Because Java array sizes are ints, the various size methods in the TJ
class have int return values. Thus, we have to guard against signed
int overflow at the JNI level, because the C functions can return sizes
greater than INT_MAX.
This also adds a test for TJ.planeWidth() and TJ.planeHeight(), in order
to validate 8a1526a442 in Java.
The documented behavior of the -progressive option is to use progressive
entropy coding in JPEG images generated by compression and transform
operations. However, setting TJFLAG_PROGRESSIVE was insufficient to
accomplish that, because TJBench doesn't enable lossless transformation
if xformOpt == 0.
- TJBench/TJUnitTest: Wordsmith command-line output
- Java: "decompress operations"="decompression operations"
- tjLoadImage(): Error message tweak
- Don't mention compression performance in the description of
TJXOPT_PROGRESSIVE/TJTransform.OPT_PROGRESSIVE, because the image has
already been compressed at that point.
(Oversights from 9a146f0f23)
This is similar to the fix that 2a9e3bd743
applied to the C API. We have to apply it separately at the JNI level
because the Java API always stores buffer sizes in 32-bit integers, and
the C buffer size functions could overflow an int when using 64-bit
code. (NOTE: The Java API stores buffer sizes in 32-bit integers
because Java itself always uses 32-bit integers for array sizes.) Since
Java don't allow no buffer overruns 'round here, this commit doesn't
change the ultimate outcome. It just makes the inevitable exception
easier to diagnose.
- Wordsmithing, formatting, and grammar tweaks
- Various clarifications and corrections, including specifying whether
a particular buffer or image is used as a source or destination
- Accommodate/mention features that were introduced since the API
documentation was created.
- For clarity, use "packed-pixel" to describe uncompressed
source/destination images that are not planar YUV.
- Use "row" rather than "line" to refer to a single horizontal group of
pixels or component values, for consistency with the libjpeg API
documentation. (libjpeg also uses "scanline", which is a more archaic
term.)
- Use "alignment" rather than "padding" to refer to the number of bytes
by which a row's width is evenly divisible. This consistifies the
documention of the YUV functions and tjLoadImage(). ("Padding"
typically refers to the number of bytes added to each row, which is
not the same thing.)
- Remove all references to "the underlying codec." Although the
TurboJPEG API originated as a cross-platform wrapper for the Intel
Integrated Performance Primitives, Sun mediaLib, QuickTime, and
libjpeg, none of those TurboJPEG implementations has been maintained
since 2009. Nothing would prevent someone from implementing the
TurboJPEG API without libjpeg-turbo, but such an implementation would
not necessarily have an "underlying codec." (It could be fully
self-contained.)
- Use "destination image" rather than "output image", for consistency,
or describe the type of image that will be output.
- Avoid the term "image buffer" and instead use "byte buffer" to
refer to buffers that will hold JPEG images, or describe the type of
image that will be contained in the buffer. (The Java documentation
doesn't use "byte buffer", because the buffer arrays literally have
"byte" in front of them, and since Java doesn't have pointers, it is
not possible for mere mortals to store any other type of data in those
arrays.)
- C: Use "unified" to describe YUV images stored in a single buffer, for
consistency with the Java documentation.
- Use "planar YUV" rather than "YUV planar". Is is our convention to
describe images using {component layout} {colorspace/pixel format}
{image function}, e.g. "packed-pixel RGB source image" or "planar YUV
destination image."
- C: Document the TurboJPEG API version in which a particular function
or macro was introduced, and reorder the backward compatibility
function stubs in turbojpeg.h alphabetically by API version.
- C: Use Markdown rather than HTML tags, where possible, in the Doxygen
comments.
Add a new TurboJPEG C API function (tjDecompressHeader4()) and Java API
method (TJDecompressor.getFlags()) that return the bitwise OR of any
flags that are relevant to the JPEG image being decompressed (currently
TJFLAG_PROGRESSIVE, TJFLAG_ARITHMETIC, TJFLAG_LOSSLESS, and their Java
equivalents.) This allows a calling program to determine whether the
image being decompressed is a lossless JPEG image, which means that the
decompression scaling feature will not be available and that a
full-sized destination buffer should be allocated.
More specifically, this fixes a buffer overrun in TJBench, TJExample,
and the decompress* fuzz targets that occurred when attempting (in vain)
to decompress a lossless JPEG image with decompression scaling enabled.
IIRC, this was only necessary with the version of Java 1.5 that shipped
with OS X 10.4 "Tiger". Apple's implementation of Java 6 ("Java for
OS X Systems") supported both .jnilib and .dylib extensions for JNI
libraries, but Oracle's implementation of Java has only ever supported
the .dylib extension.
Prevent several integer overflow issues and subsequent segfaults that
occurred when attempting to compress or decompress gigapixel images with
the TurboJPEG API:
- Modify tjBufSize(), tjBufSizeYUV2(), and tjPlaneSizeYUV() to avoid
integer overflow when computing the return values and to return an
error if such an overflow is unavoidable.
- Modify tjunittest to validate the above.
- Modify tjCompress2(), tjEncodeYUVPlanes(), tjDecompress2(), and
tjDecodeYUVPlanes() to avoid integer overflow when computing the row
pointers in the 64-bit TurboJPEG C API.
- Modify TJBench (both C and Java versions) to avoid overflowing the
size argument to malloc()/new and to fail gracefully if such an
overflow is unavoidable.
In general, this allows gigapixel images to be accommodated by the
64-bit TurboJPEG C API when using automatic JPEG buffer (re)allocation.
Such images cannot currently be accommodated without automatic JPEG
buffer (re)allocation, due to the fact that tjAlloc() accepts a 32-bit
integer argument (oops.) Such images cannot be accommodated in the
TurboJPEG Java API due to the fact that Java always uses a signed 32-bit
integer as an array index.
Fixes#361
(detected by enabling additional checkstyle modules)
This commit also removes unnecessary uses of the "private" modifier in
the Java tests/examples. The default access modifier disallows access
outside of the package, and none of these classes is in a package. The
only reason we use "private" with member variables in these classes is
to make checkstyle happy, because we want it to enforce that behavior in
the TurboJPEG API code.
... and modify tjbench.c to match the variable name changes made to
TJBench.java
("checkstyle" = http://checkstyle.sourceforge.net, not our regex-based
checkstyle script)
With rare exceptions ...
- Always separate line continuation characters by one space from
preceding code.
- Always use two-space indentation. Never use tabs.
- Always use K&R-style conditional blocks.
- Always surround operators with spaces, except in raw assembly code.
- Always put a space after, but not before, a comma.
- Never put a space between type casts and variables/function calls.
- Never put a space between the function name and the argument list in
function declarations and prototypes.
- Always surround braces ('{' and '}') with spaces.
- Always surround statements (if, for, else, catch, while, do, switch)
with spaces.
- Always attach pointer symbols ('*' and '**') to the variable or
function name.
- Always precede pointer symbols ('*' and '**') by a space in type
casts.
- Use the MIN() macro from jpegint.h within the libjpeg and TurboJPEG
API libraries (using min() from tjutil.h is still necessary for
TJBench.)
- Where it makes sense (particularly in the TurboJPEG code), put a blank
line after variable declaration blocks.
- Always separate statements in one-liners by two spaces.
The purpose of this was to ease maintenance on my part and also to make
it easier for contributors to figure out how to format patch
submissions. This was admittedly confusing (even to me sometimes) when
we had 3 or 4 different style conventions in the same source tree. The
new convention is more consistent with the formatting of other OSS code
bases.
This commit corrects deviations from the chosen formatting style in the
libjpeg API code and reformats the TurboJPEG API code such that it
conforms to the same standard.
NOTES:
- Although it is no longer necessary for the function name in function
declarations to begin in Column 1 (this was historically necessary
because of the ansi2knr utility, which allowed libjpeg to be built
with non-ANSI compilers), we retain that formatting for the libjpeg
code because it improves readability when using libjpeg's function
attribute macros (GLOBAL(), etc.)
- This reformatting project was accomplished with the help of AStyle and
Uncrustify, although neither was completely up to the task, and thus
a great deal of manual tweaking was required. Note to developers of
code formatting utilities: the libjpeg-turbo code base is an
excellent test bed, because AFAICT, it breaks every single one of the
utilities that are currently available.
- The legacy (MMX, SSE, 3DNow!) assembly code for i386 has been
formatted to match the SSE2 code (refer to
ff5685d5344273df321eb63a005eaae19d2496e3.) I hadn't intended to
bother with this, but the Loongson MMI implementation demonstrated
that there is still academic value to the MMX implementation, as an
algorithmic model for other 64-bit vector implementations. Thus, it
is desirable to improve its readability in the same manner as that of
the SSE2 implementation.
Also, set the red/green/blue offsets for TJPF_GRAY to -1 rather than 0.
It was undefined behavior for an application to use those arrays/methods
with TJPF_GRAY anyhow, and this makes it easier for applications to
programmatically detect whether a given pixel format has red, green, and
blue components.
