OpenSystemsDevelopment / qpdf

This fixes cases of warning C4800 from msvc

This makes all integer type conversions that have potential data loss
explicit with calls that do range checks and raise an exception. After
this commit, qpdf builds with no warnings when -Wsign-conversion
-Wconversion is used with gcc or clang or when -W3 -Wd4800 is used
with MSVC. This significantly reduces the likelihood of potential
crashes from bogus integer values.

There are some parts of the code that take int when they should take
size_t or an offset. Such places would make qpdf not support files
with more than 2^31 of something that usually wouldn't be so large. In
the event that such a file shows up and is valid, at least qpdf would
raise an error in the right spot so the issue could be legitimately
addressed rather than failing in some weird way because of a silent
overflow condition.

This is the type we need for the underlying zlib implementation.

Change from unsigned long to int since we pass enumerated type values
to this field.

Based on sizeof(size_t). Assumes 64 if not 32.

Bounding box X coordinates could be truncated, causing them to be off
by a fraction of a point. This was most likely not visible, but it was
still wrong.

There are more to handle, but this resolves an issue already caught by
oss-fuzz.

On read, ignore /DecodeParms when empty list; on write, delete it.
Some files have been found that include an empty list for
/DecodeParms, but this is not technically compliant with the spec, and
the only sensible interpretation is to treat it as if there are no
decode parameters.

* [bcc32 Error] QPDF.cc(375): E2268 Call to undefined function 'atof'
  Full parser context
    QPDF.cc(358): parsing: void QPDF::parse(const char *)

* [bcc32 Error] QPDFTokenizer.cc(183): E2268 Call to undefined function 'strtol'
  Full parser context
    QPDFTokenizer.cc(163): parsing: void QPDFTokenizer::resolveLiteral()

* [bcc32 Error] pdf-split-pages.cc(52): E2268 Call to undefined function 'exit'
  Full parser context
    pdf-split-pages.cc(50): parsing: void usage()

* PR #295: Including "cstdlib" should be replaced with "stdlib.h" to be more consistent. At the same time I changed the order of the surrounding includes to reflect alphabetical order, because at some files this already have been the case.

…lassic one nor newer ones based on CLANG.

JSON serialization was preserving the value as presented, but JSON
doesn't accept decimal values without a 0 before the decimal point.

Do not include the trailing EI, and handle cases where EI is not
preceded by a delimiter. Such cases have been seen in the wild.

We've actually seen a PDF file in the wild that contained EI
surrounded by delimiters inside the image data, which confused qpdf's
naive code. This significantly improves EI detection.

Add a version of expectInlineImage that takes an input source and
searches for EI. This is in preparation for improving the way EI is
found. This commit just refactors the code without changing the
functionality and adds tests to make sure the old and new code behave
identically.

The inline image token erroneously included the delimiter that
followed EI. The ObjectHandle created from it was correct.

Make explicit that copyForeignObject can be used on page objects and
will copy them properly but not update the pages tree.

When linearizing a file or getting the list of all pages in a file,
detect if the pages tree contains a duplicated page object and, if so,
shallow copy it. This makes it possible to have a one to one mapping
of page positions to page objects.

Support conversion of pages to form XObjects and placement of form
XObjects on pages.

Add getAttribute for handling inheritable page attributes, and fix
getPageImages and annotation flattening code to use it.

If we end up using our fallback font size when generating appearances
for text fields, reflect that in the Tf operator used in the
appearance stream.