libfetchers: Fix assertion

The filter expects all paths to have a prefix of the raw `actualUrl`, but
`Store::addToStore(...)` provides absolute canonicalized paths.
To fix this create an absolute and canonicalized path from the `actualUrl` and
use it instead.

Fixes #6195.

1 files changed, 6 insertions, 4 deletions

diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index d75c5d3ae..f8433bc28 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -285,9 +285,11 @@ struct GitInputScheme : InputScheme
                 auto files = tokenizeString<std::set<std::string>>(
                     runProgram("git", true, gitOpts), "\0"s);
 
+                Path actualPath(absPath(actualUrl));
+
                 PathFilter filter = [&](const Path & p) -> bool {
-                    assert(hasPrefix(p, actualUrl));
-                    std::string file(p, actualUrl.size() + 1);
+                    assert(hasPrefix(p, actualPath));
+                    std::string file(p, actualPath.size() + 1);
 
                     auto st = lstat(p);
 
@@ -300,13 +302,13 @@ struct GitInputScheme : InputScheme
                     return files.count(file);
                 };
 
-                auto storePath = store->addToStore(input.getName(), actualUrl, FileIngestionMethod::Recursive, htSHA256, filter);
+                auto storePath = store->addToStore(input.getName(), actualPath, FileIngestionMethod::Recursive, htSHA256, filter);
 
                 // FIXME: maybe we should use the timestamp of the last
                 // modified dirty file?
                 input.attrs.insert_or_assign(
                     "lastModified",
-                    hasHead ? std::stoull(runProgram("git", true, { "-C", actualUrl, "log", "-1", "--format=%ct", "--no-show-signature", "HEAD" })) : 0);
+                    hasHead ? std::stoull(runProgram("git", true, { "-C", actualPath, "log", "-1", "--format=%ct", "--no-show-signature", "HEAD" })) : 0);
 
                 return {std::move(storePath), input};
             }