path: root/t/
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authorbrian m. carlson <>2019-02-12 00:52:06 (GMT)
committerJunio C Hamano <>2019-02-12 02:20:07 (GMT)
commit79444c92943048f9ac62e9311038ebe43f5f0982 (patch)
treea83eddab899e28c0823b5a879d70bc1e0782650a /t/
parent11ad41d4cb25a41b21a7343c495aceb38d4db4d8 (diff)
utf8: handle systems that don't write BOM for UTF-16
When serializing UTF-16 (and UTF-32), there are three possible ways to write the stream. One can write the data with a BOM in either big-endian or little-endian format, or one can write the data without a BOM in big-endian format. Most systems' iconv implementations choose to write it with a BOM in some endianness, since this is the most foolproof, and it is resistant to misinterpretation on Windows, where UTF-16 and the little-endian serialization are very common. For compatibility with Windows and to avoid accidental misuse there, Git always wants to write UTF-16 with a BOM, and will refuse to read UTF-16 without it. However, musl's iconv implementation writes UTF-16 without a BOM, relying on the user to interpret it as big-endian. This causes t0028 and the related functionality to fail, since Git won't read the file without a BOM. Add a Makefile and #define knob, ICONV_OMITS_BOM, that can be set if the iconv implementation has this behavior. When set, Git will write a BOM manually for UTF-16 and UTF-32 and then force the data to be written in UTF-16BE or UTF-32BE. We choose big-endian behavior here because the tests use the raw "UTF-16" encoding, which will be big-endian when the implementation requires this knob to be set. Update the tests to detect this case and write test data with an added BOM if necessary. Always write the BOM in the tests in big-endian format, since all iconv implementations that omit a BOM must use big-endian serialization according to the Unicode standard. Preserve the existing behavior for systems which do not have this knob enabled, since they may use optimized implementations, including defaulting to the native endianness, which may improve performance. Signed-off-by: brian m. carlson <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 't/')
1 files changed, 29 insertions, 5 deletions
diff --git a/t/ b/t/
index e58ecbf..500229a 100755
--- a/t/
+++ b/t/
@@ -6,6 +6,30 @@ test_description='working-tree-encoding conversion via gitattributes'
+test_lazy_prereq NO_UTF16_BOM '
+ test $(printf abc | iconv -f UTF-8 -t UTF-16 | wc -c) = 6
+test_lazy_prereq NO_UTF32_BOM '
+ test $(printf abc | iconv -f UTF-8 -t UTF-32 | wc -c) = 12
+write_utf16 () {
+ if test_have_prereq NO_UTF16_BOM
+ then
+ printf '\xfe\xff'
+ fi &&
+ iconv -f UTF-8 -t UTF-16
+write_utf32 () {
+ if test_have_prereq NO_UTF32_BOM
+ then
+ printf '\x00\x00\xfe\xff'
+ fi &&
+ iconv -f UTF-8 -t UTF-32
test_expect_success 'setup test files' '
git config core.eol lf &&
@@ -13,8 +37,8 @@ test_expect_success 'setup test files' '
echo "*.utf16 text working-tree-encoding=utf-16" >.gitattributes &&
echo "*.utf16lebom text working-tree-encoding=UTF-16LE-BOM" >>.gitattributes &&
printf "$text" >test.utf8.raw &&
- printf "$text" | iconv -f UTF-8 -t UTF-16 >test.utf16.raw &&
- printf "$text" | iconv -f UTF-8 -t UTF-32 >test.utf32.raw &&
+ printf "$text" | write_utf16 >test.utf16.raw &&
+ printf "$text" | write_utf32 >test.utf32.raw &&
printf "\377\376" >test.utf16lebom.raw &&
printf "$text" | iconv -f UTF-8 -t UTF-32LE >>test.utf16lebom.raw &&
@@ -124,8 +148,8 @@ do
test_when_finished "rm -f crlf.utf${i}.raw lf.utf${i}.raw" &&
test_when_finished "git reset --hard HEAD^" &&
- cat lf.utf8.raw | iconv -f UTF-8 -t UTF-${i} >lf.utf${i}.raw &&
- cat crlf.utf8.raw | iconv -f UTF-8 -t UTF-${i} >crlf.utf${i}.raw &&
+ cat lf.utf8.raw | write_utf${i} >lf.utf${i}.raw &&
+ cat crlf.utf8.raw | write_utf${i} >crlf.utf${i}.raw &&
cp crlf.utf${i}.raw eol.utf${i} &&
cat >expectIndexLF <<-EOF &&
@@ -223,7 +247,7 @@ test_expect_success ICONV_SHIFT_JIS 'check roundtrip encoding' '
text="hallo there!\nroundtrip test here!" &&
printf "$text" | iconv -f UTF-8 -t SHIFT-JIS >roundtrip.shift &&
- printf "$text" | iconv -f UTF-8 -t UTF-16 >roundtrip.utf16 &&
+ printf "$text" | write_utf16 >roundtrip.utf16 &&
echo "*.shift text working-tree-encoding=SHIFT-JIS" >>.gitattributes &&
# SHIFT-JIS encoded files are round-trip checked by default...