introducing new ctrunc() function that invalidates any caches
for the passed in chan, invoked when handling wstat with a
specified file length or on file creation/truncation.
test program to reproduce the problem:
#include <u.h>
#include <libc.h>
#include <libsec.h>
void
main(int argc, char *argv[])
{
int fd;
Dir *d, nd;
fd = create("xxx", ORDWR, 0666);
write(fd, "1234", 4);
d = dirstat("xxx");
assert(d->length == 4);
nulldir(&nd);
nd.length = 0;
dirwstat("xxx", &nd);
d = dirstat("xxx");
assert(d->length == 0);
fd = open("xxx", OREAD);
assert(read(fd, (void*)&d, 4) == 0);
}
allocating AX,CX,DX last improves 64-bit multiplication-add
chains like a*b + c*d as the multiplication does not need to save
and restore AX and DX registers in most cases. reserving CX for
shifts also helps.
encode printable characters litteraly, use D() macro to
reduce DATA instruction overhead.
this halves the time spend assembling $CONF.root.s for
the kernel build.
the root fileserver is mounted with the mount cache enabled
causing the contents of the cfsctl file to be cached as well
leading to wrong results. so after we generated the new stat
buffer, we increment the qid.vers so the cache starts out
clean.
given that the igfx driver doesnt provide any acceleration functions
and drawing is usually faster with double buffering as it eleminates
reads over the pci bus, enable softscreen by default.
the rcpu client dup's fd 0,1,2 to fd 10,11,12 which
can accidentally override the pipe file descriptor
allocated by the <{} operator. to avoid this problem,
we generate the remote script as an /env file in a
separate step now.
don't use rand() and scale it to 0..1, instead call
native frand() which produces uniform random number.
instead of seeding the rng with time(0), use truerand().
on 386 kernel, each processor has its own pdb where the primary
pdb for kernel mappings is on cpu0 and other cpu's lazily pull
pdb entries from cpu0 when they fault in vmapsync().
so we have to edit the table tables in the pdb of cpu0 and not
the current processor.
on some modern machines like the x250, the bios arranges the mtrr's
and the framebuffer membar in a way that doesnt allow us to mark
the framebuffer pages as write combining, leading to slow graphics.
since the pentium III, the processor interprets the page table bit
combinations of the WT, CD and bit7 bits as an index into the
page attribute table (PAT).
to not change the semantics of the WT and CD bits, we preserve
the bit patterns 0-3 and use the last entry 7 for write combining.
(done in mmuinit() for each core).
the new patwc() function takes virtual address range and changes
the page table marking the range as write combining. no attempt
is made on invalidating tlb's. doesnt matter in our case as the
following mtrr() call in screen.c does it for us.
the assumption of only one producer ((abs)moustratrack()) is not true
for external mouse events from /dev/mousein, so protect the mouse state
and queue with ilock().
get rid of mousecreate(), just use devcreate().
reset cursor when all instances of /dev/mouse and /dev/cursor got closed,
instead of also considering /dev/mousectl. the reason is that kbdfs keeps
the mousectl file open. so exiting a program that has the cursor changed
will properly reset the cursor to arrow.
don't access user buffer while holding cursor spinlock! the memory access
can fault. theres also no lock needed there, we'r just copying *from* the
cursor memory.
fix use of strtol(), p will always be set, check for end of string.
keep pointer coordinates onscreen (off by one).
make lastms() function to get the last millisecond delta of last
call for resynchronization.
fix msg[3] buffer overflow in m5mouseputc().
get rid of mouseshifted logic, it is not used.
theres a bug is in sclose() where it doesnt check if wp is beyond
the buffer. also wp was not updated after realloc().
bug was reported by porlock on 9fans:
Plan 9's implementation of the standard C functions snprintf and
vsnprintf have a buffer overrun bug.
If the buffer length equals the output length (without the terminating
null), then one too many characters is written to the buffer.
For example,
snprintf(buf, 4, "ABCD");
will write 5 characters to buf.
