dougm [Tue, 23 Jun 2020 20:02:55 +0000 (20:02 +0000)]
Define RB_SET_PARENT to do all assignments
to rb parent pointers. Define RB_SWAP_CHILD to replace the child of a parent
with its twin, and use it in 4 places. Use RB_SET in rb_link_node to remove the
only linuxkpi reference to color, and then drop color- and parent-related
definitions that are defined and used only in rbtree.h.
This is intended to be entirely cosmetic, with no impact on program
behavior, and leave RB_PARENT and RB_SET_PARENT as the only ways to
read and write rb parent pointers.
dougm [Sat, 20 Jun 2020 20:25:39 +0000 (20:25 +0000)]
In concluding RB_REMOVE_COLOR, in the case when
the sibling of the root of the too-short tree is black and at least one of the
children of that sibling is red, either one or two rotations finish the
rebalancing. In the case when both of the children are red, the current
implementation uses two rotations where only one is necessary. This change
removes that extra rotation, and in that case also removes a needless
black-to-red-to-black recoloring.
dougm [Sat, 13 Jun 2020 01:54:09 +0000 (01:54 +0000)]
Linuxkpi uses the rb-tree structures
without using their interfaces, making them break when the representation
changes. Revert changes that eliminated the color field from rb-trees, leaving
everything as it was before.
dougm [Tue, 9 Jun 2020 20:19:11 +0000 (20:19 +0000)]
To reduce the size of an rb_node, drop the color
field. Set the least significant bit in the pointer to the node from its parent
to indicate that the node is red. Have the tree rotation macros leave the
old-parent/new-child node red and the new-parent/old-child node black.
This change makes RB_LEFT and RB_RIGHT no longer assignable, and
RB_COLOR no longer defined. Any code that modifies the tree or
examines a node color would have to be modified after this change.
dougm [Sat, 30 May 2020 01:48:12 +0000 (01:48 +0000)]
RB_REMOVE invokes RB_REMOVE_COLOR either when
child is red or child is null. In the first case, RB_REMOVE_COLOR just changes
the child to black and returns. With this change, RB_REMOVE handles that case,
and drops the child argument to RB_REMOVE_COLOR, since that value is always
null.
RB_REMOVE_COLOR is changed to remove a couple of unneeded tests, and
to eliminate some deep indentation.
RB_ISRED is defined to combine a null check with a test for redness,
to replace that combination in several places.
dougm [Thu, 21 May 2020 05:34:02 +0000 (05:34 +0000)]
For the case when RB_REMOVE requires a nontrivial
search to find the node to replace the one being removed, restructure to first
remove the replacement node and correct the parent pointers around it, and then
let the all-cases code at the end deal with the parent of the deleted node,
making it point to the replacement node. This removes one or two conditional
branches.
dougm [Mon, 27 Jan 2020 15:09:13 +0000 (15:09 +0000)]
Correct the use of RB_AUGMENT in the RB_TREE
macros so that is invoked at the root of every subtree that changes in an
insert or delete, and only once, and ordered from the bottom of the tree to the
top. For intel_gas.c, the only user of RB_AUGMENT I can find, change the
augmenting routine so that it does not climb from entry to tree root on every
call, and remove a 'tree correcting' function that can be supplanted by proper
tree augmentation.
amd64: prevent KCSan false positives on LAPIC mapping
For configurations without x2APIC support (guests, older hardware), the global
LAPIC MMIO mapping will trigger false-positive KCSan reports as it will appear
that multiple CPUs are concurrently reading and writing the same address.
This isn't actually true, as the underlying physical access will be performed
on the local CPU's APIC. Additionally, because LAPIC access can happen during
event timer configuration, the resulting KCSan printf can produce a panic due
to attempted recursion on event timer resources.
Add a __nosanitizethread preprocessor define to prevent the compiler from
inserting TSan hooks, and apply it to the x86 LAPIC accessors.
rlibby [Sat, 21 Dec 2019 02:43:20 +0000 (02:43 +0000)]
gcc: quiet Wattribute for no_sanitize("address")
This is an unfortunate instance where the __has_attribute check does
not function usefully. Gcc does have the attribute, but for gcc it only
applies to functions, not variables, and trying to apply it to a
variable generates Wattribute. So far we only apply the attribute to
variables. Only enable the attribute for clang, for now.
Reviewed by: Anton Rang <rang at acm.org>
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D22875
dab [Tue, 19 Nov 2019 14:46:28 +0000 (14:46 +0000)]
Don't sanitize linker_set
The assumptions of linker_set don't play nicely with
AddressSanitizer. AddressSanitizer adds a 'redzone' of zeros around
globals (including those in named sections), whereas linker_set
assumes they are all packed consecutively like a pointer array. So:
let's annotate linker_set so that AddressSanitizer ignores it.
jhb [Mon, 6 Aug 2018 23:51:08 +0000 (23:51 +0000)]
Make the system C11 atomics headers fully compatible with external GCC.
The <sys/cdefs.h> and <stdatomic.h> headers already included support for
C11 atomics via intrinsincs in modern versions of GCC, but these versions
tried to "hide" atomic variables inside a wrapper structure. This wrapper
is not compatible with GCC's internal <stdatomic.h> header, so that if
GCC's <stdatomic.h> was used together with <sys/cdefs.h>, use of C11
atomics would fail to compile. Fix this by not hiding atomic variables
in a structure for modern versions of GCC. The headers already avoid
using a wrapper structure on clang.
Note that this wrapper was only used if C11 was not enabled (e.g.
via -std=c99), so this also fixes compile failures if a modern version
of GCC was used with -std=c11 but with FreeBSD's <stdatomic.h> instead
of GCC's <stdatomic.h> and this change fixes that case as well.
Reported by: Mark Millard
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D16585
Cygwin: pty: Fix race condition in initialization of pseudo console.
- If output of non-cygwin process is piped to cygwin process, such
as less, the non-cygwin process sometimes fails to start and hangs.
This patch fixes the issue.
Cygwin: AF_INET and AF_LOCAL: recv_internal: fix MSG_WAITALL support
If MSG_WAITALL is set, recv_internal calls WSARecv or WSARecvFrom in a
loop, in an effort to fill all the scatter-gather buffers. The test
for whether all the buffers are full was previously incorrect.
Jon Turney [Sat, 3 Oct 2020 13:41:58 +0000 (14:41 +0100)]
Cygwin: Remove ccwrap
ccwrap massages the compiler's standard include directories to remove
'/usr/include/w32api', with the intent of allowing it to be overriden by
'--with-windows-headers' (See 4c36016b).
I'm not 100% convinced that this is always working as desired, since in
some places w32api includes are done using <w32api/something.h>, which
will find them via the path /usr/include.
If this does turn out to be needed, this could also be implemented by
constructing the appropriate compiler flags once, rather than on every
compiler invocation.
libc/time: Move internal newlib tz-structs into own header
As discussed in GCC bug 97088
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97088), parameters in
prototypes of library functions should use reserved names, or no name
at all.
This patch moves the internal struct __tzrule_struct to its own
internal header sys/_tz_structs.h. This is included from newlib's
time code as well as from Cygwin's localtime wrapper.
Jon Turney [Mon, 12 Oct 2020 13:27:55 +0000 (14:27 +0100)]
Cygwin: Drop AC_SUBST(LIBSERVER)
The autoconf variable LIBSERVER isn't defined, and it's value isn't
used. (The Makefile.in contains a literal value for the name of this
library instead).
Brian Inglis [Tue, 13 Oct 2020 15:11:08 +0000 (09:11 -0600)]
format_proc_cpuinfo: add enqcmd cpuinfo flag
Add linux-next 5.9 cpuinfo flag for Intel enqcmd/s instructions:
x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions:
Work submission instruction comes in two flavors. ENQCMD can be called
both in ring 3 and ring 0 and always uses the contents of a PASID MSR
when shipping the command to the device. ENQCMDS allows a kernel driver
to submit commands on behalf of a user process. The driver supplies the
PASID value in ENQCMDS. There isn't any usage of ENQCMD in the kernel as
of now.
The CPU feature flag is shown as "enqcmd" in /proc/cpuinfo.
Ken Brown [Tue, 29 Sep 2020 20:18:15 +0000 (16:18 -0400)]
Cygwin: always recognize AF_UNIX sockets as reparse points
If __WITH_AF_UNIX is defined when Cygwin is built, then a named
AF_UNIX socket is represented by a reparse point with a
Cygwin-specific tag and GUID. Make such files recognizable as reparse
points (but not as sockets) even if __WITH_AF_UNIX is not defined.
That way utilities such as 'ls' and 'rm' still behave reasonably.
This requires two changes:
- Define the GUID __cygwin_socket_guid unconditionally.
- Make check_reparse_point_target return PATH_REP on a reparse point
of this type if __WITH_AF_UNIX is not defined.
Ken Brown [Mon, 28 Sep 2020 20:34:44 +0000 (16:34 -0400)]
Cygwin: fix handling of known reparse points that are not symlinks
Commit aa467e6e, "Cygwin: add AF_UNIX reparse points to path
handling", changed check_reparse_point_target so that it could return
a positive value on a known reparse point that is not a symlink. But
some of the code in check_reparse_point that handles this positive
return value was executed unconditionally, when it should have been
executed only for symlinks.
As a result, posixify could be called on a buffer containing garbage,
and check_reparse_point could erroneously return a positive value on a
non-symlink. This is now fixed so that posixify is only called if the
reparse point is a symlink, and check_reparse_point returns 0 if the
reparse point is not a symlink.
Also fix symlink_info::check to handle this last case, in which
check_reparse_point returns 0 on a known reparse point.
As discussed in GCC bug 97088
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97088), parameters in
prototypes of library functions should use reserved names, or no name
at all.
This patch removes the 'ptr' parameter name from
wint_t _getwchar_r (struct _reent *);
wint_t _getwchar_unlocked_r (struct _reent *);
to avoid possible clashes with user code in case someone uses
before including Newlib's wchar.h (or uses some other conflicting
definition)
As discussed in GCC bug 97088
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97088), parameters in
prototypes of library functions should use reserved names, or no name
at all.
This patch removes the 'j' parameter name from
extern intmax_t imaxabs(intmax_t);
to avoid possible clashes with user code in case someone uses
before including Newlib's inttypes.h (or uses some other conflicting
definition)
libgloss: aarch64: Add support for Armv8-R AArch64
This patch adds support for Armv8-R AArch64.
Armv8-R AArch64 has no EL3, so we don't set vbar_el3, and adjust the
code to set up the MPU for Armv8-R. So build a different flavour of the
startup code to support that.
We also add a specs file that uses this alternative startup code which
can be used with Armv8-R AArch64 models.
Jon Turney [Sat, 19 Sep 2020 15:15:40 +0000 (16:15 +0100)]
Cygwin: avoid GCC 10 error with -Werror=narrowing
../../../../src/winsup/cygwin/pinfo.cc: In member function 'DWORD pinfo::status_exit(DWORD)':
../../../../src/winsup/cygwin/ntdll.h:21:68: error: narrowing conversion of '-536870295' from 'NTSTATUS' {aka 'int'} to 'unsigned int' [-Wnarrowing]
../../../../src/winsup/cygwin/pinfo.cc:136:10: note: in expansion of macro 'STATUS_ILLEGAL_DLL_PSEUDO_RELOCATION'
../../../../src/winsup/cygwin/sigproc.cc: In member function 'DWORD child_info::proc_retry(HANDLE)':
../../../../src/winsup/cygwin/ntdll.h:21:68: error: narrowing conversion of '-536870295' from 'NTSTATUS' {aka 'int'} to 'unsigned int' [-Wnarrowing]
../../../../src/winsup/cygwin/sigproc.cc:1120:10: note: in expansion of macro 'STATUS_ILLEGAL_DLL_PSEUDO_RELOCATION'
NT error statuses seem to be variously DWORD (unsigned) or NTSTATUS
(signed)? So use the one which doesn't cause problems here.
Jon Turney [Sat, 19 Sep 2020 14:55:09 +0000 (15:55 +0100)]
Cygwin: avoid GCC 10 error with -Werror=narrowing
../../../../src/winsup/cygwin/fhandler_console.cc: In member function 'const unsigned char* fhandler_console::write_normal(const unsigned char*, const unsigned char*)':
../../../../src/winsup/cygwin/fhandler_console.cc:2782:8: error: narrowing conversion of '-2' from 'int' to 'long unsigned int' [-Wnarrowing]
../../../../src/winsup/cygwin/fhandler_console.cc:2786:8: error: narrowing conversion of '-1' from 'int' to 'long unsigned int' [-Wnarrowing]
../../../../src/winsup/cygwin/fhandler_console.cc:2836:8: error: narrowing conversion of '-2' from 'int' to 'long unsigned int' [-Wnarrowing]
../../../../src/winsup/cygwin/fhandler_console.cc:2840:8: error: narrowing conversion of '-1' from 'int' to 'long unsigned int' [-Wnarrowing]
A mbtowc_p function returns an int, so that seems the correct type to use here.
Jon Turney [Sat, 19 Sep 2020 14:51:10 +0000 (15:51 +0100)]
Cygwin: avoid GCC 10 error with -Werror=parentheses
../../../../src/winsup/cygwin/fhandler_socket_inet.cc: In member function 'ssize_t fhandler_socket_wsock::send_internal(_WSAMSG*, int)':
../../../../src/winsup/cygwin/fhandler_socket_inet.cc:1381:69: error: suggest parentheses around assignment used as truth value [-Werror=parentheses]
Commit aa467e6e, "Cygwin: add AF_UNIX reparse points to path
handling", changed the return values of check_reparse_point_target.
Update the comment accordingly.
As discussed in GCC bug 97088
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97088), parameters in
prototypes of library functions should use reserved names, or no name
at all.
This patch removes the 'x' parameter name from
extern int __isinff (float);
extern int __isinfd (double);
extern int __isnanf (float);
extern int __isnand (double);
extern int __fpclassifyf (float);
extern int __fpclassifyd (double);
extern int __signbitf (float);
extern int __signbitd (double);
to avoid possible clashes with user code in case someone uses
before including Newlib's math.h (or uses some other conflicting
definition)
Ken Brown [Wed, 23 Sep 2020 15:04:08 +0000 (11:04 -0400)]
Cygwin: winlean.h: remove most of the extended memory API
This was added as a temporary measure in commit e18f7f99 because it
wasn't yet in the mingw-w64 headers. With one exception, it is now in
the current release of the headers (version 8.0.0), so we don't need
it in winlean.h.
The exception is that VirtualAlloc2 is declared conditionally in
<w32api/memoryapi.h>, but the compilation of Cygwin requires it to
always be declared, even though it will only be executed on systems
that support it. So retain the declaration in winlean.h. And add
"WINAPI" to the declaration, as in memoryapi.h.
Add a check that version >= 8 of the mingw-w64 headers is intalled.
Also revert commit 3d136011, which was a related temporary workaround.
Brian Inglis [Fri, 18 Sep 2020 02:53:35 +0000 (20:53 -0600)]
winsup/doc/faq-what.xml: FAQ 1.2 Windows versions supported
enumerate Vista, 7, 8, 10 progression to be clear, and earliest server 2008;
add 8.1, exclude S mode, add Cygwin32 on ARM, specify 64 bit only AMD/Intel
Cygwin: pty: Drop handling for UTF-7 in convert_mb_str().
- Charset conversion for UTF-7, ISO-2022 and ISCII, which are not
supported in cygwin, does not work properly as a result. At the
expense of the above, the code has been simplified a bit.
Cygwin: pty: Prevent garbled output for existing non-cygwin apps.
- If pseudo console is disabled, non-cygwin apps do not detect
console device. In this case, some apps output UTF-8 regardless
of the locale setting. At least git-for-windows, rust-based apps
and node.js do that. This patch provides backward compatibility
as default behaviour by setting console codepage to the charset of
the locale. Even in the cases above, garbled output is prevented
with this patch in most cases because mintty uses UTF-8 by default.
I beleave this is not really a problem in cygwin side but that in
app side, however, some users complain about garbled output with
existing apps in MSYS2 (which is based on cygwin) in which pseudo
console is disabled by default.
Cygwin: pty: setup new pty on opening the master, not in constructor
Setting up the pty in the master constructor ends up creating a new pty
on every stat(2) call on /dev/ptmx. Only do this when actually opening
the device, not when using the device class in another, non-opening
context.
- Use tmp_pathbuf instead of HeapAlloc()/HeapFree().
- Remove mb_str_free() function.
- Consider the case where the multibyte string stops in the middle
of a multibyte char.
Ken Brown [Tue, 8 Sep 2020 16:23:32 +0000 (12:23 -0400)]
Cygwin: path_conv::check: handle error from fhandler_process::exists
fhandler_process::exists is called when we are checking a path
starting with "/proc/<pid>/fd". If it returns virt_none and sets an
errno, there is no need for further checking. Just set 'error' and
return.
Ken Brown [Tue, 8 Sep 2020 15:45:09 +0000 (11:45 -0400)]
Cygwin: format_process_fd: add directory check
The incoming path is allowed to have the form "$PID/fd/[0-9]*/.*"
provided the descriptor symlink points to a directory. Check that
this is indeed the case.
Cygwin: pty: move codepage evaluation to nlsfuncs.cc
The new function __eval_codepage_from_internal_charset
is a simplified version of the former code in
fhandler_tty.cc. It probably needs some extension,
but the gist is to use knowledge of internals to
be as quick as possible.
Cygwin: drop internal O_NOSYMLINK and O_DIROPEN flags
Both flags are outdated and collide with official flags in
sys/_default_fcntl.h, which may result in weird misbehaviour
of file functions.
O_NOSYMLINK is not used anyway.
O_DIROPEN is used in fhandler_virtual and derived classes.
The collision with O_NOFOLLOW results in spurious EISDIR
errors when, e. g., reading files in the registry.
fhandler_base::open_fs uses O_DIROPEN in the call to
fhandler_base::open, but it's not used in this context
further down the road.
Drop both flags and create an alternative "diropen" bool
flag in fhandler_virtual.
libm: Fix 'gamma' and 'gammaf' functions. Clean up other gamma code. [v2]
The current gamma, gamma_r, gammaf and gammaf_r functions return
|gamma(x)| instead of ln(|gamma(x)|) due to a change made back in 2002
to the __ieee754_gamma_r implementation. This patch fixes that, making
all of these functions map too their lgamma equivalents.
To fix the underlying bug, the __ieee754_gamma functions have been
changed to return gamma(x), removing the _r variants as those are no
longer necessary. Their names have been changed to __ieee754_tgamma to
avoid potential confusion from users.
Now that the __ieee754_tgamma functions return the correctly signed
value, the tgamma functions have been modified to use them.
libm.a now exposes the following gamma functions:
ln(|gamma(x)|):
__ieee754_lgamma_r
__ieee754_lgammaf_r
lgamma
lgamma_r
gamma
gamma_r
lgammaf
lgammaf_r
gammaf
gammaf_r
lgammal (on machines where long double is double)
gamma(x):
__ieee754_tgamma
__ieee754_tgammaf
tgamma
tgammaf
tgammal (on machines where long double is double)
Additional aliases for any of the above functions can be added if
necessary; in particular, I'm not sure if we need to include
__ieee754_gamma*_r functions (which would return ln(|(gamma(x)|).
Signed-off-by: Keith Packard <keithp@keithp.com>
----
libm/riscv: Fix machine-specific sqrt build process
Like ARM, some RISC-V implementations have hardware sqrt. Support for
that can be detected at compile time, which the code did. However, the
filenames were incorrect so that both the risc-v specific and general
code were getting included in the resulting library.
Fix this by following the ARM model and #include'ing the general code
when the architecture-specific support is not available.
The MSP430 target supports both 16-bit and 20-bit size_t and intptr_t.
Some implicit casts in Newlib expect these types to be
"long", (a 32-bit type on MSP430) which causes warnings during
compilation such as:
"cast from pointer to integer of different size"
This is required to avoid colliding with files built from libm/common
that would end up with the same object name.
When libm.a was constructed from the individual sub-libraries, the
contents of the libm/common files would be replaced by that from
libm/machine/arm with the same name.
Cygwin: pty: Disable pseudo console if TERM does not have CSI6n.
- Pseudo console internally sends escape sequence CSI6n (query cursor
position) on startup of non-cygwin apps. If the terminal does not
support CSI6n, CreateProcess() hangs waiting for response. To prevent
hang, this patch disables pseudo console if the terminal does not
have CSI6n. This is checked on the first execution of non-cygwin
app using the following steps.
1) Check if the terminal support ANSI escape sequences by looking
into terminfo database. If terminfo has cursor_home (ESC [H),
the terminal is supposed to support ANSI escape sequences.
2) If the terminal supports ANSI escape sequneces, send CSI6n for
a test and wait for a responce for 40ms.
3) If there is a responce within 40ms, CSI6n is supposed to be
supported.
Also set-title capability is checked, and removes escape sequence
for setting window title if the terminal does not have the set-
title capability.
Jon Turney [Thu, 27 Aug 2020 15:12:47 +0000 (16:12 +0100)]
Cygwin: Remove waitloop argument from try_to_debug()
Currently, when using CYGWIN's error_start facility, the faulting
process isn't stopped while the error_start process is started when the
fault is caused by an exception. (it even seems possible in theory that
the faulting process could have exited before the error_start process
attaches).
This leads to e.g. the core dump written by CYGWIN='error_start=dumper'
in response to an exception being non-deterministic.
Remove the waitloop argument from try_to_debug(), only used in the
exception case, so the faulting process busy-waits until the error_start
process attaches.
Code archaeology to determine why the code is this way didn't really
turn up any answers, but this seems a low-risk change, as this only
changes the behaviour when:
- a debugger isn't already attached
- an error_start is specified in CYGWIN env var
- an exception has occurred which will be translated to a signal
If error_start invokes something which doesn't attach using
DebugActiveProcess(), we will spin indefinitely, but that will also
currently occur for any of the existing other uses of try_to_debug(),
which default to waitloop=TRUE.
Martin Storsjö [Sun, 30 Aug 2020 12:12:48 +0000 (14:12 +0200)]
Cygwin: crt: Add "volatile" to all inline assembly snippets under math
On 32 bit x86, clang seems to miss loading input parameters based
on asm constraints for inline assembly that uses the x87 floating
registers, unless the snippet has got the volatile keyword.
Corinna Vinschen [Sat, 29 Aug 2020 19:29:24 +0000 (21:29 +0200)]
Cygwin: Add C11 threads API
Code taken from FreeBSD, which implements C11 threads as
wrapper around pthreads. Fix up machine/_threads.h which
is called from newlib's machine-independent threads.h to
match Cygwin's pthreads types.
Add the FreeBSD source files to libc subdir and take
opportunity to define LIBC_OFILES var in Makefile.
Corinna Vinschen [Sat, 29 Aug 2020 19:21:21 +0000 (21:21 +0200)]
Cygwin: make pthread_yield available for internal usage
In preparation of importing FreeBSDs stdthreads functions,
change the way pthread_yield is exported, so that the symbol
can be used internally as well.
Corinna Vinschen [Sat, 29 Aug 2020 19:08:31 +0000 (21:08 +0200)]
Cygwin: pthreads: iterate over key destructors per POSIX
POSIX requires that key destructors are called in a loop
for each key with a non-NULL value until all values are
NULL, or until all destructors for non-NULL values
have been called at least PTHREAD_DESTRUCTOR_ITERATIONS
(per POSIX: 4) times.
Cygwinonly called all destructors with non-NULL values
exactly once. This patch fixes Cygwin to follow POSIX.
Jon Turney [Sun, 23 Aug 2020 19:33:22 +0000 (20:33 +0100)]
Cygwin: Add .appveyor.yml
This is a slightly more polished version of the configuration being used
for CI builds at https://ci.appveyor.com/project/cygwin/cygwin, which is
not currently under version control.
Corinna Vinschen [Fri, 28 Aug 2020 17:38:05 +0000 (19:38 +0200)]
Cygwin: sigproc: Fix a thinko in array size
We need one more entry than max children in the arrays.
There's no reason to do this for the static array, though.
One more entry in the overflow array is sufficient.
Corinna Vinschen [Fri, 28 Aug 2020 17:34:52 +0000 (19:34 +0200)]
Cygwin: sigproc: Eliminate redundant copying of chld_procs
On PROC_EXEC_CLEANUP, the pinfo's in chld_procs are removed.
This is done in a loop always removing the child with index 0.
This, however, results in copying the last child's pinfo in
chld_procs to position 0. Do this for 100 children and you
get 99 entirely useless copy operations.
git://sourceware.org / newlib-cygwin.git / log