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read-tree: --prefix=<path>/ option.

With "--prefix=<path>/" option, read-tree keeps the current
index contents, and reads the contents of named tree-ish under
directory at `<prefix>`.  The original index file cannot have
anything at the path `<prefix>` itself, and have nothing in
`<prefix>/` directory.  This can be used to graft an
independent tree into a subdirectory of the current index.

Signed-off-by: Junio C Hamano <junkio@cox.net>
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1 parent cdc08b3 commit f4c6f2d328e2f30ad63fdfca26a5e4a11cef35bf Junio C Hamano committed Jan 15, 2006
Showing with 75 additions and 8 deletions.
  1. +10 −1 Documentation/git-read-tree.txt
  2. +65 −7 read-tree.c
@@ -8,7 +8,7 @@ git-read-tree - Reads tree information into the index
SYNOPSIS
--------
-'git-read-tree' (<tree-ish> | [[-m [--aggressive]| --reset] [-u | -i]] <tree-ish1> [<tree-ish2> [<tree-ish3>]])
+'git-read-tree' (<tree-ish> | [[-m [--aggressive] | --reset | --prefix=<prefix>] [-u | -i]] <tree-ish1> [<tree-ish2> [<tree-ish3>]])
DESCRIPTION
@@ -63,6 +63,15 @@ OPTIONS
* when both sides adds a path identically. The resolution
is to add that path.
+--prefix=<prefix>/::
+ Keep the current index contents, and read the contents
+ of named tree-ish under directory at `<prefix>`. The
+ original index file cannot have anything at the path
+ `<prefix>` itself, and have nothing in `<prefix>/`
+ directory. Note that the `<prefix>/` value must end
+ with a slash.
+
+
<tree-ish#>::
The id of the tree object(s) to be read/merged.
View
@@ -21,6 +21,7 @@ static int trivial_merges_only = 0;
static int aggressive = 0;
static int verbose_update = 0;
static volatile int progress_update = 0;
+static const char *prefix = NULL;
static int head_idx = -1;
static int merge_size = 0;
@@ -369,7 +370,8 @@ static int unpack_trees(merge_fn_t fn)
posns[i] = ((struct tree *) posn->item)->entries;
posn = posn->next;
}
- if (unpack_trees_rec(posns, len, "", fn, &indpos))
+ if (unpack_trees_rec(posns, len, prefix ? prefix : "",
+ fn, &indpos))
return -1;
}
@@ -678,6 +680,28 @@ static int twoway_merge(struct cache_entry **src)
}
/*
+ * Bind merge.
+ *
+ * Keep the index entries at stage0, collapse stage1 but make sure
+ * stage0 does not have anything in prefix.
+ */
+static int bind_merge(struct cache_entry **src)
+{
+ struct cache_entry *old = src[0];
+ struct cache_entry *a = src[1];
+
+ if (merge_size != 1)
+ return error("Cannot do a bind merge of %d trees\n",
+ merge_size);
+ if (!a)
+ return merged_entry(old, NULL);
+ if (old)
+ die("Entry '%s' overlaps. Cannot bind.", a->name);
+
+ return merged_entry(a, NULL);
+}
+
+/*
* One-way merge.
*
* The rule is:
@@ -758,7 +782,7 @@ static void prime_cache_tree(void)
}
-static const char read_tree_usage[] = "git-read-tree (<sha> | -m [--aggressive] [-u | -i] <sha1> [<sha2> [<sha3>]])";
+static const char read_tree_usage[] = "git-read-tree (<sha> | [[-m [--aggressive] | --reset | --prefix=<prefix>] [-u | -i]] <sha1> [<sha2> [<sha3>]])";
static struct cache_file cache_file;
@@ -803,9 +827,24 @@ int main(int argc, char **argv)
continue;
}
+ /* "--prefix=<subdirectory>/" means keep the current index
+ * entries and put the entries from the tree under the
+ * given subdirectory.
+ */
+ if (!strncmp(arg, "--prefix=", 9)) {
+ if (stage || merge || prefix)
+ usage(read_tree_usage);
+ prefix = arg + 9;
+ merge = 1;
+ stage = 1;
+ if (read_cache_unmerged())
+ die("you need to resolve your current index first");
+ continue;
+ }
+
/* This differs from "-m" in that we'll silently ignore unmerged entries */
if (!strcmp(arg, "--reset")) {
- if (stage || merge)
+ if (stage || merge || prefix)
usage(read_tree_usage);
reset = 1;
merge = 1;
@@ -826,7 +865,7 @@ int main(int argc, char **argv)
/* "-m" stands for "merge", meaning we start in stage 1 */
if (!strcmp(arg, "-m")) {
- if (stage || merge)
+ if (stage || merge || prefix)
usage(read_tree_usage);
if (read_cache_unmerged())
die("you need to resolve your current index first");
@@ -848,12 +887,31 @@ int main(int argc, char **argv)
if ((update||index_only) && !merge)
usage(read_tree_usage);
+ if (prefix) {
+ int pfxlen = strlen(prefix);
+ int pos;
+ if (prefix[pfxlen-1] != '/')
+ die("prefix must end with /");
+ if (stage != 2)
+ die("binding merge takes only one tree");
+ pos = cache_name_pos(prefix, pfxlen);
+ if (0 <= pos)
+ die("corrupt index file");
+ pos = -pos-1;
+ if (pos < active_nr &&
+ !strncmp(active_cache[pos]->name, prefix, pfxlen))
+ die("subdirectory '%s' already exists.", prefix);
+ pos = cache_name_pos(prefix, pfxlen-1);
+ if (0 <= pos)
+ die("file '%.*s' already exists.", pfxlen-1, prefix);
+ }
+
if (merge) {
if (stage < 2)
die("just how do you expect me to merge %d trees?", stage-1);
switch (stage - 1) {
case 1:
- fn = oneway_merge;
+ fn = prefix ? bind_merge : oneway_merge;
break;
case 2:
fn = twoway_merge;
@@ -879,8 +937,8 @@ int main(int argc, char **argv)
* valid cache-tree because the index must match exactly
* what came from the tree.
*/
- if (trees->item && (!merge || (stage == 2))) {
- cache_tree_free(&active_cache_tree);
+ if (trees->item && !prefix && (!merge || (stage == 2))) {
+ cache_tree_free(&active_cache_tree);
prime_cache_tree();
}

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