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commit a90d9da1d1b14d81c4f93e1a6d1a686c3312e4ba made fgetws look for
changes to errno by fgetwc to detect encoding errors, since ISO C did
not allow the implementation to set the stream's error flag in this
case, and the fgetwc interface did not admit any other way to detect
the error. however, the possibility of fgetwc setting errno to EILSEQ
in the success path was overlooked, and in fact this can happen if the
buffer ends with a partial character, causing mbtowc to be called with
only part of the character available.
since that change was made, the C standard was amended to specify that
fgetwc set the stream error flag on encoding errors, and commit
511d70738bce11a67219d0132ce725c323d00e4e made it do so. thus, there is
no longer any need for fgetws to poke at errno to handle encoding
errors.
this commit reverts commit a90d9da1d1b14d81c4f93e1a6d1a686c3312e4ba
and thereby fixes the problem.
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this bug goes back to commit 1cc81f5cb0df2b66a795ff0c26d7bbc4d16e13c6
where zoneinfo file support was first added. in scan_trans, which
searches for the appropriate local time/dst rule in effect at a given
time, times prior to the second transition time caused the -1 slot of
the index to be read to determine the previous rule in effect. this
memory was always valid (part of another zoneinfo table in the mapped
file) but the byte value read was then used to index another table,
possibly going outside the bounds of the mmap. most of the time, the
result was limited to misinterpretation of the rule in effect at that
time (pre-1900s), but it could produce a crash if adjacent memory was
not readable.
the root cause of the problem, however, was that the logic for this
code path was all wrong. as documented in the comment, times before
the first transition should be treated as using the lowest-numbered
non-dst rule, or rule 0 if no non-dst rules exist. if the argument is
in units of local time, however, the rule prior to the first
transition is needed to determine if it falls before or after it, and
that's where the -1 index was wrongly used.
instead, use the documented logic to find out what rule would be in
effect before the first transition, and apply it as the offset if the
argument was given in local time.
the new code has not been heavily tested, but no longer performs
potentially out-of-bounds accesses, and successfully handles the 1883
transition from local mean time to central standard time in the test
case the error was reported for.
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these are specified to use the sign of the imaginary part of the input
as the sign of zero in the result, but wrongly copied the sign of the
real part.
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this is a POSIX requirement. we previously relied on the underlying fd
(or other backend) seek operation to produce the error, but since
linux lseek now supports other seek modes (SEEK_DATA and SEEK_HOLE)
which do not interact well with stdio buffering, this is insufficient.
instead, explicitly check whence before performing any operations.
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these characters combine onto a base character (initial) and therefore
need to have width 0. the original binary-search implementation of
wcwidth handled them correctly, but a regression was introduced in
commit 1b0ce9af6d2aa7b92edaf3e9c631cb635bae22bd by generating the new
tables from unicode without noticing that the classification logic in
use (unicode character category Mn/Me/Cf) was insufficient to catch
these characters.
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strtod_l, strtof_l, and strtold_l originally existed only as
glibc-ABI-compat symbols. as noted in the commit which added them,
17a60f9d327c6f8b5707a06f9497d846e75c01f2, making them aliases for the
non-_l functions was a hack and not appropriate if they ever became
public API.
unfortunately, commit 35eb1a1a9b97577e113240cd65bf9fc44b8df030 did
make them public without undoing the hack. fix that now by moving the
the _l functions to their own file as wrappers that just throw away
the locale_t argument.
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commit 7be59733d71ada3a32a98622507399253f1d5e48 introduced the
hwcap-based branches to support the SPE FPU, but wrongly coded them as
bitwise tests on the computed address of __hwcap, not a value loaded
from that address. replace the add with indexed load to fix it.
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the snd_pcm_mmap_control struct used with SNDRV_PCM_IOCTL_SYNC_PTR was
mistakenly defined in the kernel uapi with "before u32" padding both
before and after the first u32 member. our conversion between the
modern struct and the legacy time32 struct was written without
awareness of that mistake, and assumed the time64 version of the
struct was the intended form with padding to match the layout on
64-bit archs. as a result, the struct was not converted correctly when
running on old kernels, with audio glitches as the likely result.
this was discovered thanks to a related bug in the kernel, whereby
32-bit userspace running on a 64-bit kernel also suffered from the
types mismatching. the mistaken layout is now the ABI and can't be
changed -- or at least making a new ioctl to change it would just
result in a worse situation.
our conversion here is changed to treat the snd_pcm_mmap_control
substruct as two separate substructs at locations dependent on
endianness (since the displacement depends on endianness), using the
existing conversion framework.
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we make qsort a wrapper by providing a wrapper_cmp function that uses
the extra argument as a function pointer. should be optimized to a tail
call on most architectures, as long as it's built with
-fomit-frame-pointer, so the performance impact should be minimal.
to keep the git history clean, for now qsort_r is implemented in qsort.c
and qsort is implemented in qsort_nr.c. qsort.c also received a few
trivial cleanups, including replacing (*cmp)() calls with cmp().
qsort_nr.c contains only wrapper_cmp and qsort as a qsort_r wrapper
itself.
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When the soft-float ABI for PowerPC was added in commit
5a92dd95c77cee81755f1a441ae0b71e3ae2bcdb, with Freescale cpus using
the alternative SPE FPU as the main use case, it was noted that we
could probably support hard float on them, but that it would involve
determining some difficult ABI constraints. This commit is the
completion of that work.
The Power-Arch-32 ABI supplement defines the ABI profiles, and indeed
ATR-SPE is built on ATR-SOFT-FLOAT. But setjmp/longjmp compatibility
are problematic for the same reason they're problematic on ARM, where
optional float-related parts of the register file are "call-saved if
present". This requires testing __hwcap, which is now done.
In keeping with the existing powerpc-sf subarch definition, which did
not have fenv, the fenv macros are not defined for SPE and the SPEFSCR
control register is left (and assumed to start in) the default mode.
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both passing a null pointer to memcpy with length 0, and adding 0 to a
null pointer, are undefined. in some sense this is 'benign' UB, but
having it precludes use of tooling that strictly traps on UB. there
may be better ways to fix it, but conditioning the operations which
are intended to be no-ops in the k==0 case on k being nonzero is a
simple and safe solution.
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len is unsigned and can never be smaller than 0. though unlikely, an
error in read() would have lead to an out of bounds write to name.
Reported-by: Michael Forney <mforney@mforney.org>
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due to historical reasons, the mips signal set has 128 bits rather
than 64 like on every other arch. this was special-cased correctly, at
least for 32-bit mips, at one time, but was inadvertently broken in
commit 7c440977db9444d7e6b1c3dcb1fdf4ee49ca4158, and seems never to
have been right on mips64/n32.
as consequenct of this bug, applications making use of high realtime
signal numbers on mips may have been able to execute application code
in contexts where doing so was unsafe.
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previously, the contents of the TZ variable were considered a
candidate for a file/path name only if they began with a colon or
contained a slash before any comma. the latter was very sloppy logic
to avoid treating any valid POSIX TZ string as a file name, but it
also triggered on values that are not valid POSIX TZ strings,
including 3-letter timezone names without any offset.
instead, only treat the TZ variable as POSIX form if it begins with a
nonzero standard time name followed by +, -, or a digit.
also, special case GMT and UTC to always be treated as POSIX form
(with implicit zero offset) so that a stray file by the same name
cannot break software that depends on setting TZ=GMT or TZ=UTC.
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based on the pthread_setname_np implementation
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POSIX places an obscure requirement on popen which is like a limited
version of close-on-exec:
"The popen() function shall ensure that any streams from previous
popen() calls that remain open in the parent process are closed in
the new child process."
if the POSIX-future 'e' mode flag is passed, producing a pipe FILE
with FD_CLOEXEC on the underlying pipe, this requirement is
automatically satisfied. however, for applications which use multiple
concurrent popen pipes but don't request close-on-exec, fd leaks from
earlier popen calls to later ones could produce deadlock situations
where processes are waiting for a pipe EOF that will never happen.
to fix this, iterate through all open FILEs and add close actions for
those obtained from popen. this requires holding a lock on the open
file list across the posix_spawn call so that additional popen FILEs
are not created after the list is traversed. note that it's still
possible for another popen call to start and create its pipe while the
lock is held, but such pipes are created with O_CLOEXEC and only drop
close-on-exec status (when 'e' flag is omitted) under control of the
lock.
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the newly allocated FILE * has not yet leaked to the application and
is only visible to stdio internals until popen returns. since we do
not change any fields of the structure observed by libc internals,
only the pipe_pid member, locking is not necessary.
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With mallocng, calling posix_memalign() or aligned_alloc() will
SIGSEGV if the internal malloc() call returns NULL. This does not
occur with oldmalloc, which explicitly checks for allocation failure.
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this is a Linux-specific function and not covered by POSIX's
requirements for which interfaces are cancellation points, but glibc
makes it one and existing software relies on it being one.
at some point a review for similar functions that should be made
cancellation points should be done.
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dl_iterate_phdr was wrongly reporting the address of the DSO's PT_TLS
image rather than the calling thread's instance of the TLS. the man
page, which is essentially normative for a nonstandard function of
this sort, clearly specifies the latter. it does not clarify where
exactly within/relative-to the image the pointer should point, but the
reasonable thing to do is match the ABI's DTP offset, and this seems
to be what other implementations do.
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popen was special-casing the possibility (only possible when the
parent closed stdin and/or stdout) that the child's end of the pipe
was already on the final desired fd number, in which case there was no
way to get rid of its close-on-exec flag in the child. commit
6fc6ca1a323bc0b6b9e9cdc8fa72221ae18fe206 made this unnecessary by
implementing the POSIX-future requirement that dup2 file actions with
equal source and destination fd values remove the close-on-exec flag.
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this makes it possible to perform actions on file actions objects with
a libc-internal lock held without creating lock order relationships
that are silently imposed on an application-provided malloc.
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the historical function was specified to return an empty string in the
caller-provided buffer, not a null pointer, to indicate error when the
argument is non-null. only when the argument is null should it return
a null pointer on error.
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getpwuid_r can return 0 but without a result in the case where there
was no error but no record exists. in that case cuserid was treating
it as success and copying junk out of pw.pw_name to the output buffer.
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checking the length also drops the need to pull in snprintf.
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this function was removed from the standard in 2001 but appeared in
SUSv2 with an obligation to support calls with a null pointer
argument, using a static buffer.
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the threshold was wrong so expm1f overflowed to inf a bit too early
and on most targets uint32_t compare is faster than float compare so
use that.
this also fixes sinhf incorrectly returning nan for some values where
the internal expm1f overflowed.
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on some negative inputs (e.g. -0x1.1e6ae8p+5) acoshf failed to return
nan. ensure that negative inputs result nan without introducing new
branches. this was tried before in
commit 101e6012856918440b5d7474739c3fc22a8d3b85
math: fix acoshf on negative values
but that fix was wrong. there are 3 formulas used:
log1p(x-1 + sqrt((x-1)*(x-1)+2*(x-1)))
log(2*x - 1/(x+sqrt(x*x-1)))
log(x) + 0.693147180559945309417232121458176568
the first fails on large negative inputs (may compute log1p(0) or
log1p(inf)), the second one fails on some mid range or large negative
inputs (may compute log(large) or log(inf)) and the last one fails on
-0 (returns -inf).
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the omission of the flag here seems to have been an oversight when the
function was added in 8fb28b0b3e7a5e958fb844722a4b2ef9bc244af1
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as an outcome of Austin Group issue #385, future versions of the
standard will require free not to alter the value of errno. save and
restore it individually around the calls to madvise and munmap so that
the cost is not imposed on calls to free that do not result in any
syscall.
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commit 8d37958d58cf36f53d5fcc7a8aa6d633da6071b2 inadvertently broke
oldmalloc by having it implement __libc_malloc rather than
__libc_malloc_impl.
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as an outcome of Austin Group issue #385, future versions of the
standard will require free not to alter the value of errno. save and
restore it individually around the calls to madvise and munmap so that
the cost is not imposed on calls to free that do not result in any
syscall.
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commit 7586360badcae6e73f04eb1b8189ce630281c4b2 removed the unused
arguments from the definition of __libc_start_main, making it
incompatible with the declaration at the point of call, which still
passed 6 arguments. calls with mismatched function type have undefined
behavior, breaking LTO and any other tooling that checks for function
signature mismatch.
removing the extra arguments from the point of call (crt1) is not an
option for fixing this, since that would be a change in ABI surface
between application and libc.
adding back the extra arguments requires some care. on archs that pass
arguments on the stack or that reserve argument spill space for the
callee on the stack, it imposes an ABI requirement on the caller to
provide such space. the modern crt1.c entry point provides such space,
but originally there was arch-specific asm for the call to
__libc_start_main. the last of this asm was removed in commit
6fef8cafbd0f6f185897bc87feb1ff66e2e204e1, and manual review of the
code removed and its prior history was performed to check that all
archs/variants passed the legacy init/fini/ldso_fini arguments.
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these functions are specified to fail with EBADF on negative fd
arguments. apart from close, they are also specified to fail if the
value exceeds OPEN_MAX, but as written it is not clear that this
imposes any requirement when OPEN_MAX is not defined, and it's
undesirable to impose a dynamic limit (via setrlimit) here since the
limit at the time of posix_spawn may be different from the limit at
the time of setting up the file actions. this may require revisiting
later.
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commit 2412638bb39eb799b2600393bbd71cca8ae96bb2 got the size of struct
v4l2_event wrong and failed to account for the fact that the old
struct might be either 120 bytes with time misaligned mod 8, or 128
bytes with time aligned mod 8, due to the contained union having
64-bit members whose alignment is arch-dependent.
rather than adding new logic to handle the differences, use an actual
stripped-down version of the structure in question to derive the ioctl
number, size, and offsets.
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commit 2412638bb39eb799b2600393bbd71cca8ae96bb2 got the size of struct
v4l2_buffer wrong and omitted the tv_usec member slot from the offset
list, so the ioctl numbers never matched and fallback code path was
never taken. this caused the affected ioctls to fail with ENOTTY on
kernels not new enough to have the native time64 ioctls.
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this is necessary for MT-fork correctness now that the code runs under
locale lock. it would not be hard to avoid, but __get_locale is
already using libc-internal malloc anyway. this can be reconsidered
during locale overhaul later if needed.
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in general, pthread_once is not compatible with MT-fork constraints
(commit 167390f05564e0a4d3fcb4329377fd7743267560). here it actually no
longer matters, because it's now called with a lock held, but since
the lock is held it's pointless to use pthread_once.
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this allows the lock to be shared with setlocale, eliminates repeated
per-category lock/unlock in newlocale, and will allow the use of
pthread_once in newlocale to be dropped (to be done separately).
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the intent here is just to scan at least l bytes forward for the end
of the haystack and at least some decent minimum to avoid doing it
over and over if the needle is short, with no need to be precise. the
comment erroneously stated this as an estimate for MIN when it's
actually an estimate for MAX.
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pthread_once is not compatible with MT-fork constraints (commit
167390f05564e0a4d3fcb4329377fd7743267560) and is not needed here
anyway; we already have a lock suitable for initialization.
while changing this, fix a corner case where AT_MINSIGSTKSZ gives a
value that's more than MINSIGSTKSZ but by a margin of less than
2048, thereby causing the size to be reduced. it shouldn't matter but
the intent was to be the larger of a 2048-byte margin over the legacy
fixed minimum stack requirement or a 512-byte margin over the minimum
the kernel reports at runtime.
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this change should have been made when priority inheritance mutex
support was added. if priority protection is also added at some point
the implementation will need to change and will probably no longer be
a simple bit shuffling.
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both __clone and __syscall_cp_asm failed to restore the original value
of r6 after using it as a syscall argument register. the extent of
breakage is not known, and in some cases may be mitigated by the only
callers being internal to libc; if they used r6 but no longer needed
its value after the call, they may not have noticed the problem.
however at least posix_spawn (which uses __clone) was observed
returning to the application with the wrong value in r6, leading to
crash.
since the call frame ABI already provides a place to spill registers,
fixing this is just a matter of using it. in __clone, we also
spuriously restore r6 in the child, since the parent branch directly
returns to the caller. this takes the value from an uninitialized slot
of the child's stack, but is harmless since there is no caller to
return to in the child.
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reallocarray is an extension introduced by OpenBSD, which introduces
calloc overflow checking to realloc.
glibc 2.28 introduced support for this function behind _GNU_SOURCE,
while glibc 2.29 allows its usage in _DEFAULT_SOURCE.
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inability to use realpath in chroot/container without procfs access
and at early boot prior to mount of /proc has been an ongoing issue,
and it turns out realpath was one of the last remaining interfaces
that needed procfs for its core functionality. during investigation
while reimplementing, it was determined that there were also serious
problems with the procfs-based implementation. most seriously it was
unsafe on pre-O_PATH kernels, and unlike other places where O_PATH was
used, the unsafety was hard or impossible to fix because O_NOFOLLOW
can't be used (since the whole purpose was to follow symlinks).
the new implementation is a direct one, performing readlink on each
path component to resolve it. an explicit stack, as opposed to
recursion, is used to represent the remaining components to be
processed. the stack starts out holding just the input string, and
reading a link pushes the link contents onto the stack.
unlike many other implementations, this one does not call getcwd
initially for relative pathnames. instead it accumulates initial ..
components to be applied to the working directory if the result is
still a relative path. this avoids calling getcwd (which may fail) at
all when symlink traversal will eventually yield an absolute path. it
also doesn't use any form of stat operation; instead it arranges for
readlink to tell it when a non-directory is used in a context where a
directory is needed. this minimizes the number of syscalls needed,
avoids accessing inodes when the directory table suffices, and reduces
the amount of code pulled in for static linking.
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commit d1507646975cbf6c3e511ba07b193f27f032d108 added support for null
argument in oldmalloc and was overlooked when switching to mallocng.
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