am --abort: keep unrelated commits on unborn branch

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 8afdf2b5c4bfbd53e7315afe9d8ae3d88f93dd57..5a787580368bd3e6410128ff300853a10e4a50ee 100644 (file)
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -1,5 +1,5 @@
-#include "cache.h"
 #include "builtin.h"
+#include "lockfile.h"
 #include "parse-options.h"
 #include "refs.h"
 #include "commit.h"
@@ -67,6 +67,7 @@ static int update_some(const unsigned char *sha1, const char *base, int baselen,
 {
        int len;
        struct cache_entry *ce;
+       int pos;
 
        if (S_ISDIR(mode))
                return READ_TREE_RECURSIVE;
@@ -79,6 +80,23 @@ static int update_some(const unsigned char *sha1, const char *base, int baselen,
        ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
        ce->ce_namelen = len;
        ce->ce_mode = create_ce_mode(mode);
+
+       /*
+        * If the entry is the same as the current index, we can leave the old
+        * entry in place. Whether it is UPTODATE or not, checkout_entry will
+        * do the right thing.
+        */
+       pos = cache_name_pos(ce->name, ce->ce_namelen);
+       if (pos >= 0) {
+               struct cache_entry *old = active_cache[pos];
+               if (ce->ce_mode == old->ce_mode &&
+                   !hashcmp(ce->sha1, old->sha1)) {
+                       old->ce_flags |= CE_UPDATE;
+                       free(ce);
+                       return 0;
+               }
+       }
+
        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
        return 0;
 }
@@ -355,7 +373,7 @@ static int checkout_paths(const struct checkout_opts *opts,
        if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
                die(_("unable to write new index file"));
 
-       read_ref_full("HEAD", rev, 0, &flag);
+       read_ref_full("HEAD", 0, rev, &flag);
        head = lookup_commit_reference_gently(rev, 1);
 
        errs |= post_checkout_hook(head, head, 0);
@@ -775,7 +793,7 @@ static int switch_branches(const struct checkout_opts *opts,
        unsigned char rev[20];
        int flag, writeout_error = 0;
        memset(&old, 0, sizeof(old));
-       old.path = path_to_free = resolve_refdup("HEAD", rev, 0, &flag);
+       old.path = path_to_free = resolve_refdup("HEAD", 0, rev, &flag);
        old.commit = lookup_commit_reference_gently(rev, 1);
        if (!(flag & REF_ISSYMREF))
                old.path = NULL;
@@ -1072,7 +1090,7 @@ static int checkout_branch(struct checkout_opts *opts,
                unsigned char rev[20];
                int flag;
 
-               if (!read_ref_full("HEAD", rev, 0, &flag) &&
+               if (!read_ref_full("HEAD", 0, rev, &flag) &&
                    (flag & REF_ISSYMREF) && is_null_sha1(rev))
                        return switch_unborn_to_new_branch(opts);
        }
@@ -1150,10 +1168,8 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
                const char *argv0 = argv[0];
                if (!argc || !strcmp(argv0, "--"))
                        die (_("--track needs a branch name"));
-               if (starts_with(argv0, "refs/"))
-                       argv0 += 5;
-               if (starts_with(argv0, "remotes/"))
-                       argv0 += 8;
+               skip_prefix(argv0, "refs/", &argv0);
+               skip_prefix(argv0, "remotes/", &argv0);
                argv0 = strchr(argv0, '/');
                if (!argv0 || !argv0[1])
                        die (_("Missing branch name; try -b"));