On Linux sscanf, vsscanf, fscanf and sscanf_s hand their conversions to
glibc. Since glibc 2.38, code built as GNU C++ calls the C23 entry
points (__isoc23_vsscanf, __isoc23_vfscanf, __isoc23_sscanf), whose %i
reads a 0b/0B binary prefix. On main,
sscanf("0b101 x", "%i%n%7s", &value, &end, rest) stores value 5 and
end 5 and leaves "x" for the %s; " -0B11" gives -3. TechnicalDebt
records this.
FreeBSD's %i knows only the 0 and 0x prefixes. FreeBSD 11.4
lib/libc/stdio/vfscanf.c, parseint, lines 345-353 and 371-380:
case '0':
if (base == 0) {
base = 8;
flags |= PFXOK;
}
...
/* letters ok iff hex */
case 'A': case 'B': case 'C':
case 'D': case 'E': case 'F':
case 'a': case 'b': case 'c':
case 'd': case 'e': case 'f':
/* no need to fix base here */
if (base <= 10)
break; /* not legal here */
so "0b101" stores 0, consumes the "0" and leaves "b101", as C17 does
and as the strtol family here already does.
With glibc the scanf family now calls __isoc99_vsscanf and
__isoc99_vfscanf, the entry points GNU C++ used before glibc 2.38
(exported since 2.7), which read %i without the binary prefix. Other
hosts keep std::vsscanf and std::vfscanf. The TechnicalDebt entry is
removed.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
MaskedSelectEliminator walked forward from each select to see whether the
lanes its mask excludes are read. Since fda4aa90 the walks pass explicit-LOD
gathers, size queries and guarded image writes, so in a large pixel shader
most of them cover the rest of the program, and the cost grows with the
square of its size (#3504).
The pass now computes, for every value, the set of masks under which it is
unread, from its uses backwards: a use guarded by a condition contributes the
masks that condition implies, a lane-local use adds what its result is unread
under, and any other use contributes nothing. A select is dropped when its
mask is in its own set. Loops are solved as strongly connected components.
The rules for guards, lane-local uses, loops, whole quad masks, selected
execs, rebuilt mask words and guarded first-lane reads are the ones the walk
applied. A first-lane read passes the masks its read mask implies when its
own result is unread outside that read mask, which is solved once per read in
the same way. The walk's step limit, its 64-level implication depth and its
first-lane nesting depth are gone, so a proof no longer depends on the order
of the questions.
Goat Simulator 3 draws a triangle list whose indices are all 0xffffffff
with primitive restart off. Each fetch past a descriptor's records reads
zeros (out-of-bounds select 0 or 1), but the zero-padded vertex copies
were sized to the highest index: 160 GiB, which vkAllocateMemory refused.
When the highest index is at least 64Ki vertices past the largest
per-vertex record count, the draw now uses a copy of its indices with
every index past that count moved to it. Each attribute reads zeros
there as at the original index; only the vertex index the shader sees
changes, so indices closer to the records are left as they are.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
ioctl and _ioctl answered EBADF for every descriptor outside the
libSceNet socket table. Decoded call sites: PS5MC (PPSA99420, FIONBIO x3,
FIONREAD x2, TIOCGWINSZ x3), ProsperoTV (PPSA99003, FIONBIO on a pipe
once poll on pipes is in), XPSemu (PPSA97358, 21 sites).
Following FreeBSD 11.4 kern_ioctl (sys/kern/sys_generic.c:758),
vn_ioctl (sys/kern/vfs_vnops.c:1488), pipe_ioctl (sys/kern/sys_pipe.c:1346)
and randomdev_ioctl (sys/dev/random/randomdev.c:301), release/11.4.0
8c639945: FIONBIO sets or clears O_NONBLOCK through the same status
flags as fcntl F_SETFL (EFAULT for a null argument before EBADF);
FIONREAD reports the size past the offset of a file, the queued bytes of
a pipe's read end, 0 on its write end, ENOTTY on the random device, and
throws on a directory or another character device; termios requests
(group 't', TIOCGWINSZ included) fail with ENOTTY, as tcgetattr already
takes these descriptors as not a terminal; any other request throws
naming the request and descriptor kind. Sockets keep their path
unchanged.
Co-Authored-By: Claude Fable 5.1 <[email protected]>
fcntl and sceKernelFcntl answered EBADF (sceKernelFcntl threw) for
every descriptor outside the libSceNet socket table, so files, pipes,
directories and descriptors 0 to 2 could not be queried or changed.
Observed: Yamagi Quake II (PPSA99007) stops with
"Sys_Error: change stdin to blocking Bad file descriptor", from
fcntl(fileno(stdin), F_SETFL, fcntl(0, F_GETFL, 0) & ~FNDELAY)
(yquake2 src/backends/unix/system.c:81-86).
Predicted from the titles' sources and decoded call sites: XPSemu
(PPSA97358, 97 fcntl sites: F_GETFD 12, F_SETFD 20, F_GETFL 8,
F_SETFL 9, F_DUPFD 1, F_DUPFD_CLOEXEC 7, F_GETLK 9) fails in
qemu_init_main_loop, where its pipe2 (pipe plus F_SETFD FD_CLOEXEC) and
glib's g_unix_set_fd_nonblocking (F_GETFL, F_SETFL) build the event
notifier (util/event_notifier-posix.c:44-67); VLC (PPSA85300, 43 sites,
F_RDAHEAD on every file it opens), RetroArch (PPSA99169, 17),
Porpoise (PPSA99764, 13) and Ruffle (9) call it on files and pipes.
The commands follow FreeBSD 11.4 kern_fcntl and kern_dup
(sys/kern/kern_descrip.c:479-799, 812, release/11.4.0 8c639945):
F_GETFD/F_SETFD keep the close-on-exec flag per descriptor, F_GETFL
reports the host access mode with the status flags, F_SETFL changes
only O_NONBLOCK, O_APPEND, O_ASYNC, O_FSYNC, O_DIRECT and FRDAHEAD,
F_DUPFD/F_DUPFD_CLOEXEC give the lowest free descriptor at or above the
start through dup (EINVAL for a negative start), F_DUP2FD goes through
dup2, F_RDAHEAD/F_READAHEAD set FRDAHEAD on files (EBADF on pipes,
ENOTTY elsewhere), and unknown commands fail with EINVAL. Status flags
live in a guest table shared by dup, dup2 and F_DUPFD like an open file
description. O_NONBLOCK switches a pipe (PIPE_NOWAIT on Windows, where an
empty read and a full write now report EAGAIN; the host flag on Linux).
Record locks use the host POSIX locks on Linux and throw on Windows.
Changes the host cannot model throw naming the flag and descriptor kind.
Sockets keep their path unchanged.
Co-Authored-By: Claude Fable 5.1 <[email protected]>
Draws 32_ABGR exports into a tiled and a linear format 17 target and compares every texel with
the layout X in bits 0-4, Y in 5-9, Z in 10-14, W in bit 15, including the X/Z-swapped pairs, rounding
edges and texels outside the scissor. Reverting the X/Z exchange fails it.
Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Direct memory can already be mapped more than once, so there is no
aliasing to enable and the call returns 0. ProsperoEden (PPSA99008)
imports it and calls it before mapping the same direct memory again.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
readlink threw for every Windows reparse point, including the links
symlink creates. Read the target of a relative symbolic link from its
reparse data and return it with forward slashes. Absolute targets,
junctions and other reparse points still throw.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
Dean