In later patches we introduce the options and flag for commands
that modify the working directory, e.g. git-checkout.
This piece of code will answer the question:
"Is it safe to change the submodule to this new state?"
e.g. is it overwriting untracked files or are there local
changes that would be overwritten?
Signed-off-by: Stefan Beller <sbel...@google.com>
---
submodule.c | 37 +++++++++++++++++++++++++++++++++++++
submodule.h | 2 ++
2 files changed, 39 insertions(+)
diff --git a/submodule.c b/submodule.c
index 02c28ef56b..4253f7f044 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1155,6 +1155,43 @@ int ok_to_remove_submodule(const char *path)
return ok_to_remove;
}
+/**
+ * Check if a submodule update to a given sha1 is safe.
+ * Return 1 if it is safe, 0 when it is not.
+ *
+ * If the submodule is not populated, we need to check
+ */
+int is_submodule_checkout_safe(const char *path,
+ const struct object_id *new_hash)
+{
+ struct child_process cp = CHILD_PROCESS_INIT;
+
+ argv_array_pushl(&cp.args, "read-tree", "-n", "-m", "HEAD",
+ sha1_to_hex(new_hash->hash), NULL);
+
+ if (!is_submodule_populated(path)) {
+ const struct submodule *sub;
+
+ /* See if we have the submodule configured already: */
+ sub = submodule_from_path(null_sha1, path);
+
+ prepare_submodule_repo_env_no_git_dir(&cp.env_array);
+ argv_array_pushf(&cp.env_array, "GIT_DIR=%s",
+ sub ? sub->name : path);
+ argv_array_pushf(&cp.env_array, "GIT_WORK_TREE=%s", path);
+ } else {
+ prepare_submodule_repo_env(&cp.env_array);
+ }
+
+ cp.git_cmd = 1;
+ cp.no_stdin = 1;
+ cp.no_stdout = 1;
+ cp.no_stderr = 1;
+ cp.dir = path;
+
+ return run_command(&cp) == 0;
+}
+
static int find_first_merges(struct object_array *result, const char *path,
struct commit *a, struct commit *b)
{
diff --git a/submodule.h b/submodule.h
index 74df8b93d5..1dfcd6939b 100644
--- a/submodule.h
+++ b/submodule.h
@@ -72,6 +72,8 @@ extern unsigned is_submodule_modified(const char *path, int
ignore_untracked);
extern int is_submodule_populated(const char *path);
extern int submodule_uses_gitfile(const char *path);
extern int ok_to_remove_submodule(const char *path);
+extern int is_submodule_checkout_safe(const char *path,
+ const struct object_id *new_hash);
extern int merge_submodule(unsigned char result[20], const char *path,
const unsigned char base[20],
const unsigned char a[20],
--
2.11.0.rc2.28.g2673dad
