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[PATCH v3 13/19] apply: plug the three-way merge logic in

From
Junio C Hamano <gitster@pobox.com>
Date
Jun 13, 2012, 19:32 UTC
Message-ID
<1339615980-19727-14-git-send-email-gitster@pobox.com>
In-Reply-To
<1339615980-19727-1-git-send-email-gitster@pobox.com>

When a patch does not apply to what we have, but we know the preimage the patch was made against, we apply the patch to the preimage to compute what the patch author wanted the result to look like, and attempt a three-way merge between the result and our version, using the intended preimage as the base version.

When we are applying the patch using the index, we would additionally need to add the object names of these three blobs involved in the merge, which is not yet done in this step, but we add a field to "struct patch" so that later write-out step can use it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/apply.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 53 insertions(+), 6 deletions(-)
diff --git a/builtin/apply.c b/builtin/apply.c
index 6936588..5ef8652 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -16,6 +16,8 @@
 #include "dir.h"
 #include "diff.h"
 #include "parse-options.h"
+#include "xdiff-interface.h"
+#include "ll-merge.h"
 
 /*
  *  --check turns on checking that the working tree matches the
@@ -194,12 +196,16 @@ struct patch {
 	unsigned int is_copy:1;
 	unsigned int is_rename:1;
 	unsigned int recount:1;
+	unsigned int conflicted_threeway:1;
 	struct fragment *fragments;
 	char *result;
 	size_t resultsize;
 	char old_sha1_prefix[41];
 	char new_sha1_prefix[41];
 	struct patch *next;
+
+	/* three-way fallback result */
+	unsigned char threeway_stage[3][20];
 };
 
 static void free_fragment_list(struct fragment *list)
@@ -3142,11 +3148,33 @@ static int load_preimage(struct image *image,
 
 static int three_way_merge(struct image *image,
 			   char *path,
-			   unsigned char *base,
-			   unsigned char *ours,
-			   unsigned char *theirs)
+			   const unsigned char *base,
+			   const unsigned char *ours,
+			   const unsigned char *theirs)
 {
-	return -1; /* for now */
+	mmfile_t base_file, our_file, their_file;
+	mmbuffer_t result = { NULL };
+	int status;
+
+	read_mmblob(&base_file, base);
+	read_mmblob(&our_file, ours);
+	read_mmblob(&their_file, theirs);
+	status = ll_merge(&result, path,
+			  &base_file, "base",
+			  &our_file, "ours",
+			  &their_file, "theirs", NULL);
+	free(base_file.ptr);
+	free(our_file.ptr);
+	free(their_file.ptr);
+	if (status < 0 || !result.ptr) {
+		free(result.ptr);
+		return -1;
+	}
+	clear_image(image);
+	image->buf = result.ptr;
+	image->len = result.size;
+
+	return status;
 }
 
 static int try_threeway(struct image *image, struct patch *patch,
@@ -3155,6 +3183,7 @@ static int try_threeway(struct image *image, struct patch *patch,
 	unsigned char pre_sha1[20], post_sha1[20], our_sha1[20];
 	struct strbuf buf = STRBUF_INIT;
 	size_t len;
+	int status;
 	char *img;
 	struct image tmp_image;
 
@@ -3167,6 +3196,9 @@ static int try_threeway(struct image *image, struct patch *patch,
 	if (get_sha1(patch->old_sha1_prefix, pre_sha1) ||
 	    read_blob_object(&buf, pre_sha1, patch->old_mode))
 		return error("repository lacks the necessary blob to fall back on 3-way merge.");
+
+	fprintf(stderr, "Falling back to three-way merge...\n");
+
 	img = strbuf_detach(&buf, &len);
 	prepare_image(&tmp_image, img, len, 1);
 	/* Apply the patch to get the post image */
@@ -3186,8 +3218,23 @@ static int try_threeway(struct image *image, struct patch *patch,
 	clear_image(&tmp_image);
 
 	/* in-core three-way merge between post and our using pre as base */
-	return three_way_merge(image,
-			       patch->new_name, pre_sha1, our_sha1, post_sha1);
+	status = three_way_merge(image, patch->new_name,
+				 pre_sha1, our_sha1, post_sha1);
+	if (status < 0) {
+		fprintf(stderr, "Failed to fall back on three-way merge...\n");
+		return status;
+	}
+
+	if (status) {
+		patch->conflicted_threeway = 1;
+		hashcpy(patch->threeway_stage[0], pre_sha1);
+		hashcpy(patch->threeway_stage[1], our_sha1);
+		hashcpy(patch->threeway_stage[2], post_sha1);
+		fprintf(stderr, "Applied patch to '%s' with conflicts.\n", patch->new_name);
+	} else {
+		fprintf(stderr, "Applied patch to '%s' cleanly.\n", patch->new_name);
+	}
+	return 0;
 }
 
 static int apply_data(struct patch *patch, struct stat *st, struct cache_entry *ce)

-- 
1.7.11.rc3.30.g3bdace2
Previous: Junio C HamanoNext: Junio C Hamano
Message 14 of 20 in “"git apply --3way"”
  1. 00/19 "git apply --3way"Junio C Hamano, Jun 13, 2012
  2. 01/19 apply: fix an incomplete comment in check_patch()Junio C Hamano, Jun 13, 2012
  3. 02/19 apply: a bit more comments on PATH_TO_BE_DELETEDJunio C Hamano, Jun 13, 2012
  4. 03/19 apply: clear_image() clears things a bit moreJunio C Hamano, Jun 13, 2012
  5. 04/19 apply: refactor read_file_or_gitlink()Junio C Hamano, Jun 13, 2012
  6. 05/19 apply: factor out checkout_target() helper functionJunio C Hamano, Jun 13, 2012
  7. 06/19 apply: split load_preimage() helper function outJunio C Hamano, Jun 13, 2012
  8. 07/19 apply: refactor "previous patch" logicJunio C Hamano, Jun 13, 2012
  9. 08/19 apply: further split load_preimage()Junio C Hamano, Jun 13, 2012
  10. 09/19 apply: move check_to_create_blob() closer to its sole callerJunio C Hamano, Jun 13, 2012
  11. 10/19 apply: move "already exists" logic to check_to_create()Junio C Hamano, Jun 13, 2012
  12. 11/19 apply: accept -3/--3way command line optionJunio C Hamano, Jun 13, 2012
  13. 12/19 apply: fall back on three-way mergeJunio C Hamano, Jun 13, 2012
  14. 13/19 apply: plug the three-way merge logic inJunio C Hamano, Jun 13, 2012
  15. 14/19 apply: move verify_index_match() higherJunio C Hamano, Jun 13, 2012
  16. 15/19 apply: --3way with add/add conflictJunio C Hamano, Jun 13, 2012
  17. 16/19 apply: register conflicted stages to the indexJunio C Hamano, Jun 13, 2012
  18. 17/19 apply: allow rerere() upon --3way resultsJunio C Hamano, Jun 13, 2012
  19. 18/19 apply: document --3way optionJunio C Hamano, Jun 13, 2012
  20. 19/19 apply --3way: testsJunio C Hamano, Jun 13, 2012

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