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.
When attempting to decode a malformed JPEG image (refer to
https://bugzilla.mozilla.org/show_bug.cgi?id=1295044) with dimensions
61472 x 32800, the maximum_space variable within the
realize_virt_arrays() function will exceed the maximum value of a 32-bit
integer and will wrap around. The memory manager subsequently fails
with an "Insufficient memory" error (case 4, in alloc_large()), so this
commit simply causes that error to be triggered earlier, before UBSan
has a chance to complain.
Note that this issue did not ever represent an exploitable security
threat, because the POSIX-based memory manager that we use doesn't ever
do anything meaningful with the value of maximum_space.
jpeg_mem_available() simply sets avail_mem = maximum_space, so the
subsequent behavior of the memory manager is the same regardless of
whether maximum_space is correct or not. This commit simply removes a
UBSan warning in order to make it easier to detect actual security
issues.
The convention used by libjpeg:
type * variable;
is not very common anymore, because it looks too much like
multiplication. Some (particularly C++ programmers) prefer to tuck the
pointer symbol against the type:
type* variable;
to emphasize that a pointer to a type is effectively a new type.
However, this can also be confusing, since defining multiple variables
on the same line would not work properly:
type* variable1, variable2; /* Only variable1 is actually a
pointer. */
This commit reformats the entirety of the libjpeg-turbo code base so
that it uses the same code formatting convention for pointers that the
TurboJPEG API code uses:
type *variable1, *variable2;
This seems to be the most common convention among C programmers, and
it is the convention used by other codec libraries, such as libpng and
libtiff.
Because of the exposed nature of the libjpeg API, alloc_small() and
alloc_large() can potentially be called by external code. If an
application were to call either of those functions with
sizeofobject > SIZE_MAX - ALIGN_SIZE - 1, then the math in
round_up_pow2() would wrap around to zero, causing that function to
return a small value. That value would likely not exceed
MAX_ALLOC_CHUNK, so the subsequent size checks in alloc_small() and
alloc_large() would not catch the error.
A similar problem could occur in 32-bit builds if alloc_sarray() were
called with
samplesperrow > SIZE_MAX - (2 * ALIGN_SIZE / sizeof(JSAMPLE)) - 1
This patch simply ensures that the size argument to the alloc_*()
functions will never exceed MAX_ALLOC_CHUNK (1 billion). If it did,
then subsequent size checks would eventually catch that error, so we
are instead catching the error before round_up_pow2() is called.
This addresses a minor concern (LJT-01-001) expressed in a security
audit by Cure53.
The IJG README file has been renamed to README.ijg, in order to avoid
confusion (many people were assuming that that was our project's README
file and weren't reading README-turbo.txt) and to lay the groundwork for
markdown versions of the libjpeg-turbo README and build instructions.
Fix some broken assumptions and allow any alignment, not just those
associated with C types.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@12 632fc199-4ca6-4c93-a231-07263d6284db
