diff mbox series

[14/16] mktree: optionally add to an existing tree

Message ID df0c50dfea3cb77e0070246efdf7a3f070b2ad97.1718130288.git.gitgitgadget@gmail.com (mailing list archive)
State New, archived
Headers show
Series mktree: support more flexible usage | expand

Commit Message

Victoria Dye June 11, 2024, 6:24 p.m. UTC
From: Victoria Dye <vdye@github.com>

Allow users to specify a single "tree-ish" value as a positional argument.
If provided, the contents of the given tree serve as the basis for the new
tree (or trees, in --batch mode) created by 'mktree', on top of which all of
the stdin-provided tree entries are applied.

At a high level, the entries are "applied" to a base tree by iterating
through the base tree using 'read_tree' in parallel with iterating through
the sorted & deduplicated stdin entries via their iterator. That is, for
each call to the 'build_index_from_tree callback of 'read_tree':

* If the iterator entry precedes the base tree entry, add it to the in-core
  index, increment the iterator, and repeat.
* If the iterator entry has the same name as the base tree entry, add the
  iterator entry to the index, increment the iterator, and return from the
  callback to continue the 'read_tree' iteration.
* If the iterator entry follows the base tree entry, first check
  'df_name_hash' to ensure we won't be adding an entry with the same name
  later (with a different mode). If there's no directory/file conflict, add
  the base tree entry to the index. In either case, return from the callback
  to continue the 'read_tree' iteration.

Finally, once 'read_tree' is complete, add the remaining entries in the
iterator to the index and write out the index as a tree.

Signed-off-by: Victoria Dye <vdye@github.com>
---
 Documentation/git-mktree.txt |   7 +-
 builtin/mktree.c             | 134 ++++++++++++++++++++++++++++++-----
 t/t1010-mktree.sh            |  36 ++++++++++
 3 files changed, 157 insertions(+), 20 deletions(-)

Comments

Patrick Steinhardt June 12, 2024, 9:40 a.m. UTC | #1
On Tue, Jun 11, 2024 at 06:24:46PM +0000, Victoria Dye via GitGitGadget wrote:
> diff --git a/Documentation/git-mktree.txt b/Documentation/git-mktree.txt
> index afbc846d077..99abd3c31a6 100644
> --- a/Documentation/git-mktree.txt
> +++ b/Documentation/git-mktree.txt
> @@ -40,6 +40,11 @@ OPTIONS
>  	optional.  Note - if the `-z` option is used, lines are terminated
>  	with NUL.
>  
> +<tree-ish>::
> +	If provided, the tree entries provided in stdin are added to this tree
> +	rather than a new empty one, replacing existing entries with identical
> +	names. Not compatible with `--literally`.

I think it'd be a bit more intuitive is this was an option, like
`--base-tree=` or just `--base=`.

One question that comes up naturally in this context: when I have a base
tree, how do I remove entries from it?

Patrick
Junio C Hamano June 12, 2024, 7:50 p.m. UTC | #2
Patrick Steinhardt <ps@pks.im> writes:

> On Tue, Jun 11, 2024 at 06:24:46PM +0000, Victoria Dye via GitGitGadget wrote:
>> diff --git a/Documentation/git-mktree.txt b/Documentation/git-mktree.txt
>> index afbc846d077..99abd3c31a6 100644
>> --- a/Documentation/git-mktree.txt
>> +++ b/Documentation/git-mktree.txt
>> @@ -40,6 +40,11 @@ OPTIONS
>>  	optional.  Note - if the `-z` option is used, lines are terminated
>>  	with NUL.
>>  
>> +<tree-ish>::
>> +	If provided, the tree entries provided in stdin are added to this tree
>> +	rather than a new empty one, replacing existing entries with identical
>> +	names. Not compatible with `--literally`.
>
> I think it'd be a bit more intuitive is this was an option, like
> `--base-tree=` or just `--base=`.
>
> One question that comes up naturally in this context: when I have a base
> tree, how do I remove entries from it?

Presumably the same way how you remove entries with "update-index --index-info"?
I.e. mode=0 entry in the input would serve as a signal to remove the
path?
Victoria Dye June 17, 2024, 7:23 p.m. UTC | #3
Patrick Steinhardt wrote:
> On Tue, Jun 11, 2024 at 06:24:46PM +0000, Victoria Dye via GitGitGadget wrote:
>> diff --git a/Documentation/git-mktree.txt b/Documentation/git-mktree.txt
>> index afbc846d077..99abd3c31a6 100644
>> --- a/Documentation/git-mktree.txt
>> +++ b/Documentation/git-mktree.txt
>> @@ -40,6 +40,11 @@ OPTIONS
>>  	optional.  Note - if the `-z` option is used, lines are terminated
>>  	with NUL.
>>  
>> +<tree-ish>::
>> +	If provided, the tree entries provided in stdin are added to this tree
>> +	rather than a new empty one, replacing existing entries with identical
>> +	names. Not compatible with `--literally`.
> 
> I think it'd be a bit more intuitive is this was an option, like
> `--base-tree=` or just `--base=`.

To me, the positional '<tree-ish>' is more intuitive; it's reminiscent of
'read-tree' (but with '--empty' being the default, since there's no
equivalent to the existing index to overwrite). I consider 'read-tree'
relevant in this case because the updated 'mktree' allows a users to create
trees like:

$ git read-tree <tree-ish>
$ git update-index <entries
$ git write-tree

without the intermediate on-disk index. Conversely, there isn't really an
equivalent option to base the name on ('--base' is a bit overloaded, as it
typically refers to a merge/diff base), and I'd like to avoid adding more
potentially-confusing names to the overall Git UX if I can help it (even if
this is a plumbing command).

However, looking at other command documentation, I should at least drop
'[--]' from the usage string. While that is a separator used to signify "end
of options" using 'parse_options()', it's typically only included in the
usage string to separate different sets of positional arguments (e.g.
revisions from pathspecs). 

> 
> One question that comes up naturally in this context: when I have a base
> tree, how do I remove entries from it?

In patch 16 [1], entries with mode "0" are removed from the tree (similar to
'update-index').

[1] https://lore.kernel.org/git/a90d6d0c943283e9e7bd181cd6e9bb6d4572aaeb.1718130288.git.gitgitgadget@gmail.com/

> 
> Patrick
diff mbox series

Patch

diff --git a/Documentation/git-mktree.txt b/Documentation/git-mktree.txt
index afbc846d077..99abd3c31a6 100644
--- a/Documentation/git-mktree.txt
+++ b/Documentation/git-mktree.txt
@@ -9,7 +9,7 @@  git-mktree - Build a tree-object from formatted tree entries
 SYNOPSIS
 --------
 [verse]
-'git mktree' [-z] [--missing] [--literally] [--batch]
+'git mktree' [-z] [--missing] [--literally] [--batch] [--] [<tree-ish>]
 
 DESCRIPTION
 -----------
@@ -40,6 +40,11 @@  OPTIONS
 	optional.  Note - if the `-z` option is used, lines are terminated
 	with NUL.
 
+<tree-ish>::
+	If provided, the tree entries provided in stdin are added to this tree
+	rather than a new empty one, replacing existing entries with identical
+	names. Not compatible with `--literally`.
+
 INPUT FORMAT
 ------------
 Tree entries may be specified in any of the formats compatible with the
diff --git a/builtin/mktree.c b/builtin/mktree.c
index 09b3c5c6244..9e9d2554cad 100644
--- a/builtin/mktree.c
+++ b/builtin/mktree.c
@@ -12,7 +12,9 @@ 
 #include "read-cache-ll.h"
 #include "strbuf.h"
 #include "tree.h"
+#include "object-name.h"
 #include "parse-options.h"
+#include "pathspec.h"
 #include "object-store-ll.h"
 
 struct tree_entry {
@@ -206,45 +208,122 @@  static struct tree_entry *advance_tree_entry_iterator(struct tree_entry_iterator
 	return prev;
 }
 
-static int add_tree_entry_to_index(struct index_state *istate,
+struct build_index_data {
+	struct tree_entry_iterator iter;
+	struct hashmap *df_name_hash;
+	struct index_state istate;
+};
+
+static int add_tree_entry_to_index(struct build_index_data *data,
 				   struct tree_entry *ent)
 {
 	struct cache_entry *ce;
-	struct strbuf ce_name = STRBUF_INIT;
-	strbuf_add(&ce_name, ent->name, ent->len);
-
-	ce = make_cache_entry(istate, ent->mode, &ent->oid, ent->name, 0, 0);
+	ce = make_cache_entry(&data->istate, ent->mode, &ent->oid, ent->name, 0, 0);
 	if (!ce)
 		return error(_("make_cache_entry failed for path '%s'"), ent->name);
 
-	add_index_entry(istate, ce, ADD_CACHE_JUST_APPEND);
-	strbuf_release(&ce_name);
+	add_index_entry(&data->istate, ce, ADD_CACHE_JUST_APPEND);
 	return 0;
 }
 
-static void write_tree(struct tree_entry_array *arr, struct object_id *oid)
+static int build_index_from_tree(const struct object_id *oid,
+				 struct strbuf *base, const char *filename,
+				 unsigned mode, void *context)
 {
-	struct tree_entry_iterator iter = { NULL };
+	int result;
+	struct tree_entry *base_tree_ent;
+	struct build_index_data *cbdata = context;
+	size_t filename_len = strlen(filename);
+	size_t path_len = S_ISDIR(mode) ? st_add3(filename_len, base->len, 1)
+					: st_add(filename_len, base->len);
+
+	/* Create a tree entry from the current entry in read_tree iteration */
+	base_tree_ent = xcalloc(1, st_add3(sizeof(struct tree_entry), path_len, 1));
+	base_tree_ent->len = path_len;
+	base_tree_ent->mode = mode;
+	oidcpy(&base_tree_ent->oid, oid);
+
+	memcpy(base_tree_ent->name, base->buf, base->len);
+	memcpy(base_tree_ent->name + base->len, filename, filename_len);
+	if (S_ISDIR(mode))
+		base_tree_ent->name[base_tree_ent->len - 1] = '/';
+
+	while (cbdata->iter.current) {
+		struct tree_entry *ent = cbdata->iter.current;
+
+		int cmp = name_compare(ent->name, ent->len,
+				       base_tree_ent->name, base_tree_ent->len);
+		if (!cmp || cmp < 0) {
+			advance_tree_entry_iterator(&cbdata->iter);
+
+			if (add_tree_entry_to_index(cbdata, ent) < 0) {
+				result = error(_("failed to add tree entry '%s'"), ent->name);
+				goto cleanup_and_return;
+			}
+
+			if (!cmp) {
+				result = 0;
+				goto cleanup_and_return;
+			} else
+				continue;
+		}
+
+		break;
+	}
+
+	/*
+	 * If the tree entry should be replaced with an entry with the same name
+	 * (but different mode), skip it.
+	 */
+	hashmap_entry_init(&base_tree_ent->ent,
+			   memhash(base_tree_ent->name, df_path_len(base_tree_ent->len, base_tree_ent->mode)));
+	if (hashmap_get_entry(cbdata->df_name_hash, base_tree_ent, ent, NULL)) {
+		result = 0;
+		goto cleanup_and_return;
+	}
+
+	if (add_tree_entry_to_index(cbdata, base_tree_ent)) {
+		result = -1;
+		goto cleanup_and_return;
+	}
+
+	result = 0;
+
+cleanup_and_return:
+	FREE_AND_NULL(base_tree_ent);
+	return result;
+}
+
+static void write_tree(struct tree_entry_array *arr, struct tree *base_tree,
+		       struct object_id *oid)
+{
+	struct build_index_data cbdata = { 0 };
 	struct tree_entry *ent;
-	struct index_state istate = INDEX_STATE_INIT(the_repository);
-	istate.sparse_index = 1;
+	struct pathspec ps = { 0 };
 
 	sort_and_dedup_tree_entry_array(arr);
 
-	init_tree_entry_iterator(&iter, arr);
+	index_state_init(&cbdata.istate, the_repository);
+	cbdata.istate.sparse_index = 1;
+	init_tree_entry_iterator(&cbdata.iter, arr);
+	cbdata.df_name_hash = &arr->df_name_hash;
 
 	/* Construct an in-memory index from the provided entries & base tree */
-	while ((ent = advance_tree_entry_iterator(&iter))) {
-		if (add_tree_entry_to_index(&istate, ent))
+	if (base_tree &&
+	    read_tree(the_repository, base_tree, &ps, build_index_from_tree, &cbdata) < 0)
+		die(_("failed to create tree"));
+
+	while ((ent = advance_tree_entry_iterator(&cbdata.iter))) {
+		if (add_tree_entry_to_index(&cbdata, ent))
 			die(_("failed to add tree entry '%s'"), ent->name);
 	}
 
 	/* Write out new tree */
-	if (cache_tree_update(&istate, WRITE_TREE_SILENT | WRITE_TREE_MISSING_OK))
+	if (cache_tree_update(&cbdata.istate, WRITE_TREE_SILENT | WRITE_TREE_MISSING_OK))
 		die(_("failed to write tree"));
-	oidcpy(oid, &istate.cache_tree->oid);
+	oidcpy(oid, &cbdata.istate.cache_tree->oid);
 
-	release_index(&istate);
+	release_index(&cbdata.istate);
 }
 
 static void write_tree_literally(struct tree_entry_array *arr,
@@ -268,7 +347,7 @@  static void write_tree_literally(struct tree_entry_array *arr,
 }
 
 static const char *mktree_usage[] = {
-	"git mktree [-z] [--missing] [--literally] [--batch]",
+	"git mktree [-z] [--missing] [--literally] [--batch] [--] [<tree-ish>]",
 	NULL
 };
 
@@ -326,6 +405,7 @@  int cmd_mktree(int ac, const char **av, const char *prefix)
 	int is_batch_mode = 0;
 	struct tree_entry_array arr = { 0 };
 	struct mktree_line_data mktree_line_data = { .arr = &arr };
+	struct tree *base_tree = NULL;
 	int ret;
 
 	const struct option option[] = {
@@ -338,6 +418,22 @@  int cmd_mktree(int ac, const char **av, const char *prefix)
 	};
 
 	ac = parse_options(ac, av, prefix, option, mktree_usage, 0);
+	if (ac > 1)
+		usage_with_options(mktree_usage, option);
+
+	if (ac) {
+		struct object_id base_tree_oid;
+
+		if (mktree_line_data.literally)
+			die(_("option '%s' and tree-ish cannot be used together"), "--literally");
+
+		if (repo_get_oid(the_repository, av[0], &base_tree_oid))
+			die(_("not a valid object name %s"), av[0]);
+
+		base_tree = parse_tree_indirect(&base_tree_oid);
+		if (!base_tree)
+			die(_("not a tree object: %s"), oid_to_hex(&base_tree_oid));
+	}
 
 	init_tree_entry_array(&arr);
 
@@ -361,7 +457,7 @@  int cmd_mktree(int ac, const char **av, const char *prefix)
 			if (mktree_line_data.literally)
 				write_tree_literally(&arr, &oid);
 			else
-				write_tree(&arr, &oid);
+				write_tree(&arr, base_tree, &oid);
 			puts(oid_to_hex(&oid));
 			fflush(stdout);
 		}
diff --git a/t/t1010-mktree.sh b/t/t1010-mktree.sh
index 956692347f0..ea5a011405e 100755
--- a/t/t1010-mktree.sh
+++ b/t/t1010-mktree.sh
@@ -238,4 +238,40 @@  test_expect_success 'mktree with duplicate entries' '
 	test_cmp expect actual
 '
 
+test_expect_success 'mktree with base tree' '
+	tree_oid=$(cat tree) &&
+	folder_oid=$(git rev-parse ${tree_oid}:folder) &&
+	before_oid=$(git rev-parse ${tree_oid}:before) &&
+	head_oid=$(git rev-parse HEAD) &&
+
+	{
+		printf "040000 tree $folder_oid\ttest\n" &&
+		printf "100644 blob $before_oid\ttest.txt\n" &&
+		printf "040000 tree $folder_oid\ttest-\n" &&
+		printf "160000 commit $head_oid\ttest0\n"
+	} >top.base &&
+	git mktree <top.base >tree.base &&
+
+	{
+		printf "100755 blob $before_oid\tz\n" &&
+		printf "160000 commit $head_oid\ttest.xyz\n" &&
+		printf "040000 tree $folder_oid\ta\n" &&
+		printf "100644 blob $before_oid\ttest\n"
+	} >top.append &&
+	git mktree $(cat tree.base) <top.append >tree.actual &&
+
+	{
+		printf "040000 tree $folder_oid\ta\n" &&
+		printf "100644 blob $before_oid\ttest\n" &&
+		printf "040000 tree $folder_oid\ttest-\n" &&
+		printf "100644 blob $before_oid\ttest.txt\n" &&
+		printf "160000 commit $head_oid\ttest.xyz\n" &&
+		printf "160000 commit $head_oid\ttest0\n" &&
+		printf "100755 blob $before_oid\tz\n"
+	} >expect &&
+	git ls-tree $(cat tree.actual) >actual &&
+
+	test_cmp expect actual
+'
+
 test_done