Relax the check on 0 length streams.

Relax the check on 0 length streams.

CPDF_SyntaxParser::ReadStream() originally created stream objects when
the length is 0. Commit 2526930 tightened the constraint and returned
NULL. This has some adverse affects, as seen in Chromium's print
preview of PDFs.

Instead, relax the constraint a little so when the length is 0, return a
CPDF_Stream with NULL data and size 0.

BUG=531835
Committed: https://pdfium.googlesource.com/pdfium/+/4fa0e27ba39f49ba92fb4c160ab836a6f1dd2893

[Lei Zhang, 2015-10-08 03:04:43]

thestig@chromium.org changed reviewers:
+ jun_fang@foxitsoftware.com, tsepez@chromium.org

[jun_fang, 2015-10-08 09:19:52]

https://codereview.chromium.org/1394743002/diff/1/core/src/fpdfapi/fpdf_parse...
File core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp (right):

https://codereview.chromium.org/1394743002/diff/1/core/src/fpdfapi/fpdf_parse...
core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp:2524: if (len <= 0) {
Relax too?

https://codereview.chromium.org/1394743002/diff/1/core/src/fpdfapi/fpdf_parse...
core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp:2539: if (pCryptoHandler) {
If pData is nullptr, there is no data to be decrypted. 
It should be changed to "if (pCryptoHandler && pData) {"

[Lei Zhang, 2015-10-08 17:21:49]

https://codereview.chromium.org/1394743002/diff/1/core/src/fpdfapi/fpdf_parse...
File core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp (right):

https://codereview.chromium.org/1394743002/diff/1/core/src/fpdfapi/fpdf_parse...
core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp:2539: if (pCryptoHandler) {
On 2015/10/08 09:19:52, jun_fang wrote:
> If pData is nullptr, there is no data to be decrypted. 
> It should be changed to "if (pCryptoHandler && pData) {"

Ok. Since |pData| can only be a nullptr when len == 0, I just moved this block
into the if (len > 0) block.

[Lei Zhang, 2015-10-08 17:33:08]

https://codereview.chromium.org/1394743002/diff/1/core/src/fpdfapi/fpdf_parse...
File core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp (right):

https://codereview.chromium.org/1394743002/diff/1/core/src/fpdfapi/fpdf_parse...
core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp:2524: if (len <= 0) {
On 2015/10/08 09:19:52, jun_fang wrote:
> Relax too?

Done.

[Lei Zhang, 2015-10-08 17:34:13]

All the tests pass locally for me. I'm going to land patch set 3. Please check
in when you get a chance and let me know if it's ok.

[Lei Zhang, 2015-10-08 17:34:23]

AKA TBR

[Lei Zhang, 2015-10-08 17:34:34]

Committed patchset #3 (id:40001) manually as
4fa0e27ba39f49ba92fb4c160ab836a6f1dd2893 (presubmit successful).

[jun_fang, 2015-10-09 02:25:03]

On 2015/10/08 17:34:34, Lei Zhang wrote:
> Committed patchset #3 (id:40001) manually as
> 4fa0e27ba39f49ba92fb4c160ab836a6f1dd2893 (presubmit successful).

LGTM.

[jun_fang, 2015-10-09 02:25:04]

On 2015/10/08 17:34:34, Lei Zhang wrote:
> Committed patchset #3 (id:40001) manually as
> 4fa0e27ba39f49ba92fb4c160ab836a6f1dd2893 (presubmit successful).

LGTM.