git-diff: turn on recursion by default
[gitweb.git] / unpack-trees.c
index 20251822e4a8dd410b0232b5e0b13d436758df85..3b32718436ea4da838c98b53b3dba25bb99e3e9a 100644 (file)
@@ -1,15 +1,16 @@
-#include <signal.h>
-#include <sys/time.h>
 #include "cache.h"
+#include "dir.h"
 #include "tree.h"
 #include "tree-walk.h"
+#include "cache-tree.h"
 #include "unpack-trees.h"
+#include "progress.h"
+#include "refs.h"
+
+#define DBRT_DEBUG 1
 
 struct tree_entry_list {
        struct tree_entry_list *next;
-       unsigned directory : 1;
-       unsigned executable : 1;
-       unsigned symlink : 1;
        unsigned int mode;
        const char *name;
        const unsigned char *sha1;
@@ -22,8 +23,10 @@ static struct tree_entry_list *create_tree_entry_list(struct tree *tree)
        struct tree_entry_list *ret = NULL;
        struct tree_entry_list **list_p = &ret;
 
-       desc.buf = tree->buffer;
-       desc.size = tree->size;
+       if (!tree->object.parsed)
+               parse_tree(tree);
+
+       init_tree_desc(&desc, tree->buffer, tree->size);
 
        while (tree_entry(&desc, &one)) {
                struct tree_entry_list *entry;
@@ -32,9 +35,6 @@ static struct tree_entry_list *create_tree_entry_list(struct tree *tree)
                entry->name = one.path;
                entry->sha1 = one.sha1;
                entry->mode = one.mode;
-               entry->directory = S_ISDIR(one.mode) != 0;
-               entry->executable = (one.mode & S_IXUSR) != 0;
-               entry->symlink = S_ISLNK(one.mode) != 0;
                entry->next = NULL;
 
                *list_p = entry;
@@ -66,11 +66,16 @@ static int entcmp(const char *name1, int dir1, const char *name2, int dir2)
 
 static int unpack_trees_rec(struct tree_entry_list **posns, int len,
                            const char *base, struct unpack_trees_options *o,
-                           int *indpos,
                            struct tree_entry_list *df_conflict_list)
 {
        int baselen = strlen(base);
        int src_size = len + 1;
+       int i_stk = i_stk;
+       int retval = 0;
+
+       if (o->dir)
+               i_stk = push_exclude_per_directory(o->dir, base, strlen(base));
+
        do {
                int i;
                const char *first;
@@ -90,7 +95,7 @@ static int unpack_trees_rec(struct tree_entry_list **posns, int len,
                cache_name = NULL;
 
                /* Check the cache */
-               if (o->merge && *indpos < active_nr) {
+               if (o->merge && o->pos < active_nr) {
                        /* This is a bit tricky: */
                        /* If the index has a subdirectory (with
                         * contents) as the first name, it'll get a
@@ -108,7 +113,7 @@ static int unpack_trees_rec(struct tree_entry_list **posns, int len,
                         * file case.
                         */
 
-                       cache_name = active_cache[*indpos]->name;
+                       cache_name = active_cache[o->pos]->name;
                        if (strlen(cache_name) > baselen &&
                            !memcmp(cache_name, base, baselen)) {
                                cache_name += baselen;
@@ -130,14 +135,14 @@ static int unpack_trees_rec(struct tree_entry_list **posns, int len,
 #endif
                        if (!first || entcmp(first, firstdir,
                                             posns[i]->name,
-                                            posns[i]->directory) > 0) {
+                                            S_ISDIR(posns[i]->mode)) > 0) {
                                first = posns[i]->name;
-                               firstdir = posns[i]->directory;
+                               firstdir = S_ISDIR(posns[i]->mode);
                        }
                }
                /* No name means we're done */
                if (!first)
-                       return 0;
+                       goto leave_directory;
 
                pathlen = strlen(first);
                ce_size = cache_entry_size(baselen + pathlen);
@@ -148,8 +153,8 @@ static int unpack_trees_rec(struct tree_entry_list **posns, int len,
 
                if (cache_name && !strcmp(cache_name, first)) {
                        any_files = 1;
-                       src[0] = active_cache[*indpos];
-                       remove_cache_entry_at(*indpos);
+                       src[0] = active_cache[o->pos];
+                       remove_cache_entry_at(o->pos);
                }
 
                for (i = 0; i < len; i++) {
@@ -166,7 +171,7 @@ static int unpack_trees_rec(struct tree_entry_list **posns, int len,
                                continue;
                        }
 
-                       if (posns[i]->directory) {
+                       if (S_ISDIR(posns[i]->mode)) {
                                struct tree *tree = lookup_tree(posns[i]->sha1);
                                any_dirs = 1;
                                parse_tree(tree);
@@ -194,7 +199,7 @@ static int unpack_trees_rec(struct tree_entry_list **posns, int len,
 
                        any_files = 1;
 
-                       memcpy(ce->sha1, posns[i]->sha1, 20);
+                       hashcpy(ce->sha1, posns[i]->sha1);
                        src[i + o->merge] = ce;
                        subposns[i] = df_conflict_list;
                        posns[i] = posns[i]->next;
@@ -218,7 +223,7 @@ static int unpack_trees_rec(struct tree_entry_list **posns, int len,
 #if DBRT_DEBUG > 1
                                printf("Added %d entries\n", ret);
 #endif
-                               *indpos += ret;
+                               o->pos += ret;
                        } else {
                                for (i = 0; i < src_size; i++) {
                                        if (src[i]) {
@@ -234,23 +239,32 @@ static int unpack_trees_rec(struct tree_entry_list **posns, int len,
                        newbase[baselen + pathlen] = '/';
                        newbase[baselen + pathlen + 1] = '\0';
                        if (unpack_trees_rec(subposns, len, newbase, o,
-                                            indpos, df_conflict_list))
-                               return -1;
+                                            df_conflict_list)) {
+                               retval = -1;
+                               goto leave_directory;
+                       }
                        free(newbase);
                }
                free(subposns);
                free(src);
        } while (1);
+
+ leave_directory:
+       if (o->dir)
+               pop_exclude_per_directory(o->dir, i_stk);
+       return retval;
 }
 
 /* Unlink the last component and attempt to remove leading
  * directories, in case this unlink is the removal of the
  * last entry in the directory -- empty directories are removed.
  */
-static void unlink_entry(char *name)
+static void unlink_entry(char *name, char *last_symlink)
 {
        char *cp, *prev;
 
+       if (has_symlink_leading_path(name, last_symlink))
+               return;
        if (unlink(name))
                return;
        prev = NULL;
@@ -272,36 +286,14 @@ static void unlink_entry(char *name)
        }
 }
 
-static volatile int progress_update = 0;
-
-static void progress_interval(int signum)
-{
-       progress_update = 1;
-}
-
-static void setup_progress_signal(void)
-{
-       struct sigaction sa;
-       struct itimerval v;
-
-       memset(&sa, 0, sizeof(sa));
-       sa.sa_handler = progress_interval;
-       sigemptyset(&sa.sa_mask);
-       sa.sa_flags = SA_RESTART;
-       sigaction(SIGALRM, &sa, NULL);
-
-       v.it_interval.tv_sec = 1;
-       v.it_interval.tv_usec = 0;
-       v.it_value = v.it_interval;
-       setitimer(ITIMER_REAL, &v, NULL);
-}
-
 static struct checkout state;
 static void check_updates(struct cache_entry **src, int nr,
-               struct unpack_trees_options *o)
+                       struct unpack_trees_options *o)
 {
        unsigned short mask = htons(CE_UPDATE);
-       unsigned last_percent = 200, cnt = 0, total = 0;
+       unsigned cnt = 0, total = 0;
+       struct progress progress;
+       char last_symlink[PATH_MAX];
 
        if (o->update && o->verbose_update) {
                for (total = cnt = 0; cnt < nr; cnt++) {
@@ -310,71 +302,57 @@ static void check_updates(struct cache_entry **src, int nr,
                                total++;
                }
 
-               /* Don't bother doing this for very small updates */
-               if (total < 250)
-                       total = 0;
-
-               if (total) {
-                       fprintf(stderr, "Checking files out...\n");
-                       setup_progress_signal();
-                       progress_update = 1;
-               }
+               start_progress_delay(&progress, "Checking %u files out...",
+                                    "", total, 50, 2);
                cnt = 0;
        }
 
+       *last_symlink = '\0';
        while (nr--) {
                struct cache_entry *ce = *src++;
 
-               if (total) {
-                       if (!ce->ce_mode || ce->ce_flags & mask) {
-                               unsigned percent;
-                               cnt++;
-                               percent = (cnt * 100) / total;
-                               if (percent != last_percent ||
-                                   progress_update) {
-                                       fprintf(stderr, "%4u%% (%u/%u) done\r",
-                                               percent, cnt, total);
-                                       last_percent = percent;
-                                       progress_update = 0;
-                               }
-                       }
-               }
+               if (total)
+                       if (!ce->ce_mode || ce->ce_flags & mask)
+                               display_progress(&progress, ++cnt);
                if (!ce->ce_mode) {
                        if (o->update)
-                               unlink_entry(ce->name);
+                               unlink_entry(ce->name, last_symlink);
                        continue;
                }
                if (ce->ce_flags & mask) {
                        ce->ce_flags &= ~mask;
-                       if (o->update)
+                       if (o->update) {
                                checkout_entry(ce, &state, NULL);
+                               *last_symlink = '\0';
+                       }
                }
        }
-       if (total) {
-               signal(SIGALRM, SIG_IGN);
-               fputc('\n', stderr);
-       }
+       if (total)
+               stop_progress(&progress);;
 }
 
 int unpack_trees(struct object_list *trees, struct unpack_trees_options *o)
 {
-       int indpos = 0;
        unsigned len = object_list_length(trees);
        struct tree_entry_list **posns;
        int i;
        struct object_list *posn = trees;
        struct tree_entry_list df_conflict_list;
-       struct cache_entry df_conflict_entry;
+       static struct cache_entry *dfc;
 
        memset(&df_conflict_list, 0, sizeof(df_conflict_list));
        df_conflict_list.next = &df_conflict_list;
+       memset(&state, 0, sizeof(state));
        state.base_dir = "";
        state.force = 1;
        state.quiet = 1;
        state.refresh_cache = 1;
 
        o->merge_size = len;
-       o->df_conflict_entry = &df_conflict_entry;
+
+       if (!dfc)
+               dfc = xcalloc(1, sizeof(struct cache_entry) + 1);
+       o->df_conflict_entry = dfc;
 
        if (len) {
                posns = xmalloc(len * sizeof(struct tree_entry_list *));
@@ -383,7 +361,7 @@ int unpack_trees(struct object_list *trees, struct unpack_trees_options *o)
                        posn = posn->next;
                }
                if (unpack_trees_rec(posns, len, o->prefix ? o->prefix : "",
-                                    o, &indpos, &df_conflict_list))
+                                    o, &df_conflict_list))
                        return -1;
        }
 
@@ -393,3 +371,543 @@ int unpack_trees(struct object_list *trees, struct unpack_trees_options *o)
        check_updates(active_cache, active_nr, o);
        return 0;
 }
+
+/* Here come the merge functions */
+
+static void reject_merge(struct cache_entry *ce)
+{
+       die("Entry '%s' would be overwritten by merge. Cannot merge.",
+           ce->name);
+}
+
+static int same(struct cache_entry *a, struct cache_entry *b)
+{
+       if (!!a != !!b)
+               return 0;
+       if (!a && !b)
+               return 1;
+       return a->ce_mode == b->ce_mode &&
+              !hashcmp(a->sha1, b->sha1);
+}
+
+
+/*
+ * When a CE gets turned into an unmerged entry, we
+ * want it to be up-to-date
+ */
+static void verify_uptodate(struct cache_entry *ce,
+               struct unpack_trees_options *o)
+{
+       struct stat st;
+
+       if (o->index_only || o->reset)
+               return;
+
+       if (!lstat(ce->name, &st)) {
+               unsigned changed = ce_match_stat(ce, &st, 1);
+               if (!changed)
+                       return;
+               errno = 0;
+       }
+       if (errno == ENOENT)
+               return;
+       die("Entry '%s' not uptodate. Cannot merge.", ce->name);
+}
+
+static void invalidate_ce_path(struct cache_entry *ce)
+{
+       if (ce)
+               cache_tree_invalidate_path(active_cache_tree, ce->name);
+}
+
+/*
+ * Check that checking out ce->sha1 in subdir ce->name is not
+ * going to overwrite any working files.
+ *
+ * Currently, git does not checkout subprojects during a superproject
+ * checkout, so it is not going to overwrite anything.
+ */
+static int verify_clean_submodule(struct cache_entry *ce, const char *action,
+                                     struct unpack_trees_options *o)
+{
+       return 0;
+}
+
+static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
+                                     struct unpack_trees_options *o)
+{
+       /*
+        * we are about to extract "ce->name"; we would not want to lose
+        * anything in the existing directory there.
+        */
+       int namelen;
+       int pos, i;
+       struct dir_struct d;
+       char *pathbuf;
+       int cnt = 0;
+       unsigned char sha1[20];
+
+       if (S_ISGITLINK(ntohl(ce->ce_mode)) &&
+           resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
+               /* If we are not going to update the submodule, then
+                * we don't care.
+                */
+               if (!hashcmp(sha1, ce->sha1))
+                       return 0;
+               return verify_clean_submodule(ce, action, o);
+       }
+
+       /*
+        * First let's make sure we do not have a local modification
+        * in that directory.
+        */
+       namelen = strlen(ce->name);
+       pos = cache_name_pos(ce->name, namelen);
+       if (0 <= pos)
+               return cnt; /* we have it as nondirectory */
+       pos = -pos - 1;
+       for (i = pos; i < active_nr; i++) {
+               struct cache_entry *ce = active_cache[i];
+               int len = ce_namelen(ce);
+               if (len < namelen ||
+                   strncmp(ce->name, ce->name, namelen) ||
+                   ce->name[namelen] != '/')
+                       break;
+               /*
+                * ce->name is an entry in the subdirectory.
+                */
+               if (!ce_stage(ce)) {
+                       verify_uptodate(ce, o);
+                       ce->ce_mode = 0;
+               }
+               cnt++;
+       }
+
+       /*
+        * Then we need to make sure that we do not lose a locally
+        * present file that is not ignored.
+        */
+       pathbuf = xmalloc(namelen + 2);
+       memcpy(pathbuf, ce->name, namelen);
+       strcpy(pathbuf+namelen, "/");
+
+       memset(&d, 0, sizeof(d));
+       if (o->dir)
+               d.exclude_per_dir = o->dir->exclude_per_dir;
+       i = read_directory(&d, ce->name, pathbuf, namelen+1, NULL);
+       if (i)
+               die("Updating '%s' would lose untracked files in it",
+                   ce->name);
+       free(pathbuf);
+       return cnt;
+}
+
+/*
+ * We do not want to remove or overwrite a working tree file that
+ * is not tracked, unless it is ignored.
+ */
+static void verify_absent(struct cache_entry *ce, const char *action,
+               struct unpack_trees_options *o)
+{
+       struct stat st;
+
+       if (o->index_only || o->reset || !o->update)
+               return;
+
+       if (has_symlink_leading_path(ce->name, NULL))
+               return;
+
+       if (!lstat(ce->name, &st)) {
+               int cnt;
+
+               if (o->dir && excluded(o->dir, ce->name))
+                       /*
+                        * ce->name is explicitly excluded, so it is Ok to
+                        * overwrite it.
+                        */
+                       return;
+               if (S_ISDIR(st.st_mode)) {
+                       /*
+                        * We are checking out path "foo" and
+                        * found "foo/." in the working tree.
+                        * This is tricky -- if we have modified
+                        * files that are in "foo/" we would lose
+                        * it.
+                        */
+                       cnt = verify_clean_subdirectory(ce, action, o);
+
+                       /*
+                        * If this removed entries from the index,
+                        * what that means is:
+                        *
+                        * (1) the caller unpack_trees_rec() saw path/foo
+                        * in the index, and it has not removed it because
+                        * it thinks it is handling 'path' as blob with
+                        * D/F conflict;
+                        * (2) we will return "ok, we placed a merged entry
+                        * in the index" which would cause o->pos to be
+                        * incremented by one;
+                        * (3) however, original o->pos now has 'path/foo'
+                        * marked with "to be removed".
+                        *
+                        * We need to increment it by the number of
+                        * deleted entries here.
+                        */
+                       o->pos += cnt;
+                       return;
+               }
+
+               /*
+                * The previous round may already have decided to
+                * delete this path, which is in a subdirectory that
+                * is being replaced with a blob.
+                */
+               cnt = cache_name_pos(ce->name, strlen(ce->name));
+               if (0 <= cnt) {
+                       struct cache_entry *ce = active_cache[cnt];
+                       if (!ce_stage(ce) && !ce->ce_mode)
+                               return;
+               }
+
+               die("Untracked working tree file '%s' "
+                   "would be %s by merge.", ce->name, action);
+       }
+}
+
+static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
+               struct unpack_trees_options *o)
+{
+       merge->ce_flags |= htons(CE_UPDATE);
+       if (old) {
+               /*
+                * See if we can re-use the old CE directly?
+                * That way we get the uptodate stat info.
+                *
+                * This also removes the UPDATE flag on
+                * a match.
+                */
+               if (same(old, merge)) {
+                       *merge = *old;
+               } else {
+                       verify_uptodate(old, o);
+                       invalidate_ce_path(old);
+               }
+       }
+       else {
+               verify_absent(merge, "overwritten", o);
+               invalidate_ce_path(merge);
+       }
+
+       merge->ce_flags &= ~htons(CE_STAGEMASK);
+       add_cache_entry(merge, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
+       return 1;
+}
+
+static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
+               struct unpack_trees_options *o)
+{
+       if (old)
+               verify_uptodate(old, o);
+       else
+               verify_absent(ce, "removed", o);
+       ce->ce_mode = 0;
+       add_cache_entry(ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
+       invalidate_ce_path(ce);
+       return 1;
+}
+
+static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
+{
+       add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
+       return 1;
+}
+
+#if DBRT_DEBUG
+static void show_stage_entry(FILE *o,
+                            const char *label, const struct cache_entry *ce)
+{
+       if (!ce)
+               fprintf(o, "%s (missing)\n", label);
+       else
+               fprintf(o, "%s%06o %s %d\t%s\n",
+                       label,
+                       ntohl(ce->ce_mode),
+                       sha1_to_hex(ce->sha1),
+                       ce_stage(ce),
+                       ce->name);
+}
+#endif
+
+int threeway_merge(struct cache_entry **stages,
+               struct unpack_trees_options *o)
+{
+       struct cache_entry *index;
+       struct cache_entry *head;
+       struct cache_entry *remote = stages[o->head_idx + 1];
+       int count;
+       int head_match = 0;
+       int remote_match = 0;
+
+       int df_conflict_head = 0;
+       int df_conflict_remote = 0;
+
+       int any_anc_missing = 0;
+       int no_anc_exists = 1;
+       int i;
+
+       for (i = 1; i < o->head_idx; i++) {
+               if (!stages[i] || stages[i] == o->df_conflict_entry)
+                       any_anc_missing = 1;
+               else
+                       no_anc_exists = 0;
+       }
+
+       index = stages[0];
+       head = stages[o->head_idx];
+
+       if (head == o->df_conflict_entry) {
+               df_conflict_head = 1;
+               head = NULL;
+       }
+
+       if (remote == o->df_conflict_entry) {
+               df_conflict_remote = 1;
+               remote = NULL;
+       }
+
+       /* First, if there's a #16 situation, note that to prevent #13
+        * and #14.
+        */
+       if (!same(remote, head)) {
+               for (i = 1; i < o->head_idx; i++) {
+                       if (same(stages[i], head)) {
+                               head_match = i;
+                       }
+                       if (same(stages[i], remote)) {
+                               remote_match = i;
+                       }
+               }
+       }
+
+       /* We start with cases where the index is allowed to match
+        * something other than the head: #14(ALT) and #2ALT, where it
+        * is permitted to match the result instead.
+        */
+       /* #14, #14ALT, #2ALT */
+       if (remote && !df_conflict_head && head_match && !remote_match) {
+               if (index && !same(index, remote) && !same(index, head))
+                       reject_merge(index);
+               return merged_entry(remote, index, o);
+       }
+       /*
+        * If we have an entry in the index cache, then we want to
+        * make sure that it matches head.
+        */
+       if (index && !same(index, head)) {
+               reject_merge(index);
+       }
+
+       if (head) {
+               /* #5ALT, #15 */
+               if (same(head, remote))
+                       return merged_entry(head, index, o);
+               /* #13, #3ALT */
+               if (!df_conflict_remote && remote_match && !head_match)
+                       return merged_entry(head, index, o);
+       }
+
+       /* #1 */
+       if (!head && !remote && any_anc_missing)
+               return 0;
+
+       /* Under the new "aggressive" rule, we resolve mostly trivial
+        * cases that we historically had git-merge-one-file resolve.
+        */
+       if (o->aggressive) {
+               int head_deleted = !head && !df_conflict_head;
+               int remote_deleted = !remote && !df_conflict_remote;
+               struct cache_entry *ce = NULL;
+
+               if (index)
+                       ce = index;
+               else if (head)
+                       ce = head;
+               else if (remote)
+                       ce = remote;
+               else {
+                       for (i = 1; i < o->head_idx; i++) {
+                               if (stages[i] && stages[i] != o->df_conflict_entry) {
+                                       ce = stages[i];
+                                       break;
+                               }
+                       }
+               }
+
+               /*
+                * Deleted in both.
+                * Deleted in one and unchanged in the other.
+                */
+               if ((head_deleted && remote_deleted) ||
+                   (head_deleted && remote && remote_match) ||
+                   (remote_deleted && head && head_match)) {
+                       if (index)
+                               return deleted_entry(index, index, o);
+                       else if (ce && !head_deleted)
+                               verify_absent(ce, "removed", o);
+                       return 0;
+               }
+               /*
+                * Added in both, identically.
+                */
+               if (no_anc_exists && head && remote && same(head, remote))
+                       return merged_entry(head, index, o);
+
+       }
+
+       /* Below are "no merge" cases, which require that the index be
+        * up-to-date to avoid the files getting overwritten with
+        * conflict resolution files.
+        */
+       if (index) {
+               verify_uptodate(index, o);
+       }
+
+       o->nontrivial_merge = 1;
+
+       /* #2, #3, #4, #6, #7, #9, #10, #11. */
+       count = 0;
+       if (!head_match || !remote_match) {
+               for (i = 1; i < o->head_idx; i++) {
+                       if (stages[i] && stages[i] != o->df_conflict_entry) {
+                               keep_entry(stages[i], o);
+                               count++;
+                               break;
+                       }
+               }
+       }
+#if DBRT_DEBUG
+       else {
+               fprintf(stderr, "read-tree: warning #16 detected\n");
+               show_stage_entry(stderr, "head   ", stages[head_match]);
+               show_stage_entry(stderr, "remote ", stages[remote_match]);
+       }
+#endif
+       if (head) { count += keep_entry(head, o); }
+       if (remote) { count += keep_entry(remote, o); }
+       return count;
+}
+
+/*
+ * Two-way merge.
+ *
+ * The rule is to "carry forward" what is in the index without losing
+ * information across a "fast forward", favoring a successful merge
+ * over a merge failure when it makes sense.  For details of the
+ * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
+ *
+ */
+int twoway_merge(struct cache_entry **src,
+               struct unpack_trees_options *o)
+{
+       struct cache_entry *current = src[0];
+       struct cache_entry *oldtree = src[1];
+       struct cache_entry *newtree = src[2];
+
+       if (o->merge_size != 2)
+               return error("Cannot do a twoway merge of %d trees",
+                            o->merge_size);
+
+       if (oldtree == o->df_conflict_entry)
+               oldtree = NULL;
+       if (newtree == o->df_conflict_entry)
+               newtree = NULL;
+
+       if (current) {
+               if ((!oldtree && !newtree) || /* 4 and 5 */
+                   (!oldtree && newtree &&
+                    same(current, newtree)) || /* 6 and 7 */
+                   (oldtree && newtree &&
+                    same(oldtree, newtree)) || /* 14 and 15 */
+                   (oldtree && newtree &&
+                    !same(oldtree, newtree) && /* 18 and 19 */
+                    same(current, newtree))) {
+                       return keep_entry(current, o);
+               }
+               else if (oldtree && !newtree && same(current, oldtree)) {
+                       /* 10 or 11 */
+                       return deleted_entry(oldtree, current, o);
+               }
+               else if (oldtree && newtree &&
+                        same(current, oldtree) && !same(current, newtree)) {
+                       /* 20 or 21 */
+                       return merged_entry(newtree, current, o);
+               }
+               else {
+                       /* all other failures */
+                       if (oldtree)
+                               reject_merge(oldtree);
+                       if (current)
+                               reject_merge(current);
+                       if (newtree)
+                               reject_merge(newtree);
+                       return -1;
+               }
+       }
+       else if (newtree)
+               return merged_entry(newtree, current, o);
+       else
+               return deleted_entry(oldtree, current, o);
+}
+
+/*
+ * Bind merge.
+ *
+ * Keep the index entries at stage0, collapse stage1 but make sure
+ * stage0 does not have anything there.
+ */
+int bind_merge(struct cache_entry **src,
+               struct unpack_trees_options *o)
+{
+       struct cache_entry *old = src[0];
+       struct cache_entry *a = src[1];
+
+       if (o->merge_size != 1)
+               return error("Cannot do a bind merge of %d trees\n",
+                            o->merge_size);
+       if (a && old)
+               die("Entry '%s' overlaps.  Cannot bind.", a->name);
+       if (!a)
+               return keep_entry(old, o);
+       else
+               return merged_entry(a, NULL, o);
+}
+
+/*
+ * One-way merge.
+ *
+ * The rule is:
+ * - take the stat information from stage0, take the data from stage1
+ */
+int oneway_merge(struct cache_entry **src,
+               struct unpack_trees_options *o)
+{
+       struct cache_entry *old = src[0];
+       struct cache_entry *a = src[1];
+
+       if (o->merge_size != 1)
+               return error("Cannot do a oneway merge of %d trees",
+                            o->merge_size);
+
+       if (!a)
+               return deleted_entry(old, old, o);
+       if (old && same(old, a)) {
+               if (o->reset) {
+                       struct stat st;
+                       if (lstat(old->name, &st) ||
+                           ce_match_stat(old, &st, 1))
+                               old->ce_flags |= htons(CE_UPDATE);
+               }
+               return keep_entry(old, o);
+       }
+       return merged_entry(a, old, o);
+}