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Rich Felker [Tue, 16 Oct 2018 18:08:01 +0000 (14:08 -0400)]
make thread-pointer-loading asm non-volatile
this will allow the compiler to cache and reuse the result, meaning we
no longer have to take care not to load it more than once for the sake
of archs where the load may be expensive.
depends on commit
1c84c99913bf1cd47b866ed31e665848a0da84a2 for
correctness, since otherwise the compiler could hoist loads during
stage 3 of dynamic linking before the initial thread-pointer setup.
Rich Felker [Tue, 16 Oct 2018 17:55:55 +0000 (13:55 -0400)]
remove ancient clang workaround from powerpc pthread_arch.h asm
versions of clang all the way back to 3.1 lack the bug this was
purportedly working around.
Rich Felker [Tue, 16 Oct 2018 17:48:10 +0000 (13:48 -0400)]
restore attribute((const)) to pthread_self and errno location decls
revert commit
a603a75a72bb469c6be4963ed1b55fabe675fe15.
as a result of commit
1c84c99913bf1cd47b866ed31e665848a0da84a2 this is
now safe, assuming an interpretation of the somewhat-underspecified
attribute((const)) consistent with real-world usage.
Rich Felker [Tue, 16 Oct 2018 17:36:51 +0000 (13:36 -0400)]
add new stage 2b to dynamic linker bootstrap for thread pointer
commit
a603a75a72bb469c6be4963ed1b55fabe675fe15 removed attribute
const from __errno_location and pthread_self, and the same reasoning
forced arch definitions of __pthread_self to use volatile asm,
significantly impacting code generation and imposing manual caching of
pointers where the impact might be noticable.
reorder the thread pointer setup and place it across a strong barrier
(symbolic function lookup) so that there is no assumed ordering
between the initialization and the accesses to the thread pointer in
stage 3.
Rich Felker [Tue, 16 Oct 2018 04:59:43 +0000 (00:59 -0400)]
move stdio locking MAYBE_WAITERS definition to stdio_impl.h
don't repeat definition in two places.
Rich Felker [Mon, 15 Oct 2018 19:31:02 +0000 (15:31 -0400)]
fix misleading placement of statement on same line as for loop in ldso
the placement triggered -Wmisleading-indentation warnings if enabled,
and was gratuitously confusing to anyone reading the code.
Szabolcs Nagy [Sat, 22 Sep 2018 21:43:42 +0000 (21:43 +0000)]
x86_64: add single instruction fma
fma is only available on recent x86_64 cpus and it is much faster than
a software fma, so this should be done with a runtime check, however
that requires more changes, this patch just adds the code so it can be
tested when musl is compiled with -mfma or -mfma4.
Szabolcs Nagy [Sat, 22 Sep 2018 18:47:27 +0000 (18:47 +0000)]
arm: add single instruction fma
vfma is available in the vfpv4 fpu and above, the ACLE standard feature
test for double precision hardware fma support is
__ARM_FEATURE_FMA && __ARM_FP&8
we need further checks to work around clang bugs (fixed in clang >=7.0)
&& !__SOFTFP__
because __ARM_FP is defined even with -mfloat-abi=soft
&& !BROKEN_VFP_ASM
to disable the single precision code when inline asm handling is broken.
For runtime selection the HWCAP_ARM_VFPv4 hwcap flag can be used, but
that requires further work.
Szabolcs Nagy [Thu, 20 Sep 2018 23:14:11 +0000 (23:14 +0000)]
powerpc: add single instruction fabs, fabsf, fma, fmaf, sqrt, sqrtf
These are only available on hard float target and sqrt is not available
in the base ISA, so further check is used.
Szabolcs Nagy [Thu, 13 Sep 2018 22:35:13 +0000 (22:35 +0000)]
s390x: add single instruction fma and fmaf
These are available in the s390x baseline isa -march=z900.
Rich Felker [Sat, 13 Oct 2018 04:55:48 +0000 (00:55 -0400)]
allow escaped path-separator slashes in glob
previously (before and after rewrite), spurious escaping of path
separators as \/ was not treated the same as /, but rather got split
as an unpaired \ at the end of the fnmatch pattern and an unescaped /,
resulting in a mismatch/error.
for the case of \/ as part of the maximal literal prefix, remove the
explicit rejection of it and move the handling of / below escape
processing.
for the case of \/ after a proper glob pattern, it's hard to parse the
pattern, so don't. instead cheat and count repetitions of \ prior to
the already-found / character. if there are an odd number, the last is
escaping the /, so back up the split position by one. now the
char clobbered by null termination is variable, so save it and restore
as needed.
Rich Felker [Sat, 13 Oct 2018 02:32:41 +0000 (22:32 -0400)]
rewrite core of the glob implementation for correctness & optimization
this code has been long overdue for a rewrite, but the immediate cause
that necessitated it was total failure to see past unreadable path
components. for example, A/B/* would fail to match anything, even
though it should succeed, when both A and A/B are searchable but only
A/B is readable. this problem both was caught in conformance testing,
and impacted users.
the old glob implementation insisted on searching the listing of each
path component for a match, even if the next component was a literal.
it also used considerable stack space, up to length of the pattern,
per recursion level, and relied on an artificial bound of the pattern
length by PATH_MAX, which was incorrect because a pattern can be much
longer than PATH_MAX while having matches shorter (for example, with
necessarily long bracket expressions, or with redundancy).
in the new implementation, each level of recursion starts by consuming
the maximal literal (possibly escaped-literal) path prefix remaining
in the pattern, and only opening a directory to read when there is a
proper glob pattern in the next path component. it then recurses into
each matching entry. the top-level glob function provided automatic
storage (up to PATH_MAX) for construction of candidate/result strings,
and allocates a duplicate of the pattern that can be modified in-place
with temporary null-termination to pass to fnmatch. this allocation is
not a big deal since glob already has to perform allocation, and has
to link free to clean up if it experiences an allocation failure or
other error after some results have already been allocated.
care is taken to use the d_type field from iterated dirents when
possible; stat is called only when there are literal path components
past the last proper-glob component, or when needed to disambiguate
symlinks for the purpose of GLOB_MARK.
one peculiarity with the new implementation is the manner in which the
error handling callback will be called. if attempting to match */B/C/D
where a directory A exists that is inaccessible, the error reported
will be a stat error for A/B/C/D rather than (previous and wrong
implementation) an opendir error for A, or (likely on other
implementations) a stat error for A/B. such behavior does not seem to
be non-conforming, but if it turns out to be undesirable for any
reason, backtracking could be done on error to report the first
component producing it.
also, redundant slashes are no longer normalized, but preserved as
they appear in the pattern; this is probably more correct, and falls
out naturally from the algorithm used. since trailing slashes (which
force all matches to be directories) are preserved as well, the
behavior of GLOB_MARK has been adjusted not to append an additional
slash to results that already end in slash.
Rich Felker [Fri, 12 Oct 2018 16:26:44 +0000 (12:26 -0400)]
fix dlsym of thread-local symbols on archs with DTP_OFFSET!=0
commit
6ba5517a460c6c438f64d69464fdfc3269a4c91a modified
__tls_get_addr to offset the address by +DTP_OFFSET (0x8000 on
powerpc, mips, etc.) and adjusted the result of DTPREL relocations by
-DTP_OFFSET to compensate, but missed changing the argument setup for
calls to __tls_get_addr from dlsym.
Rich Felker [Fri, 12 Oct 2018 04:30:34 +0000 (00:30 -0400)]
combine arch ABI's DTP_OFFSET into DTV pointers
as explained in commit
6ba5517a460c6c438f64d69464fdfc3269a4c91a, some
archs use an offset (typicaly -0x8000) with their DTPOFF relocations,
which __tls_get_addr needs to invert. on affected archs, which lack
direct support for large immediates, this can cost multiple extra
instructions in the hot path. instead, incorporate the DTP_OFFSET into
the DTV entries. this means they are no longer valid pointers, so
store them as an array of uintptr_t rather than void *; this also
makes it easier to access slot 0 as a valid slot count.
commit
e75b16cf93ebbc1ce758d3ea6b2923e8b2457c68 left behind cruft in
two places, __reset_tls and __tls_get_new, from back when it was
possible to have uninitialized gap slots indicated by a null pointer
in the DTV. since the concept of null pointer is no longer meaningful
with an offset applied, remove this cruft.
presently there are no archs with both TLSDESC and nonzero DTP_OFFSET,
but the dynamic TLSDESC relocation code is also updated to apply an
inverted offset to its offset field, so that the offset DTV would not
impose a runtime cost in TLSDESC resolver functions.
Rich Felker [Thu, 11 Oct 2018 18:27:15 +0000 (14:27 -0400)]
fix redundant computations of strlen in glob append function
len was already passed as an argument, so don't use strcat, and use
memcpy instead of strcpy.
Rich Felker [Thu, 11 Oct 2018 18:23:14 +0000 (14:23 -0400)]
fix invalid substitute of [1] for flexible array member in glob
Szabolcs Nagy [Mon, 10 Sep 2018 19:06:21 +0000 (19:06 +0000)]
fix fesetround error checking
Rounding modes are not bit flags, but arbitrary non-negative integers.
Rich Felker [Tue, 9 Oct 2018 14:59:39 +0000 (10:59 -0400)]
fix build regression on armhf in tlsdesc asm
when invoking the assembler, arm gcc does not always pass the right
flags to enable use of vfp instruction mnemonics. for C code it
produces, it emits the .fpu directive, but this does not help when
building asm source files, which tlsdesc needs to be. to fix, use an
explicit directive here.
commit
0beb9dfbecad38af9759b1e83eeb007e28b70abb introduced this
regression. it has not appeared in any release.
Rich Felker [Fri, 5 Oct 2018 00:27:17 +0000 (20:27 -0400)]
allow freeaddrinfo of arbitrary sublists of addrinfo list
the specification for freeaddrinfo allows it to be used to free
"arbitrary sublists" of the list returned by getaddrinfo. it's not
clearly stated how such sublists come into existence, but the
interpretation seems to be that the application can edit the ai_next
pointers to cut off a portion of the list and then free it.
actual freeing of individual list slots is contrary to the design of
our getaddrinfo implementation, which has no failure paths after
making a single allocation, so that light callers can avoid linking
realloc/free. freeing individual slots is also incompatible with
sharing the string for ai_canonname, which the current implementation
does despite no requirement that it be present except on the first
result. so, rather than actually freeing individual slots, provide a
way to find the start of the allocated array, and reference-count it,
freeing the memory all at once after the last slot has been freed.
since the language in the spec is "arbitrary sublists", no provision
for handling other constructs like multiple lists glued together,
circular links, etc. is made. presumably passing such a construct to
freeaddrinfo produces undefined behavior.
Rich Felker [Mon, 1 Oct 2018 23:36:14 +0000 (19:36 -0400)]
inline cp15 thread pointer load in arm dynamic TLSDESC asm when possible
the indirect function call is a significant portion of the code path
for the dynamic case, and most users are probably building for ISA
levels where it can be omitted.
we could drop at least one register save/restore (lr) with this
change, and possibly another (ip) with some clever shuffling, but it's
not clear whether there's a way to do it that's not more expensive, or
whether avoiding the save/restore would have any practical effect, so
in the interest of avoiding complexity it's omitted for now.
Rich Felker [Mon, 1 Oct 2018 22:37:02 +0000 (18:37 -0400)]
add TLSDESC support for 32-bit arm
unlike other asm where the baseline ISA is used, these functions are
hot paths and use ISA-level specializations.
call-clobbered vfp registers are saved before calling __tls_get_new,
since there is no guarantee it won't use them. while setjmp/longjmp
have to use hwcap to decide whether to the fpu is in use, since
application code could be using vfp registers even if libc was
compiled as pure softfloat, __tls_get_new is part of libc and can be
assumed not to have access to vfp registers if tlsdesc.S does not.
thus it suffices just to check the predefined preprocessor macros. the
check for __ARM_PCS_VFP is redundant; !__SOFTFP__ must always be true
if the target ISA level includes fpu instructions/registers.
Rich Felker [Wed, 26 Sep 2018 18:39:10 +0000 (14:39 -0400)]
fix aliasing-based undefined behavior in string functions
use the GNU C may_alias attribute if available, and fallback to naive
byte-by-byte loops if __GNUC__ is not defined.
this patch has been written to minimize changes so that history
remains reviewable; it does not attempt to bring the affected code
into a more consistent or elegant form.
Rich Felker [Sun, 23 Sep 2018 06:51:01 +0000 (02:51 -0400)]
optimize nop case of wmemmove
Rich Felker [Sun, 23 Sep 2018 06:48:25 +0000 (02:48 -0400)]
fix undefined pointer comparison in wmemmove
Rich Felker [Sun, 23 Sep 2018 04:03:08 +0000 (00:03 -0400)]
fix undefined pointer comparison in memmove
the comparison must take place in the address space model as an
integer type, since comparing pointers that are not pointing into the
same array is undefined.
the subsequent d<s comparison however is valid, because it's only
reached in the case where the source and dest overlap, in which case
they are necessarily pointing to parts of the same array.
to make the comparison, use an unsigned range check for dist(s,d)>=n,
algebraically !(-n<s-d<n). subtracting n yields !(-2*n<s-d-n<0), which
mapped into unsigned modular arithmetic is !(-2*n<s-d-n) or rather
-2*n>=s-d-n.
Szabolcs Nagy [Sun, 21 Aug 2016 20:06:56 +0000 (20:06 +0000)]
new tsearch implementation
Rewrote the AVL tree implementation:
- It is now non-recursive with fixed stack usage (large enough for
worst case tree height). twalk and tdestroy are still recursive as
that's smaller/simpler.
- Moved unrelated interfaces into separate translation units.
- The node structure is changed to use indexed children instead of
left/right pointers, this simplifies the balancing logic.
- Using void * pointers instead of struct node * in various places,
because this better fits the api (node address is passed in a void**
argument, so it is tempting to incorrectly cast it to struct node **).
- As a further performance improvement the rebalancing now stops
when it is not needed (subtree height is unchanged). Otherwise
the behaviour should be the same as before (checked over generated
random inputs that the resulting tree shape is equivalent).
- Removed the old copyright notice (including prng related one: it
should be licensed under the same terms as the rest of the project).
.text size of pic tsearch + tfind + tdelete + twalk:
x86_64 i386 aarch64 arm mips powerpc ppc64le sh4 m68k s390x
old 941 899 1220 1068 1852 1400 1600 1008 1008 1488
new 857 881 1040 976 1564 1192 1360 736 820 1408
Szabolcs Nagy [Thu, 13 Sep 2018 21:18:57 +0000 (21:18 +0000)]
add arm and sh bits/ptrace.h
These should have been added in commit
df6d9450ea19fd71e52cf5cdb4c85beb73066394
that added target specific PTRACE_ macros, but somehow got missed.
Rich Felker [Wed, 19 Sep 2018 22:03:22 +0000 (18:03 -0400)]
fix getaddrinfo regression with AI_ADDRCONFIG on some configurations
despite not being documented to do so in the standard or Linux
documentation, attempts to udp connect to 127.0.0.1 or ::1 generate
EADDRNOTAVAIL when the loopback device is not configured and there is
no default route for IPv6. this caused getaddrinfo with AI_ADDRCONFIG
to fail with EAI_SYSTEM and EADDRNOTAVAIL on some no-IPv6
configurations, rather than the intended behavior of detecting IPv6 as
unsuppported and producing IPv4-only results.
previously, only EAFNOSUPPORT was treated as unavailability of the
address family being probed. instead, treat all errors related to
inability to get an address or route as conclusive that the family
being probed is unsupported, and only fail with EAI_SYSTEM on other
errors.
further improvements may be desirable, such as reporting EAI_AGAIN
instead of EAI_SYSTEM for errors which are expected to be transient,
but this patch should suffice to fix the serious regression.
Rich Felker [Wed, 19 Sep 2018 05:31:26 +0000 (01:31 -0400)]
support clang internal assembler when building for arm as thumb2 code
the clang internal assembler does not accept assembler options passed
via the usual -Wa mechanism, but it does accept -mimplicit-it directly
as an option to the compiler driver.
Rich Felker [Wed, 19 Sep 2018 03:54:18 +0000 (23:54 -0400)]
support setting of default thread stack size via PT_GNU_STACK header
this facilitates building software that assumes a large default stack
size without any patching to call pthread_setattr_default_np or
pthread_attr_setstacksize at each thread creation site, using just
LDFLAGS.
normally the PT_GNU_STACK header is used only to reflect whether
executable stack is desired, but with GNU ld at least, passing
-Wl,-z,stack-size=N will set a size on the program header. with this
patch, that size will be incorporated into the default stack size
(subject to increase-only rule and DEFAULT_STACK_MAX limit).
both static and dynamic linking honor the program header. for dynamic
linking, all libraries loaded at program start, including preloaded
ones, are considered. dlopened libraries are not considered, for
several reasons. extra logic would be needed to defer processing until
the load of the new library is commited, synchronization woud be
needed since other threads may be running concurrently, and the
effectiveness woud be limited since the larger size would not apply to
threads that already existed at the time of dlopen. programs that will
dlopen code expecting a large stack need to declare the requirement
themselves, or pthread_setattr_default_np can be used.
Rich Felker [Wed, 19 Sep 2018 03:11:49 +0000 (23:11 -0400)]
increase default thread stack/guard size
stack size default is increased from 80k to 128k. this coincides with
Linux's hard-coded default stack for the main thread (128k is
initially committed; growth beyond that up to ulimit is contingent on
additional allocation succeeding) and GNU ld's default PT_GNU_STACK
size for FDPIC, at least on sh.
guard size default is increased from 4k to 8k to reduce the risk of
guard page jumping on overflow, since use of just over 4k of stack is
common (PATH_MAX buffers, etc.).
Rich Felker [Wed, 19 Sep 2018 03:06:50 +0000 (23:06 -0400)]
limit the configurable default stack/guard size for threads
limit to 8MB/1MB, repectively. since the defaults cannot be reduced
once increased, excessively large settings would lead to an
unrecoverably broken state. this change is in preparation to allow
defaults to be increased via program headers at the linker level.
creation of threads that really need larger sizes needs to be done
with an explicit attribute.
Rich Felker [Tue, 18 Sep 2018 23:43:52 +0000 (19:43 -0400)]
remove redundant declarations of __default_stacksize, __default_guardsize
these are now declared in pthread_impl.h.
Rich Felker [Tue, 18 Sep 2018 23:41:03 +0000 (19:41 -0400)]
fix benign data race in pthread_attr_init
access to defaults should be protected against concurrent changes.
Rich Felker [Tue, 18 Sep 2018 03:33:03 +0000 (23:33 -0400)]
fix deletion of pthread tsd keys that still have non-null values stored
per POSIX, deletion of a key for which some threads still have values
stored is permitted, and newly created keys must initially hold the
null value in all threads. these properties were not met by our
implementation; if a key was deleted with values left and a new key
was created in the same slot, the old values were still visible.
moreover, due to lack of any synchronization in pthread_key_delete,
there was a TOCTOU race whereby a concurrent pthread_exit could
attempt to call a null destructor pointer for the newly orphaned
value.
this commit introduces a solution based on __synccall, stopping the
world to zero out the values for deleted keys, but only does so lazily
when all key slots have been exhausted. pthread_key_delete is split
off into a separate translation unit so that static-linked programs
which only create keys but never delete them will not pull in the
__synccall machinery.
a global rwlock is added to synchronize creation and deletion of keys
with dtor execution. since the dtor execution loop now has to release
and retake the lock around its call to each dtor, checks are made not
to call the nodtor dummy function for keys which lack a dtor.
Kaarle Ritvanen [Tue, 18 Sep 2018 07:03:27 +0000 (10:03 +0300)]
fix race condition in file locking
The condition occurs when
- thread #1 is holding the lock
- thread #2 is waiting for it on __futexwait
- thread #1 is about to release the lock and performs a_swap
- thread #3 enters the __lockfile function and manages to grab the lock
before thread #1 calls __wake, resetting the MAYBE_WAITERS flag
- thread #1 calls __wake
- thread #2 wakes up but goes again to __futexwait as the lock is
held by thread #3
- thread #3 releases the lock but does not call __wake as the
MAYBE_WAITERS flag is not set
This condition results in thread #2 not being woken up. This patch fixes
the problem by making the woken up thread ensure that the flag is
properly set before going to sleep again.
Mainainer's note: This fixes a regression introduced in commit
c21f750727515602a9e84f2a190ee8a0a2aeb2a1.
Rich Felker [Mon, 17 Sep 2018 02:42:59 +0000 (22:42 -0400)]
getdelim: only grow buffer when necessary, improve OOM behavior
commit
b114190b29417fff6f701eea3a3b3b6030338280 introduced spurious
realloc of the output buffer in cases where the result would exactly
fit in the caller-provided buffer. this is contrary to a strict
reading of the spec, which only allows realloc when the provided
buffer is "of insufficient size".
revert the adjustment of the realloc threshold, and instead push the
byte read by getc_unlocked (for which the adjustment was made) back
into the stdio buffer if it does not fit in the output buffer, to be
read in the next loop iteration.
in order not to leave a pushed-back byte in the stdio buffer if
realloc fails (which would violate the invariant that logical FILE
position and underlying open file description offset match for
unbuffered FILEs), the OOM code path must be changed. it would suffice
move just one byte in this case, but from a QoI perspective, in the
event of ENOMEM the entire output buffer (up to the allocated length
reported via *n) should contain bytes read from the FILE stream.
otherwise the caller has no way to distinguish trunated data from
uninitialized buffer space.
the SIZE_MAX/2 check is removed since the sum of disjoint object sizes
is assumed not to be able to overflow, leaving just one OOM code path.
Rich Felker [Sun, 16 Sep 2018 17:46:46 +0000 (13:46 -0400)]
fix null pointer subtraction and comparison in stdio
morally, for null pointers a and b, a-b, a<b, and a>b should all be
defined as 0; however, C does not define any of them.
the stdio implementation makes heavy use of such pointer comparison
and subtraction for buffer logic, and also uses null pos/base/end
pointers to indicate that the FILE is not in the corresponding (read
or write) mode ready for accesses through the buffer.
all of the comparisons are fixed trivially by using != in place of the
relational operators, since the opposite relation (e.g. pos>end) is
logically impossible. the subtractions have been reviewed to check
that they are conditional the stream being in the appropriate reading-
or writing-through-buffer mode, with checks added where needed.
in fgets and getdelim, the checks added should improve performance for
unbuffered streams by avoiding a do-nothing call to memchr, and should
be negligible for buffered streams.
Rich Felker [Sun, 16 Sep 2018 12:40:46 +0000 (08:40 -0400)]
fix failure of getdelim to set stream orientation on error
if EINVAL or ENOMEM happened before the first getc_unlocked, it was
possible that the stream orientation had not yet been set.
Rich Felker [Sat, 15 Sep 2018 17:45:41 +0000 (13:45 -0400)]
check for kernel support before allowing robust mutex creation
on some archs, linux support for futex operations (including
robust_list processing) that depend on kernelspace CAS is conditional
on a runtime check. as of linux 4.18, this check fails unconditionally
on nommu archs that perform it, and spurious failure on powerpc64 was
observed but not explained. it's also possible that futex support is
omitted entirely, or that the kernel is older than 2.6.17. for most
futex ops, ENOSYS does not yield hard breakage; userspace will just
spin at 100% cpu load. but for robust mutexes, correct behavior
depends on the kernel functionality.
use the get_robust_list syscall to probe for support at the first call
to pthread_mutexattr_setrobust, and block creation of robust mutexes
with a reportable error if they can't be supported.
Benjamin Peterson [Sat, 15 Sep 2018 17:05:24 +0000 (10:05 -0700)]
always reset DST rules during tzset
do_tzset() did't always reset the DST transition rules r0 and r1. That
means the rules from older TZ settings could leak into newer ones.
Rich Felker [Sat, 15 Sep 2018 06:33:08 +0000 (02:33 -0400)]
fix undefined behavior in strto* via FILE buffer pointer abuse
in order to produce FILE objects to pass to the intscan/floatscan
backends without any (prohibitively costly) extra buffering layer, the
strto* functions set the FILE's rend (read end) buffer pointer to an
invalid value at the end of the address space, or SIZE_MAX/2 past the
beginning of the string. this led to undefined behavior comparing and
subtracting the end pointer with the buffer position pointer (rpos).
the comparison issue is easily eliminated by using != instead of <.
however the subtractions require nontrivial changes:
previously, f->shcnt stored the count that would have been read if
consuming the whole buffer, which required an end pointer for the
buffer. the purpose for this was that it allowed reading it and adding
rpos-rend at any time to get the actual count so far, and required no
adjustment at the time of __shgetc (actual function call) since the
call would only happen when reaching the end of the buffer.
to get rid of the dependency on rend, instead offset shcnt by buf-rpos
(start of buffer) at the time of last __shlim/__shgetc call. this
makes for slightly more work in __shgetc the function, but for the
inline macro it's still just as easy to compute the current count.
since the scan helper interfaces used here are a big hack, comments
are added to document their contracts and what's going on with their
implementations.
Benjamin Peterson [Thu, 13 Sep 2018 21:23:42 +0000 (14:23 -0700)]
improve error handling of ttyname_r and isatty
POSIX allows ttyname(_r) and isatty to return EBADF if passed file
descriptor is invalid.
maintainer's note: these are optional ("may fail") errors, but it's
non-conforming for ttyname_r to return ENOTTY when it failed for a
different reason.
Rich Felker [Sat, 15 Sep 2018 03:08:53 +0000 (23:08 -0400)]
add hidden version of &errno accessor function
this significantly improves codegen in functions that need to access
errno but otherwise have no need for a GOT pointer.
we could probably improve it much more by including an inline version
of the &errno accessor function, but that depends on having the
definitions of struct __pthread and __pthread_self(), which at present
would expose a lot more than is appropriate. moving them to a small
tls.h later might make this more reasonable.
Rich Felker [Fri, 14 Sep 2018 20:25:56 +0000 (16:25 -0400)]
fix build regression in sysconf for archs with variable page size
commit
5ce3737931bb411a8d167356d4d0287b53b0cbdc removed the inclusion
of libc.h from this file as spurious, but it's needed to get PAGE_SIZE
on archs where PAGE_SIZE is not a constant defined by limits.h.
Rich Felker [Fri, 14 Sep 2018 17:00:41 +0000 (13:00 -0400)]
drop lazy plural forms init in dcngettext
there is no good reason to wait to find and process the plural rules
for a translated message file until a gettext form requesting plural
rule processing is used. it just imposes additional synchronization,
here in the form of clunky use of atomics.
it looks like there may also have been a race condition where nplurals
could be seen without plural_rule being seen, possibly leading to null
pointer dereference. if so, this commit fixes it.
Rich Felker [Fri, 14 Sep 2018 14:47:16 +0000 (10:47 -0400)]
fix broken atomic store on powerpc[64]
in our memory model, all atomics are supposed to be full barriers;
stores are not release-only. this is important because store is used
as an unlock operation in places where it needs to acquire the waiter
count to determine if a futex wake is needed. at least in the
malloc-internal locks, but possibly elsewhere, soft deadlocks from
missing futex wake (breakable by poking the threads to restart the
syscall, e.g. by attaching a tracer) were reported to occur.
once the malloc lock is replaced with Jens Gustedt's new lock
implementation (see commit
47d0bcd4762f223364e5b58d5a381aaa0cbd7c38),
malloc will not be affected by the issue, but it's not clear that
other uses won't be. reducing the strength of the ordering properties
required from a_store would require a thorough analysis of how it's
used.
to fix the problem, I'm removing the powerpc[64]-specific a_store
definition; now, the top-level atomic.h will implement a_store using
a_barrier on both sides of the store.
it's not clear to me yet whether there might be issues with the other
atomics. it's possible that a_post_llsc needs to be replaced with a
full barrier to guarantee the formal semanics we want, but either way
I think the difference is unlikely to impact the way we use them.
Khem Raj [Thu, 13 Sep 2018 14:00:05 +0000 (07:00 -0700)]
define MAX_HANDLE_SZ for use with name_to_handle_at
MAX_HANDLE_SZ is described in name_to_handle_at() to contain maximum
expected size for a file handle
Rich Felker [Thu, 13 Sep 2018 04:03:20 +0000 (00:03 -0400)]
fix regression with compilers not incorporating C99 DR#289 resolution
as originally published, the C99 syntax only allowed static index
parameter declarators when a gratuitous parameter name was included.
gcc 3, which some projects use for bootstrapping, is a supported C99
compiler, but does not have the fix to the standard incorporated, so
edit the affected declaration to conform to the earlier buggy C99
syntax.
Rich Felker [Thu, 13 Sep 2018 02:43:38 +0000 (22:43 -0400)]
configure: only try -Qunused-arguments for clang
other compilers don't need this option, but gcc 3 and perhaps others
accept it despite not understanding it, then print warnings about it
at build time.
omitting it when not needed will also help shorten the command lines.
Khem Raj [Thu, 13 Sep 2018 01:02:11 +0000 (18:02 -0700)]
wireup linux/name_to_handle_at and name_to_handle_at syscalls
Rich Felker [Wed, 12 Sep 2018 22:49:08 +0000 (18:49 -0400)]
remove vis.h protected-visibility hack
since commit
dc2f368e565c37728b0d620380b849c3a1ddd78f this has been
disabled by default, but was left available in case users unhappy with
the resulting size or performance regressions wanted to try to make it
work. now that we make widespread use of hidden visibility for
internal interfaces, this no longer makes sense. if any costly calls
remain they can be fixed with hidden aliases.
Rich Felker [Wed, 12 Sep 2018 14:19:54 +0000 (10:19 -0400)]
split internal lock API out of libc.h, creating lock.h
this further reduces the number of source files which need to include
libc.h and thereby be potentially exposed to libc global state and
internals.
this will also facilitate further improvements like adding an inline
fast-path, if we want to do so later.
Rich Felker [Wed, 12 Sep 2018 14:10:14 +0000 (10:10 -0400)]
move misplaced __fork_handler declaration
pthread_atfork.c does not actually include pthread_impl.h and has no
reason to, so it wasn't getting the declaration. move it to libc.h
which is already included by both fork.c and pthread_atfork.c. this
makes more sense anyway since the function has little to do with
pthreads anyway aside from the name.
Rich Felker [Wed, 12 Sep 2018 04:28:34 +0000 (00:28 -0400)]
remove spurious inclusion of libc.h for LFS64 ABI aliases
the LFS64 macro was not self-documenting and barely saved any
characters. simply use weak_alias directly so that it's clear what's
being done, and doesn't depend on a header to provide a strange macro.
Rich Felker [Wed, 12 Sep 2018 04:08:09 +0000 (00:08 -0400)]
reduce spurious inclusion of libc.h
libc.h was intended to be a header for access to global libc state and
related interfaces, but ended up included all over the place because
it was the way to get the weak_alias macro. most of the inclusions
removed here are places where weak_alias was needed. a few were
recently introduced for hidden. some go all the way back to when
libc.h defined CANCELPT_BEGIN and _END, and all (wrongly implemented)
cancellation points had to include it.
remaining spurious users are mostly callers of the LOCK/UNLOCK macros
and files that use the LFS64 macro to define the awful *64 aliases.
in a few places, new inclusion of libc.h is added because several
internal headers no longer implicitly include libc.h.
declarations for __lockfile and __unlockfile are moved from libc.h to
stdio_impl.h so that the latter does not need libc.h. putting them in
libc.h made no sense at all, since the macros in stdio_impl.h are
needed to use them correctly anyway.
Rich Felker [Tue, 11 Sep 2018 19:58:46 +0000 (15:58 -0400)]
use wrapper headers to hide most namespaced/internally-public symbols
not all prefixed symbols can be made hidden. some are part of
ABI-compat (e.g. __nl_langinfo_l) and others are ABI as a consequence
of the way copy relocations for weak aliases work in ELF shared
libraries. most, however, can be made hidden.
with this commit, there should be no remaining unintentionally visible
symbols exported from libc.so.
Rich Felker [Tue, 11 Sep 2018 19:26:51 +0000 (15:26 -0400)]
remove __vfork alias
this was added so that posix_spawn and possibly other functionality
could be implemented in terms of vfork, but that turned out to be
unsafe. any such usage needs __clone with proper handling of stack
lifetime.
Rich Felker [Tue, 11 Sep 2018 19:13:35 +0000 (15:13 -0400)]
hide purely dependency-triggering functions in stdio __toread & __towrite
Rich Felker [Tue, 11 Sep 2018 19:10:01 +0000 (15:10 -0400)]
declare __env_rm_add in wrapper stdlib.h
this is perhaps not the ideal place, but no better alternatives stand
out.
Rich Felker [Tue, 11 Sep 2018 19:08:08 +0000 (15:08 -0400)]
hide dependency-triggering pointer object in malloc_usable_size.c
Rich Felker [Tue, 11 Sep 2018 19:07:16 +0000 (15:07 -0400)]
rework malloc_usable_size to use malloc_impl.h
Rich Felker [Tue, 11 Sep 2018 19:03:23 +0000 (15:03 -0400)]
remove unused __futex function and source file
the direct syscall or various thin and mostly-inline wrappers around
it are used instead internally. at some point a public futex function
should be added, but it's not yet clear what the signature should be,
and in the mean time this file is not useful.
Rich Felker [Tue, 11 Sep 2018 18:56:09 +0000 (14:56 -0400)]
hide __pthread_once_full symbol
this is a special case that does not need a declaration, because it's
not even a libc-internal interface between translation units. instead
it's a poor hack around compilers' inability to shrink-wrap critical
code paths. after vis.h was disabled, it became more of a
pessimization on many archs due to the extra layer of machinery to
support a call through the PLT, but now it should be efficient again.
Rich Felker [Tue, 11 Sep 2018 18:49:22 +0000 (14:49 -0400)]
declare and make hidden additional internal init/exit symbols
Rich Felker [Tue, 11 Sep 2018 18:28:57 +0000 (14:28 -0400)]
declare and make hidden additional internal stdio symbols
Rich Felker [Tue, 11 Sep 2018 18:21:06 +0000 (14:21 -0400)]
move declaration and apply hidden visibility to __utc string
Rich Felker [Tue, 11 Sep 2018 18:15:03 +0000 (14:15 -0400)]
declare and make hidden more internal locale functions
Rich Felker [Tue, 11 Sep 2018 18:09:20 +0000 (14:09 -0400)]
remove unused __getdents, rename and move file
the __-prefixed filename does not make sense when the only purpose of
this file is implementing a public function that's not used as a
backend for implementing the standard dirent functions.
Rich Felker [Tue, 11 Sep 2018 18:02:58 +0000 (14:02 -0400)]
remove or make static various unused __-prefixed symbols
Rich Felker [Tue, 11 Sep 2018 17:57:17 +0000 (13:57 -0400)]
move additional pthread internal declarations to pthread_impl.h, hide
these were overlooked for various reasons in earlier stages.
Rich Felker [Tue, 11 Sep 2018 16:32:46 +0000 (12:32 -0400)]
apply hidden visibility to various remaining internal interfaces
Rich Felker [Tue, 11 Sep 2018 15:57:31 +0000 (11:57 -0400)]
apply hidden visibility to sigreturn code fragments
these were overlooked in the declarations overhaul work because they
are not properly declared, and the current framework even allows their
declared types to vary by arch. at some point this should be cleaned
up, but I'm not sure what the right way would be.
Rich Felker [Tue, 11 Sep 2018 15:40:51 +0000 (11:40 -0400)]
apply hidden visibility to pthread internals
Rich Felker [Tue, 11 Sep 2018 15:39:07 +0000 (11:39 -0400)]
apply hidden visibility to stdio internals
Rich Felker [Tue, 11 Sep 2018 15:16:55 +0000 (11:16 -0400)]
apply hidden visibility to internal time[zone] implementation functions
Rich Felker [Tue, 11 Sep 2018 15:04:35 +0000 (11:04 -0400)]
apply hidden visibility to internal math functions
this makes significant differences to codegen on archs with an
expensive PLT-calling ABI; on i386 and gcc 7.3 for example, the sin
and sinf functions no longer touch call-saved registers or the stack
except for pushing outgoing arguments. performance is likely improved
too, but no measurements were taken.
Rich Felker [Tue, 11 Sep 2018 03:26:40 +0000 (23:26 -0400)]
overhaul internally-public declarations using wrapper headers
commits leading up to this one have moved the vast majority of
libc-internal interface declarations to appropriate internal headers,
allowing them to be type-checked and setting the stage to limit their
visibility. the ones that have not yet been moved are mostly
namespace-protected aliases for standard/public interfaces, which
exist to facilitate implementing plain C functions in terms of POSIX
functionality, or C or POSIX functionality in terms of extensions that
are not standardized. some don't quite fit this description, but are
"internally public" interfacs between subsystems of libc.
rather than create a number of newly-named headers to declare these
functions, and having to add explicit include directives for them to
every source file where they're needed, I have introduced a method of
wrapping the corresponding public headers.
parallel to the public headers in $(srcdir)/include, we now have
wrappers in $(srcdir)/src/include that come earlier in the include
path order. they include the public header they're wrapping, then add
declarations for namespace-protected versions of the same interfaces
and any "internally public" interfaces for the subsystem they
correspond to.
along these lines, the wrapper for features.h is now responsible for
the definition of the hidden, weak, and weak_alias macros. this means
source files will no longer need to include any special headers to
access these features.
over time, it is my expectation that the scope of what is "internally
public" will expand, reducing the number of source files which need to
include *_impl.h and related headers down to those which are actually
implementing the corresponding subsystems, not just using them.
Rich Felker [Tue, 11 Sep 2018 03:10:18 +0000 (23:10 -0400)]
declare __getopt_msg in stdio_impl.h
it's not ideal, but the function is essentially an extended stdio
function specialized to getopt's needs. the only reason it exists is
avoiding pulling printf code into every program using getopt.
Rich Felker [Tue, 11 Sep 2018 03:04:42 +0000 (23:04 -0400)]
use lighter internal stdio lock in getopt error printing
the public flockfile interface is significantly heavier because it has
to handle the possibility of caller returning or thread exiting while
holding the lock.
Rich Felker [Tue, 11 Sep 2018 00:42:35 +0000 (20:42 -0400)]
add crypt_des header for declarations shared with encrypt function
Rich Felker [Tue, 11 Sep 2018 00:35:58 +0000 (20:35 -0400)]
make mkostemps source file include the header for its declaration
Rich Felker [Tue, 11 Sep 2018 00:28:47 +0000 (20:28 -0400)]
move __memalign declaration to malloc_impl.h
the malloc-implementation-private header is the only right place for
this, because, being in the reserved namespace, __memalign is not
interposable and thus not valid to use anywhere else. anything outside
of the malloc implementation must call an appropriate-namespace public
function (aligned_alloc or posix_memalign).
Rich Felker [Mon, 10 Sep 2018 20:25:49 +0000 (16:25 -0400)]
use hidden visibility for sh __unmapself backends
Rich Felker [Mon, 10 Sep 2018 20:13:29 +0000 (16:13 -0400)]
rework mechanism for posix_spawnp calling posix_spawn
previously, a common __posix_spawnx backend was used that accepted an
additional argument for the execve variant to call in the child. this
moderately bloated up the posix_spawn function, shuffling arguments
between stack and/or registers to call a 7-argument function from a
6-argument one.
instead, tuck the exec function pointer in an unused part of the
(large) pthread_spawnattr_t structure, and have posix_spawnp duplicate
the attributes and fill in a pointer to __execvpe. the net code size
change is minimal, but the weight is shifted to the "heavier" function
which already pulls in more dependencies.
as a bonus, we get rid of an external symbol (__posix_spawnx) that had
no really good place for a declaration because it shouldn't have
existed to begin with.
Rich Felker [Mon, 10 Sep 2018 19:51:44 +0000 (15:51 -0400)]
make arch __fesetround backends hidden
these are not public interfaces and do not match the public function,
but delegate argument checking to it.
Rich Felker [Mon, 10 Sep 2018 19:42:03 +0000 (15:42 -0400)]
make arch __set_thread_area backends hidden
this is not a public interface, and does not even necessarily match
the syscall on all archs that have a syscall by that name.
on archs where it's implemented in C, no action on the source file is
needed; the hidden declaration in pthread_arch.h suffices.
Rich Felker [Mon, 10 Sep 2018 19:36:33 +0000 (15:36 -0400)]
make arch __clone backends hidden
these are not a public interface and are not intended to be callable
from anywhere but the public clone function or other places in libc.
Rich Felker [Sun, 9 Sep 2018 05:12:30 +0000 (01:12 -0400)]
move tlsdesc and internal dl function declarations to dynlink.h
Rich Felker [Sun, 9 Sep 2018 04:55:28 +0000 (00:55 -0400)]
add internal header for declaring __pleval function (used by gettext)
locale_impl.h could have been used, but this function is completely
independent of anything else, and preserving that property seems nice.
Rich Felker [Sun, 9 Sep 2018 04:53:11 +0000 (00:53 -0400)]
move __stdio_exit_needed to stdio_impl.h
this functions is glue for linking dependency logic.
Rich Felker [Sun, 9 Sep 2018 04:34:31 +0000 (00:34 -0400)]
move __loc_is_allocated declaration to locale_impl.h
Rich Felker [Sat, 8 Sep 2018 22:46:06 +0000 (18:46 -0400)]
move declarations of tls setup/access functions to pthread_impl.h
it's already included in all places where these are needed, and aside
from __tls_get_addr, they're all implementation internals.
Rich Felker [Sat, 8 Sep 2018 03:02:40 +0000 (23:02 -0400)]
add and use internal header for *rand48 lcg
Rich Felker [Sat, 8 Sep 2018 02:52:03 +0000 (22:52 -0400)]
move __strftime_fmt_1 declaration to time_impl.h
this is a helper function from strftime that's also used by wcsftime.
Rich Felker [Sat, 8 Sep 2018 02:48:19 +0000 (22:48 -0400)]
move __tm_to_tzname declaration to time_impl.h with related functions
this function was added later for strftime use and the existence of
time_impl.h as the appropriate place for it seems to have been
overlooked.
Rich Felker [Sat, 8 Sep 2018 02:36:12 +0000 (22:36 -0400)]
remove unused code from strcpy.c
Rich Felker [Sat, 8 Sep 2018 00:03:32 +0000 (20:03 -0400)]
move __res_msend_rc declaration to lookup.h
unlike the other res/dn functions, this one is tied to struct
resolvconf which is not a public interface, so put it in the private
header for its subsystem.
Rich Felker [Fri, 7 Sep 2018 23:49:21 +0000 (19:49 -0400)]
fix type-mismatched declarations of __nl_langinfo_l in source files
obviously the type "should be" const, but it inherited non-const from
the standard nl_langinfo_l.
Rich Felker [Fri, 7 Sep 2018 20:20:39 +0000 (16:20 -0400)]
for c11 mtx and cnd functions, use externally consistent type names
despite looking like undefined behavior, the affected code is correct
both before and after this patch. the pairs mtx_t and pthread_mutex_t,
and cnd_t and pthread_cond_t, are not mutually compatible within a
single translation unit (because they are distinct untagged aggregate
instances), but they are compatible with an object of either type from
another translation unit (6.2.7 ΒΆ1), and therefore a given translation
unit can choose which one it wants to use.
in the interest of being able to move declarations out of source files
to headers that facilitate checking, use the pthread type names in
declaring the namespace-safe versions of the pthread functions and
cast the argument pointer types when calling them.