Commit Graph

19453 Commits

Author SHA1 Message Date
Jon Turney c2d6e6f7f6
doc: Various fixes to makedocbook for python3.8
Also update shebang to explicitly use python3, since python2 is EOL and
(per PEP 0394) 'python' may not exist at all.
2020-08-24 17:36:10 +01:00
Ken Brown c1f177d6a9 Cygwin: cwdstuff::get: clean up debug_printf output
Set errno = 0 at the beginning so that the debug_printf call at the
end doesn't report a nonzero errno left over from some other function
call.
2020-08-23 18:50:00 -04:00
Takashi Yano bb42852062 Cygwin: pty: Implement new pseudo console support.
- In this implementation, pseudo console is created for each native
  console app. Advantages and disadvantages of this implementation
  over the previous implementation are as follows.

  Advantages:
  1) No performance degradation in pty output for cygwin process.
      https://cygwin.com/pipermail/cygwin/2020-February/243858.html
  2) Free from the problem caused by difference of behaviour of control
     sequences between real terminal and pseudo console.
      https://cygwin.com/pipermail/cygwin/2019-December/243281.html
      https://cygwin.com/pipermail/cygwin/2020-February/243855.html
  3) Free from the problem in cgdb and emacs gud.
      https://cygwin.com/pipermail/cygwin/2020-January/243601.html
      https://cygwin.com/pipermail/cygwin/2020-March/244146.html
  4) Redrawing screen on executing native console apps is not necessary.
  5) cygwin-console-helper is not necessary for the pseudo console
     support.
  6) The codes for pseudo console support are much simpler than that
     of the previous one.

  Disadvantages:
  1) The cygwin program which calls console API directly does not work.
  2) The apps which use console API cannot be debugged with gdb. This
     is because pseudo console is not activated since gdb uses
     CreateProcess() rather than exec(). Even with this limitation,
     attaching gdb to native apps, in which pseudo console is already
     activated, works.
  3) Typeahead key inputs are discarded while native console app is
     executed. Simirally, typeahead key inputs while cygwin app is
     executed are not inherited to native console app.
  4) Code page cannot be changed by chcp.com. Acctually, chcp works
     itself and changes code page of its own pseudo console.  However,
     since pseudo console is recreated for another process, it cannot
     inherit the code page.
  5) system_printf() does not work after stderr is closed. (Same with
     cygwin 3.0.7)
  6) Startup time of native console apps is about 3 times slower than
     previous implemenation.
  7) Pseudo console cannot be activated if it is already activated for
     another process on same pty.
2020-08-22 13:43:49 +02:00
Corinna Vinschen b9261fa1d9 Cygwin: bump version to 3.2.0
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2020-08-22 13:43:46 +02:00
Ken Brown a93a85a1ff Cygwin: strace: ignore GCC exceptions
Any C++ app that calls 'throw' on 64-bit Cygwin results in an
exception of type STATUS_GCC_THROW (0x20474343) generated by the C++
runtime.  Don't pollute the strace output by printing information
about this and other GCC exceptions.
2020-08-20 10:48:48 -04:00
Ken Brown 14c0a4c67d Cygwin: add header defining GCC exception codes
Include it in exceptions.cc instead of defining the exception codes
there.
2020-08-20 10:46:23 -04:00
Ken Brown 74cf7dabcb Cygwin: main exception handler (64-bit): continue GCC exceptions
This is necessary in order to be consistent with the following comment
in the definition of _Unwind_RaiseException() in the GCC source file
libgcc/unwind-seh.c:

     The exception handler installed in crt0 will continue any GCC
     exception that reaches there (and isn't marked non-continuable).

Previously we failed to do this and, as a consequence, the C++ runtime
didn't call std::terminate after an unhandled exception.

This fixes the problem reported here:

  https://cygwin.com/pipermail/cygwin/2019-October/242795.html
  https://sourceware.org/pipermail/cygwin/2020-August/245897.html
2020-08-18 07:04:25 -04:00
Keith Packard via Newlib 8a7ec55c53 libm/stdlib: Realloc when shrinking by 2* or more
This reduces memory usage when reallocating objects much smaller.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-17 11:43:55 +02:00
Keith Packard via Newlib ce4044adee libm/stdlib: don't read past source in nano_realloc
Save the computed block size and use it to avoid reading past
the end of the source block.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-17 11:43:55 +02:00
Takashi Yano via Cygwin-patches 70d02aaca6 Cygwin: pty: Change the timing of set_locale() call again.
- After commit 095972ce5b, charset
  conversion in mintty is broken if charset is set to other than
  UTF-8. This seems to be caused because mintty does not set locale
  yet at fork() call. This patch changes the timing of set_locale()
  call again to avoid this issue.
2020-08-17 11:12:59 +02:00
Takashi Yano via Cygwin-patches 095972ce5b Cygwin: pty: Change the timing of setup_locale() call.
- If native app is exec()'ed in a new pty, setup_locale() loses the
  chance to be called. For example, with "mintty -e cmd", charset
  conversion does not work as expected. This patch fixes the issue.
2020-08-13 10:20:53 +02:00
Craig Blackmore ab215e3dd1 libc/stdlib: Fix build failure in nano_calloc
commit 588a5e1dde added a non-reentrant
call to nano_malloc which causes a build failure if INTERNAL_NEWLIB is
defined.

Here is a snippet of the error:

In file included from .../newlib/newlib/libc/stdlib/nano-mallocr.c:38:
.../newlib/newlib/libc/include/malloc.h:42:25: note: expected 'struct _reent *' but argument is of type 'ptrdiff_t' {aka 'int'}
   42 | extern void *_malloc_r (struct _reent *, size_t);
      |                         ^~~~~~~~~~~~~~~
.../newlib/newlib/libc/stdlib/nano-mallocr.c:67:22: error: too few arguments to function '_malloc_r'
   67 | #define nano_malloc  _malloc_r
      |                      ^~~~~~~~~
.../newlib/newlib/libc/stdlib/nano-mallocr.c:456:11: note: in expansion of macro 'nano_malloc'
  456 |     mem = nano_malloc(bytes);
      |           ^~~~~~~~~~~
In file included from .../newlib/newlib/libc/stdlib/nano-mallocr.c:38:
.../newlib/newlib/libc/include/malloc.h:42:14: note: declared here
   42 | extern void *_malloc_r (struct _reent *, size_t);
      |              ^~~~~~~~~
.../newlib/newlib/libc/stdlib/nano-mallocr.c:43: warning: "assert" redefined
   43 | #define assert(x) ((void)0)
      |

This patch adds a missing RCALL to the args when calling nano_malloc
from nano_calloc, so that if the call is reentrant, reent_ptr is passed
as the first argument.

The variable `bytes` (also added in 588a5e1d) has been changed from a
`ptrdiff_t` to `malloc_size_t` as it does not need to be signed. It is
used to store the product of two unsigned malloc_size_t variables and
then iff there was no overflow is it passed to malloc and memset which
both expect size_t which is unsigned.

Signed-off-by: Craig Blackmore <craig.blackmore@embecosm.com>
2020-08-13 09:59:45 +02:00
Keith Packard via Newlib 588a5e1dde libc/stdlib: Use __builtin_mul_overflow for reallocarray and calloc
This built-in function (available in both gcc and clang) is more
efficient and generates shorter code than open-coding the test.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-12 10:09:56 +02:00
Keith Packard via Newlib bafd65f2fb libm/machine/riscv: Add custom fma/sqrt functions when supported [v2]
Check for HW FMA and SQRT support and use those instructions in place
of software implementations.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-12 09:52:19 +02:00
Takashi Yano f14d123ac6 Cygwin: pty: Add a workaround for issue of starting a lot of mintty.
- If a lot of mintty are started in a short time from a mintty, some
  of them hang with empty screen, crash immediately or hang on exiting
  mintty. The following report seems to be related to this issue.
    https://cygwin.com/pipermail/cygwin/2020-August/245751.html
  The cause is not clear at all, but this patch seems to solve the
  issue.
2020-08-11 12:19:33 +02:00
Keith Packard via Newlib a44bc679a4 libm/machine/arm: Add optimized fmaf and fma when available
When HAVE_FAST_FMAF is set, use the vfma.f32 instruction, when
HAVE_FAST_FMA is set, use the vfma.f64 instruction.

Usually the compiler built-ins will already have inlined these
instructions, but provide these symbols for cases where that doesn't
work instead of falling back to the (inaccurate) common code versions.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-10 21:04:12 +02:00
Keith Packard via Newlib 0c1989070e libm: Detect fast fmaf support
Anything with fast FMA is assumed to have fast FMAF, along with
32-bit arms that advertise 32-bit FP support and __ARM_FEATURE_FMA

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-10 21:01:46 +02:00
Keith Packard via Newlib 432b331c79 libm: ARM without HW double does not have fast FMA
32-bit ARM processors with HW float (but not HW double) may define
__ARM_FEATURE_FMA, but that only means they have fast FMA for 32-bit
floats.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-10 21:01:46 +02:00
Keith Packard via Newlib 73b02710ec libm/math: ensure that expf(-huge) sets FE_UNDERFLOW exception
It was calling __math_uflow(0) instead of __math_uflowf(0), which
resulted in no exception being set on machines with exception support
for float but not double.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-10 10:31:36 +02:00
Ken Brown 225d376b70 Cygwin: cygserver: build with -Wimplicit-fallthrough=5
Define the pseudo keyword 'fallthrough' in woutsup.h to support this.
2020-08-07 13:40:13 -04:00
Jon Turney 1be41b802a
Cygwin: Use documented QueryWorkingSetEx() in dumper
In dumper, use the documented QueryWorkingSetEx(), rather than the
undocumented NtQueryVirtualMemory() with MemoryWorkingSetExInformation.
2020-08-07 15:08:30 +01:00
Jozef Lawrynowicz e3f29b2472 MSP430: Increase the amount of main memory available in sim ld scripts
The main memory region of the GDB simulator ends at address 0xFFBF,
but the simulator linker scripts do not make full use of this available
memory.

>From 61f3d212741acee583e21ff2c2808775584ecad6 Mon Sep 17 00:00:00 2001
From: Jozef Lawrynowicz <jozef.l@mittosystems.com>
Date: Mon, 3 Aug 2020 19:38:23 +0100
Subject: [PATCH 2/2] MSP430: Increase the amount of main memory available in
 sim ld scripts

The main memory region of the GDB simulator ends at address 0xFFBF,
but the simulator linker scripts do not make full use of this available
memory.
2020-08-07 15:16:43 +02:00
Jozef Lawrynowicz 748970c833 MSP430: Word align __*_array_start symbols in sim linker scripts
__{preinit,init,fini}_array_start symbols must be word aligned in
linker scripts. If the section preceding the __*_array_start symbol
has an odd size, then a NULL byte will be present between the start
symbol and the .*_array section itself, when the section gets
automatically word-aligned.

This results in a branch to an invalid address when the CRT startup
code tries to run through the functions listed in the array sections.

>From de115144d05ecbaa82c9c737cc261715ca4b7d67 Mon Sep 17 00:00:00 2001
From: Jozef Lawrynowicz <jozef.l@mittosystems.com>
Date: Mon, 3 Aug 2020 19:09:46 +0100
Subject: [PATCH 1/2] MSP430: Word align __*_array_start symbols in sim linker
 scripts

__{preinit,init,fini}_array_start symbols must be word aligned in
linker scripts. If the section preceding the __*_array_start symbol
has an odd size, then a NULL byte will be present between the start
symbol and the .*_array section itself, when the section gets
automatically word-aligned.

This results in a branch to an invalid address when the CRT startup
code tries to run through the functions listed in the array sections.
2020-08-07 15:16:43 +02:00
Corinna Vinschen c8dc3fa0ba Cygwin: cygserver: build with -Wimplicit-fallthrough=4 -Werror
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2020-08-07 15:09:56 +02:00
Corinna Vinschen acfed1364a Cygwin: utils: build with -Wimplicit-fallthrough=4 -Werror
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2020-08-07 15:09:56 +02:00
Corinna Vinschen e7fca6f867 Cygwin: utils: convert usage() to proper noreturn function throughout
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2020-08-07 15:09:56 +02:00
Corinna Vinschen 9beb7b9771 Cygwin: utils: cygcheck: avoid GCC warning concatenating strings
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2020-08-07 15:09:48 +02:00
Corinna Vinschen 238c2b14ca Cygwin: utils: refresh tzmap
- update path to Unicode windowsZones.xml file
- drop Windows XP considerations
- regenerate tzmap.h

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2020-08-07 15:09:39 +02:00
Keith Packard via Newlib c3ce8405c1 libm: Control errno support with _IEEE_LIBM configuration parameter
This removes the run-time configuration of errno support present in
portions of the math library and unifies all of the compile-time errno
configuration under a single parameter so that the whole library
is consistent.

The run-time support provided by _LIB_VERSION is no longer present in
the public API, although it is still used internally to disable errno
setting in some functions. Now that it is a constant, the compiler should
remove that code when errno is not supported.

This removes s_lib_ver.c as _LIB_VERSION is no longer variable.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-05 22:23:02 +02:00
Keith Packard via Newlib e108d04432 libm/math: Don't modify __ieee754_pow return values in pow
The __ieee754 functions already return the right value in exception
cases, so don't modify those. Setting the library to _POSIX_/_IEEE_
mode now only affects whether errno is modified.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-05 22:16:31 +02:00
Keith Packard via Newlib 98a4f8de47 libm/math: Set errno to ERANGE for pow(0, -y)
POSIX says that the errno for pow(0, -y) should be ERANGE instead of
EDOM.

https://pubs.opengroup.org/onlinepubs/9699919799/functions/pow.html

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-05 22:16:31 +02:00
Keith Packard via Newlib 2eafcc78df libm/math: Make yx functions set errno=ERANGE for x=0
The y0, y1 and yn functions need separate conditions when x is zero as
that returns ERANGE instead of EDOM.

Also stop adjusting the return value from the __ieee754_y* functions
as that is already correct and we were just breaking it.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-05 22:16:31 +02:00
Keith Packard via Newlib 905aa4c013 libm/math: set errno to ERANGE at gamma poles
For POSIX, gamma(i) (i non-positive integer) should set errno to
ERANGE instead of EDOM.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-05 22:16:31 +02:00
Corinna Vinschen 50ad198085 Cygwin: Add 'fallthrough' pseudo keyword for switch/case use
This patch has been inspired by the Linux kernel patch

  294f69e662d1 compiler_attributes.h: Add 'fallthrough' pseudo keyword for switch/case use

written by Joe Perches <joe AT perches DOT com> based on an idea from
Dan Carpenter <dan DOT carpenter AT oracle DOT com>.  The following text
is from the original log message:

Reserve the pseudo keyword 'fallthrough' for the ability to convert the
various case block /* fallthrough */ style comments to appear to be an
actual reserved word with the same gcc case block missing fallthrough
warning capability.

All switch/case blocks now should end in one of:

	break;
	fallthrough;
	goto <label>;
	return [expression];
	continue;

In C mode, GCC supports the __fallthrough__ attribute since 7.1,
the same time the warning and the comment parsing were introduced.

Cygwin-only: add an explicit -Wimplicit-fallthrough=5 to the build
flags.
2020-08-05 21:58:22 +02:00
Corinna Vinschen 5898a044c3 Cygwin: Fix missing breaks in switch statement
Two switch statements in sysconf() and
fhandler_fifo::take_ownership were missing breaks.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2020-08-05 21:46:53 +02:00
Keith Packard via Newlib 45efe659b8 libm: Set math_errhandling to match library and hardware [v2]
math_errhandling is specified to contain two bits of information:

 1. MATH_ERRNO     -- Set when the library sets errno
 2. MATH_ERREXCEPT -- Set when math operations report exceptions

MATH_ERRNO should match whether the original math code is compiled in
_IEEE_LIBM mode and the new math code has WANT_ERRNO == 1.

MATH_ERREXCEPT should match whether the underlying hardware has
exception support. This patch adds configurations of this value for
RISC-V, ARM, Aarch64, x86 and x86_64 when using HW float.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-04 19:30:45 +02:00
Keith Packard via Newlib bb166cfc3e libm/common: Set WANT_ERRNO based on _IEEE_LIBM value
_IEEE_LIBM is the configuration value which controls whether the
original libm functions modify errno. Use that in the new math code as
well so that the resulting library is internally consistent.

Signed-off-by: Keith Packard <keithp@keithp.com>
2020-08-04 19:30:45 +02:00
Ken Brown 4f5b52ffe7 Cygwin: FIFO: add a third pass to raw_read
Currently raw_read makes two passes through the list of clients.  On
the first pass it tries to read from the client from which it last
read successfully.  On the second pass it tries to read from all
connected clients.

Add a new pass in between these two, in which raw_read tries to read
from all clients that are in the fc_input_avail case.  This should be
more efficient in case select was previously called and detected input
available.

Slightly tweak the first pass.  If a client is marked as having the
last successful read but reading from it now finds no input, don't
unmark it unless we successfully read from a different client on one
of the later passes.
2020-08-04 08:15:19 -04:00
Ken Brown 55b93b27d6 Cygwin: FIFO: fix indentation 2020-08-04 08:15:19 -04:00
Ken Brown 0fda55133a Cygwin: FIFO: synchronize the fifo_reader and fifosel threads
The fifo_reader thread function and the function select.cc:peek_fifo()
can both change the state of a fifo_client_handler.  These changes are
made under fifo_client_lock, so there is no race, but the changes can
still be incompatible.

Add code to make sure that only one of these functions can change the
state from its initial fc_listening state.  Whichever function does
this calls the fhandler_fifo::record_connection method, which is now
public so that peek_fifo can call it.

Slightly modify that method to make it suitable for being called by
peek_fifo.

Make a few other small changes to the fifo_reader thread function to
change how it deals with the STATUS_PIPE_CLOSING value that can
(rarely) be returned by NtFsControlFile.

Add commentary to fhandler_fifo.cc to explain fifo_client connect
states and where they can be changed.
2020-08-04 08:15:19 -04:00
Ken Brown 251624a352 Cygwin: FIFO: don't read from pipes that are closing
Don't try to read from fifo_client_handlers that are in the fc_closing
state.  Experiments have shown that this always yields
STATUS_PIPE_BROKEN, so it just wastes a Windows system call.

Re-order the values in enum fifo_client_connect_state to reflect the
new status of fc_closing.
2020-08-04 08:15:19 -04:00
Ken Brown 289af73a89 Cygwin: FIFO: reorganize some fifo_client_handler methods
Rename the existing set_state() to query_and_set_state() to reflect
what it really does.  (It queries the O/S for the pipe state.)  Add a
new set_state() method, which is a standard setter, and a
corresponding getter get_state().
2020-08-04 08:15:19 -04:00
Ken Brown 6ed067a0ae Cygwin: FIFO: add a timeout to take_ownership
fhandler_fifo::take_ownership() is called from select.cc::peek_fifo
and fhandler_fifo::raw_read and could potentially block indefinitely
if something goes wrong.  This is always undesirable in peek_fifo, and
it is undesirable in a nonblocking read.  Fix this by adding a timeout
parameter to take_ownership.

Arbitrarily use a 1 ms timeout in peek_fifo and a 10 ms timeout in
raw_read.  These numbers may have to be tweaked based on experience.

Replace the call to cygwait in take_ownership by a call to WFSO.
There's no need to allow interruption now that we have a timeout.
2020-08-04 08:15:19 -04:00
Ken Brown 6acce025d0 Cygwin: FIFO: fix timing issue with owner change
fhandler_fifo::take_ownership() tacitly assumes that the current
owner's fifo_reader_thread will be woken up from WFMO when
update_needed_evt is signaled.  But it's possible that the the current
owner's fifo_reader_thread is at the beginning of its main loop rather
than in its WFMO call when that event is signaled.

In this case the owner will never see that the event has been
signaled, and it will never update the shared fifo_client_handlers.
The reader that wants to take ownership will then spin its wheels
forever.

Fix this by having the current owner call update_shared_handlers at
the beginning of its loop, if necessary.
2020-08-04 08:02:07 -04:00
Ken Brown e319fd0e62 Cygwin: FIFO: lock fixes
Add some missing locks and remove one extra unlock.  Clarify for some
functions whether caller or callee acquires lock, and add appropriate
comments.
2020-08-04 07:57:45 -04:00
Brian Inglis cb7fba2f3e fhandler_proc.cc(format_proc_cpuinfo): use _small_sprintf %X for microcode
microcode is unsigned long long, printed by _small_sprintf using %x;
Cygwin32 used last 4 bytes of microcode for next field MHz, printing 0;
use correct _small_sprintf format %X to print microcode, producing
correct MHz value under Cygwin32
2020-08-04 10:10:40 +02:00
Brian Inglis 4ecc804d54 fhandler_proc.cc(format_proc_cpuinfo): add SERIALIZE instruction flag
CPUID 7:0 EDX[14] serialize added in linux-next 5.8 by Ricardo Neri-Calderon:
The Intel architecture defines a set of Serializing Instructions (a
detailed definition can be found in Vol.3 Section 8.3 of the Intel "main"
manual, SDM). However, these instructions do more than what is required,
have side effects and/or may be rather invasive. Furthermore, some of
these instructions are only available in kernel mode or may cause VMExits.
Thus, software using these instructions only to serialize execution (as
defined in the manual) must handle the undesired side effects.

As indicated in the name, SERIALIZE is a new Intel architecture
Serializing Instruction. Crucially, it does not have any of the mentioned
side effects. Also, it does not cause VMExit and can be used in user mode.

This new instruction is currently documented in the latest "extensions"
manual (ISE). It will appear in the "main" manual in the future.

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/arch/x86/include/asm/cpufeatures.h?id=85b23fbc7d88f8c6e3951721802d7845bc39663d
2020-08-04 10:10:40 +02:00
Keith Packard 12ad9a46df libm/math: Use __math_xflow in obsolete math code [v2]
C compilers may fold const values at compile time, so expressions
which try to elicit underflow/overflow by performing simple
arithemetic on suitable values will not generate the required
exceptions.

Work around this by replacing code which does these arithmetic
operations with calls to the existing __math_xflow functions that are
designed to do this correctly.

Signed-off-by: Keith Packard <keithp@keithp.com>

----

v2:
	libm/math: Pass sign to __math_xflow instead of muliplying result
2020-08-03 13:29:27 +02:00
Corinna Vinschen 5717262b8e select.h: update FD macros to latest FreeBSD, fix type conversion warning
Compiling

#include <sys/select.h>
void f(int X)
{
  fd_set set;
  FD_ZERO(&set);
  FD_SET(X,&set);
  FD_CLR(X+1,&set);
  (void)FD_ISSET(X+2,&set);
}

results in plenty of gcc warnings when compiled with
-Wconversion -Wsign-conversion:

  fds.c:7:2: warning: conversion to ‘long unsigned int’ from ‘int’ may
    FD_SET(X,&set);
    ^~~~~~
  [...]

The unsigned NFDBITS macro combined with the signed 1L constant
are causing lots of implicit signed/unsigned type conversions.

Fix this by updating the FD_* macro code to the latest from FreeBSD
and adding an (int) cast to _NFDBITS.

As a side-effect, this fixes the visibility of NFDBITS and
fds_bits (only if __BSD_VISIBLE).

This also eliminates the old, outdated fd_set workaround.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2020-08-03 12:41:45 +02:00
Corinna Vinschen 3fbfcd11fb Cygwin: posix_spawn: add Cygwin-specific code fixing process synchronisation
Newlib's posix_spawn has been taken from FreeBSD.  The code relies on
BSD-specific behaviour of vfork, namely the fact that vfork blocks
the parent until the child exits or calls execve as well as the fact
that the child shares parent memory in non-COW mode.

This behaviour can't be emulated by Cygwin.  Cygwin's vfork is
equivalent to fork.  This is POSIX-compliant, but it's lacking BSD's
vfork ingrained synchronization of the parent to wait for the child
calling execve, or the chance to just write a variable and the parent
will see the result.

So this requires a Cygwin-specific solution.  The core function of
posix_spawn, called do_posix_spawn is now implemented twice, once using
the BSD method, and once for Cygwin using Windows synchronization under
the hood waiting for the child to call execve and signalling errors
upstream.  The Windows specifics are hidden inside Cygwin, so newlib
only calls internal Cygwin functions.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2020-08-03 12:41:44 +02:00