Merge branch 'en/fast-export-encoding'

The "git fast-export/import" pair has been taught to handle commits
with log messages in encoding other than UTF-8 better.

* en/fast-export-encoding:
  fast-export: do automatic reencoding of commit messages only if requested
  fast-export: differentiate between explicitly UTF-8 and implicitly UTF-8
  fast-export: avoid stripping encoding header if we cannot reencode
  fast-import: support 'encoding' commit header
  t9350: fix encoding test to actually test reencoding

8 files changed, 163 insertions, 17 deletions

diff --git a/Documentation/git-fast-export.txt b/Documentation/git-fast-export.txt
index 64c01ba918..11427acdde 100644
--- a/Documentation/git-fast-export.txt
+++ b/Documentation/git-fast-export.txt
@@ -129,6 +129,13 @@ marks the same across runs.
 	for intermediary filters (e.g. for rewriting commit messages
 	which refer to older commits, or for stripping blobs by id).
 
+--reencode=(yes|no|abort)::
+	Specify how to handle `encoding` header in commit objects.  When
+	asking to 'abort' (which is the default), this program will die
+	when encountering such a commit object.  With 'yes', the commit
+	message will be reencoded into UTF-8.  With 'no', the original
+	encoding will be preserved.
+
 --refspec::
 	Apply the specified refspec to each ref exported. Multiple of them can
 	be specified.
diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
index d65cdb3d08..7baf9e47b5 100644
--- a/Documentation/git-fast-import.txt
+++ b/Documentation/git-fast-import.txt
@@ -388,6 +388,7 @@ change to the project.
 	original-oid?
 	('author' (SP <name>)? SP LT <email> GT SP <when> LF)?
 	'committer' (SP <name>)? SP LT <email> GT SP <when> LF
+	('encoding' SP <encoding>)?
 	data
 	('from' SP <commit-ish> LF)?
 	('merge' SP <commit-ish> LF)?
@@ -455,6 +456,12 @@ that was selected by the --date-format=<fmt> command-line option.
 See ``Date Formats'' above for the set of supported formats, and
 their syntax.
 
+`encoding`
+^^^^^^^^^^
+The optional `encoding` command indicates the encoding of the commit
+message.  Most commits are UTF-8 and the encoding is omitted, but this
+allows importing commit messages into git without first reencoding them.
+
 `from`
 ^^^^^^
 The `from` command is used to specify the commit to initialize
diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index 9e283482ef..c22cef3b2f 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -33,6 +33,7 @@ static const char *fast_export_usage[] = {
 static int progress;
 static enum { SIGNED_TAG_ABORT, VERBATIM, WARN, WARN_STRIP, STRIP } signed_tag_mode = SIGNED_TAG_ABORT;
 static enum { TAG_FILTERING_ABORT, DROP, REWRITE } tag_of_filtered_mode = TAG_FILTERING_ABORT;
+static enum { REENCODE_ABORT, REENCODE_YES, REENCODE_NO } reencode_mode = REENCODE_ABORT;
 static int fake_missing_tagger;
 static int use_done_feature;
 static int no_data;
@@ -77,6 +78,31 @@ static int parse_opt_tag_of_filtered_mode(const struct option *opt,
 	return 0;
 }
 
+static int parse_opt_reencode_mode(const struct option *opt,
+				   const char *arg, int unset)
+{
+	if (unset) {
+		reencode_mode = REENCODE_ABORT;
+		return 0;
+	}
+
+	switch (git_parse_maybe_bool(arg)) {
+	case 0:
+		reencode_mode = REENCODE_NO;
+		break;
+	case 1:
+		reencode_mode = REENCODE_YES;
+		break;
+	default:
+		if (!strcasecmp(arg, "abort"))
+			reencode_mode = REENCODE_ABORT;
+		else
+			return error("Unknown reencoding mode: %s", arg);
+	}
+
+	return 0;
+}
+
 static struct decoration idnums;
 static uint32_t last_idnum;
 
@@ -453,7 +479,7 @@ static const char *find_encoding(const char *begin, const char *end)
 	bol = memmem(begin, end ? end - begin : strlen(begin),
 		     needle, strlen(needle));
 	if (!bol)
-		return git_commit_encoding;
+		return NULL;
 	bol += strlen(needle);
 	eol = strchrnul(bol, '\n');
 	*eol = '\0';
@@ -633,18 +659,32 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
 	}
 
 	mark_next_object(&commit->object);
-	if (anonymize)
+	if (anonymize) {
 		reencoded = anonymize_commit_message(message);
-	else if (!is_encoding_utf8(encoding))
-		reencoded = reencode_string(message, "UTF-8", encoding);
+	} else if (encoding) {
+		switch(reencode_mode) {
+		case REENCODE_YES:
+			reencoded = reencode_string(message, "UTF-8", encoding);
+			break;
+		case REENCODE_NO:
+			break;
+		case REENCODE_ABORT:
+			die("Encountered commit-specific encoding %s in commit "
+			    "%s; use --reencode=[yes|no] to handle it",
+			    encoding, oid_to_hex(&commit->object.oid));
+		}
+	}
 	if (!commit->parents)
 		printf("reset %s\n", refname);
 	printf("commit %s\nmark :%"PRIu32"\n", refname, last_idnum);
 	if (show_original_ids)
 		printf("original-oid %s\n", oid_to_hex(&commit->object.oid));
-	printf("%.*s\n%.*s\ndata %u\n%s",
+	printf("%.*s\n%.*s\n",
 	       (int)(author_end - author), author,
-	       (int)(committer_end - committer), committer,
+	       (int)(committer_end - committer), committer);
+	if (!reencoded && encoding)
+		printf("encoding %s\n", encoding);
+	printf("data %u\n%s",
 	       (unsigned)(reencoded
 			  ? strlen(reencoded) : message
 			  ? strlen(message) : 0),
@@ -1088,6 +1128,9 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 		OPT_CALLBACK(0, "tag-of-filtered-object", &tag_of_filtered_mode, N_("mode"),
 			     N_("select handling of tags that tag filtered objects"),
 			     parse_opt_tag_of_filtered_mode),
+		OPT_CALLBACK(0, "reencode", &reencode_mode, N_("mode"),
+			     N_("select handling of commit messages in an alternate encoding"),
+			     parse_opt_reencode_mode),
 		OPT_STRING(0, "export-marks", &export_filename, N_("file"),
 			     N_("Dump marks to this file")),
 		OPT_STRING(0, "import-marks", &import_filename, N_("file"),
diff --git a/fast-import.c b/fast-import.c
index f38d04fa58..76a7bd3699 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -2585,6 +2585,7 @@ static void parse_new_commit(const char *arg)
 	struct branch *b;
 	char *author = NULL;
 	char *committer = NULL;
+	const char *encoding = NULL;
 	struct hash_list *merge_list = NULL;
 	unsigned int merge_count;
 	unsigned char prev_fanout, new_fanout;
@@ -2607,6 +2608,8 @@ static void parse_new_commit(const char *arg)
 	}
 	if (!committer)
 		die("Expected committer but didn't get one");
+	if (skip_prefix(command_buf.buf, "encoding ", &encoding))
+		read_next_command();
 	parse_data(&msg, 0, NULL);
 	read_next_command();
 	parse_from(b);
@@ -2670,9 +2673,13 @@ static void parse_new_commit(const char *arg)
 	}
 	strbuf_addf(&new_data,
 		"author %s\n"
-		"committer %s\n"
-		"\n",
+		"committer %s\n",
 		author ? author : committer, committer);
+	if (encoding)
+		strbuf_addf(&new_data,
+			"encoding %s\n",
+			encoding);
+	strbuf_addch(&new_data, '\n');
 	strbuf_addbuf(&new_data, &msg);
 	free(author);
 	free(committer);
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index 3668263c40..141b7fa35e 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -3299,4 +3299,24 @@ test_expect_success !MINGW 'W: get-mark & empty orphan commit with erroneous thi
 	sed -e s/LFs/LLL/ W-input | tr L "\n" | test_must_fail git fast-import
 '
 
+###
+### series X (other new features)
+###
+
+test_expect_success 'X: handling encoding' '
+	test_tick &&
+	cat >input <<-INPUT_END &&
+	commit refs/heads/encoding
+	committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+	encoding iso-8859-7
+	data <<COMMIT
+	INPUT_END
+
+	printf "Pi: \360\nCOMMIT\n" >>input &&
+
+	git fast-import <input &&
+	git cat-file -p encoding | grep $(printf "\360") &&
+	git log -1 --format=%B encoding | grep $(printf "\317\200")
+'
+
 test_done
diff --git a/t/t9350-fast-export.sh b/t/t9350-fast-export.sh
index 5690fe2810..b4004e05c2 100755
--- a/t/t9350-fast-export.sh
+++ b/t/t9350-fast-export.sh
@@ -94,22 +94,83 @@ test_expect_success 'fast-export --show-original-ids | git fast-import' '
 	test $MUSS = $(git rev-parse --verify refs/tags/muss)
 '
 
-test_expect_success 'iso-8859-1' '
+test_expect_success 'reencoding iso-8859-7' '
 
-	git config i18n.commitencoding ISO8859-1 &&
-	# use author and committer name in ISO-8859-1 to match it.
-	. "$TEST_DIRECTORY"/t3901/8859-1.txt &&
+	test_when_finished "git reset --hard HEAD~1" &&
+	test_config i18n.commitencoding iso-8859-7 &&
 	test_tick &&
 	echo rosten >file &&
-	git commit -s -m den file &&
-	git fast-export wer^..wer >iso8859-1.fi &&
-	sed "s/wer/i18n/" iso8859-1.fi |
+	git commit -s -F "$TEST_DIRECTORY/t9350/simple-iso-8859-7-commit-message.txt" file &&
+	git fast-export --reencode=yes wer^..wer >iso-8859-7.fi &&
+	sed "s/wer/i18n/" iso-8859-7.fi |
 		(cd new &&
 		 git fast-import &&
+		 # The commit object, if not re-encoded, would be 240 bytes.
+		 # Removing the "encoding iso-8859-7\n" header drops 20 bytes.
+		 # Re-encoding the Pi character from \xF0 (\360) in iso-8859-7
+		 # to \xCF\x80 (\317\200) in UTF-8 adds a byte.  Check for
+		 # the expected size.
+		 test 221 -eq "$(git cat-file -s i18n)" &&
+		 # ...and for the expected translation of bytes.
 		 git cat-file commit i18n >actual &&
-		 grep "Áéí óú" actual)
+		 grep $(printf "\317\200") actual &&
+		 # Also make sure the commit does not have the "encoding" header
+		 ! grep ^encoding actual)
+'
+
+test_expect_success 'aborting on iso-8859-7' '
 
+	test_when_finished "git reset --hard HEAD~1" &&
+	test_config i18n.commitencoding iso-8859-7 &&
+	echo rosten >file &&
+	git commit -s -F "$TEST_DIRECTORY/t9350/simple-iso-8859-7-commit-message.txt" file &&
+	test_must_fail git fast-export --reencode=abort wer^..wer >iso-8859-7.fi
 '
+
+test_expect_success 'preserving iso-8859-7' '
+
+	test_when_finished "git reset --hard HEAD~1" &&
+	test_config i18n.commitencoding iso-8859-7 &&
+	echo rosten >file &&
+	git commit -s -F "$TEST_DIRECTORY/t9350/simple-iso-8859-7-commit-message.txt" file &&
+	git fast-export --reencode=no wer^..wer >iso-8859-7.fi &&
+	sed "s/wer/i18n-no-recoding/" iso-8859-7.fi |
+		(cd new &&
+		 git fast-import &&
+		 # The commit object, if not re-encoded, is 240 bytes.
+		 # Removing the "encoding iso-8859-7\n" header would drops 20
+		 # bytes.  Re-encoding the Pi character from \xF0 (\360) in
+		 # iso-8859-7 to \xCF\x80 (\317\200) in UTF-8 adds a byte.
+		 # Check for the expected size...
+		 test 240 -eq "$(git cat-file -s i18n-no-recoding)" &&
+		 # ...as well as the expected byte.
+		 git cat-file commit i18n-no-recoding >actual &&
+		 grep $(printf "\360") actual &&
+		 # Also make sure the commit has the "encoding" header
+		 grep ^encoding actual)
+'
+
+test_expect_success 'encoding preserved if reencoding fails' '
+
+	test_when_finished "git reset --hard HEAD~1" &&
+	test_config i18n.commitencoding iso-8859-7 &&
+	echo rosten >file &&
+	git commit -s -F "$TEST_DIRECTORY/t9350/broken-iso-8859-7-commit-message.txt" file &&
+	git fast-export --reencode=yes wer^..wer >iso-8859-7.fi &&
+	sed "s/wer/i18n-invalid/" iso-8859-7.fi |
+		(cd new &&
+		 git fast-import &&
+		 git cat-file commit i18n-invalid >actual &&
+		 # Make sure the commit still has the encoding header
+		 grep ^encoding actual &&
+		 # Verify that the commit has the expected size; i.e.
+		 # that no bytes were re-encoded to a different encoding.
+		 test 252 -eq "$(git cat-file -s i18n-invalid)" &&
+		 # ...and check for the original special bytes
+		 grep $(printf "\360") actual &&
+		 grep $(printf "\377") actual)
+'
+
 test_expect_success 'import/export-marks' '
 
 	git checkout -b marks master &&
@@ -224,7 +285,6 @@ GIT_COMMITTER_NAME='C O Mitter'; export GIT_COMMITTER_NAME
 
 test_expect_success 'setup copies' '
 
-	git config --unset i18n.commitencoding &&
 	git checkout -b copy rein &&
 	git mv file file3 &&
 	git commit -m move1 &&
diff --git a/t/t9350/broken-iso-8859-7-commit-message.txt b/t/t9350/broken-iso-8859-7-commit-message.txt
new file mode 100644
index 0000000000..d06ad75b44
--- /dev/null
+++ b/t/t9350/broken-iso-8859-7-commit-message.txt
@@ -0,0 +1 @@
+Pi: �; Invalid: �
\ No newline at end of file
diff --git a/t/t9350/simple-iso-8859-7-commit-message.txt b/t/t9350/simple-iso-8859-7-commit-message.txt
new file mode 100644
index 0000000000..8b3f0c3dba
--- /dev/null
+++ b/t/t9350/simple-iso-8859-7-commit-message.txt
@@ -0,0 +1 @@
+Pi: �
\ No newline at end of file