thodg/got

diff --git a/lib/got_lib_privsep.h b/lib/got_lib_privsep.h
index af9557d..8b9f4c0 100644
--- a/lib/got_lib_privsep.h
+++ b/lib/got_lib_privsep.h
@@ -613,6 +613,7 @@ struct got_imsg_patch {
 	int	git;
 	char	old[PATH_MAX];
 	char	new[PATH_MAX];
+	char	blob[41];
 };
 
 /*
diff --git a/lib/patch.c b/lib/patch.c
index 0a98afc..9fbe217 100644
--- a/lib/patch.c
+++ b/lib/patch.c
@@ -42,12 +42,15 @@
 #include "got_reference.h"
 #include "got_cancel.h"
 #include "got_worktree.h"
+#include "got_repository.h"
 #include "got_opentemp.h"
 #include "got_patch.h"
 
 #include "got_lib_delta.h"
+#include "got_lib_diff.h"
 #include "got_lib_object.h"
 #include "got_lib_privsep.h"
+#include "got_lib_sha1.h"
 
 #define MIN(a, b) ((a) < (b) ? (a) : (b))
 
@@ -70,6 +73,7 @@ STAILQ_HEAD(got_patch_hunk_head, got_patch_hunk);
 struct got_patch {
 	char	*old;
 	char	*new;
+	char	 blob[41];
 	struct got_patch_hunk_head head;
 };
 
@@ -180,11 +184,14 @@ recv_patch(struct imsgbuf *ibuf, int *done, struct got_patch *p, int strip)
 	memcpy(&patch, imsg.data, sizeof(patch));
 
 	if (patch.old[sizeof(patch.old)-1] != '\0' ||
-	    patch.new[sizeof(patch.new)-1] != '\0') {
+	    patch.new[sizeof(patch.new)-1] != '\0' ||
+	    patch.blob[sizeof(patch.blob)-1] != '\0') {
 		err = got_error(GOT_ERR_PRIVSEP_LEN);
 		goto done;
 	}
 
+	strlcpy(p->blob, patch.blob, sizeof(p->blob));
+
 	/* automatically set strip=1 for git-style diffs */
 	if (strip == -1 && patch.git &&
 	    (*patch.old == '\0' || !strncmp(patch.old, "a/", 2)) &&
@@ -569,18 +576,75 @@ patch_add(void *arg, unsigned char status, const char *path)
 }
 
 static const struct got_error *
-apply_patch(struct got_worktree *worktree, struct got_repository *repo,
-    struct got_fileindex *fileindex, const char *old, const char *new,
-    struct got_patch *p, int nop, struct patch_args *pa,
-    got_cancel_cb cancel_cb, void *cancel_arg)
+open_blob(char **path, FILE **fp, const char *blobid,
+    struct got_repository *repo)
 {
 	const struct got_error *err = NULL;
-	int file_renamed = 0;
+	struct got_blob_object *blob = NULL;
+	struct got_object_id id;
+
+	*fp = NULL;
+	*path = NULL;
+
+	if (!got_parse_sha1_digest(id.sha1, blobid))
+		return got_error(GOT_ERR_BAD_OBJ_ID_STR);
+
+	err = got_object_open_as_blob(&blob, repo, &id, 8192);
+	if (err)
+		goto done;
+
+	err = got_opentemp_named(path, fp, GOT_TMPDIR_STR "/got-patch-blob");
+	if (err)
+		goto done;
+
+	err = got_object_blob_dump_to_file(NULL, NULL, NULL, *fp, blob);
+	if (err)
+		goto done;
+
+done:
+	if (blob)
+		got_object_blob_close(blob);
+	if (err) {
+		if (*fp != NULL)
+			fclose(*fp);
+		if (*path != NULL)
+			unlink(*path);
+		free(*path);
+		*fp = NULL;
+		*path = NULL;
+	}
+	return err;
+}
+
+static const struct got_error *
+apply_patch(int *overlapcnt, struct got_worktree *worktree,
+    struct got_repository *repo, struct got_fileindex *fileindex,
+    const char *old, const char *new, struct got_patch *p, int nop,
+    struct patch_args *pa, got_cancel_cb cancel_cb, void *cancel_arg)
+{
+	const struct got_error *err = NULL;
+	int do_merge = 0, file_renamed = 0;
+	char *oldlabel = NULL, *newlabel = NULL;
 	char *oldpath = NULL, *newpath = NULL;
 	char *tmppath = NULL, *template = NULL, *parent = NULL;
-	FILE *oldfile = NULL, *tmp = NULL;
+	char *apath = NULL, *mergepath = NULL;
+	FILE *oldfile = NULL, *tmpfile = NULL, *afile = NULL, *mergefile = NULL;
+	int outfd;
+	const char *outpath;
 	mode_t mode = GOT_DEFAULT_FILE_MODE;
 
+	*overlapcnt = 0;
+
+	/* don't run the diff3 merge on creations/deletions */
+	if (*p->blob != '\0' && p->old != NULL && p->new != NULL) {
+		err = open_blob(&apath, &afile, p->blob, repo);
+		if (err && err->code != GOT_ERR_NOT_REF)
+			return err;
+		else if (err == NULL)
+			do_merge = 1;
+		err = NULL;
+	}
+
 	if (asprintf(&oldpath, "%s/%s", got_worktree_get_root_path(worktree),
 	    old) == -1) {
 		err = got_error_from_errno("asprintf");
@@ -606,13 +670,48 @@ apply_patch(struct got_worktree *worktree, struct got_repository *repo,
 		goto done;
 	}
 
-	err = got_opentemp_named(&tmppath, &tmp, template);
+	err = got_opentemp_named(&tmppath, &tmpfile, template);
 	if (err)
 		goto done;
-	err = patch_file(p, oldfile, tmp, &mode);
+	outpath = tmppath;
+	outfd = fileno(tmpfile);
+	err = patch_file(p, afile != NULL ? afile : oldfile, tmpfile, &mode);
 	if (err)
 		goto done;
 
+	if (do_merge) {
+		if (fseeko(afile, 0, SEEK_SET) == -1 ||
+		    fseeko(oldfile, 0, SEEK_SET) == -1 ||
+		    fseeko(tmpfile, 0, SEEK_SET) == -1) {
+			err = got_error_from_errno("fseeko");
+			goto done;
+		}
+
+		if (asprintf(&oldlabel, "--- %s", p->old) == -1) {
+			err = got_error_from_errno("asprintf");
+			oldlabel = NULL;
+			goto done;
+		}
+
+		if (asprintf(&newlabel, "+++ %s", p->new) == -1) {
+			err = got_error_from_errno("asprintf");
+			newlabel = NULL;
+			goto done;
+		}
+
+		err = got_opentemp_named(&mergepath, &mergefile, template);
+		if (err)
+			goto done;
+		outpath = mergepath;
+		outfd = fileno(mergefile);
+
+		err = got_merge_diff3(overlapcnt, outfd, tmpfile, afile,
+		    oldfile, oldlabel, p->blob, newlabel,
+		    GOT_DIFF_ALGORITHM_PATIENCE);
+		if (err)
+			goto done;
+	}
+
 	if (nop)
 		goto done;
 
@@ -622,14 +721,14 @@ apply_patch(struct got_worktree *worktree, struct got_repository *repo,
 		goto done;
 	}
 
-	if (fchmod(fileno(tmp), mode) == -1) {
+	if (fchmod(outfd, mode) == -1) {
 		err = got_error_from_errno2("chmod", tmppath);
 		goto done;
 	}
 
-	if (rename(tmppath, newpath) == -1) {
+	if (rename(outpath, newpath) == -1) {
 		if (errno != ENOENT) {
-			err = got_error_from_errno3("rename", tmppath,
+			err = got_error_from_errno3("rename", outpath,
 			    newpath);
 			goto done;
 		}
@@ -640,8 +739,8 @@ apply_patch(struct got_worktree *worktree, struct got_repository *repo,
 		err = got_path_mkdir(parent);
 		if (err != NULL)
 			goto done;
-		if (rename(tmppath, newpath) == -1) {
-			err = got_error_from_errno3("rename", tmppath,
+		if (rename(outpath, newpath) == -1) {
+			err = got_error_from_errno3("rename", outpath,
 			    newpath);
 			goto done;
 		}
@@ -661,21 +760,40 @@ apply_patch(struct got_worktree *worktree, struct got_repository *repo,
 		    fileindex, patch_add, pa);
 		if (err)
 			unlink(newpath);
-	} else
+	} else if (*overlapcnt != 0)
+		err = report_progress(pa, old, new, GOT_STATUS_CONFLICT, NULL);
+	else
 		err = report_progress(pa, old, new, GOT_STATUS_MODIFY, NULL);
 
 done:
 	free(parent);
 	free(template);
+
 	if (tmppath != NULL)
 		unlink(tmppath);
-	if (tmp != NULL && fclose(tmp) == EOF && err == NULL)
+	if (tmpfile != NULL && fclose(tmpfile) == EOF && err == NULL)
 		err = got_error_from_errno("fclose");
 	free(tmppath);
+
 	free(oldpath);
 	if (oldfile != NULL && fclose(oldfile) == EOF && err == NULL)
 		err = got_error_from_errno("fclose");
+
+	if (apath != NULL)
+		unlink(apath);
+	if (afile != NULL && fclose(afile) == EOF && err == NULL)
+		err = got_error_from_errno("fclose");
+	free(apath);
+
+	if (mergepath != NULL)
+		unlink(mergepath);
+	if (mergefile != NULL && fclose(mergefile) == EOF && err == NULL)
+		err = got_error_from_errno("fclose");
+	free(mergepath);
+
 	free(newpath);
+	free(oldlabel);
+	free(newlabel);
 	return err;
 }
 
@@ -719,7 +837,7 @@ got_patch(int fd, struct got_worktree *worktree, struct got_repository *repo,
 	char *oldpath, *newpath;
 	struct imsgbuf *ibuf;
 	int imsg_fds[2] = {-1, -1};
-	int done = 0, failed = 0;
+	int overlapcnt, done = 0, failed = 0;
 	pid_t pid;
 
 	ibuf = calloc(1, sizeof(*ibuf));
@@ -778,8 +896,9 @@ got_patch(int fd, struct got_worktree *worktree, struct got_repository *repo,
 		err = got_worktree_patch_check_path(p.old, p.new, &oldpath,
 		    &newpath, worktree, repo, fileindex);
 		if (err == NULL)
-			err = apply_patch(worktree, repo, fileindex, oldpath,
-			    newpath, &p, nop, &pa, cancel_cb, cancel_arg);
+			err = apply_patch(&overlapcnt, worktree, repo,
+			    fileindex, oldpath, newpath, &p, nop, &pa,
+			    cancel_cb, cancel_arg);
 		if (err != NULL) {
 			failed = 1;
 			/* recoverable errors */
@@ -791,6 +910,8 @@ got_patch(int fd, struct got_worktree *worktree, struct got_repository *repo,
 				err = report_progress(&pa, p.old, p.new,
 				    GOT_STATUS_CANNOT_UPDATE, NULL);
 		}
+		if (overlapcnt != 0)
+			failed = 1;
 
 		free(oldpath);
 		free(newpath);
diff --git a/libexec/got-read-patch/got-read-patch.c b/libexec/got-read-patch/got-read-patch.c
index 23212ab..ba9f841 100644
--- a/libexec/got-read-patch/got-read-patch.c
+++ b/libexec/got-read-patch/got-read-patch.c
@@ -56,11 +56,12 @@
 #include "got_lib_delta.h"
 #include "got_lib_object.h"
 #include "got_lib_privsep.h"
+#include "got_lib_sha1.h"
 
 struct imsgbuf ibuf;
 
 static const struct got_error *
-send_patch(const char *oldname, const char *newname, int git)
+send_patch(const char *oldname, const char *newname, const char *blob, int git)
 {
 	struct got_imsg_patch p;
 
@@ -72,9 +73,11 @@ send_patch(const char *oldname, const char *newname, int git)
 	if (newname != NULL)
 		strlcpy(p.new, newname, sizeof(p.new));
 
+	if (blob != NULL)
+		strlcpy(p.blob, blob, sizeof(p.blob));
+
 	p.git = git;
-	if (imsg_compose(&ibuf, GOT_IMSG_PATCH, 0, 0, -1,
-	    &p, sizeof(p)) == -1)
+	if (imsg_compose(&ibuf, GOT_IMSG_PATCH, 0, 0, -1, &p, sizeof(p)) == -1)
 		return got_error_from_errno("imsg_compose GOT_IMSG_PATCH");
 	return NULL;
 }
@@ -123,10 +126,31 @@ filename(const char *at, char **name)
 }
 
 static const struct got_error *
+blobid(const char *line, char **blob)
+{
+	uint8_t digest[SHA1_DIGEST_LENGTH];
+	size_t len;
+
+	*blob = NULL;
+
+	len = strspn(line, "0123456789abcdefABCDEF");
+	if ((*blob = strndup(line, len)) == NULL)
+		return got_error_from_errno("strndup");
+
+	if (!got_parse_sha1_digest(digest, *blob)) {
+		/* silently ignore invalid blob ids */
+		free(*blob);
+		*blob = NULL;
+	}
+	return NULL;
+}
+
+static const struct got_error *
 find_patch(int *done, FILE *fp)
 {
 	const struct got_error *err = NULL;
 	char	*old = NULL, *new = NULL;
+	char	*blob = NULL;
 	char	*line = NULL;
 	size_t	 linesize = 0;
 	ssize_t	 linelen;
@@ -147,13 +171,19 @@ find_patch(int *done, FILE *fp)
 		} else if (!strncmp(line, "+++ ", 4)) {
 			free(new);
 			err = filename(line+4, &new);
+		} else if (!git && !strncmp(line, "blob - ", 7)) {
+			free(blob);
+			err = blobid(line + 7, &blob);
 		} else if (rename && !strncmp(line, "rename to ", 10)) {
 			free(new);
 			err = filename(line + 10, &new);
 		} else if (git && !strncmp(line, "similarity index 100%", 21))
 			rename = 1;
-		else if (!strncmp(line, "diff --git a/", 13))
+		else if (!strncmp(line, "diff --git a/", 13)) {
 			git = 1;
+			free(blob);
+			blob = NULL;
+		}
 
 		if (err)
 			break;
@@ -165,7 +195,7 @@ find_patch(int *done, FILE *fp)
 		 */
 		if (rename && old != NULL && new != NULL) {
 			*done = 1;
-			err = send_patch(old, new, git);
+			err = send_patch(old, new, blob, git);
 			break;
 		}
 
@@ -175,7 +205,7 @@ find_patch(int *done, FILE *fp)
 			    (!create && old == NULL))
 				err = got_error(GOT_ERR_PATCH_MALFORMED);
 			else
-				err = send_patch(old, new, git);
+				err = send_patch(old, new, blob, git);
 
 			if (err)
 				break;
@@ -189,6 +219,7 @@ find_patch(int *done, FILE *fp)
 
 	free(old);
 	free(new);
+	free(blob);
 	free(line);
 	if (ferror(fp) && err == NULL)
 		err = got_error_from_errno("getline");
diff --git a/regress/cmdline/patch.sh b/regress/cmdline/patch.sh
index c1e703a..6c9ee03 100755
--- a/regress/cmdline/patch.sh
+++ b/regress/cmdline/patch.sh
@@ -1443,6 +1443,177 @@ EOF
 	test_done $testroot $ret
 }
 
+test_patch_merge_simple() {
+	local testroot=`test_init patch_merge_simple`
+
+	got checkout $testroot/repo $testroot/wt > /dev/null
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		test_done $testroot $ret
+		return 1
+	fi
+
+	jot 10 > $testroot/wt/numbers
+	(cd $testroot/wt && got add numbers && got commit -m +numbers) \
+		> /dev/null
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		test_done $testroot $ret
+		return 1
+	fi
+
+	jot 10 | sed 's/4/four/g' > $testroot/wt/numbers
+
+	(cd $testroot/wt && got diff > $testroot/old.diff \
+		&& got revert numbers) >/dev/null
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		test_done $testroot $ret
+		return 1
+	fi
+
+	jot 10 | sed 's/6/six/g' > $testroot/wt/numbers
+	(cd $testroot/wt && got commit -m 'edit numbers') \
+		> /dev/null
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		test_done $testroot $ret
+		return 1
+	fi
+
+	(cd $testroot/wt && got patch $testroot/old.diff) \
+		2>&1 > /dev/null
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		test_done $testroot $ret
+		return 1
+	fi
+
+	jot 10 | sed -e s/4/four/ -e s/6/six/ > $testroot/wt/numbers.expected
+	cmp -s $testroot/wt/numbers $testroot/wt/numbers.expected
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		diff -u $testroot/wt/numbers $testroot/wt/numbers.expected
+	fi
+	test_done $testroot $ret
+}
+
+test_patch_merge_conflict() {
+	local testroot=`test_init patch_merge_conflict`
+
+	got checkout $testroot/repo $testroot/wt > /dev/null
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		test_done $testroot $ret
+		return 1
+	fi
+
+	jot 10 > $testroot/wt/numbers
+	(cd $testroot/wt && got add numbers && got commit -m +numbers) \
+		> /dev/null
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		test_done $testroot $ret
+		return 1
+	fi
+
+	jot 10 | sed 's/6/six/g' > $testroot/wt/numbers
+
+	(cd $testroot/wt && got diff > $testroot/old.diff \
+		&& got revert numbers) >/dev/null
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		test_done $testroot $ret
+		return 1
+	fi
+
+	jot 10 | sed 's/6/3+3/g' > $testroot/wt/numbers
+	(cd $testroot/wt && got commit -m 'edit numbers') \
+		> /dev/null
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		test_done $testroot $ret
+		return 1
+	fi
+
+	(cd $testroot/wt && got patch $testroot/old.diff) \
+		>/dev/null 2>&1
+	ret=$?
+	if [ $ret -eq 0 ]; then
+		echo "got patch merged a diff that should conflict" >&2
+		test_done $testroot 0
+		return 1
+	fi
+
+	# XXX: prefixing every line with a tab otherwise got thinks
+	# the file has conflicts in it.
+	cat <<-EOF > $testroot/wt/numbers.expected
+	1
+	2
+	3
+	4
+	5
+	<<<<<<< --- numbers
+	six
+	||||||| f00c965d8307308469e537302baa73048488f162
+	6
+	=======
+	3+3
+	>>>>>>> +++ numbers
+	7
+	8
+	9
+	10
+EOF
+
+	cmp -s $testroot/wt/numbers $testroot/wt/numbers.expected
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		diff -u $testroot/wt/numbers $testroot/wt/numbers.expected
+	fi
+	test_done $testroot $ret
+}
+
+test_patch_merge_unknown_blob() {
+	local testroot=`test_init patch_merge_unknown_blob`
+
+	got checkout $testroot/repo $testroot/wt > /dev/null
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		test_done $testroot $ret
+		return 1
+	fi
+
+	cat <<EOF > $testroot/wt/patch
+I've got a
+blob - aaaabbbbccccddddeeeeffff0000111122223333
+and also a
+blob + 0000111122223333444455556666888899990000
+for this dummy diff
+--- alpha
++++ alpha
+@@ -1 +1 @@
+-alpha
++ALPHA
+will it work?
+EOF
+
+	(cd $testroot/wt/ && got patch patch) > $testroot/stdout
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		test_done $testroot $ret
+		return 1
+	fi
+
+	echo 'M  alpha' > $testroot/stdout.expected
+	cmp -s $testroot/stdout.expected $testroot/stdout
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		diff -u $testroot/stdout.expected $testroot/stdout
+	fi
+	test_done $testroot $ret
+}
+
 test_parseargs "$@"
 run_test test_patch_simple_add_file
 run_test test_patch_simple_rm_file
@@ -1468,3 +1639,6 @@ run_test test_patch_relative_paths
 run_test test_patch_with_path_prefix
 run_test test_patch_relpath_with_path_prefix
 run_test test_patch_reverse
+run_test test_patch_merge_simple
+run_test test_patch_merge_conflict
+run_test test_patch_merge_unknown_blob