[PATCH v3 13/19] pull: implement pulling into an unborn branch
From: Paul Tan <hidden>
Date: 2016-06-15 23:05:18
Subsystem:
the rest · Maintainer:
Linus Torvalds
b4dc085 (pull: merge into unborn by fast-forwarding from empty
tree, 2013-06-20) established git-pull's current behavior of pulling
into an unborn branch by fast-forwarding the work tree from an empty
tree to the merge head, then setting HEAD to the merge head.
Re-implement this behavior by introducing pull_into_void() which will be
called instead of run_merge() if HEAD is invalid.
Helped-by: Stephen Robin [off-list ref]
Signed-off-by: Paul Tan <redacted>
---
Notes:
v3
* style fixes
builtin/pull.c | 29 ++++++++++++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)
diff --git a/builtin/pull.c b/builtin/pull.c
index 0e48a14..a2dd0ba 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c@@ -13,6 +13,7 @@ #include "sha1-array.h" #include "remote.h" #include "dir.h" +#include "refs.h" static const char * const pull_usage[] = { N_("git pull [options] [<repository> [<refspec>...]]"),
@@ -368,6 +369,27 @@ static int run_fetch(const char *repo, const char **refspecs) } /** + * "Pulls into void" by branching off merge_head. + */ +static int pull_into_void(const unsigned char *merge_head, + const unsigned char *curr_head) +{ + /* + * Two-way merge: we treat the index as based on an empty tree, + * and try to fast-forward to HEAD. This ensures we will not lose + * index/worktree changes that the user already made on the unborn + * branch. + */ + if (checkout_fast_forward(EMPTY_TREE_SHA1_BIN, merge_head, 0)) + return 1; + + if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR)) + return 1; + + return 0; +} + +/** * Runs git-merge, returning its exit status. */ static int run_merge(void)
@@ -476,5 +498,10 @@ int cmd_pull(int argc, const char **argv, const char *prefix) if (!merge_heads.nr) die_no_merge_candidates(repo, refspecs); - return run_merge(); + if (is_null_sha1(orig_head)) { + if (merge_heads.nr > 1) + die(_("Cannot merge multiple branches into empty head.")); + return pull_into_void(*merge_heads.sha1, curr_head); + } else + return run_merge(); }
--
2.1.4