From: lars.schneider@autodesk.com
To: git@vger.kernel.org
Cc: gitster@pobox.com, tboegi@web.de, j6t@kdbg.org,
sunshine@sunshineco.com, peff@peff.net,
ramsay@ramsayjones.plus.com, Johannes.Schindelin@gmx.de,
pclouds@gmail.com, Lars Schneider <larsxschneider@gmail.com>
Subject: [PATCH v11 04/10] utf8: add function to detect prohibited UTF-16/32 BOM
Date: Fri, 9 Mar 2018 18:35:30 +0100 [thread overview]
Message-ID: <20180309173536.62012-5-lars.schneider@autodesk.com> (raw)
In-Reply-To: <20180309173536.62012-1-lars.schneider@autodesk.com>
From: Lars Schneider <larsxschneider@gmail.com>
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>
---
utf8.c | 26 ++++++++++++++++++++++++++
utf8.h | 9 +++++++++
2 files changed, 35 insertions(+)
diff --git a/utf8.c b/utf8.c
index 2c27ce0137..e4b99580f0 100644
--- a/utf8.c
+++ b/utf8.c
@@ -538,6 +538,32 @@ 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 (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 (
+ (!strcasecmp(enc, "UTF-16BE") || !strcasecmp(enc, "UTF-16LE") ||
+ !strcasecmp(enc, "UTF16BE") || !strcasecmp(enc, "UTF16LE")) &&
+ (has_bom_prefix(data, len, utf16_be_bom, sizeof(utf16_be_bom)) ||
+ has_bom_prefix(data, len, utf16_le_bom, sizeof(utf16_le_bom)))
+ ) || (
+ (!strcasecmp(enc, "UTF-32BE") || !strcasecmp(enc, "UTF-32LE") ||
+ !strcasecmp(enc, "UTF32BE") || !strcasecmp(enc, "UTF32LE")) &&
+ (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`.
diff --git a/utf8.h b/utf8.h
index 6bbcf31a83..0db1db4519 100644
--- a/utf8.h
+++ b/utf8.h
@@ -70,4 +70,13 @@ typedef enum {
void strbuf_utf8_align(struct strbuf *buf, align_type position, unsigned int width,
const char *s);
+/*
+ * If a data stream is declared as UTF-16BE or UTF-16LE, then a UTF-16
+ * BOM must not be used [1]. The same applies for the UTF-32 equivalents.
+ * The function returns true if this rule is violated.
+ *
+ * [1] http://unicode.org/faq/utf_bom.html#bom10
+ */
+int has_prohibited_utf_bom(const char *enc, const char *data, size_t len);
+
#endif
--
2.16.2
next prev parent reply other threads:[~2018-03-09 17:37 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-09 17:35 [PATCH v11 00/10] convert: add support for different encodings lars.schneider
2018-03-09 17:35 ` [PATCH v11 01/10] strbuf: remove unnecessary NUL assignment in xstrdup_tolower() lars.schneider
2018-03-09 17:35 ` [PATCH v11 02/10] strbuf: add xstrdup_toupper() lars.schneider
2018-03-09 17:35 ` [PATCH v11 03/10] strbuf: add a case insensitive starts_with() lars.schneider
2018-03-09 17:35 ` lars.schneider [this message]
2018-03-09 17:35 ` [PATCH v11 05/10] utf8: add function to detect a missing UTF-16/32 BOM lars.schneider
2018-03-09 17:35 ` [PATCH v11 06/10] convert: add 'working-tree-encoding' attribute lars.schneider
2018-03-09 19:10 ` Junio C Hamano
2018-03-15 21:23 ` Lars Schneider
2018-03-18 7:24 ` Torsten Bögershausen
2018-04-01 13:24 ` Lars Schneider
2018-04-05 16:41 ` Torsten Bögershausen
2018-04-15 16:54 ` Lars Schneider
2018-03-09 17:35 ` [PATCH v11 07/10] convert: check for detectable errors in UTF encodings lars.schneider
2018-03-09 19:00 ` Junio C Hamano
2018-03-09 19:04 ` Lars Schneider
2018-03-09 19:10 ` Junio C Hamano
2018-03-09 17:35 ` [PATCH v11 08/10] convert: advise canonical UTF encoding names lars.schneider
2018-03-09 19:11 ` Junio C Hamano
2018-03-15 22:42 ` Lars Schneider
2018-03-09 17:35 ` [PATCH v11 09/10] convert: add tracing for 'working-tree-encoding' attribute lars.schneider
2018-03-09 17:35 ` [PATCH v11 10/10] convert: add round trip check based on 'core.checkRoundtripEncoding' lars.schneider
2018-03-09 20:18 ` Eric Sunshine
2018-03-09 20:22 ` Junio C Hamano
2018-03-09 20:27 ` Eric Sunshine
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