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authorGravatar Thomas Bétous <tomspycell@gmail.com> 2021-08-02 21:07:30 +0000
committerGravatar Junio C Hamano <gitster@pobox.com> 2021-08-02 15:10:58 -0700
commit3e7d4888e5b83f1ed75667ff557b8996f427adf0 (patch)
tree558f1c282646845fd7a5a406f5b8e286293b29e2
parentebf3c04b262aa27fbb97f8a0156c2347fecafafb (diff)
downloadgit-3e7d4888e5b83f1ed75667ff557b8996f427adf0.tar.gz
git-3e7d4888e5b83f1ed75667ff557b8996f427adf0.zip
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 <tomspycell@gmail.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--compat/mingw.c21
-rwxr-xr-xt/t3400-rebase.sh10
-rw-r--r--t/test-lib.sh6
3 files changed, 37 insertions, 0 deletions
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
'