ref` exists, it's used.

3
src/libexpr/primops/fetchTree.cc
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@ -394,7 +394,8 @@ static RegisterPrimOp primop_fetchGit({
[Git reference]: https://git-scm.com/book/en/v2/Git-Internals-Git-References
By default, the `ref` value is prefixed with `refs/heads/`.
As of 2.3.0, Nix will not prefix `refs/heads/` if `ref` starts with `refs/`.
As of 2.3.0, Nix will not prefix `refs/heads/` if `ref` starts with `refs/` or
if `ref` looks like a commit hash for backwards compatibility with CppNix 2.3.
- `submodules` (default: `false`)

107
src/libfetchers/git.cc
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@ -1,3 +1,4 @@
#include "error.hh"
#include "fetchers.hh"
#include "cache.hh"
#include "globals.hh"
@ -257,6 +258,28 @@ std::pair<StorePath, Input> fetchFromWorkdir(ref<Store> store, Input & input, co
}
} // end namespace
static std::optional<Path> resolveRefToCachePath(
Input & input,
const Path & cacheDir,
std::vector<Path> & gitRefFileCandidates,
std::function<bool(const Path&)> condition)
{
if (input.getRef()->starts_with("refs/")) {
Path fullpath = cacheDir + "/" + *input.getRef();
if (condition(fullpath)) {
return fullpath;
}
}
for (auto & candidate : gitRefFileCandidates) {
if (condition(candidate)) {
return candidate;
}
}
return std::nullopt;
}
struct GitInputScheme : InputScheme
{
std::optional<Input> inputFromURL(const ParsedURL & url, bool requireTree) const override
@ -539,10 +562,13 @@ struct GitInputScheme : InputScheme
runProgram("git", true, { "-c", "init.defaultBranch=" + gitInitialBranch, "init", "--bare", repoDir });
}
Path localRefFile =
input.getRef()->compare(0, 5, "refs/") == 0
? cacheDir + "/" + *input.getRef()
: cacheDir + "/refs/heads/" + *input.getRef();
std::vector<Path> gitRefFileCandidates;
for (auto & infix : {"", "tags/", "heads/"}) {
Path p = cacheDir + "/refs/" + infix + *input.getRef();
gitRefFileCandidates.push_back(p);
}
Path localRefFile;
bool doFetch;
time_t now = time(0);
@ -564,29 +590,70 @@ struct GitInputScheme : InputScheme
if (allRefs) {
doFetch = true;
} else {
/* If the local ref is older than ‘tarball-ttl’ seconds, do a
git fetch to update the local ref to the remote ref. */
struct stat st;
doFetch = stat(localRefFile.c_str(), &st) != 0 ||
!isCacheFileWithinTtl(now, st);
std::function<bool(const Path&)> condition;
condition = [&now](const Path & path) {
/* If the local ref is older than ‘tarball-ttl’ seconds, do a
git fetch to update the local ref to the remote ref. */
struct stat st;
return stat(path.c_str(), &st) == 0 &&
isCacheFileWithinTtl(now, st);
};
if (auto result = resolveRefToCachePath(
input,
cacheDir,
gitRefFileCandidates,
condition
)) {
localRefFile = *result;
doFetch = false;
} else {
doFetch = true;
}
}
}
// When having to fetch, we don't know `localRefFile` yet.
// Because git needs to figure out what we're fetching
// (i.e. is it a rev? a branch? a tag?)
if (doFetch) {
Activity act(*logger, lvlTalkative, actUnknown, fmt("fetching Git repository '%s'", actualUrl));
// FIXME: git stderr messes up our progress indicator, so
// we're using --quiet for now. Should process its stderr.
auto ref = input.getRef();
std::string fetchRef;
if (allRefs) {
fetchRef = "refs/*";
} else if (
ref->starts_with("refs/")
|| *ref == "HEAD"
|| std::regex_match(*ref, revRegex))
{
fetchRef = *ref;
} else {
fetchRef = "refs/*/" + *ref;
}
try {
auto ref = input.getRef();
auto fetchRef = allRefs
? "refs/*"
: ref->compare(0, 5, "refs/") == 0
? *ref
: ref == "HEAD"
? *ref
: "refs/heads/" + *ref;
runProgram("git", true, { "-C", repoDir, "--git-dir", gitDir, "fetch", "--quiet", "--force", "--", actualUrl, fmt("%s:%s", fetchRef, fetchRef) }, true);
Finally finally([&]() {
if (auto p = resolveRefToCachePath(
input,
cacheDir,
gitRefFileCandidates,
pathExists
)) {
localRefFile = *p;
}
});
// FIXME: git stderr messes up our progress indicator, so
// we're using --quiet for now. Should process its stderr.
runProgram("git", true, {
"-C", repoDir,
"--git-dir", gitDir,
"fetch",
"--quiet",
"--force",
"--", actualUrl, fmt("%s:%s", fetchRef, fetchRef)
}, true);
} catch (Error & e) {
if (!pathExists(localRefFile)) throw;
warn("could not update local clone of Git repository '%s'; continuing with the most recent version", actualUrl);

45
tests/functional/fetchGit.sh
View file

@ -53,8 +53,17 @@ out=$(nix eval --impure --raw --expr "builtins.fetchGit { url = \"file://$repo\"
[[ $status == 1 ]]
[[ $out =~ 'Cannot find Git revision' ]]
# allow revs as refs (for 2.3 compat)
[[ $(nix eval --raw --expr "builtins.readFile (builtins.fetchGit { url = \"file://$repo\"; rev = \"$devrev\"; allRefs = true; } + \"/differentbranch\")") = 'different file' ]]
rm -rf "$TEST_ROOT/test-home"
[[ $(nix eval --raw --expr "builtins.readFile (builtins.fetchGit { url = \"file://$repo\"; rev = \"$devrev\"; allRefs = true; } + \"/differentbranch\")") = 'different file' ]]
rm -rf "$TEST_ROOT/test-home"
out=$(nix eval --raw --expr "builtins.readFile (builtins.fetchGit { url = \"file://$repo\"; rev = \"$devrev\"; ref = \"lolkek\"; } + \"/differentbranch\")" 2>&1) || status=$?
[[ $status == 1 ]]
[[ $out =~ 'Cannot find Git revision' ]]
# In pure eval mode, fetchGit without a revision should fail.
[[ $(nix eval --impure --raw --expr "builtins.readFile (fetchGit \"file://$repo\" + \"/hello\")") = world ]]
(! nix eval --raw --expr "builtins.readFile (fetchGit \"file://$repo\" + \"/hello\")")
@ -228,6 +237,12 @@ export _NIX_FORCE_HTTP=1
rev_tag1_nix=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$repo\"; ref = \"refs/tags/tag1\"; }).rev")
rev_tag1=$(git -C $repo rev-parse refs/tags/tag1)
[[ $rev_tag1_nix = $rev_tag1 ]]
# Allow fetching tags w/o specifying refs/tags
rm -rf "$TEST_ROOT/test-home"
rev_tag1_nix_alt=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$repo\"; ref = \"tag1\"; }).rev")
[[ $rev_tag1_nix_alt = $rev_tag1 ]]
rev_tag2_nix=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$repo\"; ref = \"refs/tags/tag2\"; }).rev")
rev_tag2=$(git -C $repo rev-parse refs/tags/tag2)
[[ $rev_tag2_nix = $rev_tag2 ]]
@ -254,3 +269,33 @@ git -C "$repo" add hello .gitignore
git -C "$repo" commit -m 'Bla1'
cd "$repo"
path11=$(nix eval --impure --raw --expr "(builtins.fetchGit ./.).outPath")
# test behavior if both branch and tag with same name exist
repo="$TEST_ROOT/git"
rm -rf "$repo"/.git
git init "$repo"
git -C "$repo" config user.email "foobar@example.com"
git -C "$repo" config user.name "Foobar"
touch "$repo"/test
echo "hello world" > "$repo"/test
git -C "$repo" checkout -b branch
git -C "$repo" add test
git -C "$repo" commit -m "Init"
git -C "$repo" tag branch
echo "goodbye world" > "$repo"/test
git -C "$repo" add test
git -C "$repo" commit -m "Update test"
path12=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$repo\"; ref = \"branch\"; }).outPath")
[[ "$(cat "$path12"/test)" =~ 'hello world' ]]
[[ "$(cat "$repo"/test)" =~ 'goodbye world' ]]
path13=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$repo\"; ref = \"refs/heads/branch\"; }).outPath")
[[ "$(cat "$path13"/test)" =~ 'goodbye world' ]]
path14=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$repo\"; ref = \"refs/tags/branch\"; }).outPath")
[[ "$path14" = "$path12" ]]