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this is a POSIX requirement.
also remove the gratuitous locking shenanigans and simply access f->fd
under control of the lock. there is no advantage to not doing so, and
it made the correctness non-obvious at best.
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this is a POSIX requirement.
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__aeabi_read_tp used to call c code, but that was incorrect as the
arm runtime abi specifies special pcs for this function: it is only
allowed to clobber r0, ip, lr and cpsr.
maintainer's note: the old code explicitly saved and restored all
general-purpose registers which are call-clobbered in the normal
calling convention, so it's unlikely that any real-world compilers
produced code that could break. however theoretically they could have
chosen to use floating point registers, in which case the caller's
values of those registers would be clobbered.
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commit 201995f382cc698ae19289623cc06a70048ffe7b introduced a hack
utilizing the signedness of character constants at the preprocessor
level to avoid depending on the gcc-specific __CHAR_UNSIGNED__ predef.
while this trick works on gcc and presumably other compilers being
used, it's not clear that the behavior it depends on is actually
conforming. C11 6.4.4.4 ¶10 defines character constants as having type
int, and 6.10.1 ¶4 defines preprocessor #if arithmetic to take place
in intmax_t or uintmax_t, depending on the signedness of the integer
operand types, and it is specified that "this includes interpreting
character constants".
if character literals had type char and just promoted to int, it would
be clear that when char is unsigned they should behave as uintmax_t at
the preprocessor level. however, as written the text of the standard
seems to require that character constants always behave as intmax_t,
corresponding to int, at the preprocessor level.
since there is a good deal of ambiguity about the correct behavior and
a risk that compilers will disagree or that an interpretation may
mandate a change in the behavior, do not rely on it for defining
CHAR_MIN and CHAR_MAX correctly. instead, use the signedness of the
value (as opposed to the type) of '\xff', which will be positive if
and only if plain char is unsigned. this behavior is clearly
specified, and the specific case '\xff' is even used in an example,
under 6.4.4.4 of the standard.
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with async cancellation enabled, pthread_cancel(pthread_self())
deadlocked due to pthread_kill holding killlock which is needed by
pthread_exit.
this could be solved by making pthread_kill block signals around the
critical section, at least when the target thread is itself, but the
issue only arises for cancellation, and otherwise would just be
imposing unnecessary cost.
instead just have pthread_cancel explicitly check for async
self-cancellation and call pthread_exit(PTHREAD_CANCELED) directly
rather than going through the signal machinery.
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This manifests itself in mktime if tm_isdst = 1 and the current TZ= is
a POSIX timezone specification. mktime would see that tm_isdst was set
to 0 by __secs_to_zone, and subtract 'oppoff' (dst_off) - gmtoff from
the resultant time. This meant that mktime returned a time that was
exactly double the GMT offset of the desired timezone when tm_isdst
was = 1.
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commit 610c5a8524c3d6cd3ac5a5f1231422e7648a3791 changed the thread
pointer setup so tp points at the end of the pthread struct on arm,
but failed to update __aeabi_read_tp so it was off by 8.
this broke tls access in code that is compiled with -mtp=soft, which
is the default when target arch is pre armv6k or thumb1.
maintainer's note: no release versions are affected.
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this is an obsolete error code from RFS, an obsolete predecessor of
NFS. POSIX documents it only as "Reserved", but maintains the
requirement that it be defined. as long as it is defined, it needs a
string for strerror to produce; the one chosen matches glibc and
documentation from other language runtimes I could find.
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the code to perform rounding to the desired precision wrongly assumed
the long double mantissa was an integral number of nibbles (hex
digits) in length. this is true for 80-bit extended precision (64-bit
mantissa) but not for double (53) or quad (113).
scale the rounding value by 1<<(LDBL_MANT_DIG%4) to compensate.
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the text of the specification for getopt's handling of options that
require an argument, which requires updating optarg and optind, does
not exclude the error case where the end of the argument list has been
reached. in that case, it is expected that optarg be assigned
argv[argc] (normally null) and optind be incremented by 2, resulting
in a value of argc+1.
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commit 98c9af500125df41fdb46d7e384b00982d72493a wrongly claimed they
do not need to be valid for such usage, but the last sentence of C11
7.1.4 ¶1 imposes a broad requirement that all macros specified as
integer constant expressions also need to be valid for #if.
simply write the value out explicitly. there is no value here in
pretending that the width of int will vary.
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POSIX requires the symlink function to fail with ENAMETOOLONG if the
link contents to be written exceed SYMLINK_MAX in length, but neither
Linux nor our syscall wrapper code enforce this. the value 255 for
SYMLINK_MAX is not meaningful and does not seem to have been motivated
by anything except perhaps a wrong assumption that a definition was
mandatory. it has been present (though moving through bits to
top-level limits.h) since the beginning of the project history.
[f]pathconf is entitled to return -1 as the limit for conf names for
which there is no hard limit, with the usual POSIX note that an
indefinite limit does not imply an infinite limit. in principle we
might should report a limit for filesystems that impose one, but such
functionality is not currently present for any of the pathconf limits,
and adding it is beyond the scope of fixing the incorrect limit.
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Call SYS_exit on return from fn in __clone. This is the expected
behavior of this function. Without this the child task will crash on
return from fn, since it will return to nowhere.
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due to moved code, commit b8742f32602add243ee2ce74d804015463726899
inadvertently used the return value of __clone, rather than the return
value of SYS_sched_setscheduler in the new thread, to check whether it
needed to report failure. since a successful __clone returns the tid
of the new thread, which is never zero, this caused pthread_create
always to return with an invalid error number in the code path for
PTHREAD_EXPLICIT_SCHED.
this regression was not present in any releases.
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the sign character produced came from the sign of tm_gmtoff/3600 as an
integer division, which is zero for negative offsets smaller in
magnitude than 3600. instead of printing the hours and minutes as
separate fields, print them as a single value of the form
hours*100+minutes, which naturally has the correct sign.
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the specfile for the wrapper was written assuming output is pie only
if -pie appears on the command line. recent (and older patched)
versions of gcc can be configured to produce pie output by default,
adn when used with such a toolchain, the wrapper linked the wrong
startfiles (crt*) containing pic-incompatible code.
rather than trying to figure out gcc's default, simply always use the
pic-compatible start files.
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this fixes a major gap in the intended functionality of
pthread_setattr_default_np. if application/library code creating a
thread does not pass a null attribute pointer to pthread_create, but
sets up an attribute object to change other properties while leaving
the stack alone, the created thread will get a stack with size
DEFAULT_STACK_SIZE. this makes pthread_setattr_default_np useless for
working around stack overflow issues in such applications, and leaves
a major risk of regression if previously-working code switches from
using a null attribute pointer to an attribute object.
this change aligns the behavior more closely with the glibc
pthread_setattr_default_np functionality too, albeit via a different
mechanism. glibc encodes "default" specially in the attribute object
and reads the actual default at thread creation time. with this
commit, we now copy the current default into the attribute object at
pthread_attr_init time, so that applications that query the properties
of the attribute object will see the right values.
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maintainer's note: the key observation here is that the compared
element is the first slot of the second ceil(half) of the array, and
thus can be removed for further comparison when it does not match, so
that we descend into the second ceil(half)-1 rather than ceil(half)
elements. this change ensures that nel strictly decreases with each
iteration, so that the case of != but nel==1 does not need to be
special-cased anymore.
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maintainer's note: while musl does not use the linux kernel headers,
it does provide these three sys/* headers which do nothing but include
the corresponding linux/* headers, since the sys/* versions are the
ones documented for application use (and they arguably provide
interfaces that are not linux-specific but common to other unices).
these headers should probably not be provided by libc (rather by a
separate package), but as long as they are, use the bits header
framework as an aid to out-of-tree ports of musl for non-linux systems
that want to implement them in some other way.
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maintainer's note: at some point, probably long before linux separated
the uapi headers, it was the case, or at least I believed it was the
case, that linux/types.h was unsafe to include from userspace. thus,
the inclusion guard macro _LINUX_TYPES_H was defined in sys/kd.h to
prevent linux/kd.h from including linux/types.h (which it spuriously
includes but does not use). as far as I can tell, whatever problem
this was meant to solve does not seem to have been present for a long
time, and the hack was not done correctly anyway, so removing it is
the right thing to do.
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commit 32482f61da7650ff10741bd5aedd66bbc3ea165b reduced the number of
int members before the dirent buf from 4 to 3, thereby misaligning it
mod sizeof(off_t), producing invalid accesses on any arch where
alignof(off_t)==sizeof(off_t).
rather than re-adding wasted padding, reorder the struct to meet the
requirement and add a comment and static assertion to prevent this
from getting broken again.
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sys/ptrace.h is target specific, use bits/ptrace.h to add target
specific macro definitions.
these macros are kept in the generic sys/ptrace.h even though some
targets don't support them:
PTRACE_GETREGS
PTRACE_SETREGS
PTRACE_GETFPREGS
PTRACE_SETFPREGS
PTRACE_GETFPXREGS
PTRACE_SETFPXREGS
so no macro definition got removed in this patch on any target. only
s390x has a numerically conflicting macro definition (PTRACE_SINGLEBLOCK).
the PT_ aliases follow glibc headers, otherwise the definitions come
from linux uapi headers except ones that are skipped in glibc and
there is no real kernel support (s390x PTRACE_*_AREA) or need special
type definitions (mips PTRACE_*_WATCH_*) or only relevant for linux
2.4 compatibility (PTRACE_OLDSETOPTIONS).
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new in linux v3.1 commit 3544d72a0e10d0aa1c1bd59ed77a53a59cdc12f7
changed in linux v3.4 commit 5cdf389aee90109e2e3d88085dea4dd5508a3be7
A tracer recieves this event in the waitpid status of a PTRACED_SEIZED
process.
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including uchar.h in c++ code is only well defined in c++11 onwards
where char16_t and char32_t type definitions must be hidden since they
are keywords. however some c++ code compiled for older c++ standard
include uchar.h too and they need the typedefs, this fix makes such
code work.
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previously, this operation succeeded, and the relocation results
worked for access from new threads created after dlopen, but produced
invalid accesses (and possibly clobbered other memory) from threads
that already existed.
the way the check is written, it still permits dlopen of libraries
containing initial-exec references to static TLS (TLS in the main
program or in a dynamic library loaded at startup).
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tls_id is one-based, whereas [static_]tls_cnt is a count, so
comparison for checking that a given tls_id is dynamic rather than
static needs to use strict inequality.
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this flag is notoriously under-/mis-specified, and in the past it was
implemented as a nop, essentially considering the absence of a
loopback interface with 127.0.0.1 and ::1 addresses an unsupported
configuration. however, common real-world container environments omit
IPv6 support (even for the network-namespaced loopback interface), and
some kernels omit IPv6 support entirely. future systems on the other
hand might omit IPv4 entirely.
treat these as supported configurations and suppress results of the
unconfigured/unsupported address families when AI_ADDRCONFIG is
requested. use routability of the loopback address to make the
determination; unlike other implementations, we do not exclude
loopback from the "an address is configured" condition, since there is
no basis in the specification for such exclusion. obtaining a result
with AI_ADDRCONFIG does not imply routability of the result, and
applications must still be able to cope with unroutable results even
if they pass AI_ADDRCONFIG.
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commit 0b80a7b0404b6e49b0b724e3e3fe0ed5af3b08ef, which added non-stub
setvbuf, applied the UNGET pushback adjustment to the size of the
buffer passed in, but inadvertently omitted offsetting the start by
the same amount, thereby allowing unget to clobber up to 8 bytes
before the start of the buffer. this bug was introduced in the present
release cycle; no releases are affected.
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to produce sorted results roughly corresponding to RFC 3484/6724,
__lookup_name computes routability and choice of source address via
dummy UDP connect operations (which do not produce any packets). since
at the logical level, the properties fed into the sort key are
computed on ipv6 addresses, the code was written to use the v4mapped
ipv6 form of ipv4 addresses and share a common code path for them all.
however, on kernels where ipv6 support has been completely omitted,
this causes ipv4 to appear equally unroutable as ipv6, thereby putting
unreachable ipv6 addresses before ipv4 addresses in the results.
instead, use only ipv4 sockets to compute routability for ipv4
addresses. some gratuitous conversion back and forth is left so that
the logic is not affected by these changes. it may be possible to
simplify the ipv4 case considerably, thereby reducing code size and
complexity.
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Avoid saving/restoring the incoming argument by reusing memset return
value.
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since slack space at the beginning and/or end of writable load maps is
donated to malloc, the application could obtain valid pointers in
these ranges which dladdr would erroneously identify as part of the
shared object whose mapping they came from.
instead of checking the queried address against the mapping base and
length, check it against the load segments from the program headers,
and only match the dso if it lies within the bounds of one of them.
as a shortcut, if the address does match the range of the mapping but
not any of the load segments, we know it cannot match any other dso
and can immediately return failure.
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the early-exit condition for the symbol match loop on exact matches
caused dladdr to produce the first match for an exact match, but the
last match for an inexact match. in the interest of consistency,
require a strictly-closer match to replace an already-found one.
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commit 8b8fb7f03721c42445f982582f462144ab60a1a0 added logic to prevent
matching a symbol with no recorded size (closest-match) when there is
an intervening symbol whose size was recorded, but it only worked when
the intervening symbol was encountered later in the search.
instead of rejecting symbols where addr falls outside their recorded
size during the closest-match search, accept them to find the true
closest-match, then reject such a result only once the search has
finished.
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based on patch by Axel Siebenborn, with fixes discussed on the mailing
list after submission and and rebased around the UB fix in commit
e829695fcc880f8578c2b964ea2d090f0016c9d7.
avoid spurious symbol matches by dladdr beyond symbol size. for
symbols with a size recorded, only match if the queried address lies
within the address range determined by the symbol address and size.
for symbols with no size recorded, the old closest-match behavior is
kept, as long as there is no intervening symbol with a recorded size.
the case where no symbol is matched, but the address does lie within
the memory range of a shared object, is specified as success. fix the
return value and produce a valid (with null dli_sname and dli_saddr)
Dl_info structure.
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maintainer's note: past sentiment was that, despite being imperfect
and unable to force clearing of all possible copies of sensitive data
(e.g. in registers, register spills, signal contexts left on the
stack, etc.) this function would be added if major implementations
agreed on it, which has happened -- several BSDs and glibc all include
it.
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maintainer's note: this change is for conformance with RFC 5952,
4.2.2, which explicitly forbids use of :: to shorten a single 16-bit 0
field when producing the canonical text representation for an IPv6
address. fixes a test failure reported by Philip Homburg, who also
submitted a patch, but this fix is simpler and should produce smaller
code.
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the expression (tm->__tm_gmtoff)/3600 has type long. use %+.2ld instead.
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if a final dot was included in the queried host name to anchor it to
the dns root/suppress search domains, and the result was not a CNAME,
the returned canonical name included the final dot. this was not
consistent with other implementations, confused some applications, and
does not seem desirable.
POSIX specifies returning a pointer to, or to a copy of, the input
nodename, when the canonical name is not available, but does not
attempt to specify what constitutes "not available". in the case of
search, we already have an implementation-defined "availability" of a
canonical name as the fully-qualified name resulting from search, so
defining it similarly in the no-search case seems reasonable in
addition to being consistent with other implementations.
as a bonus, fix the case where more than one trailing dot is included,
since otherwise the changes made here would wrongly cause lookups with
two trailing dots to succeed. previously this case resulted in
malformed dns queries and produced EAI_AGAIN after a timeout. now it
fails immediately with EAI_NONAME.
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commit 587f5a53bc3a68d80b239ba515d583df690a96df moved the definition
of SO_PEERSEC to bits/socket.h for archs where the SO_* macros differ
from their standard values, but failed to add copies of the generic
definition for powerpc and powerpc64.
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adapted from patch by Matthias Schiffer.
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writable load segments can have size-in-memory larger than their size
in the ELF file, representing bss or equivalent. the initial partial
page has to be zero-filled, and additional anonymous pages have to be
mapped such that accesses don't failt with SIGBUS.
map_library skips redundant MAP_FIXED mapping of the initial
(lowest-address) segment when processing LOAD segments since it was
already mapped when reserving the virtual address range, but in doing
so, inadvertently also skipped the code to fill/map bss. typical
executable and library files have two or more LOAD segments, and the
first one is text/rodata (non-writable) and thus has no bss, but it is
syntactically valid for an ELF program/library to put its writable
segment first, or to have only one segment (everything writable). the
binutils bfd-based linker has been observed to create such programs in
the presence of unusual sections or linker scripts.
fix by moving only the mmap_fixed operation under the conditional
rather than skipping the remainder of the loop body. add a check to
avoid bss processing in the case where the segment is not writable;
this should not happen, but if it does, the change would be a crashing
regression without this check.
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memfd_create was added in linux v3.17 and glibc has api for it.
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mlock2 syscall was added in linux v4.4 and glibc has api for it.
It falls back to mlock in case of flags==0, so that case works
even on older kernels.
MLOCK_ONFAULT is moved under _GNU_SOURCE following glibc.
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unlike the x86 variant, the m68k ld80 format allows (biased) exponent
zero with mantissa msb set, thereby extending the normal range.
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the mode member of struct ipc_perm is specified by POSIX to have type
mode_t, which is uniformly defined as unsigned int. however, Linux
defines it with type __kernel_mode_t, and defines __kernel_mode_t as
unsigned short on some archs. since there is a subsequent padding
field, treating it as a 32-bit unsigned int works on little endian
archs, but the order is backwards on big endian archs with the
erroneous definition.
since multiple archs are affected, remedy the situation with fixup
code in the affected functions (shmctl, semctl, and msgctl) rather
than repeating the same shims in syscall_arch.h for every affected
arch.
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