The _REENT_GLOBAL_STDIO_STREAMS was introduced by commit
668a4c8722 in 2017. Since then it was enabled by
default for RTEMS. Recently, the option was enabled for Cygwin which
previously used an alternative implementation to use global stdio streams.
In Newlib, the stdio streams are defined to thread-specific pointers
_reent::_stdin, _reent::_stdout and _reent::_stderr. If the option is disabled
(the default for most systems), then these pointers are initialized to
thread-specific FILE objects which use file descriptors 0, 1, and 2,
respectively. There are at least three problems with this:
(1) The thread-specific FILE objects are closed by _reclaim_reent(). This
leads to problems with language run-time libraries that provide wrappers to
the C/POSIX stdio streams (for example C++ and Ada), since they use the
thread-specific FILE objects of the initialization thread. In case the
initialization thread is deleted, then they use freed memory.
(2) Since thread-specific FILE objects are used with a common output device via
file descriptors 0, 1 and 2, the locking at FILE object level cannot ensure
atomicity of the output, e.g. a call to printf().
(3) There are resource managment issues, see:
https://sourceware.org/pipermail/newlib/2022/019558.htmlhttps://bugs.linaro.org/show_bug.cgi?id=5841
This patch enables the _REENT_GLOBAL_STDIO_STREAMS behaviour for all Newlib
configurations and removes the option. This removes a couple of #ifdef blocks.
For _REENT_GLOBAL_STDIO_STREAMS, lock/unlock all FILE objects. In the
repository, this function is only used by Cygwin during process forks. Since
Cygwin enabled _REENT_GLOBAL_STDIO_STREAMS recently, without this fix no FILE
object at all was locked.
Do not initialize __sglue with the FILE objects of _GLOBAL_REENT to avoid a
double use in the !_REENT_SMALL and !_REENT_GLOBAL_STDIO_STREAMS configurations
which didn't use a thread-specific reentrancy structure.
The __sFILE::_lock member is present if __SINGLE_THREAD__ is not defined. In
this case, it is initialized in __sfp(). It is a bug to do it sometimes also
in std().
Added a new global __sglue object for all configurations.
Decouples the global file object list from the _GLOBAL_REENT
structure by using this new object instead of the __sglue member
of _GLOBAL_REENT in __sfp() and _fwalk_sglue().
Replaced _fwalk_reent() with _fwalk_sglue(). The change adds an
extra __sglue object as a parameter, which will allow the passing
of a global __sglue object separate from the __sglue member of
struct _reent. The global __sglue object will be added in a
follow-on patch.
Define the configuration-dependent constant CLEANUP_FILE for use in
cleanup_stdio(). This will reduce duplicate code during the addition
of a dedicated stdio atexit handler in a follow-on patch.
Moved last remaining __sglue initializations from __sinit() to
__sfp(). The move better encapsulates access to __sglue and
facilitates its decoupling from struct _reent in a follow-on patch.
Remove __sinit_lock_acquire() and __sinit_lock_release(). Replace these with
__sfp_lock_acquire() and __sfp_lock_release(), respectively. This eliminates a
potential deadlock issue between __sinit() and __sfp(). Remove now unused
__sinit_recursive_mutex and __lock___sinit_recursive_mutex.
Added _REENT_INIT_SGLUE and _REENT_INIT_SGLUE_ZEROED macros
to initialize __sglue member of struct _reent. This allows
further simplification of __sinit() and facilitates the removal
of __sglue as a member of struct _reent for certain configurations
in a follow-on patch.
Removed duplicate sglue initializations from __sinit(). These
are already initialized in the _REENT_INIT macro in sys/reent.h.
This simplification enables the reduction of _GLOBAL_REENT
dependency in a follow-on patch.
Removed duplicate stdio initializations from __sinit(). These
are already initialized in the _REENT_INIT macro in sys/reent.h.
This simplification enables the reduction of _GLOBAL_REENT
dependency in a follow-on patch.
This fixes a bug introduced in a previous patch (Commit 44b60f0c:
Make __sdidinit unused). Removed intitialization of __cleanup from
__smakebuf_r(). All callers of __smakebuf_r() call __sinit()
through the_CHECK_INIT macro, thus __cleanup is already
initialized. This fix also allows _cleanup_r() to be made static.
Changed its name to cleanup_stdio() and removed its declaration
from local.h.
Rename __sfmoreglue() in sfmoreglue() and make it static. This function is
only used by __sfp() in the same translation unit.
Remove use of register keyword.
[PATCH] newlib: Only call _fputwc_r if ELIX_LEVEL >= 4
(nano-)vfprintf.c is enabled for ELIX_LEVEL >= 1. When _WIDE_ORIENT
is set, its __sprint_r / __sfputs_r functions unconditionally called
_fputwc_r which is only in ELEX_LEVEL >= 4. With this commit,
the _WIDE support in (nano-)vfprintf.c is disabled for ELEX_LEVEL < 4.
Convert all the libc/ subdir makes into the top-level Makefile. This
allows us to build all of libc from the top Makefile without using any
recursive make calls. This is faster and avoids the funky lib.a logic
where we unpack subdir archives to repack into a single libc.a. The
machine override logic is maintained though by way of Makefile include
ordering, and source file accumulation in libc_a_SOURCES.
There's a few dummy.c files that are no longer necessary since we aren't
doing the lib.a accumulating, so punt them.
The winsup code has been pulling the internal newlib ssp library out,
but that doesn't exist anymore, so change that to pull the objects.
Rather than define per-object rules in the Makefile, have small files
that define & include the right content. This simplifies the build
rules, and makes understanding the source a little easier (imo) as it
makes all the subdirs behave the same: you have 1 source file and it
produces 1 object. It's also about the same amount of boiler plate,
without having to define custom build rules that can fall out of sync.
Some of these rules were already unnecessary as they were compiling a
single source file into the same named object w/out custom flags, and
Automake handles that for us completely.
This will also be important as we merge the libc.a build into the top
dir since it relies on a single flat list of objects for overrides.
Also take the opportunity to clean up the unnecessary header deps in
here. Automake provides dependency generation for free now.
This kills off the last configure script under libc/ and folds it
into the top newlib configure script. The a lot of the logic was
already in the top configure script, so move what's left into a
libc/acinclude.m4 file.
Remove dependency on __sdidinit member of struct _reent to check
object initialization. Like __sdidinit, the __cleanup member of
struct _reent is initialized in the __sinit() function. Checking
initialization against __cleanup serves the same purpose and will
reduce overhead in the __sfp() function in a follow up patch.
The crt0.o was handled in a subdir-by-subdir basis: it would be compiled
in one (e.g. libc/sys/$arch/), then copied up one level (libc/sys/), then
copied up another (libc/) before finally being copied & installed in the
top newlib dir. The libc/sys/ copy was cleaned up, and then the top dir
was changed to copy it directly out of the libc/sys/$arch/ dir. But the
libc/sys/ copy to libc/ was left behind. Clean that up now too.
This is used in a bunch of places, but nowhere is it ever set, and
nowhere can I find any documentation, nor can I find any other project
using it. So delete the flags to simplify.
This was only ever used for i?86-pc-linux-gnu targets, but that's been
broken for years, and has since been dropped. So clean this up too.
This also deletes the funky objectlist logic since it only existed for
the libtool libraries. Since it was the only thing left in the small
Makefile.shared file, we can punt that too.
Now that we use AC_NO_EXECUTABLES, and we require a recent version of
autoconf, we don't need to define our own copies of these macros. So
switch to the standard AC_PROG_CC.
This allows building the libc & libm pages in parallel, and drops
the duplication in the subdirs with the chew/chapter settings.
The unused rules in Makefile.shared are left in place to minimize
noise in the change.
This doesn't migrate all the docs, just the libc's manual (pdf/info).
This is to show the basic form of migrating the chew files.
For subdirs that didn't have any docs, I've stripped their settings
for clarity. If someone wanted to suddenly add docs, they can add
the corresponding Makefile.inc files easily.
THe stdio subdir is actually required by the documentation. The
stdio/def is handled dynamically, but libc.texi always expects it
to be included, and fails if it isn't. So making it required when
building docs is safe.
The xdr subdir is handled dynamically, but it doesn't include any
docs, so the dynamic logic isn't (currently) adding any value. So
making it required when building docs is safe.
That leaves: iconv, stdio64, posix, and signal subdirs. The chapters
have a little disclaimer saying they are system-dependent, but even
then, imo having stable manuals regardless of the target is preferable,
and we can add more disclaimer language to these chapters if we want.
This doesn't touch the man page codepaths, just the info/pdf.
When using the top-level configure script but subdir Makefiles, the
newlib_basedir value gets a bit out of sync: it's relative to where
configure lives, not where the Makefile lives. Move the abs setting
from the top-level configure script into acinclude.m4 so we can rely
on it being available everywhere. Although this commit doesn't use
it anywhere, just lays the groundwork.
The machine configure scripts are all effectively stub scripts that
pass the higher level options to its own makefile. There were only
three doing custom tests. The rest were all effectively the same as
the libc/ configure script.
So instead of recursively running configure in all of these subdirs,
generate their makefiles from the top-level configure. For the few
unique ones, deploy a pattern of including subdir logic via m4:
m4_include([machine/nds32/acinclude.m4])
Some of the generated machine makefiles have a bunch of extra stuff
added to them, but that's because they were inconsistent in their
configure libtool calls. The top-level has it, so it exports some
new vars to the ones that weren't already.
The sys/{configure,Makefile} files exist to fan out to the specific
sys/$arch/ subdir, and to possibly generate a crt0. We already have
all that same info in the libc/ dir itself, so by moving the recursive
configure and make calls into it, we can cut off some of this logic
entirely and save the overhead.
For arches that don't have a sys subdir, it means they can skip the
logic entirely.
The sys subdir itself is kept for the crt0 logic, for now. We'll try
and clean that up next.
The machine/{configure,Makefile} files exist only to fan out to the
specific machine/$arch/ subdir. We already have all that same info
in the libc/ dir itself, so by moving the recursive configure and
make calls into it, we can cut off this logic entirely and save the
overhead.
For arches that don't have a machine subdir, it means they can skip
the logic entirely. Although there's prob not too many of those.
This was added decades ago, but the commit message lacks any
explanation, and it was unused when it was merged. It's still
unused today. So punt it all.
Generating these files is very cheap, so let's just do it all the time.
This makes the build logic simpler, and keeps errors for slipping in in
codepaths that are not well tested. Creating these files doesn't mean
they'll be included in the manual implicitly.
For example, some of the nano stdio files break documentation because
they don't have any chew directives in them. But no one noticed since
that code path is rarely enabled. So drop the _i and _float def files.
This matches what the other GNU toolchain projects have done already.
The generated diff in practice isn't terribly large. This will allow
more use of subdir local.mk includes due to fixes & improvements that
came after the 1.11 release series.
The newlib & libgloss dirs are already generated using autoconf-2.69.
To avoid merging new code and/or accidental regeneration using diff
versions, leverage config/override.m4 to pin to 2.69 exactly. This
matches what gcc/binutils/gdb are already doing.
The README file already says to use autoconf-2.69.
To accomplish this, it's just as simple as adding -I flags to the
top-level config/ dir when running aclocal. This is because the
override.m4 file overrides AC_INIT to first require the specific
autoconf version before calling the real AC_INIT.
Since automake deprecated the INCLUDES name in favor of AM_CPPFLAGS,
change all existing users over. The generated code is the same since
the two variables have been used in the same exact places by design.
There are other cleanups to be done, but lets focus on just renaming
here so we can upgrade to a newer automake version w/out triggering
new warnings.
The 'cygnus' option was removed from automake 1.13 in 2012, so the
presence of this option prevents that or a later version of automake
being used.
A check-list of the effects of '--cygnus' from the automake 1.12
documentation, and steps taken (where possible) to preserve those
effects (See also this thread [1] for discussion on that):
[1] https://lists.gnu.org/archive/html/bug-automake/2012-03/msg00048.html
1. The foreign strictness is implied.
Already present in AM_INIT_AUTOMAKE in newlib/acinclude.m4
2. The options no-installinfo, no-dependencies and no-dist are implied.
Already present in AM_INIT_AUTOMAKE in newlib/acinclude.m4
Future work: Remove no-dependencies and any explicit header dependencies,
and use automatic dependency tracking instead. Are there explicit rules
which are now redundant to removing no-installinfo and no-dist?
3. The macro AM_MAINTAINER_MODE is required.
Already present in newlib/acinclude.m4
Note that maintainer-mode is still disabled by default.
4. Info files are always created in the build directory, and not in the
source directory.
This appears to be an error in the automake documentation describing
'--cygnus' [2]. newlib's info files are generated in the source
directory, and no special steps are needed to keep doing that.
[2] https://lists.gnu.org/archive/html/bug-automake/2012-04/msg00028.html
5. texinfo.tex is not required if a Texinfo source file is specified.
(The assumption is that the file will be supplied, but in a place that
automake cannot find.)
This effect is overriden by an explicit setting of the TEXINFO_TEX
variable (the directory part of which is fed into texi2X via the
TEXINPUTS environment variable).
6. Certain tools will be searched for in the build tree as well as in the
user's PATH. These tools are runtest, expect, makeinfo and texi2dvi.
For obscure automake reasons, this effect of '--cygnus' is not active
for makeinfo in newlib's configury.
However, there appears to be top-level configury which selects in-tree
runtest, expect and makeinfo, if present. So, if that works as it
appears, this effect is preserved. If not, this may cause problem if
anyone is building those tools in-tree.
This effect is not preserved for texi2dvi. This may cause problems if
anyone is building texinfo in-tree.
If needed, explicit checks for those tools looking in places relative to
$(top_srcdir)/../ as well as in PATH could be added.
7. The check target doesn't depend on all.
This effect is not preseved. The check target now depends on the all
target.
This concern seems somewhat academic given the current state of the
testsuite.
Also note that this doesn't touch libgloss.
Sebastian Huber
Matt Joyce
Jeff Johnston
Mike Frysinger
Jon Turney