From: Torsten Bögershausen <tboegi@xxxxxx>
When an UTF-16 file is commited and later changed, `git diff` shows
"Binary files XX and YY differ".
When the user wants a diff in UTF-8, a textconv needs to be specified
in .gitattributes and the textconv must be configured.
A more user-friendly diff can be produced for UTF-16 if
- the user did not use `git diff --binary`
- the blob is identified as binary
- the blob has an UTF-16 BOM
- the blob can be converted into UTF-8
Enhance the diff machinery to auto-detect UTF-16 blobs and show them
as UTF-8, unless the user specifies `git diff --binary` which creates
a binary diff.
Signed-off-by: Torsten Bögershausen <tboegi@xxxxxx>
---
diff.c | 43 ++++++++++++++++++++-
diffcore.h | 3 ++
t/t4066-diff-encoding.sh | 98 ++++++++++++++++++++++++++++++++++++++++++++++++
utf8.h | 11 ++++++
4 files changed, 153 insertions(+), 2 deletions(-)
create mode 100755 t/t4066-diff-encoding.sh
diff --git a/diff.c b/diff.c
index fb22b19f09..51831ee94d 100644
--- a/diff.c
+++ b/diff.c
@@ -3192,6 +3192,10 @@ static void builtin_diff(const char *name_a,
strbuf_reset(&header);
}
+ if (one && one->reencoded_from_utf16)
+ strbuf_addf(&header, "a is converted to UTF-8 from UTF-16\n");
+ if (two && two->reencoded_from_utf16)
+ strbuf_addf(&header, "b is converted to UTF-8 from UTF-16\n");
mf1.size = fill_textconv(textconv_one, one, &mf1.ptr);
mf2.size = fill_textconv(textconv_two, two, &mf2.ptr);
@@ -3611,8 +3615,25 @@ int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
s->size = size;
s->should_free = 1;
}
- }
- else {
+ if (!s->binary && buffer_is_binary(s->data, s->size) &&
+ buffer_has_utf16_bom(s->data, s->size)) {
+ int outsz = 0;
+ char *outbuf;
+ outbuf = reencode_string_len(s->data, (int)s->size,
+ "UTF-8", "UTF-16", &outsz);
+ if (outbuf) {
+ if (s->should_free)
+ free(s->data);
+ if (s->should_munmap)
+ munmap(s->data, s->size);
+ s->should_munmap = 0;
+ s->data = outbuf;
+ s->size = outsz;
+ s->reencoded_from_utf16 = 1;
+ s->should_free = 1;
+ }
+ }
+ } else {
enum object_type type;
if (size_only || (flags & CHECK_BINARY)) {
type = sha1_object_info(s->oid.hash, &s->size);
@@ -3629,6 +3650,19 @@ int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
s->data = read_sha1_file(s->oid.hash, &type, &s->size);
if (!s->data)
die("unable to read %s", oid_to_hex(&s->oid));
+ if (!s->binary && buffer_is_binary(s->data, s->size) &&
+ buffer_has_utf16_bom(s->data, s->size)) {
+ int outsz = 0;
+ char *buf;
+ buf = reencode_string_len(s->data, (int)s->size,
+ "UTF-8", "UTF-16", &outsz);
+ if (buf) {
+ free(s->data);
+ s->data = buf;
+ s->size = outsz;
+ s->reencoded_from_utf16 = 1;
+ }
+ }
s->should_free = 1;
}
return 0;
@@ -5695,6 +5729,10 @@ static int diff_filespec_is_identical(struct diff_filespec *one,
static int diff_filespec_check_stat_unmatch(struct diff_filepair *p)
{
+ if (p->binary) {
+ p->one->binary = 1;
+ p->two->binary = 1;
+ }
if (p->done_skip_stat_unmatch)
return p->skip_stat_unmatch_result;
@@ -5735,6 +5773,7 @@ static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
for (i = 0; i < q->nr; i++) {
struct diff_filepair *p = q->queue[i];
+ p->binary = diffopt->flags.binary;
if (diff_filespec_check_stat_unmatch(p))
diff_q(&outq, p);
else {
diff --git a/diffcore.h b/diffcore.h
index a30da161da..3cd97bb93b 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -47,6 +47,8 @@ struct diff_filespec {
unsigned has_more_entries : 1; /* only appear in combined diff */
/* data should be considered "binary"; -1 means "don't know yet" */
signed int is_binary : 2;
+ unsigned binary : 1;
+ unsigned reencoded_from_utf16 : 1;
struct userdiff_driver *driver;
};
@@ -72,6 +74,7 @@ struct diff_filepair {
unsigned is_unmerged : 1;
unsigned done_skip_stat_unmatch : 1;
unsigned skip_stat_unmatch_result : 1;
+ unsigned binary : 1;
};
#define DIFF_PAIR_UNMERGED(p) ((p)->is_unmerged)
diff --git a/t/t4066-diff-encoding.sh b/t/t4066-diff-encoding.sh
new file mode 100755
index 0000000000..9bb3c70ada
--- /dev/null
+++ b/t/t4066-diff-encoding.sh
@@ -0,0 +1,98 @@
+#!/bin/sh
+
+test_description='git diff with encoding attribute'
+
+. ./test-lib.sh
+
+printf '\303\244rger\n\303\266se\n\303\274bel\n' |
+ iconv -f UTF-8 -t UTF-16 >UTF-16
+printf '\303\266se\n\303\274bel\n\303\245st\n' |
+ iconv -f UTF-8 -t UTF-16 >file2
+
+test_expect_success 'setup' '
+ cp UTF-16 file &&
+ git add file &&
+ git commit -m "add file in UTF-16" &&
+ test_tick &&
+ echo "file encoding=UTF-16" >.gitattributes
+'
+
+test_expect_success 'diff against local change' '
+ cp file2 file &&
+ test_tick &&
+ cat >expect <<-\EOF &&
+ diff --git a/file b/file
+ index 26acf09..e98d27a 100644
+ a is converted to UTF-8 from UTF-16
+ b is converted to UTF-8 from UTF-16
+ --- a/file
+ +++ b/file
+ @@ -1,3 +1,3 @@
+ -ärger
+ öse
+ übel
+ +åst
+EOF
+ git diff file >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success 'diff --binary against local change' '
+ cp file2 file &&
+ test_tick &&
+ cat >expect <<-\EOF &&
+ diff --git a/file b/file
+ index 26acf09b0aad19fb22566956d1a39cb4e2a3b420..e98d27acfb90cfcfc84fcc5173baa4aa7828290f 100644
+ GIT binary patch
+ literal 28
+ ecmezW?;ArgLn;Fo!ykquAe{qbJq3!C0BHb{ln3Pi
+
+ literal 32
+ icmezW?+HT@Lpnn$kmO?c#!w7oaWVX1NCMJ1Ko$VA_z0~4
+
+EOF
+ git diff --binary file >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success 'commit local change' '
+ git add file &&
+ git commit -m "add file V2 in UTF-16" &&
+ test_tick
+'
+
+test_expect_success 'diff HEAD against HEAD^' '
+ cat >expect <<-\EOF &&
+ diff --git a/file b/file
+ index 26acf09..e98d27a 100644
+ a is converted to UTF-8 from UTF-16
+ b is converted to UTF-8 from UTF-16
+ --- a/file
+ +++ b/file
+ @@ -1,3 +1,3 @@
+ -ärger
+ öse
+ übel
+ +åst
+EOF
+ git diff HEAD^ HEAD -- file >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success 'diff --binary HEAD against HEAD^' '
+ cat >expect <<-\EOF &&
+ diff --git a/file b/file
+ index 26acf09b0aad19fb22566956d1a39cb4e2a3b420..e98d27acfb90cfcfc84fcc5173baa4aa7828290f 100644
+ GIT binary patch
+ literal 28
+ ecmezW?;ArgLn;Fo!ykquAe{qbJq3!C0BHb{ln3Pi
+
+ literal 32
+ icmezW?+HT@Lpnn$kmO?c#!w7oaWVX1NCMJ1Ko$VA_z0~4
+
+EOF
+ git diff --binary HEAD^ HEAD -- file >actual &&
+ test_cmp expect actual
+'
+
+test_done
diff --git a/utf8.h b/utf8.h
index 6bbcf31a83..a2184d0300 100644
--- a/utf8.h
+++ b/utf8.h
@@ -16,6 +16,17 @@ int utf8_fprintf(FILE *, const char *, ...);
extern const char utf8_bom[];
extern int skip_utf8_bom(char **, size_t);
+static inline int buffer_has_utf16_bom(const void *buf, size_t len) {
+ const unsigned char *text = (unsigned char *)buf;
+ if (!text || len < 2)
+ return 0;
+ if (text[0] == 0xff && text[1] == 0xfe)
+ return 1;
+ if (text[0] == 0xfe && text[1] == 0xff)
+ return 1;
+ return 0;
+}
+
void strbuf_add_wrapped_text(struct strbuf *buf,
const char *text, int indent, int indent2, int width);
void strbuf_add_wrapped_bytes(struct strbuf *buf, const char *data, int len,
--
2.16.1.194.gb2e45c695d
