From: Thomas Bétous Date: Mon, 2 Aug 2021 21:07:30 +0000 (+0000) Subject: mingw: align symlinks-related rmdir() behavior with Linux X-Git-Tag: v2.33.0-rc1~5^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3e7d4888e5b83f1ed75667ff557b8996f427adf0;p=thirdparty%2Fgit.git mingw: align symlinks-related rmdir() behavior with Linux When performing a rebase, rmdir() is called on the folder .git/logs. On Unix rmdir() exits without deleting anything in case .git/logs is a symbolic link but the equivalent functions on Windows (_rmdir, _wrmdir and RemoveDirectoryW) do not behave the same and remove the folder if it is symlinked even if it is not empty. This creates issues when folders in .git/ are symlinks which is especially the case when git-repo[1] is used: It replaces `.git/logs/` with a symlink. One such issue is that the _target_ of that symlink is removed e.g. during a `git rebase`, where `delete_reflog("REBASE_HEAD")` will not only try to remove `.git/logs/REBASE_HEAD` but then recursively try to remove the parent directories until an error occurs, a technique that obviously relies on `rmdir()` refusing to remove a symlink. This was reported in https://github.com/git-for-windows/git/issues/2967. This commit updates mingw_rmdir() so that its behavior is the same as Linux rmdir() in case of symbolic links. To verify that Git does not regress on the reported issue, this patch adds a regression test for the `git rebase` symptom, even if the same `rmdir()` behavior is quite likely to cause potential problems in other Git commands as well. [1]: git-repo is a python tool built on top of Git which helps manage many Git repositories. It stores all the .git/ folders in a central place by taking advantage of symbolic links. More information: https://gerrit.googlesource.com/git-repo/ Signed-off-by: Thomas Bétous Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- diff --git a/compat/mingw.c b/compat/mingw.c index aa647b367b..9e0cd1e097 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -341,6 +341,27 @@ int mingw_rmdir(const char *pathname) { int ret, tries = 0; wchar_t wpathname[MAX_PATH]; + struct stat st; + + /* + * Contrary to Linux' `rmdir()`, Windows' _wrmdir() and _rmdir() + * (and `RemoveDirectoryW()`) will attempt to remove the target of a + * symbolic link (if it points to a directory). + * + * This behavior breaks the assumption of e.g. `remove_path()` which + * upon successful deletion of a file will attempt to remove its parent + * directories recursively until failure (which usually happens when + * the directory is not empty). + * + * Therefore, before calling `_wrmdir()`, we first check if the path is + * a symbolic link. If it is, we exit and return the same error as + * Linux' `rmdir()` would, i.e. `ENOTDIR`. + */ + if (!mingw_lstat(pathname, &st) && S_ISLNK(st.st_mode)) { + errno = ENOTDIR; + return -1; + } + if (xutftowcs_path(wpathname, pathname) < 0) return -1; diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh index 0bb88aa982..23dbd3c82e 100755 --- a/t/t3400-rebase.sh +++ b/t/t3400-rebase.sh @@ -406,4 +406,14 @@ test_expect_success 'refuse to switch to branch checked out elsewhere' ' test_i18ngrep "already checked out" err ' +test_expect_success MINGW,SYMLINKS_WINDOWS 'rebase when .git/logs is a symlink' ' + git checkout main && + mv .git/logs actual_logs && + cmd //c "mklink /D .git\logs ..\actual_logs" && + git rebase -f HEAD^ && + test -L .git/logs && + rm .git/logs && + mv actual_logs .git/logs +' + test_done diff --git a/t/test-lib.sh b/t/test-lib.sh index adaf03543e..73f6d645b6 100644 --- a/t/test-lib.sh +++ b/t/test-lib.sh @@ -1513,6 +1513,12 @@ test_lazy_prereq SYMLINKS ' ln -s x y && test -h y ' +test_lazy_prereq SYMLINKS_WINDOWS ' + # test whether symbolic links are enabled on Windows + test_have_prereq MINGW && + cmd //c "mklink y x" &> /dev/null && test -h y +' + test_lazy_prereq FILEMODE ' test "$(git config --bool core.filemode)" = true '