Finally implement "git log --follow"
[gitweb.git] / merge-recursive.c
index ef9932a68ccb11416e0412f02c5dade02505b104..c8539ec0bafce5e238d97d6397a9d08c2c92a09c 100644 (file)
 #include "unpack-trees.h"
 #include "path-list.h"
 #include "xdiff-interface.h"
+#include "interpolate.h"
+#include "attr.h"
+
+static int subtree_merge;
+
+static struct tree *shift_tree_object(struct tree *one, struct tree *two)
+{
+       unsigned char shifted[20];
+
+       /*
+        * NEEDSWORK: this limits the recursion depth to hardcoded
+        * value '2' to avoid excessive overhead.
+        */
+       shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
+       if (!hashcmp(two->object.sha1, shifted))
+               return two;
+       return lookup_tree(shifted);
+}
 
 /*
  * A virtual commit has
@@ -67,11 +85,19 @@ struct stage_data
        unsigned processed:1;
 };
 
+struct output_buffer
+{
+       struct output_buffer *next;
+       char *str;
+};
+
 static struct path_list current_file_set = {NULL, 0, 0, 1};
 static struct path_list current_directory_set = {NULL, 0, 0, 1};
 
 static int call_depth = 0;
 static int verbosity = 2;
+static int buffer_output = 1;
+static struct output_buffer *output_list, *output_end;
 
 static int show (int v)
 {
@@ -82,7 +108,16 @@ static void output(int v, const char *fmt, ...)
 {
        va_list args;
        va_start(args, fmt);
-       if (show(v)) {
+       if (buffer_output && show(v)) {
+               struct output_buffer *b = xmalloc(sizeof(*b));
+               nfvasprintf(&b->str, fmt, args);
+               b->next = NULL;
+               if (output_end)
+                       output_end->next = b;
+               else
+                       output_list = b;
+               output_end = b;
+       } else if (show(v)) {
                int i;
                for (i = call_depth; i--;)
                        fputs("  ", stdout);
@@ -92,9 +127,27 @@ static void output(int v, const char *fmt, ...)
        va_end(args);
 }
 
+static void flush_output(void)
+{
+       struct output_buffer *b, *n;
+       for (b = output_list; b; b = n) {
+               int i;
+               for (i = call_depth; i--;)
+                       fputs("  ", stdout);
+               fputs(b->str, stdout);
+               fputc('\n', stdout);
+               n = b->next;
+               free(b->str);
+               free(b);
+       }
+       output_list = NULL;
+       output_end = NULL;
+}
+
 static void output_commit_title(struct commit *commit)
 {
        int i;
+       flush_output();
        for (i = call_depth; i--;)
                fputs("  ", stdout);
        if (commit->util)
@@ -148,7 +201,7 @@ static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
        struct cache_entry *ce;
        ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
        if (!ce)
-               return error("cache_addinfo failed: %s", strerror(cache_errno));
+               return error("addinfo_cache failed for path '%s'", path);
        return add_cache_entry(ce, options);
 }
 
@@ -205,8 +258,16 @@ static struct tree *git_write_tree(void)
 {
        struct tree *result = NULL;
 
-       if (unmerged_index())
+       if (unmerged_index()) {
+               int i;
+               output(0, "There are unmerged index entries:");
+               for (i = 0; i < active_nr; i++) {
+                       struct cache_entry *ce = active_cache[i];
+                       if (ce_stage(ce))
+                               output(0, "%d %.*s", ce_stage(ce), ce_namelen(ce), ce->name);
+               }
                return NULL;
+       }
 
        if (!active_cache_tree)
                active_cache_tree = cache_tree();
@@ -310,7 +371,7 @@ struct rename
 };
 
 /*
- * Get information of all renames which occured between 'o_tree' and
+ * Get information of all renames which occurred between 'o_tree' and
  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
  * 'b_tree') to be able to associate the correct cache entries with
  * the rename information. 'tree' is always equal to either a_tree or b_tree.
@@ -474,6 +535,31 @@ static void flush_buffer(int fd, const char *buf, unsigned long size)
        }
 }
 
+static int make_room_for_path(const char *path)
+{
+       int status;
+       const char *msg = "failed to create path '%s'%s";
+
+       status = mkdir_p(path, 0777);
+       if (status) {
+               if (status == -3) {
+                       /* something else exists */
+                       error(msg, path, ": perhaps a D/F conflict?");
+                       return -1;
+               }
+               die(msg, path, "");
+       }
+
+       /* Successful unlink is good.. */
+       if (!unlink(path))
+               return 0;
+       /* .. and so is no existing file */
+       if (errno == ENOENT)
+               return 0;
+       /* .. but not some other error (who really cares what?) */
+       return error(msg, path, ": perhaps a D/F conflict?");
+}
+
 static void update_file_flags(const unsigned char *sha,
                              unsigned mode,
                              const char *path,
@@ -484,21 +570,22 @@ static void update_file_flags(const unsigned char *sha,
                update_wd = 0;
 
        if (update_wd) {
-               char type[20];
+               enum object_type type;
                void *buf;
                unsigned long size;
 
-               buf = read_sha1_file(sha, type, &size);
+               buf = read_sha1_file(sha, &type, &size);
                if (!buf)
                        die("cannot read object %s '%s'", sha1_to_hex(sha), path);
-               if (strcmp(type, blob_type) != 0)
+               if (type != OBJ_BLOB)
                        die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 
-               if (S_ISREG(mode)) {
+               if (make_room_for_path(path) < 0) {
+                       update_wd = 0;
+                       goto update_index;
+               }
+               if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
                        int fd;
-                       if (mkdir_p(path, 0777))
-                               die("failed to create path %s: %s", path, strerror(errno));
-                       unlink(path);
                        if (mode & 0100)
                                mode = 0777;
                        else
@@ -513,12 +600,14 @@ static void update_file_flags(const unsigned char *sha,
                        memcpy(lnk, buf, size);
                        lnk[size] = '\0';
                        mkdir_p(path, 0777);
-                       unlink(lnk);
+                       unlink(path);
                        symlink(lnk, path);
+                       free(lnk);
                } else
                        die("do not know what to do with %06o %s '%s'",
                            mode, sha1_to_hex(sha), path);
        }
+ update_index:
        if (update_cache)
                add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 }
@@ -544,7 +633,7 @@ struct merge_file_info
 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 {
        unsigned long size;
-       char type[20];
+       enum object_type type;
 
        if (!hashcmp(sha1, null_sha1)) {
                mm->ptr = xstrdup("");
@@ -552,12 +641,396 @@ static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
                return;
        }
 
-       mm->ptr = read_sha1_file(sha1, type, &size);
-       if (!mm->ptr || strcmp(type, blob_type))
+       mm->ptr = read_sha1_file(sha1, &type, &size);
+       if (!mm->ptr || type != OBJ_BLOB)
                die("unable to read blob object %s", sha1_to_hex(sha1));
        mm->size = size;
 }
 
+/*
+ * Customizable low-level merge drivers support.
+ */
+
+struct ll_merge_driver;
+typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
+                          const char *path,
+                          mmfile_t *orig,
+                          mmfile_t *src1, const char *name1,
+                          mmfile_t *src2, const char *name2,
+                          mmbuffer_t *result);
+
+struct ll_merge_driver {
+       const char *name;
+       const char *description;
+       ll_merge_fn fn;
+       const char *recursive;
+       struct ll_merge_driver *next;
+       char *cmdline;
+};
+
+/*
+ * Built-in low-levels
+ */
+static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
+                       const char *path_unused,
+                       mmfile_t *orig,
+                       mmfile_t *src1, const char *name1,
+                       mmfile_t *src2, const char *name2,
+                       mmbuffer_t *result)
+{
+       xpparam_t xpp;
+
+       if (buffer_is_binary(orig->ptr, orig->size) ||
+                       buffer_is_binary(src1->ptr, src1->size) ||
+                       buffer_is_binary(src2->ptr, src2->size))
+               return error("Cannot merge binary files: %s vs. %s\n",
+                       name1, name2);
+
+       memset(&xpp, 0, sizeof(xpp));
+       return xdl_merge(orig,
+                        src1, name1,
+                        src2, name2,
+                        &xpp, XDL_MERGE_ZEALOUS,
+                        result);
+}
+
+static int ll_union_merge(const struct ll_merge_driver *drv_unused,
+                         const char *path_unused,
+                         mmfile_t *orig,
+                         mmfile_t *src1, const char *name1,
+                         mmfile_t *src2, const char *name2,
+                         mmbuffer_t *result)
+{
+       char *src, *dst;
+       long size;
+       const int marker_size = 7;
+
+       int status = ll_xdl_merge(drv_unused, path_unused,
+                                 orig, src1, NULL, src2, NULL, result);
+       if (status <= 0)
+               return status;
+       size = result->size;
+       src = dst = result->ptr;
+       while (size) {
+               char ch;
+               if ((marker_size < size) &&
+                   (*src == '<' || *src == '=' || *src == '>')) {
+                       int i;
+                       ch = *src;
+                       for (i = 0; i < marker_size; i++)
+                               if (src[i] != ch)
+                                       goto not_a_marker;
+                       if (src[marker_size] != '\n')
+                               goto not_a_marker;
+                       src += marker_size + 1;
+                       size -= marker_size + 1;
+                       continue;
+               }
+       not_a_marker:
+               do {
+                       ch = *src++;
+                       *dst++ = ch;
+                       size--;
+               } while (ch != '\n' && size);
+       }
+       result->size = dst - result->ptr;
+       return 0;
+}
+
+static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
+                          const char *path_unused,
+                          mmfile_t *orig,
+                          mmfile_t *src1, const char *name1,
+                          mmfile_t *src2, const char *name2,
+                          mmbuffer_t *result)
+{
+       /*
+        * The tentative merge result is "ours" for the final round,
+        * or common ancestor for an internal merge.  Still return
+        * "conflicted merge" status.
+        */
+       mmfile_t *stolen = index_only ? orig : src1;
+
+       result->ptr = stolen->ptr;
+       result->size = stolen->size;
+       stolen->ptr = NULL;
+       return 1;
+}
+
+#define LL_BINARY_MERGE 0
+#define LL_TEXT_MERGE 1
+#define LL_UNION_MERGE 2
+static struct ll_merge_driver ll_merge_drv[] = {
+       { "binary", "built-in binary merge", ll_binary_merge },
+       { "text", "built-in 3-way text merge", ll_xdl_merge },
+       { "union", "built-in union merge", ll_union_merge },
+};
+
+static void create_temp(mmfile_t *src, char *path)
+{
+       int fd;
+
+       strcpy(path, ".merge_file_XXXXXX");
+       fd = mkstemp(path);
+       if (fd < 0)
+               die("unable to create temp-file");
+       if (write_in_full(fd, src->ptr, src->size) != src->size)
+               die("unable to write temp-file");
+       close(fd);
+}
+
+/*
+ * User defined low-level merge driver support.
+ */
+static int ll_ext_merge(const struct ll_merge_driver *fn,
+                       const char *path,
+                       mmfile_t *orig,
+                       mmfile_t *src1, const char *name1,
+                       mmfile_t *src2, const char *name2,
+                       mmbuffer_t *result)
+{
+       char temp[3][50];
+       char cmdbuf[2048];
+       struct interp table[] = {
+               { "%O" },
+               { "%A" },
+               { "%B" },
+       };
+       struct child_process child;
+       const char *args[20];
+       int status, fd, i;
+       struct stat st;
+
+       if (fn->cmdline == NULL)
+               die("custom merge driver %s lacks command line.", fn->name);
+
+       result->ptr = NULL;
+       result->size = 0;
+       create_temp(orig, temp[0]);
+       create_temp(src1, temp[1]);
+       create_temp(src2, temp[2]);
+
+       interp_set_entry(table, 0, temp[0]);
+       interp_set_entry(table, 1, temp[1]);
+       interp_set_entry(table, 2, temp[2]);
+
+       output(1, "merging %s using %s", path,
+              fn->description ? fn->description : fn->name);
+
+       interpolate(cmdbuf, sizeof(cmdbuf), fn->cmdline, table, 3);
+
+       memset(&child, 0, sizeof(child));
+       child.argv = args;
+       args[0] = "sh";
+       args[1] = "-c";
+       args[2] = cmdbuf;
+       args[3] = NULL;
+
+       status = run_command(&child);
+       if (status < -ERR_RUN_COMMAND_FORK)
+               ; /* failure in run-command */
+       else
+               status = -status;
+       fd = open(temp[1], O_RDONLY);
+       if (fd < 0)
+               goto bad;
+       if (fstat(fd, &st))
+               goto close_bad;
+       result->size = st.st_size;
+       result->ptr = xmalloc(result->size + 1);
+       if (read_in_full(fd, result->ptr, result->size) != result->size) {
+               free(result->ptr);
+               result->ptr = NULL;
+               result->size = 0;
+       }
+ close_bad:
+       close(fd);
+ bad:
+       for (i = 0; i < 3; i++)
+               unlink(temp[i]);
+       return status;
+}
+
+/*
+ * merge.default and merge.driver configuration items
+ */
+static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
+static const char *default_ll_merge;
+
+static int read_merge_config(const char *var, const char *value)
+{
+       struct ll_merge_driver *fn;
+       const char *ep, *name;
+       int namelen;
+
+       if (!strcmp(var, "merge.default")) {
+               if (value)
+                       default_ll_merge = strdup(value);
+               return 0;
+       }
+
+       /*
+        * We are not interested in anything but "merge.<name>.variable";
+        * especially, we do not want to look at variables such as
+        * "merge.summary", "merge.tool", and "merge.verbosity".
+        */
+       if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
+               return 0;
+
+       /*
+        * Find existing one as we might be processing merge.<name>.var2
+        * after seeing merge.<name>.var1.
+        */
+       name = var + 6;
+       namelen = ep - name;
+       for (fn = ll_user_merge; fn; fn = fn->next)
+               if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
+                       break;
+       if (!fn) {
+               char *namebuf;
+               fn = xcalloc(1, sizeof(struct ll_merge_driver));
+               namebuf = xmalloc(namelen + 1);
+               memcpy(namebuf, name, namelen);
+               namebuf[namelen] = 0;
+               fn->name = namebuf;
+               fn->fn = ll_ext_merge;
+               fn->next = NULL;
+               *ll_user_merge_tail = fn;
+               ll_user_merge_tail = &(fn->next);
+       }
+
+       ep++;
+
+       if (!strcmp("name", ep)) {
+               if (!value)
+                       return error("%s: lacks value", var);
+               fn->description = strdup(value);
+               return 0;
+       }
+
+       if (!strcmp("driver", ep)) {
+               if (!value)
+                       return error("%s: lacks value", var);
+               /*
+                * merge.<name>.driver specifies the command line:
+                *
+                *      command-line
+                *
+                * The command-line will be interpolated with the following
+                * tokens and is given to the shell:
+                *
+                *    %O - temporary file name for the merge base.
+                *    %A - temporary file name for our version.
+                *    %B - temporary file name for the other branches' version.
+                *
+                * The external merge driver should write the results in the
+                * file named by %A, and signal that it has done with zero exit
+                * status.
+                */
+               fn->cmdline = strdup(value);
+               return 0;
+       }
+
+       if (!strcmp("recursive", ep)) {
+               if (!value)
+                       return error("%s: lacks value", var);
+               fn->recursive = strdup(value);
+               return 0;
+       }
+
+       return 0;
+}
+
+static void initialize_ll_merge(void)
+{
+       if (ll_user_merge_tail)
+               return;
+       ll_user_merge_tail = &ll_user_merge;
+       git_config(read_merge_config);
+}
+
+static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
+{
+       struct ll_merge_driver *fn;
+       const char *name;
+       int i;
+
+       initialize_ll_merge();
+
+       if (ATTR_TRUE(merge_attr))
+               return &ll_merge_drv[LL_TEXT_MERGE];
+       else if (ATTR_FALSE(merge_attr))
+               return &ll_merge_drv[LL_BINARY_MERGE];
+       else if (ATTR_UNSET(merge_attr)) {
+               if (!default_ll_merge)
+                       return &ll_merge_drv[LL_TEXT_MERGE];
+               else
+                       name = default_ll_merge;
+       }
+       else
+               name = merge_attr;
+
+       for (fn = ll_user_merge; fn; fn = fn->next)
+               if (!strcmp(fn->name, name))
+                       return fn;
+
+       for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
+               if (!strcmp(ll_merge_drv[i].name, name))
+                       return &ll_merge_drv[i];
+
+       /* default to the 3-way */
+       return &ll_merge_drv[LL_TEXT_MERGE];
+}
+
+static const char *git_path_check_merge(const char *path)
+{
+       static struct git_attr_check attr_merge_check;
+
+       if (!attr_merge_check.attr)
+               attr_merge_check.attr = git_attr("merge", 5);
+
+       if (git_checkattr(path, 1, &attr_merge_check))
+               return NULL;
+       return attr_merge_check.value;
+}
+
+static int ll_merge(mmbuffer_t *result_buf,
+                   struct diff_filespec *o,
+                   struct diff_filespec *a,
+                   struct diff_filespec *b,
+                   const char *branch1,
+                   const char *branch2)
+{
+       mmfile_t orig, src1, src2;
+       char *name1, *name2;
+       int merge_status;
+       const char *ll_driver_name;
+       const struct ll_merge_driver *driver;
+
+       name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
+       name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
+
+       fill_mm(o->sha1, &orig);
+       fill_mm(a->sha1, &src1);
+       fill_mm(b->sha1, &src2);
+
+       ll_driver_name = git_path_check_merge(a->path);
+       driver = find_ll_merge_driver(ll_driver_name);
+
+       if (index_only && driver->recursive)
+               driver = find_ll_merge_driver(driver->recursive);
+       merge_status = driver->fn(driver, a->path,
+                                 &orig, &src1, name1, &src2, name2,
+                                 result_buf);
+
+       free(name1);
+       free(name2);
+       free(orig.ptr);
+       free(src1.ptr);
+       free(src2.ptr);
+       return merge_status;
+}
+
 static struct merge_file_info merge_file(struct diff_filespec *o,
                struct diff_filespec *a, struct diff_filespec *b,
                const char *branch1, const char *branch2)
@@ -586,30 +1059,11 @@ static struct merge_file_info merge_file(struct diff_filespec *o,
                else if (sha_eq(b->sha1, o->sha1))
                        hashcpy(result.sha, a->sha1);
                else if (S_ISREG(a->mode)) {
-                       mmfile_t orig, src1, src2;
                        mmbuffer_t result_buf;
-                       xpparam_t xpp;
-                       char *name1, *name2;
                        int merge_status;
 
-                       name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
-                       name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
-
-                       fill_mm(o->sha1, &orig);
-                       fill_mm(a->sha1, &src1);
-                       fill_mm(b->sha1, &src2);
-
-                       memset(&xpp, 0, sizeof(xpp));
-                       merge_status = xdl_merge(&orig,
-                                                &src1, name1,
-                                                &src2, name2,
-                                                &xpp, XDL_MERGE_ZEALOUS,
-                                                &result_buf);
-                       free(name1);
-                       free(name2);
-                       free(orig.ptr);
-                       free(src1.ptr);
-                       free(src2.ptr);
+                       merge_status = ll_merge(&result_buf, o, a, b,
+                                               branch1, branch2);
 
                        if ((merge_status < 0) || !result_buf.ptr)
                                die("Failed to execute internal merge");
@@ -648,18 +1102,29 @@ static void conflict_rename_rename(struct rename *ren1,
        const char *dst_name2 = ren2_dst;
        if (path_list_has_path(&current_directory_set, ren1_dst)) {
                dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
-               output(1, "%s is a directory in %s adding as %s instead",
+               output(1, "%s is a directory in %s added as %s instead",
                       ren1_dst, branch2, dst_name1);
                remove_file(0, ren1_dst, 0);
        }
        if (path_list_has_path(&current_directory_set, ren2_dst)) {
                dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
-               output(1, "%s is a directory in %s adding as %s instead",
+               output(1, "%s is a directory in %s added as %s instead",
                       ren2_dst, branch1, dst_name2);
                remove_file(0, ren2_dst, 0);
        }
-       update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
-       update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
+       if (index_only) {
+               remove_file_from_cache(dst_name1);
+               remove_file_from_cache(dst_name2);
+               /*
+                * Uncomment to leave the conflicting names in the resulting tree
+                *
+                * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
+                * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
+                */
+       } else {
+               update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
+               update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
+       }
        while (delp--)
                free(del[delp]);
 }
@@ -668,7 +1133,7 @@ static void conflict_rename_dir(struct rename *ren1,
                                const char *branch1)
 {
        char *new_path = unique_path(ren1->pair->two->path, branch1);
-       output(1, "Renaming %s to %s instead", ren1->pair->one->path, new_path);
+       output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
        remove_file(0, ren1->pair->two->path, 0);
        update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
        free(new_path);
@@ -681,7 +1146,7 @@ static void conflict_rename_rename_2(struct rename *ren1,
 {
        char *new_path1 = unique_path(ren1->pair->two->path, branch1);
        char *new_path2 = unique_path(ren2->pair->two->path, branch2);
-       output(1, "Renaming %s to %s and %s to %s instead",
+       output(1, "Renamed %s to %s and %s to %s instead",
               ren1->pair->one->path, new_path1,
               ren2->pair->one->path, new_path2);
        remove_file(0, ren1->pair->two->path, 0);
@@ -775,10 +1240,16 @@ static int process_renames(struct path_list *a_renames,
                        if (strcmp(ren1_dst, ren2_dst) != 0) {
                                clean_merge = 0;
                                output(1, "CONFLICT (rename/rename): "
-                                      "Rename %s->%s in branch %s "
-                                      "rename %s->%s in %s",
+                                      "Rename \"%s\"->\"%s\" in branch \"%s\" "
+                                      "rename \"%s\"->\"%s\" in \"%s\"%s",
                                       src, ren1_dst, branch1,
-                                      src, ren2_dst, branch2);
+                                      src, ren2_dst, branch2,
+                                      index_only ? " (left unresolved)": "");
+                               if (index_only) {
+                                       remove_file_from_cache(src);
+                                       update_file(0, ren1->pair->one->sha1,
+                                                   ren1->pair->one->mode, src);
+                               }
                                conflict_rename_rename(ren1, branch1, ren2, branch2);
                        } else {
                                struct merge_file_info mfi;
@@ -789,10 +1260,10 @@ static int process_renames(struct path_list *a_renames,
                                                 branch1,
                                                 branch2);
                                if (mfi.merge || !mfi.clean)
-                                       output(1, "Renaming %s->%s", src, ren1_dst);
+                                       output(1, "Renamed %s->%s", src, ren1_dst);
 
                                if (mfi.merge)
-                                       output(2, "Auto-merging %s", ren1_dst);
+                                       output(2, "Auto-merged %s", ren1_dst);
 
                                if (!mfi.clean) {
                                        output(1, "CONFLICT (content): merge conflict in %s",
@@ -815,7 +1286,7 @@ static int process_renames(struct path_list *a_renames,
                        struct diff_filespec src_other, dst_other;
                        int try_merge, stage = a_renames == renames1 ? 3: 2;
 
-                       remove_file(1, ren1_src, index_only);
+                       remove_file(1, ren1_src, index_only || stage == 3);
 
                        hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
                        src_other.mode = ren1->src_entry->stages[stage].mode;
@@ -826,14 +1297,14 @@ static int process_renames(struct path_list *a_renames,
 
                        if (path_list_has_path(&current_directory_set, ren1_dst)) {
                                clean_merge = 0;
-                               output(1, "CONFLICT (rename/directory): Rename %s->%s in %s "
+                               output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
                                       " directory %s added in %s",
                                       ren1_src, ren1_dst, branch1,
                                       ren1_dst, branch2);
                                conflict_rename_dir(ren1, branch1);
                        } else if (sha_eq(src_other.sha1, null_sha1)) {
                                clean_merge = 0;
-                               output(1, "CONFLICT (rename/delete): Rename %s->%s in %s "
+                               output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
                                       "and deleted in %s",
                                       ren1_src, ren1_dst, branch1,
                                       branch2);
@@ -842,19 +1313,19 @@ static int process_renames(struct path_list *a_renames,
                                const char *new_path;
                                clean_merge = 0;
                                try_merge = 1;
-                               output(1, "CONFLICT (rename/add): Rename %s->%s in %s. "
+                               output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
                                       "%s added in %s",
                                       ren1_src, ren1_dst, branch1,
                                       ren1_dst, branch2);
                                new_path = unique_path(ren1_dst, branch2);
-                               output(1, "Adding as %s instead", new_path);
+                               output(1, "Added as %s instead", new_path);
                                update_file(0, dst_other.sha1, dst_other.mode, new_path);
                        } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
                                ren2 = item->util;
                                clean_merge = 0;
                                ren2->processed = 1;
-                               output(1, "CONFLICT (rename/rename): Rename %s->%s in %s. "
-                                      "Rename %s->%s in %s",
+                               output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
+                                      "Renamed %s->%s in %s",
                                       ren1_src, ren1_dst, branch1,
                                       ren2->pair->one->path, ren2->pair->two->path, branch2);
                                conflict_rename_rename_2(ren1, branch1, ren2, branch2);
@@ -877,20 +1348,31 @@ static int process_renames(struct path_list *a_renames,
                                mfi = merge_file(o, a, b,
                                                a_branch, b_branch);
 
-                               if (mfi.merge || !mfi.clean)
-                                       output(1, "Renaming %s => %s", ren1_src, ren1_dst);
-                               if (mfi.merge)
-                                       output(2, "Auto-merging %s", ren1_dst);
-                               if (!mfi.clean) {
-                                       output(1, "CONFLICT (rename/modify): Merge conflict in %s",
-                                              ren1_dst);
-                                       clean_merge = 0;
-
-                                       if (!index_only)
-                                               update_stages(ren1_dst,
-                                                               o, a, b, 1);
+                               if (mfi.clean &&
+                                   sha_eq(mfi.sha, ren1->pair->two->sha1) &&
+                                   mfi.mode == ren1->pair->two->mode)
+                                       /*
+                                        * This messaged is part of
+                                        * t6022 test. If you change
+                                        * it update the test too.
+                                        */
+                                       output(3, "Skipped %s (merged same as existing)", ren1_dst);
+                               else {
+                                       if (mfi.merge || !mfi.clean)
+                                               output(1, "Renamed %s => %s", ren1_src, ren1_dst);
+                                       if (mfi.merge)
+                                               output(2, "Auto-merged %s", ren1_dst);
+                                       if (!mfi.clean) {
+                                               output(1, "CONFLICT (rename/modify): Merge conflict in %s",
+                                                      ren1_dst);
+                                               clean_merge = 0;
+
+                                               if (!index_only)
+                                                       update_stages(ren1_dst,
+                                                                     o, a, b, 1);
+                                       }
+                                       update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
                                }
-                               update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
                        }
                }
        }
@@ -900,9 +1382,9 @@ static int process_renames(struct path_list *a_renames,
        return clean_merge;
 }
 
-static unsigned char *has_sha(const unsigned char *sha)
+static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
 {
-       return is_null_sha1(sha) ? NULL: (unsigned char *)sha;
+       return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
 }
 
 /* Per entry merge function */
@@ -915,12 +1397,12 @@ static int process_entry(const char *path, struct stage_data *entry,
        print_index_entry("\tpath: ", entry);
        */
        int clean_merge = 1;
-       unsigned char *o_sha = has_sha(entry->stages[1].sha);
-       unsigned char *a_sha = has_sha(entry->stages[2].sha);
-       unsigned char *b_sha = has_sha(entry->stages[3].sha);
        unsigned o_mode = entry->stages[1].mode;
        unsigned a_mode = entry->stages[2].mode;
        unsigned b_mode = entry->stages[3].mode;
+       unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
+       unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
+       unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
 
        if (o_sha && (!a_sha || !b_sha)) {
                /* Case A: Deleted in one */
@@ -930,7 +1412,7 @@ static int process_entry(const char *path, struct stage_data *entry,
                        /* Deleted in both or deleted in one and
                         * unchanged in the other */
                        if (a_sha)
-                               output(2, "Removing %s", path);
+                               output(2, "Removed %s", path);
                        /* do not touch working file if it did not exist */
                        remove_file(1, path, !a_sha);
                } else {
@@ -977,12 +1459,12 @@ static int process_entry(const char *path, struct stage_data *entry,
                        const char *new_path = unique_path(path, add_branch);
                        clean_merge = 0;
                        output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
-                              "Adding %s as %s",
+                              "Added %s as %s",
                               conf, path, other_branch, path, new_path);
                        remove_file(0, path, 0);
                        update_file(0, sha, mode, new_path);
                } else {
-                       output(2, "Adding %s", path);
+                       output(2, "Added %s", path);
                        update_file(1, sha, mode, path);
                }
        } else if (a_sha && b_sha) {
@@ -996,7 +1478,7 @@ static int process_entry(const char *path, struct stage_data *entry,
                        reason = "add/add";
                        o_sha = (unsigned char *)null_sha1;
                }
-               output(2, "Auto-merging %s", path);
+               output(2, "Auto-merged %s", path);
                o.path = a.path = b.path = (char *)path;
                hashcpy(o.sha1, o_sha);
                o.mode = o_mode;
@@ -1021,6 +1503,12 @@ static int process_entry(const char *path, struct stage_data *entry,
                                update_file_flags(mfi.sha, mfi.mode, path,
                                              0 /* update_cache */, 1 /* update_working_directory */);
                }
+       } else if (!o_sha && !a_sha && !b_sha) {
+               /*
+                * this entry was deleted altogether. a_mode == 0 means
+                * we had that path and want to actively remove it.
+                */
+               remove_file(1, path, !a_mode);
        } else
                die("Fatal merge failure, shouldn't happen.");
 
@@ -1035,6 +1523,12 @@ static int merge_trees(struct tree *head,
                       struct tree **result)
 {
        int code, clean;
+
+       if (subtree_merge) {
+               merge = shift_tree_object(head, merge);
+               common = shift_tree_object(head, common);
+       }
+
        if (sha_eq(common->object.sha1, merge->object.sha1)) {
                output(0, "Already uptodate!");
                *result = head;
@@ -1064,9 +1558,8 @@ static int merge_trees(struct tree *head,
                for (i = 0; i < entries->nr; i++) {
                        const char *path = entries->items[i].path;
                        struct stage_data *e = entries->items[i].util;
-                       if (e->processed)
-                               continue;
-                       if (!process_entry(path, e, branch1, branch2))
+                       if (!e->processed
+                               && !process_entry(path, e, branch1, branch2))
                                clean = 0;
                }
 
@@ -1097,7 +1590,7 @@ static struct commit_list *reverse_commit_list(struct commit_list *list)
 
 /*
  * Merge the commits h1 and h2, return the resulting virtual
- * commit object and a flag indicating the cleaness of the merge.
+ * commit object and a flag indicating the cleanness of the merge.
  */
 static int merge(struct commit *h1,
                 struct commit *h2,
@@ -1135,7 +1628,7 @@ static int merge(struct commit *h1,
 
                tree->object.parsed = 1;
                tree->object.type = OBJ_TREE;
-               write_sha1_file(NULL, 0, tree_type, tree->object.sha1);
+               pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
                merged_common_ancestors = make_virtual_commit(tree, "ancestor");
        }
 
@@ -1144,8 +1637,8 @@ static int merge(struct commit *h1,
                /*
                 * When the merge fails, the result contains files
                 * with conflict markers. The cleanness flag is
-                * ignored, it was never acutally used, as result of
-                * merge_trees has always overwritten it: the commited
+                * ignored, it was never actually used, as result of
+                * merge_trees has always overwritten it: the committed
                 * "conflicts" were already resolved.
                 */
                discard_cache();
@@ -1175,6 +1668,7 @@ static int merge(struct commit *h1,
                commit_list_insert(h1, &(*result)->parents);
                commit_list_insert(h2, &(*result)->parents->next);
        }
+       flush_output();
        return clean;
 }
 
@@ -1228,6 +1722,13 @@ int main(int argc, char *argv[])
        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
        int index_fd;
 
+       if (argv[0]) {
+               int namelen = strlen(argv[0]);
+               if (8 < namelen &&
+                   !strcmp(argv[0] + namelen - 8, "-subtree"))
+                       subtree_merge = 1;
+       }
+
        git_config(merge_config);
        if (getenv("GIT_MERGE_VERBOSITY"))
                verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
@@ -1243,6 +1744,8 @@ int main(int argc, char *argv[])
        }
        if (argc - i != 3) /* "--" "<head>" "<remote>" */
                die("Not handling anything other than two heads merge.");
+       if (verbosity >= 5)
+               buffer_output = 0;
 
        branch1 = argv[++i];
        branch2 = argv[++i];
@@ -1252,10 +1755,11 @@ int main(int argc, char *argv[])
 
        branch1 = better_branch_name(branch1);
        branch2 = better_branch_name(branch2);
+
        if (show(3))
                printf("Merging %s with %s\n", branch1, branch2);
 
-       index_fd = hold_lock_file_for_update(lock, get_index_file(), 1);
+       index_fd = hold_locked_index(lock, 1);
 
        for (i = 0; i < bases_count; i++) {
                struct commit *ancestor = get_ref(bases[i]);
@@ -1265,7 +1769,7 @@ int main(int argc, char *argv[])
 
        if (active_cache_changed &&
            (write_cache(index_fd, active_cache, active_nr) ||
-            close(index_fd) || commit_lock_file(lock)))
+            close(index_fd) || commit_locked_index(lock)))
                        die ("unable to write %s", get_index_file());
 
        return clean ? 0: 1;