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author | Lars Schneider <larsxschneider@gmail.com> | 2018-04-15 20:16:05 +0200 |
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committer | Junio C Hamano <gitster@pobox.com> | 2018-04-16 11:40:56 +0900 |
commit | 10ecb82e4f1f507d5f122e00fd4829b30953f853 (patch) | |
tree | 58e2245d175a29290fc4405988ab650b5b669207 /utf8.c | |
parent | 2f0c4a362c5db677ee392a6a550632bfb22d8319 (diff) | |
download | git-10ecb82e4f1f507d5f122e00fd4829b30953f853.tar.gz |
utf8: add function to detect prohibited UTF-16/32 BOM
Whenever a data stream is declared to be UTF-16BE, UTF-16LE, UTF-32BE
or UTF-32LE a BOM must not be used [1]. The function returns true if
this is the case.
This function is used in a subsequent commit.
[1] http://unicode.org/faq/utf_bom.html#bom10
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'utf8.c')
-rw-r--r-- | utf8.c | 26 |
1 files changed, 26 insertions, 0 deletions
@@ -560,6 +560,32 @@ char *reencode_string_len(const char *in, int insz, } #endif +static int has_bom_prefix(const char *data, size_t len, + const char *bom, size_t bom_len) +{ + return data && bom && (len >= bom_len) && !memcmp(data, bom, bom_len); +} + +static const char utf16_be_bom[] = {0xFE, 0xFF}; +static const char utf16_le_bom[] = {0xFF, 0xFE}; +static const char utf32_be_bom[] = {0x00, 0x00, 0xFE, 0xFF}; +static const char utf32_le_bom[] = {0xFF, 0xFE, 0x00, 0x00}; + +int has_prohibited_utf_bom(const char *enc, const char *data, size_t len) +{ + return ( + (same_utf_encoding("UTF-16BE", enc) || + same_utf_encoding("UTF-16LE", enc)) && + (has_bom_prefix(data, len, utf16_be_bom, sizeof(utf16_be_bom)) || + has_bom_prefix(data, len, utf16_le_bom, sizeof(utf16_le_bom))) + ) || ( + (same_utf_encoding("UTF-32BE", enc) || + same_utf_encoding("UTF-32LE", enc)) && + (has_bom_prefix(data, len, utf32_be_bom, sizeof(utf32_be_bom)) || + has_bom_prefix(data, len, utf32_le_bom, sizeof(utf32_le_bom))) + ); +} + /* * Returns first character length in bytes for multi-byte `text` according to * `encoding`. |