qDecodeDataUrl(): treat ";base64" marker as case-insensitive

RFC2397 doesn't explicitly mention it, but references RFC2045, which,
in Section 2, states:

> All media type values, subtype values, and parameter names as
> defined are case-insensitive.

and goes on, in 6.1:

>   mechanism := "7bit" / "8bit" / "binary" /
>                  "quoted-printable" / "base64" /
>                  ietf-token / x-token
>
>   These values are not case sensitive

So regardless of whether "base64" is a parameter name, or a mechanism,
we need to treat it case-insensitively.

Use QLatin1String::endsWith() instead of QByteArray::endsWith(),
because the former takes Qt::CaseInsensitive while the latter would
need a toLower().

Add a test.

As a drive-by, use the same trick for the existing case-insensitive
comparison with "charset".

As a further drive-by, fix inappropriate uses of QLatin1String (=
where they don't prevent allocations).

[ChangeLog][QtCore][QUrl] Now recognizes the ";base64" marker in
"data:" URLs case-insensitively.

Pick-to: 6.3 6.2
Change-Id: Ife6ba771553aaad3b7c119c1fa631f41ffa8f590
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/tests/auto/corelib/io/qdataurl/tst_qdataurl.cpp b/tests/auto/corelib/io/qdataurl/tst_qdataurl.cpp
index 2a743194b7..dc1278b150 100644
--- a/tests/auto/corelib/io/qdataurl/tst_qdataurl.cpp
+++ b/tests/auto/corelib/io/qdataurl/tst_qdataurl.cpp
@@ -57,6 +57,8 @@ void tst_QDataUrl::decode_data()
         "text/plain;charset=US-ASCII"_L1);
     row("alreadyPercentageEncoded", "data:text/plain,%E2%88%9A", true,
         "text/plain"_L1, QByteArray::fromPercentEncoding("%E2%88%9A"));
+    row("everythingIsCaseInsensitive", "Data:texT/PlaiN;charSet=iSo-8859-1;Base64,SGVsbG8=", true,
+        "texT/PlaiN;charSet=iSo-8859-1"_L1, QByteArrayLiteral("Hello"));
 }
 
 void tst_QDataUrl::decode()