Cygwin: path_conv: Rework handling native symlinks as inner path components
commit 456c3a46386f was only going half-way. It handled symlinks and
junction points as inner path components and made realpath return the
correct path, but it ignored drive letter substitution, i. e., virtual
drives created with, e. g.
subst X: C:\foo\bar
It was also too simple. Just returning an error code from
symlink_info::check puts an unnecessary onus on the symlink evaluation
loop in path_conv::check.
Rework the code to use GetFinalPathNameByHandle, and only do this after
checking the current file for being a symlink failed.
If the final path returned by GetFinalPathNameByHandle is not the same
as the incoming path, replace the incoming path with the POSIXified
final path. This also short-circuits path evaluation, because
path_conv::check doesn't have to recurse over the inner path components
multiple times if all symlinks are of a native type, while still getting
the final path as end result.
Virtual drives are now handled like symlinks. This is a necessary change
from before to make sure virtual drives are handled identically across
different access methods. An example is realpath(1) from coreutils. It
doesn't call readlink(2), but iterates over all path components using
lstat/readlink calls. Both methods should result in the same real path.
Fixes: 456c3a46386f ("path_conv: Try to handle native symlinks more sanely") Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Ola Olsson [Mon, 26 Apr 2021 08:57:02 +0000 (10:57 +0200)]
Nano-malloc: Fix for unwanted external heap fragmentation
The only reason why it is tough for us to use nano malloc
is because of the small shortcoming where nano_malloc()
splits a bigger chunk from the free list into two pieces
while handing back the second one (the tail) to the user.
This is error prone and especially bad for smaller heaps,
where nano malloc is supposed to be superior. The normal
malloc doesn't have this issue and we need to use it even
though it costs us ~2k bytes compared to nano-malloc.
The problem arise especially after giving back _every_
malloced memory to the heap and then starting to exercise
the heap again by allocating something small. This small
item might split the whole heap in two equally big parts
depending on how the heap has been exercised before.
I have uploaded the smallest possible application
(only tested on ST and Nordic devices) to show the issue
while the real customer applications are far more complicated:
https://drive.google.com/file/d/1kfSC2KOm3Os3mI7EBd-U0j63qVs8xMbt/view?usp=sharing
The application works like the following pseudo code,
where we assume a heap of 100 bytes
(I haven't taken padding and other nitty and gritty
details into account. Everything to simplify understanding):
void *ptr = malloc(52); // We get 52 bytes and we have
// 48 bytes to use.
free(ptr); // Hand back the 52 bytes to nano_malloc
// This is the magic line that shows the issue of
// nano_malloc
ptr = malloc(1); // Nano malloc will split the 52 bytes
// in the free list and hand you a pointer
// somewhere in the
// middle of the heap.
ptr2 = malloc(52); // Out of memory...
I have done a fix which hands back the first part of the
splitted chunk. Once this is fixed we obviously
have the 1 byte placed in position 0 of the heap instead
of somewhere in the middle.
However, this won't let us malloc 52 new bytes even though
we potentially have 99 bytes left to use in the heap. The
reason is that when we try to do the allocation,
nano-malloc looks into the free list and sees a 51 byte
chunk to be used.
This is not big enough so nano-malloc decides to call
sbrk for _another_ 52 bytes which is not possible since
there is only 48 bytes left to ask for.
The solution for this problem is to check if the last
item in the free list is adjacent to sbrk(0). If it is,
as it is in this case, we can just ask sbrk for the
remainder of what is needed. In this case 1 byte.
NB! I have only tested the solution on our ST device.
Brian Inglis [Fri, 30 Apr 2021 13:19:20 +0000 (07:19 -0600)]
format_proc_swaps: ensure space between fields for clarity
page/swap space name >= 40 or size/used >= 8 leaves no space between fields;
ensure a space after name and add extra tabs after size and used fields;
output appears like Linux 5.8 after changes to mm/swapfile(swap_show);
proc-swaps-space-before.log:
==> /proc/swaps <==
Filename Type Size Used Priority
/mnt/c/pagefile.sys file 11567748292920 0
/mnt/d/pagefile.sys file 12582912205960 0
proc-swaps-space-after.log:
==> /proc/swaps <==
Filename Type Size Used Priority
/mnt/c/pagefile.sys file 11567748 241024 0
/mnt/d/pagefile.sys file 12582912 182928 0
Jon Turney [Tue, 27 Oct 2020 16:29:45 +0000 (16:29 +0000)]
Cygwin: CI configuration update
Install autoconf and automake, and run winsup/autogen.sh, and don't have
it silently ignore failures.
On AppVeyor:
- use latest VM image, to reduce time spent installing updates.
- run the testsuite, but ignore the result, as some tests don't work
correctly.
- hardcode the python-lxml and python-ply packages to install, so we get
ones for the right python.
- install texlive collections now needed to build documentation.
On github:
- Use a copr for cocom, since RPMSphere's package updates don't track
fedora:latest very efficently.
Cygwin: POSIX mq: avoid double calls to ipc_mutex_unlock
_mq_send as well as _mq_receive call ipc_mutex_unlock twice in case
of success, after having introduced __try/__except blocks.
Fixes: 3f3bd10104550 ("* Throughout, use __try/__except/__endtry blocks, rather than myfault handler.") Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Cygwin: POSIX mq: only allo priority up to MQ_PRIO_MAX - 1
POSIX requires that message priorities range from 0 (low) to
sysconf(_SC_MQ_PRIO_MAX) - 1 (high). Cygwin's mq_send erroneously
allowed a message priority of sysconf(_SC_MQ_PRIO_MAX). Fix it.
Jon Turney [Wed, 28 Apr 2021 09:46:02 +0000 (11:46 +0200)]
Cygwin: specify toollibdir toolincludedir in terms of tooldir
Specify toollibdir and toolincludedir in terms of tooldir, so the
install location is correct if tooldir is the default
($(exec_prefix)/$(target_alias)), or explicitly specified on the 'make'
command line.
Linux 5.12 Frozen Wasteland added features and changes:
add AMD 0x8000000a EDX:20 v_spec_ctrl virtual speculation control support
add Intel 0x00000007 ECX:24 bus_lock_detect bus lock detect debug exception
Jon Turney [Tue, 6 Oct 2020 15:11:54 +0000 (16:11 +0100)]
Cygwin: Use automake (v5)
v2:
* Include tzmap.h in BUILT_SOURCES
* Make per-file flags appear after user-supplied CXXFLAGS, so they can
override optimization level.
* Correct .o files used to define symbols exported by libm.a
* Drop gcrt0.o mistakenly included in libgmon.a
* Add missing line continuations in GMON_FILES value
v3:
* use per-file flags for .c compilation
* override C{XX,}FLAGS, as they are set on the command line by top-level make
v4:
* Drop -Wno-error=write-strings from path_testsuite CXXFLAGS
v5:
* Update for changes in master
- Add -fno-threadsafe-statics to CXX flags
- Add hypotl.cc
- Remove fenv.cc (in favour of newlib), add fenv.c stub
- Add proc.5 manpage rules
Ken Brown [Fri, 23 Apr 2021 22:17:57 +0000 (18:17 -0400)]
Cygwin: connect: implement resetting a connected DGRAM socket
Following POSIX and Linux, allow a connected DGRAM socket's connection
to be reset (so that the socket becomes unconnected). This is done by
calling connect and specifing an address whose family is AF_UNSPEC.
Ken Brown [Fri, 23 Apr 2021 18:40:07 +0000 (14:40 -0400)]
Cygwin: connect: set connect state for DGRAM sockets
When connect is called on a DGRAM socket, the call to Winsock's
connect can immediately return successfully rather than failing with
WSAEWOULDBLOCK. Set the connect state to "connected" in this case.
Previously the connect state remained "connect_pending" after the
successful connection.
- In commit bb93c6d7, the race issue was not completely fixed. In
the pseudo console inheritance, if the destination process to
which the ownership of pseudo console switches, is found but exits
before switching, the inheritance fails. Currently, this extremely
rarely happens. This patch fixes the issue.
Cygwin: skip native symlink check in Windows dir under WOW64
Commit 456c3a46386f added a workaround when handling paths with native
symlinks as inner path components. This patch introduced a problem for
paths handled by the WOW64 File System Redirector (FSR).
Fix this problem by not performing the new code from commit 456c3a46386f
for paths under the Windows directory. Only do this in WOW64.
Cygwin: path_conv: Try to handle native symlinks more sanely
For local paths, add a check if the inner path components contain native
symlinks or junctions. Compare the incoming path with the path returned
by NtQueryInformationFile(FileNameInformation). If they differ, there
must be at least one native symlink or junction in the path. If so,
treat the currently evaluated file as non-existant. This forces
path_conv::check to backtrack inner path components until we eliminated
all native symlinks or junctions and have a normalized path.
The simple newlib hypotl for real long double architectures is too
simple at this point. It's implemented as a real call to sqrtl(x^2+y^2).
This has a fatal tendency to overflow for big input numbers. Hypotl
isn't supposed to do that if the result would still be valid in range of
long double.
Given the complexity of implementing hypotl for various architectures,
we just take the hypotl function from Mingw-w64, which is in the public
domain.
Even though this hypotl is an architecture-independent implementation,
we can't use it for newlib yet, unfortunately, because it requires logbl
under the hood. Logbl is yet another function missing in newlib for
real long double architectures.
Corinna Vinschen [Wed, 24 Mar 2021 09:58:56 +0000 (10:58 +0100)]
fenv: drop Cygwin-specific implementation in favor of newlib code
Drop the Cygwin-specific fenv.cc and fenv.h file and use the equivalent
newlib functionality now, so we have at least one example of a user for
this new mechanism.
fenv.c: allow _feinitialise to be called from Cygwin startup code
fenv.h: add declarations for fegetprec and fesetprec for Cygwin only.
Fix a comment.
Corinna Vinschen [Wed, 24 Mar 2021 09:32:50 +0000 (10:32 +0100)]
Add build mechanism to share common header files between machines
So far the build mechanism in newlib only allowed to either define
machine-specific headers, or headers shared between all machines.
In some cases, architectures are sufficiently alike to share header
files between them, but not with other architectures. A good example
is ix86 vs. x86_64, which share certain traits with each other, but
not with other architectures.
Introduce a new configure variable called "shared_machine_dir". This
dir can then be used for headers shared between architectures.
Kito Cheng [Tue, 13 Apr 2021 09:33:03 +0000 (17:33 +0800)]
RISC-V: Using SYS_clock_gettime64 for rv32 libgloss.
- RISC-V 32 bits linux/glibc didn't provide gettimeofday anymore
after upstream, because RV32 didn't have backward compatible issue,
so RV32 only support 64 bits time related system call.
- So using clock_gettime64 call instead for rv32 libgloss.
An FD_CLOSE event sets a socket descriptor ready for writing.
This is incorrect if the FD_CLOSE is a result of shutdown(SHUT_RD).
Only set the socket descriptor ready for writing if the FD_CLOSE
is indicating an connection abort or reset error condition.
This requires to tweak fhandler_socket_wsock::evaluate_events.
FD_CLOSE in conjunction with FD_ACCEPT/FD_CONNECT special cases
a shutdown condition by setting an error code. This is correct
for accept/connect, but not for select. In this case, make sure
to return with an error code only if FD_CLOSE indicates a
connection error.
Cygwin: select: don't set ready for exception on socket shutdown
So far select wrongly sets the descriptor as ready for exception
when a shutdown occurs. This is entirely non-standard. Only set
this bit on an out-of-band event.
Cygwin: fhandler: Rename handles from XXX_cyg/XXX to XXX/XXX_nat.
- Currently, functions/variables regarding the handles for cygwin
apps are with "_cyg", and those of handles for non-cygwin apps
are without "_cyg", such as get_handle_cyg() and get_handle().
This patch renames these to the names without "_nat" and with
"_nat" respectively, such as get_handle() and get_handle_nat().
Cygwin: Treat Windows Store's "app execution aliases" as symbolic links
When the Windows Store version of Python is installed, so-called "app
execution aliases" are put into the `PATH`. These are reparse points
under the hood, with an undocumented format.
We do know a bit about this format, though, as per the excellent analysis:
https://www.tiraniddo.dev/2019/09/overview-of-windows-execution-aliases.html
The first 4 bytes is the reparse tag, in this case it's
0x8000001B which is documented in the Windows SDK as
IO_REPARSE_TAG_APPEXECLINK. Unfortunately there doesn't seem to
be a corresponding structure, but with a bit of reverse
engineering we can work out the format is as follows:
Cygwin: Allow executing Windows Store's "app execution aliases"
The Windows Store version of Python (and apparently other Windows Store
applications) install a special reparse point called "app execution
alias" into the user's `PATH`.
These applications can be executed without any problem, but they cannot
be read as if they were files. This trips up Cygwin's beautiful logic that
tries to determine whether we're about to execute a Cygwin executable or
not: instead of executing the application, it will fail, saying
"Permission denied".
Let's detect this situation (`NtOpenFile()` helpfully says that this
operation is not supported on this reparse point type), and simply skip
the logic: Windows Store apps are not Cygwin executables (and even if
they were, it is unlikely that they would come with a compatible
`cygwin1.dll` or `msys-2.0.dll`).
This fixes https://github.com/msys2/MSYS2-packages/issues/1943
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
- Currently, names of output pipes are "pty%d-to-master" and "pty%d-
to-master-cyg" and names of input pipes are "pty%d-to-slave" and
"pty%d-from-master". With this patch, these pipes are renamed to
"pty%d-to-master-nat", "pty%d-to-master", "pty%d-from-master-nat"
and "pty%d-from-master" respectively.
Cygwin: pty: Transfer input for native app only if the stdin is pcon.
- Currently, transfer input is triggered even if the stdin of native
app is not a pseudo console. With this patch it is triggered only
if the stdin is a pseudo console.
Cygwin: pty: Attach to stub process when non-cygwin app inherits pcon.
- If two non-cygwin apps are started simultaneously, attaching to
pseudo console sometimes fails. This is because the second app
trys to attach to the process not started yet. This patch avoids
the issue by attaching to the stub process rather than the other
non-cygwin app.
Cygwin: console, pty: Stop ignoring Ctrl-C by IGNBRK.
- Perhaps current code misunderstand meaning of the IGNBRK. As far
as I investigated, IGNBRK is concerned with break signal in serial
port but there is no evidence that it has effect to ignore Ctrl-C.
This patch stops ignoring Ctrl-C by IGNBRK for non-cygwin apps.
It turned out that this patch has undesired side effects. To wit, if a
newer, post-uname_x executable was linked against or loading an older,
pre-uname_x DLL, and this DLL called uname. This call would jump into
the old uname with the old struct utsname as parameter, but given the
newer executable it would get redirected to uname_x. uname_x in turn
would overwrite stack memory it should leave well alone, given it
expects the newer, larger struct utsname.
For the entire discussion see the thread starting at
https://cygwin.com/pipermail/cygwin/2021-February/247870.html
and continuing in March at
https://cygwin.com/pipermail/cygwin/2021-March/247930.html
For a description where we're coming from, see
https://cygwin.com/pipermail/cygwin/2021-March/247959.html
While we *could* make the scenario in question work by patching dlsym,
the problem would actually be the same, just for dynamic loading. In
the end, we're missing the information, which Cygwin version has been
used when building DLLs.
Cygwin: pty: Fix a race issue in startup of pseudo console.
- If two non-cygwin apps are started simultaneously and this is the
first execution of non-cygwin apps in the pty, these occasionally
hang up. The cause is the race issue between term_has_pcon_cap(),
reset_switch_to_pcon() and setup_pseudoconsole(). This patch fixes
the issue.
Ken Brown [Thu, 25 Feb 2021 12:54:10 +0000 (07:54 -0500)]
Cygwin: simplify linkat with AT_EMPTY_PATH
linkat(olddirfd, oldpath, oldname, newdirfd, newname, AT_EMPTY_PATH)
is supposed to create a link to the file referenced by olddirfd if
oldname is the empty string. Currently this is done via the /proc
filesystem by converting the call to
Ken Brown [Wed, 24 Feb 2021 15:43:15 +0000 (10:43 -0500)]
Cygwin: fix linkat(2) on sockets that are not socket files
If linkat(2) is called with AT_EMPTY_PATH on an AF_LOCAL or
AF_UNIX socket that is not a socket file, the current code calls
fhandler_disk_file::link in most cases. The latter expects to be
operating on a disk file and uses the socket's io_handle, which
is not a file handle.
Fix this by calling fhandler_disk_file::link only if the
fhandler_socket object is a file (determined by testing
dev().isfs()).
Also fix the case of a socket file opened with O_PATH by setting
the fhandler_disk_file's io_handle.
Ken Brown [Mon, 22 Feb 2021 15:13:09 +0000 (10:13 -0500)]
Cygwin: fix facl on sockets that are not socket files
If facl(2) is called on an AF_LOCAL or AF_UNIX socket that is not a
socket file, the current code calls fhandler_disk_file::facl in most
cases. The latter expects to be operating on a disk file and uses the
socket's io_handle, which is not a file handle.
Fix this by calling fhandler_disk_file::facl only if the
fhandler_socket object is a file (determined by testing dev().isfs()).
Ken Brown [Mon, 22 Feb 2021 14:50:34 +0000 (09:50 -0500)]
Cygwin: fix fchown on sockets that are not socket files
If fchown(2) is called on an AF_LOCAL or AF_UNIX socket that is not a
socket file, the current code calls fhandler_disk_file::fchown in most
cases. The latter expects to be operating on a disk file and uses the
socket's io_handle, which is not a file handle.
Fix this by calling fhandler_disk_file::fchown only if the
fhandler_socket object is a file (determined by testing dev().isfs()).
Ken Brown [Mon, 22 Feb 2021 14:34:36 +0000 (09:34 -0500)]
Cygwin: fix fchmod on sockets that are not socket files
If fchmod(2) is called on an AF_LOCAL or AF_UNIX socket that is not a
socket file, the current code calls fhandler_disk_file::fchmod in most
cases. The latter expects to be operating on a disk file and uses the
socket's io_handle, which is not a file handle.
Fix this by calling fhandler_disk_file::fchmod only if the
fhandler_socket object is a file (determined by testing dev().isfs()).
Ken Brown [Mon, 22 Feb 2021 14:21:00 +0000 (09:21 -0500)]
Cygwin: fix fstatvfs on sockets that are not socket files
If fstatvfs(2) is called on an AF_LOCAL or AF_UNIX socket that is not
a socket file, the current code calls fhandler_disk_file::fstatvfs in
most cases. The latter expects to be operating on a disk file and
uses the socket's io_handle, which is not a file handle.
Fix this by calling fhandler_disk_file::fstatvfs only if the
fhandler_socket object is a socket file (determined by testing
dev().isfs()).
Ken Brown [Mon, 22 Feb 2021 14:08:04 +0000 (09:08 -0500)]
Cygwin: fix fstat on sockets that are not socket files
If fstat(2) is called on an AF_LOCAL or AF_UNIX socket that is not a
socket file, the current code calls fstat_fs. The latter expects to
be operating on a disk file and uses the socket's io_handle, which is
not a file handle.
Fix this by calling fstat_fs only if the fhandler_socket object is a
file (determined by testing dev().isfs()).
Ken Brown [Tue, 23 Feb 2021 22:07:00 +0000 (17:07 -0500)]
Cygwin: facl: fail with EBADF on files opened with O_PATH
This is in the spirit of the Linux requirement that file operations
like fchmod(2), fchown(2), and fgetxattr(2) fail with EBADF on files
opened with O_PATH.
Ken Brown [Tue, 23 Feb 2021 16:48:46 +0000 (11:48 -0500)]
Cygwin: AF_UNIX: allow opening with the O_PATH flag
This was done for the fhandler_socket_local class in commits 3a2191653a, 141437d374, and 477121317d, but the fhandler_socket_unix
class was overlooked.
Kito Cheng [Tue, 23 Feb 2021 08:14:36 +0000 (16:14 +0800)]
Bump config.guess and config.sub
Hi:
RISC-V has added big-endian support recently, which require config.*
stuff update, and we'll send further patch for fix big-endian build,
so I believe this fundamental change should upstream first.
Cygwin: pty: Fix segfault caused when tcflush() is called.
- After commit 253352e796ff9ec9a447e5375f5bc3e2b92b5293, mc (midnight
commander) crashes with segfault if the shell is bash. This is due
to NULL pointer access in read(). This patch fixes the issue.
Addresses::
https://cygwin.com/pipermail/cygwin/2021-February/247870.html
Ken Brown [Tue, 9 Feb 2021 17:11:02 +0000 (12:11 -0500)]
Cygwin: FIFO: temporarily keep a conv_handle in syscalls.cc:open
When a FIFO is opened, syscalls.cc:open always calls fstat on the
newly-created fhandler_fifo. This results from a call to
device_access_denied.
To speed-up this fstat call, and therefore the open(2) call, use
PC_KEEP_HANDLE when the fhandler is created. The resulting
conv_handle is retained until after the fstat call if the fhandler is
a FIFO; otherwise, it is closed immediately.
Ken Brown [Thu, 11 Feb 2021 02:15:20 +0000 (21:15 -0500)]
Cygwin: fstat_helper: always use handle in call to get_file_attribute
Previously, the call to get_file_attribute for FIFOs set the first
argument to NULL instead of the handle h returned by get_stat_handle,
thereby forcing the file to be opened for fetching the security
descriptor in get_file_sd(). This was done because h might have been
a pipe handle rather than a file handle, and its permissions would not
necessarily reflect those of the file.
That situation can no longer occur with the new fhandler_fifo::fstat
introduced in the previous commit.
Ken Brown [Thu, 18 Feb 2021 15:18:41 +0000 (10:18 -0500)]
Cygwin: define fhandler_fifo::fstat
Previously fstat on a FIFO would call fhandler_base::fstat.
The latter is not appropriate if fhandler_fifo::open has already been
called (and O_PATH is not set), for the following reason. If a FIFO
has been opened as a writer or duplexer, then it has an io_handle that
is a pipe handle rather than a file handle. fhandler_base::fstat will
use this handle and potentially return incorrect results. If the FIFO
has been opened as a reader, then it has no io_handle, and a call to
fhandler_base::fstat will lead to a call to fhandler_base::open.
Opening the fhandler a second time can change it in undesired ways;
for example, it can modify the flags and status_flags.
The new fhandler_fifo::fstat avoids these problems by creating an
fhandler_disk_file and calling its fstat method in case
fhandler_fifo::open has already been called and O_PATH is not set.
This scenario circumventing the mount point handling which is automated
in terms of /, depending on the path returned from GetModuleFileNameW
for the Cygwin DLL. When calling D:\cygwin64\bin\bash the dir returned
from GetModuleFileNameW is D:\cygwin64\bin, thus root is D:\cygwin64.
However, junctions are treated as symlinks in Cygwin which explains why
the path gets converted to a cygdrive path.
Fix this by calling GetFinalPathNameByHandleW on the result from
GetModuleFileNameW to get the correct root path, even if accessed via
a junction point.
Corinna Vinschen [Fri, 19 Feb 2021 17:12:37 +0000 (18:12 +0100)]
Cygwin: default to O_BINARY in fhandler_base::reset_to_open_binmode()
This only affects the very seldom bordercase of apps calling setmode(fd,
0) on fhandlers not calling fhandler_base::set_open_status(). All
fhandlers not calling set_open_status() are binary mode only, but the
way reset_to_open_binmode worked, calling setmode(fd, 0) would have
"reset" their open flags to O_TEXT accidentally.
- If ENABLE_LINE_INPUT is set, Ctrl-S is handled by Windows if the
OS is Windows 7. This conflicts with Ctrl-S handling in cygwin
console code. This patch unsets ENABLE_LINE_INPUT flag in cygwin
and set it when native app is executed.
- If ENABLE_VIRTUAL_TERMINAL_INPUT is not set, changing window height
does not generate WINDOW_BUFFER_SIZE_EVENT. This happens if console
is in the legacy mode. Therefore, with this patch, the windows size
is checked every time in cons_master_thread() if the cosole is in
the legacy mode.
Brian Inglis [Wed, 17 Feb 2021 16:28:36 +0000 (09:28 -0700)]
cpuinfo: add AVX features; move SME, SEV/_ES features
Linux 5.11 💕 Valentine's Day Edition 💕 added features and changes:
add Intel 0x00000007 EDX:23 avx512_fp16 and 0x00000007:1 EAX:4 avx_vnni;
group scattered AMD 0x8000001f EAX Secure Mem/Encrypted Virt features at end:
0 sme, 1 sev, 3 sev_es (more to come not yet displayed)
Cygwin: console: Introduce new thread which handles input signal.
- Currently, Ctrl-Z, Ctrl-\ and SIGWINCH does not work in console
if the process does not call read() or select(). This is because
these are processed in process_input_message() which is called
from read() or select(). This is a long standing issue of console.
Addresses:
https://cygwin.com/pipermail/cygwin/2020-May/244898.html
https://cygwin.com/pipermail/cygwin/2021-February/247779.html
With this patch, new thread which handles only input signals is
introduced so that Crtl-Z, etc. work without calling read() or
select(). Ctrl-S and Ctrl-Q are also handled in this thread.
git://sourceware.org / newlib-cygwin.git / log