The seac command provides the base and accented character that are
needed to create an accented character glyph. Storing these values is
all that was left to properly support these composed glyphs.
Type1 accented character glyphs are composed of two other glyphs in the
same font: a base glyph and an accent glyph, given as char codes in the
standard encoding. These two glyphs are then composed together to form
the accented character.
This commit adds the data structures to hold the information for
accented characters, and also the routine that composes the final glyph
path out of the two individual components. All glyphs must have been
loaded by the time this composition takes place, and thus a new
protected consolidate_glyphs() routine has been added to perform this
calculation.
Glyph was a simple structure, but even now it's become more complex that
it was initially. Turning it into a class hides some of that complexity,
and make sit easier to understand to external eyes.
While doing this I also decided to remove the float + bool combo for
keeping track of the glyph's width, and replaced it with an Optional
instead.
Storing glyphs indexed by char code in a Type1 Font Program binds a Font
Program instance to the particular Encoding that was used at Font
Program construction time. This makes it difficult to reuse Font Program
instances against different Encodings, which would be otherwise
possible.
This commit changes how we store the glyphs on Type1 Font Programs.
Instead of storing them on a map indexed by char code, the map is now
indexed by glyph name. In turn, when rendering a glyph we use the
Encoding object to turn the char code into a glyph name, which in turn
is used to index into the map of glyphs.
This is the first step towards reusability of Type1 Font Programs. It
also unlocks the ability to render glyphs that are described via the
"seac" command (standard encoding accented character), which requires
accessing the base and accent glyphs by name.
This is useful in general (I'd imagine), but in particular having this
will allow us to implement accented PDF Type1 Font glyphs, which consist
of two separate glyphs that are composed into a single one.
When parsing streams we rely on a /Length item being defined in the
stream's dictionary to know how much data comprises the stream. Its
value is usually a direct value, but it can be indirect. There was
however a contradiction in the code: the condition that allowed it to
read and use the /Length value required it to be a direct value, but the
actual code using the value would have worked with indirect ones. This
meant that indirect /Length values triggered the fallback, "manual"
stream parsing code.
On the other hand, this latter code was also buggy, because it relied on
the "endstream" keyword to appear on a separate line, which isn't always
the case.
This commit both fixes the bug in the manual stream parsing scenario,
while also allowing for indirect /Length values to be used to parse
streams more directly and avoid the manual approach. The main caveat to
this second change is that for a brief period of time the Document is
not able to resolve references (i.e., before the xref table itself is
not parsed). Any parsing happening before that (e..g, the linearization
dictionary) must therefore use the manual stream parsing approach.
This is needed so we can retrieve the registers of a traced
thread that was attached to while it was running.
Attaching with ptrace to a running thread sends SIGSTOP to it.
This adds the necessary code to init.cpp to be able to execute the first
userspace process. To do this, first the filesystem code is initialized,
which will use the ramdisk embedded into the kernel image. Then the
first userspace process, /bin/SystemServer is executed. :^)
The ramdisk code is used as it is useful for the bring-up of the aarch64
port, however once the kernel has support for better ram-based
filesystems, the ramdisk code will be removed again.
The emulated aarch64 CPU does not contain the RNG cpu feature, so the
random number generator was not seeded. This commit adds a fallback to
use TimeManagement as a entropy source, such that get_good_random_bytes
works, which is needed for running the first userspace application on
aarch64.
This sets up the correct ThreadRegisters state when a process is
exec'ed, which happens when the first userspace application is executed.
Also changes Processor.cpp to get the stack pointer from the
ThreadRegisters.
This allows the function to be called from other translation units, in
particular this allows the CrashHandler.cpp file to be shared between
aarch64 and x86_64.
Setting the kernel_load_base variable caused backtracking to regress, so
to have proper backtracing the calculation of the symbol address in
KSyms.cpp needs to keep into account that the aarch64 kernel is linked
at a high virtual memory address.
When we execute in userspace, the exception level is EL0, so to handle
exceptions, such as interrupts, and syscalls, we need to add handlers to
vector_table.S. For now we only support running userspace applications
in AArch64 mode, so this commit only adds the handlers for that mode.
To detect instruction aborts, a helper to Registers.h is added, and used
in Interrupts.cpp. Additionally, the PageFault class gets a setter to
set the PageFaults m_is_instruction_fetch bool, and is also used in
Interrupts.cpp.
This reverts commit 4e0f85432a as the
ramdisk code is useful for the bring-up of the aarch64 port. Once the
kernel supports better ram-based filesystems, this code will be removed
again.
Functionality for checking image size in advance has been removed, as
this would require a SeekableStream and we now check for read errors
everywhere anyways.
