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libfetchers/git: restore compat with builtins.fetchGit from 2.3

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Since fb38459d6e, each `ref` is appended
with `refs/heads` unless it starts with `refs/` already. This regressed
two use-cases that worked fine before:

* Specifying a commit hash as `ref`: now, if `ref` looks like a commit
  hash it will be directly passed to `git fetch`.

* Specifying a tag without `refs/tags` as prefix: now, the fetcher prepends
  `refs/*` to a ref that doesn't start with `refs/` and doesn't look
  like a commit hash. That way, both a branch and a tag specified in
  `ref` can be fetched.

  The order of preference in git is

  * file in `refs/` (e.g. `HEAD`)
  * file in `refs/tags/`
  * file in `refs/heads` (i.e. a branch)

  After fetching `refs/*`, ref is resolved the same way as git does.

Change-Id: Idd49b97cbdc8c6fdc8faa5a48bef3dec25e4ccc3
This commit is contained in:
Maximilian Bosch
2024-09-28 14:52:06 +02:00
parent 14dc84ed03
commit 04daff94e3
4 changed files with 157 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/libexpr/primops/fetchTree.cc
+2 -1
View File
@@ -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`)
src/libfetchers/git.cc
+87 -20
View File
@@ -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);