some 32-on-64 archs require that the actual syscall args be long long.
in that case syscall_arch.h can define syscall_arg_t to whatever it needs
and syscall.h picks it up.
all other archs just use long as usual.
this allows syscall_arch.h to define the macro __scc if special
casting is needed, as is the case for x32, where the actual syscall
arguments are 64bit, but, in case of pointers, would get sign-extended
and thus become invalid.
the other atomic FD_CLOEXEC interfaces (dup3, pipe2, socket) already
had such emulation in place. the justification for doing the emulation
here is the same as for the other functions: it allows applications to
simply use accept4 rather than having to have their own fallback code
for ENOSYS/EINVAL (which one you get is arch-specific!) and there is
no reasonable way an application could benefit from knowing the
operation is emulated/non-atomic since there is no workaround at the
application level for non-atomicity (that is the whole reason these
interfaces were added).
this was unlikely to lead to any crash or dangerous behavior, but
caused adjacent string constants to be treated as part of the
protocols table, possibly returning nonsensical results for unknown
protocol names/numbers or when getprotoent was called in a loop to
enumerate all protocols.
gcc -Wsign-compare warns about expanded macros that were defined in
standard headers (before gcc 4.8) which can make builds fail that
use -Werror. changed macros: WIFSIGNALED, __CPU_op_S
The architecture-specific assembly versions of clone did not set errno on
failure, which is inconsistent with glibc. __clone still returns the error
via its return value, and clone is now a wrapper that sets errno as needed.
The public clone has also been moved to src/linux, as it's not directly
related to the pthreads API.
__clone is called by pthread_create, which does not report errors via
errno. Though not strictly necessary, it's nice to avoid clobbering errno
here.
the default fenv was not set up properly, in particular the
tag word that indicates the contents of the x87 registers was
set to 0 (used) instead of 0xffff (empty)
this could cause random crashes after setting the default fenv
because it corrupted the fpu stack and then any float computation
gives NaN result breaking the program logic (usually after a
float to integer conversion).
this saves a syscall in the case where the underlying open already
took place with O_APPEND, which is common because fopen with append
modes sets O_APPEND at the time of open before passing the file
descriptor to __fdopen.
when there is unflushed output, ftello (and ftell) compute the logical
stream position as the underlying file descriptor's offset plus an
adjustment for the amount of buffered data. however, this can give the
wrong result for append-mode streams where the unflushed writes should
adjust the logical position to be at the end of the file, as if a seek
to end-of-file takes place before the write.
the solution turns out to be a simple trick: when ftello (indirectly)
calls lseek to determine the current file offset, use SEEK_END instead
of SEEK_CUR if the stream is append-mode and there's unwritten
buffered data.
the ISO C rules regarding switching between reading and writing for a
stream opened in an update mode, along with the POSIX rules regarding
switching "active handles", conveniently leave undefined the
hypothetical usage cases where this fix might lead to observably
incorrect offsets.
the bug being fixed was discovered via the test case for glibc issue
the affected part of the header is responsible for providing both GNU
and BSD versions of the udphdr structure. previously, the
namespace-polluting GNU names were always used for the actual struct
members, and the BSD names, which are named in a manner resembling a
sane namespace, were always macros defined to expand to the GNU names.
now, unless _GNU_SOURCE is defined, the BSD names are used as the
actual structure members, and the macros and GNU names only come into
play when the application requests them.
there are two versions of this structure: the BSD version and the GNU
version. previously only the GNU version was supported. the only way
to support both simultaneously is with an anonymous union, which was a
nonstandard extension prior to C11, so some effort is made to avoid
breakage with compilers which do not support anonymous unions.
this commit is based on a patch by Timo Teräs, but with some changes.
in particular, the GNU version of the structure is not exposed unless
_GNU_SOURCE is defined; this both avoids namespace pollution and
dependency on anonymous unions in the default feature profile.
these are poorly designed (illogical argument order) and even poorly
implemented (brace issues) on glibc, but unfortunately some software
is using them. we could consider removing them again in the future at
some point if they're documented as deprecated, but for now the
simplest thing to do is just to provide them under _GNU_SOURCE.
some applications expect it to be defined, despite the standard making
it impossible for it to ever be returned as a value distinct from
NO_DATA. since these macros are outside the scope of the current
standards, no special effort is made to hide NO_ADDRESS under
conditions where the others are exposed.
STB_WEAK is only a weak reference for undefined symbols (those with a
section of SHN_UNDEF). otherwise, it's a weak definition. normally
this distinction would not matter, since a relocation referencing a
symbol that also provides a definition (not SHN_UNDEF) will always
succeed in finding the referenced symbol itself. however, in the case
of copy relocations, the referenced symbol itself is ignored in order
to search for another symbol to copy from, and thus it's possible that
no definition is found. in this case, if the symbol being resolved
happened to be a weak definition, it was misinterpreted as a weak
reference, suppressing the error path and causing a crash when the
copy relocation was performed with a null source pointer passed to
memcpy.
there are almost certainly still situations in which invalid
combinations of symbol and relocation types can cause the dynamic
linker to crash (this is pretty much inevitable), but the intent is
that crashes not be possible for symbol/relocation tables produced by
a valid linker.
setstate could use the results of previous initstate or setstate
calls (they return the old state buffer), but the documentation
requires that an initialized state buffer should be possible to
use in setstate immediately, which means that initstate should
save the generator parameters in it.
I also removed the copyright notice since it is present in the
copyright file.
install.sh was wrongly waiting until after atomically replacing the
old file to set the correct permissions on the new file. in the case
of the dynamic linker, this would cause a dynamic-linked chmod command
not to run (due to missing executable permissions on the dynamic
linker) and thus leave the system in an unusable state.
even if chmod is static-linked, the old behavior had a race window
where dynamic-linked programs could fail to run.
the operand size is unnecessary, since the assembler knows it from the
destination register size. removing the suffix makes it so the same
code should work for x32.
in fixing this, I've changed the logic from ugly #if/#else blocks
inside the struct shm_info definition to a fixed struct definition and
optional macros to rename the elements. this will be helpful if we
need to move shm_info to a bits header in the future, as it will keep
the feature test logic out of bits.
the fix should be complete on archs that use the generic definitions
(i386, arm, x86_64, microblaze), but mips and powerpc have not been
checked thoroughly and may need more fixes.
the imr_, imsf_, ip6_, ip6m_, ipi_, ipi6_, SCM_, and SOL_ prefixes are
not in the reserved namespace for this header. thus the constants and
structures using them need to be protected under appropriate feature
test macros.
this also affects some headers which are permitted to include
netinet/in.h, particularly netdb.h and arpa/inet.h.
the SOL_ macros are moved to sys/socket.h where they are in the
reserved namespace (SO*). they are still accessible via netinet/in.h
since it includes sys/socket.h implicitly (which is permitted).
the SCM_SRCRT macro is simply removed, since the definition used for
it, IPV6_RXSRCRT is not defined anywhere. it could be re-added, this
time in sys/socket.h, if the appropriate value can be determined;
however, given that the erroneous definition was not caught, it is
unlikely that any software actually attempts to use SCM_SRCRT.
per POSIX, the variadic argument has type union semun, which may
contain a pointer or int; the type read depends on the command being
issued. this allows the userspace part of the implementation to be
type-correct without requiring special-casing for different commands.
the kernel always expects to receive the argument interpreted as
unsigned long (or equivalently, a pointer), and does its own handling
of extracting the int portion from the representation, as needed.
this change fixes two possible issues: most immediately, reading the
argument as a (signed) long and passing it to the syscall would
perform incorrect sign-extension of pointers on the upcoming x32
target. the other possible issue is that some archs may use different
(user-space) argument-passing convention for unions, preventing va_arg
from correctly obtaining the argument when the type long (or even
unsigned long or void *) is passed to it.
really, fcntl should be changed to use the correct type corresponding
to cmd when calling va_arg, and to carry the correct type through
until making the syscall. however, this greatly increases binary size
and does not seem to offer any benefits except formal correctness, so
I'm holding off on that change for now.
the minimal changes made in this patch are in preparation for addition
of the x32 port, where the syscall macros need to know whether their
arguments are pointers or integers in order to properly pass them to
the 64-bit kernel.
it's unclear what the historical signature for this function was, but
semantically, the argument should be a pointer to const, and this is
what glibc uses. correct programs should not be using this function
anyway, so it's unlikely to matter.
this change is consistent with the corresponding glibc functions and
is semantically const-correct. the incorrect argument types without
const seem to have been taken from erroneous man pages.
this functionality has essentially always been deprecated in linux,
and was never supported by musl. the presence of the header was
reported to cause some software to attempt to use the nonexistant
function, so removing the header is the cleanest solution.
this was wrong since the original commit adding inotify, and I don't
see any explanation for it. not even the man pages have it wrong. it
was most likely a copy-and-paste error.
this practice came from very early, before internal/syscall.h defined
macros that could accept pointer arguments directly and handle them
correctly. aside from being ugly and unnecessary, it looks like it
will be problematic when we add support for 32-bit ABIs on archs where
registers (and syscall arguments) are 64-bit, e.g. x32 and mips n32.
this agrees with implementation practice on glibc and BSD systems, and
is the const-correct way to do things; it eliminates warnings from
passing pointers to const. the prototype without const came from
seemingly erroneous man pages.
rofl0r
Rich Felker
Szabolcs Nagy
Bobby Bingham
Timo Teräs