git/submodule.h
Stefan Beller a6d7eb2c7a pull: optionally rebase submodules (remote submodule changes only)
Teach pull to optionally update submodules when '--recurse-submodules'
is provided.  This will teach pull to run 'submodule update --rebase'
when the '--recurse-submodules' and '--rebase' flags are given under
specific circumstances.

On a rebase workflow:
=====================

1. Both sides change the submodule
 ------------------------------
Let's assume the following history in a submodule:

  H---I---J---K---L local branch
       \
        M---N---O---P remote branch

and the following in the superproject (recorded submodule in parens):

  A(H)---B(I)---F(K)---G(L)  local branch
          \
           C(N)---D(N)---E(P) remote branch

In an ideal world this would rebase the submodule and rewrite
the submodule pointers that the superproject points at such that
the superproject looks like

  A(H)---B(I)              F(K')---G(L')  rebased branch
           \                /
           C(N)---D(N)---E(P) remote branch

and the submodule as:

        J---K---L (old dangeling tip)
       /
  H---I               J'---K'---L' rebased branch
       \             /
        M---N---O---P remote branch

And if a conflict arises in the submodule the superproject rebase
would stop at that commit at which the submodule conflict occurs.

Currently a "pull --rebase" in the superproject produces
a merge conflict as the submodule pointer changes are
conflicting and cannot be resolved.

2. Local submodule changes only
 -----------------------
Assuming histories as above, except that the remote branch
would not contain submodule changes, then a result as

  A(H)---B(I)               F(K)---G(L)  rebased branch
           \                /
           C(I)---D(I)---E(I) remote branch

is desire-able. This is what currently happens in rebase.

If the recursive flag is given, the ideal git would
produce a superproject as:

  A(H)---B(I)              F(K')---G(L')  rebased branch (incl. sub rebase!)
           \                /
           C(I)---D(I)---E(I) remote branch

and the submodule as:

        J---K---L (old dangeling tip)
       /
  H---I               J'---K'---L' locally rebased branch
       \             /
        M---N---O---P advanced branch

This patch doesn't address this issue, however
a test is added that this fails up front.

3. Remote submodule changes only
 ----------------------
Assuming histories as in (1) except that the local superproject branch
would not have touched the submodule the rebase already works out in the
superproject with no conflicts:

  A(H)---B(I)               F(P)---G(P)  rebased branch (no sub changes)
           \                 /
           C(N)---D(N)---E(P) remote branch

The recurse flag as presented in this patch would additionally
update the submodule as:

  H---I              J'---K'---L' rebased branch
       \            /
        M---N---O---P remote branch

As neither J, K, L nor J', K', L' are referred to from the superproject,
no rewriting of the superproject commits is required.

Conclusion for 'pull --rebase --recursive'
 -----------------------------------------
If there are no local superproject changes it is sufficient to call
"submodule update --rebase" as this produces the desired results. In case
of conflicts, the behavior is the same as in 'submodule update --recursive'
which is assumed to be sane.

This patch implements (3) only.

On a merge workflow:
====================

We'll start off with the same underlying DAG as in (1) in the rebase
workflow. So in an ideal world a 'pull --merge --recursive' would
produce this:

  H---I---J---K---L----X
       \              /
        M---N---O---P

with X as the new merge-commit in the submodule and the superproject
as:

  A(H)---B(I)---F(K)---G(L)---Y(X)
          \                  /
           C(N)---D(N)---E(P)

However modifying the submodules on the fly is not supported in git-merge
such that Y(X) is not easy to produce in a single patch. In fact git-merge
doesn't know about submodules at all.

However when at least one side does not contain commits touching the
submodule at all, then we do not need to perform the merge for the
submodule but a fast-forward can be done via checking out either L or P
in the submodule.  This strategy is implemented in 68d03e4a6e (Implement
automatic fast-forward merge for submodules, 2010-07-07) already, so
to align with the rebase behavior we need to also update the worktree
of the submodule.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 15:36:53 -07:00

148 lines
5.6 KiB
C

#ifndef SUBMODULE_H
#define SUBMODULE_H
struct diff_options;
struct argv_array;
struct oid_array;
struct remote;
enum {
RECURSE_SUBMODULES_ONLY = -5,
RECURSE_SUBMODULES_CHECK = -4,
RECURSE_SUBMODULES_ERROR = -3,
RECURSE_SUBMODULES_NONE = -2,
RECURSE_SUBMODULES_ON_DEMAND = -1,
RECURSE_SUBMODULES_OFF = 0,
RECURSE_SUBMODULES_DEFAULT = 1,
RECURSE_SUBMODULES_ON = 2
};
enum submodule_update_type {
SM_UPDATE_UNSPECIFIED = 0,
SM_UPDATE_CHECKOUT,
SM_UPDATE_REBASE,
SM_UPDATE_MERGE,
SM_UPDATE_NONE,
SM_UPDATE_COMMAND
};
struct submodule_update_strategy {
enum submodule_update_type type;
const char *command;
};
#define SUBMODULE_UPDATE_STRATEGY_INIT {SM_UPDATE_UNSPECIFIED, NULL}
extern int is_staging_gitmodules_ok(void);
extern int update_path_in_gitmodules(const char *oldpath, const char *newpath);
extern int remove_path_from_gitmodules(const char *path);
extern void stage_updated_gitmodules(void);
extern void set_diffopt_flags_from_submodule_config(struct diff_options *,
const char *path);
extern int submodule_config(const char *var, const char *value, void *cb);
extern int git_default_submodule_config(const char *var, const char *value, void *cb);
struct option;
int option_parse_recurse_submodules_worktree_updater(const struct option *opt,
const char *arg, int unset);
void load_submodule_cache(void);
extern void gitmodules_config(void);
extern void gitmodules_config_sha1(const unsigned char *commit_sha1);
extern int is_submodule_initialized(const char *path);
/*
* Determine if a submodule has been populated at a given 'path' by checking if
* the <path>/.git resolves to a valid git repository.
* If return_error_code is NULL, die on error.
* Otherwise the return error code is the same as of resolve_gitdir_gently.
*/
extern int is_submodule_populated_gently(const char *path, int *return_error_code);
extern void die_in_unpopulated_submodule(const struct index_state *istate,
const char *prefix);
extern void die_path_inside_submodule(const struct index_state *istate,
const struct pathspec *ps);
extern int parse_submodule_update_strategy(const char *value,
struct submodule_update_strategy *dst);
extern const char *submodule_strategy_to_string(const struct submodule_update_strategy *s);
extern void handle_ignore_submodules_arg(struct diff_options *, const char *);
extern void show_submodule_summary(FILE *f, const char *path,
const char *line_prefix,
struct object_id *one, struct object_id *two,
unsigned dirty_submodule, const char *meta,
const char *del, const char *add, const char *reset);
extern void show_submodule_inline_diff(FILE *f, const char *path,
const char *line_prefix,
struct object_id *one, struct object_id *two,
unsigned dirty_submodule, const char *meta,
const char *del, const char *add, const char *reset,
const struct diff_options *opt);
extern void set_config_fetch_recurse_submodules(int value);
/* Check if we want to update any submodule.*/
extern int should_update_submodules(void);
/*
* Returns the submodule struct if the given ce entry is a submodule
* and it should be updated. Returns NULL otherwise.
*/
extern const struct submodule *submodule_from_ce(const struct cache_entry *ce);
extern void check_for_new_submodule_commits(struct object_id *oid);
extern int fetch_populated_submodules(const struct argv_array *options,
const char *prefix, int command_line_option,
int quiet, int max_parallel_jobs);
extern unsigned is_submodule_modified(const char *path, int ignore_untracked);
extern int submodule_uses_gitfile(const char *path);
#define SUBMODULE_REMOVAL_DIE_ON_ERROR (1<<0)
#define SUBMODULE_REMOVAL_IGNORE_UNTRACKED (1<<1)
#define SUBMODULE_REMOVAL_IGNORE_IGNORED_UNTRACKED (1<<2)
extern int bad_to_remove_submodule(const char *path, unsigned flags);
extern int merge_submodule(struct object_id *result, const char *path,
const struct object_id *base,
const struct object_id *a,
const struct object_id *b, int search);
/* Checks if there are submodule changes in a..b. */
extern int submodule_touches_in_range(struct object_id *a,
struct object_id *b);
extern int find_unpushed_submodules(struct oid_array *commits,
const char *remotes_name,
struct string_list *needs_pushing);
extern int push_unpushed_submodules(struct oid_array *commits,
const struct remote *remote,
const char **refspec, int refspec_nr,
const struct string_list *push_options,
int dry_run);
extern void connect_work_tree_and_git_dir(const char *work_tree, const char *git_dir);
extern int parallel_submodules(void);
/*
* Given a submodule path (as in the index), return the repository
* path of that submodule in 'buf'. Return -1 on error or when the
* submodule is not initialized.
*/
int submodule_to_gitdir(struct strbuf *buf, const char *submodule);
#define SUBMODULE_MOVE_HEAD_DRY_RUN (1<<0)
#define SUBMODULE_MOVE_HEAD_FORCE (1<<1)
extern int submodule_move_head(const char *path,
const char *old,
const char *new,
unsigned flags);
/*
* Prepare the "env_array" parameter of a "struct child_process" for executing
* a submodule by clearing any repo-specific envirionment variables, but
* retaining any config in the environment.
*/
extern void prepare_submodule_repo_env(struct argv_array *out);
#define ABSORB_GITDIR_RECURSE_SUBMODULES (1<<0)
extern void absorb_git_dir_into_superproject(const char *prefix,
const char *path,
unsigned flags);
/*
* Return the absolute path of the working tree of the superproject, which this
* project is a submodule of. If this repository is not a submodule of
* another repository, return NULL.
*/
extern const char *get_superproject_working_tree(void);
#endif