[PATCH 4/8] add-patch: add support for in-memory index patching

From

Patrick Steinhardt <ps@pks.im>

Date

Mar 2, 2026, 12:13 UTC

Message-ID

<20260302-pks-history-split-v1-4-444fc987a324@pks.im>

In-Reply-To

<20260302-pks-history-split-v1-0-444fc987a324@pks.im>

This new function will be used in a subsequent commit.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 add-patch.c | 149 ++++++++++++++++++++++++++++++++++++++++++++++++++----------
 add-patch.h |   8 ++++
 2 files changed, 132 insertions(+), 25 deletions(-)

diff --git a/add-patch.c b/add-patch.c
index 4f089c82d0..b4dc7d2293 100644
--- a/add-patch.c
+++ b/add-patch.c
@@ -4,11 +4,13 @@
 #include "git-compat-util.h"
 #include "add-patch.h"
 #include "advice.h"
+#include "commit.h"
 #include "config.h"
 #include "diff.h"
 #include "editor.h"
 #include "environment.h"
 #include "gettext.h"
+#include "hex.h"
 #include "object-name.h"
 #include "pager.h"
 #include "read-cache-ll.h"
@@ -263,6 +265,8 @@ struct hunk {
 
 struct add_p_state {
 	struct repository *r;
+	struct index_state *index;
+	const char *index_file;
 	struct interactive_config cfg;
 	struct strbuf answer, buf;
 
@@ -438,7 +442,7 @@ static void setup_child_process(struct add_p_state *s,
 
 	cp->git_cmd = 1;
 	strvec_pushf(&cp->env,
-		     INDEX_ENVIRONMENT "=%s", s->r->index_file);
+		     INDEX_ENVIRONMENT "=%s", s->index_file);
 }
 
 static int parse_range(const char **p,
@@ -1559,7 +1563,7 @@ static void apply_patch(struct add_p_state *s, struct file_diff *file_diff)
 		strbuf_reset(&s->buf);
 		reassemble_patch(s, file_diff, 0, &s->buf);
 
-		discard_index(s->r->index);
+		discard_index(s->index);
 		if (s->mode->apply_for_checkout)
 			apply_for_checkout(s, &s->buf,
 					s->mode->is_reverse);
@@ -1570,9 +1574,11 @@ static void apply_patch(struct add_p_state *s, struct file_diff *file_diff)
 					NULL, 0, NULL, 0))
 				error(_("'git apply' failed"));
 		}
-		if (repo_read_index(s->r) >= 0)
+		if (read_index_from(s->index, s->index_file, s->r->gitdir) >= 0 &&
+		    s->index == s->r->index) {
 			repo_refresh_and_write_index(s->r, REFRESH_QUIET, 0,
 						     1, NULL, NULL, NULL);
+		}
 	}
 
 }
@@ -1996,18 +2002,51 @@ static size_t patch_update_file(struct add_p_state *s, size_t idx)
 	return patch_update_resp;
 }
 
+static int run_add_p_common(struct add_p_state *state,
+			    const struct pathspec *ps)
+{
+	size_t binary_count = 0;
+	size_t i;
+
+	if (parse_diff(state, ps) < 0)
+		return -1;
+
+	for (i = 0; i < state->file_diff_nr;) {
+		if (state->file_diff[i].binary && !state->file_diff[i].hunk_nr) {
+			binary_count++;
+			i++;
+			continue;
+		}
+		if ((i = patch_update_file(state, i)) == state->file_diff_nr)
+			break;
+	}
+
+	if (!state->cfg.auto_advance)
+		for (i = 0; i < state->file_diff_nr; i++)
+			apply_patch(state, state->file_diff + i);
+
+	if (state->file_diff_nr == 0)
+		err(state, _("No changes."));
+	else if (binary_count == state->file_diff_nr)
+		err(state, _("Only binary files changed."));
+
+	return 0;
+}
+
 int run_add_p(struct repository *r, enum add_p_mode mode,
 	      struct interactive_options *opts, const char *revision,
 	      const struct pathspec *ps)
 {
 	struct add_p_state s = {
 		.r = r,
+		.index = r->index,
+		.index_file = r->index_file,
 		.answer = STRBUF_INIT,
 		.buf = STRBUF_INIT,
 		.plain = STRBUF_INIT,
 		.colored = STRBUF_INIT,
 	};
-	size_t i, binary_count = 0;
+	int ret;
 
 	interactive_config_init(&s.cfg, r, opts);
 
@@ -2040,30 +2079,90 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	if (repo_read_index(r) < 0 ||
 	    (!s.mode->index_only &&
 	     repo_refresh_and_write_index(r, REFRESH_QUIET, 0, 1,
-					  NULL, NULL, NULL) < 0) ||
-	    parse_diff(&s, ps) < 0) {
-		add_p_state_clear(&s);
-		return -1;
+					  NULL, NULL, NULL) < 0)) {
+		ret = -1;
+		goto out;
 	}
 
-	for (i = 0; i < s.file_diff_nr;) {
-		if (s.file_diff[i].binary && !s.file_diff[i].hunk_nr) {
-			binary_count++;
-			i++;
-			continue;
-		}
-		 if ((i = patch_update_file(&s, i)) == s.file_diff_nr)
-			break;
-    }
-	if (!s.cfg.auto_advance)
-		for (i = 0; i < s.file_diff_nr; i++)
-			apply_patch(&s, s.file_diff + i);
+	ret = run_add_p_common(&s, ps);
+	if (ret < 0)
+		goto out;
 
-	if (s.file_diff_nr == 0)
-		err(&s, _("No changes."));
-	else if (binary_count == s.file_diff_nr)
-		err(&s, _("Only binary files changed."));
+	ret = 0;
 
+out:
 	add_p_state_clear(&s);
-	return 0;
+	return ret;
+}
+
+int run_add_p_index(struct repository *r,
+		    struct index_state *index,
+		    const char *index_file,
+		    struct interactive_options *opts,
+		    const char *revision,
+		    const struct pathspec *ps)
+{
+	struct patch_mode mode = {
+		.apply_args = { "--cached", NULL },
+		.apply_check_args = { "--cached", NULL },
+		.prompt_mode = {
+			N_("Stage mode change [y,n,q,a,d%s,?]? "),
+			N_("Stage deletion [y,n,q,a,d%s,?]? "),
+			N_("Stage addition [y,n,q,a,d%s,?]? "),
+			N_("Stage this hunk [y,n,q,a,d%s,?]? ")
+		},
+		.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
+				     "will immediately be marked for staging."),
+		.help_patch_text =
+			N_("y - stage this hunk\n"
+			   "n - do not stage this hunk\n"
+			   "q - quit; do not stage this hunk or any of the remaining "
+				"ones\n"
+			   "a - stage this hunk and all later hunks in the file\n"
+			   "d - do not stage this hunk or any of the later hunks in "
+				"the file\n"),
+		.index_only = 1,
+	};
+	struct add_p_state s = {
+		.r = r,
+		.index = index,
+		.index_file = index_file,
+		.answer = STRBUF_INIT,
+		.buf = STRBUF_INIT,
+		.plain = STRBUF_INIT,
+		.colored = STRBUF_INIT,
+		.mode = &mode,
+		.revision = revision,
+	};
+	char parent_tree_oid[GIT_MAX_HEXSZ + 1];
+	struct commit *commit;
+	int ret;
+
+	interactive_config_init(&s.cfg, r, opts);
+
+	commit = lookup_commit_reference_by_name(revision);
+	if (!commit) {
+		err(&s, _("Revision does not refer to a commit"));
+		ret = -1;
+		goto out;
+	}
+
+	if (commit->parents)
+		oid_to_hex_r(parent_tree_oid, get_commit_tree_oid(commit->parents->item));
+	else
+		oid_to_hex_r(parent_tree_oid, r->hash_algo->empty_tree);
+
+	mode.diff_cmd[0] = "diff-tree";
+	mode.diff_cmd[1] = "-r";
+	mode.diff_cmd[2] = parent_tree_oid;
+
+	ret = run_add_p_common(&s, ps);
+	if (ret < 0)
+		goto out;
+
+	ret = 0;
+
+out:
+	add_p_state_clear(&s);
+	return ret;
 }
diff --git a/add-patch.h b/add-patch.h
index e6868c60a2..cf2a31a40f 100644
--- a/add-patch.h
+++ b/add-patch.h
@@ -3,6 +3,7 @@
 
 #include "color.h"
 
+struct index_state;
 struct pathspec;
 struct repository;
 
@@ -56,4 +57,11 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	      struct interactive_options *opts, const char *revision,
 	      const struct pathspec *ps);
 
+int run_add_p_index(struct repository *r,
+		    struct index_state *index,
+		    const char *index_file,
+		    struct interactive_options *opts,
+		    const char *revision,
+		    const struct pathspec *ps);
+
 #endif

-- 
2.53.0.697.g625c4fb2da.dirty