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.
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.
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.
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 ¶1), 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.
eliminate gratuitous glue function for reporting the version, which
was probably leftover from the old dynamic linker design which lacked
a clear barrier for when/how it could access global data. put the
declaration for the data object that replaces it in libc.h where it
can be type checked.
logically these belong to the intersection of the stdio and pthread
subsystems, and either place the declarations could go (stdio_impl.h
or pthread_impl.h) requires a forward declaration for one of the
argument types.
these exist for the sake of defining the corresponding weak public
aliases (for C11 and POSIX namespace conformance reasons). they are
not referenced by anything else in libc, so make them static.
get rid of a gratuitous translation unit and call frame between
asctime_r and the actual implementation of the function. this is the
way gmtime_r and localtime_r are already done.
syscall.h was chosen as the header to declare it, since its intended
usage is alongside syscalls as a fallback for operations the direct
syscall does not support.
policy is that all public functions which have a public declaration
should be defined in a context where that public declaration is
visible, to avoid preventable type mismatches.
an audit performed using GCC's -Wmissing-declarations turned up the
violations corrected here. in some cases the public header had not
been included; in others, a feature test macro needed to make the
declaration visible had been omitted.
in the case of gethostent and getnetent, the omission seems to have
been intentional, as a hack to admit a single stub definition for both
functions. this kind of hack is no longer acceptable; it's UB and
would not fly with LTO or advanced toolchains. the hack is undone to
make exposure of the declarations possible.
this cleans up what had become widespread direct inline use of "GNU C"
style attributes directly in the source, and lowers the barrier to
increased use of hidden visibility, which will be useful to recovering
some of the efficiency lost when the protected visibility hack was
dropped in commit dc2f368e56, especially
on archs where the PLT ABI is costly.
commit 4f35eb7591 introduced this bug.
it is not present in any released versions. inadvertent use of the &
operator on an array into which we're indexing produced arithmetic on
the wrong-type pointer, with undefined behavior.
this code in sigaction was the only place where sizeof was being
applied to the kernel sigaction's mask member to get the size argument
to pass to the kernel. everywhere else, _NSIG/8 is used for this
purpose.
Linux makes this surprisingly difficult, but it can be done. the trick
here is using the fact that we control the implementation of sigaction
to prevent changing the disposition of SIGABRT to anything but SIG_DFL
after abort has tried and failed to terminate the process simply by
calling raise(SIGABRT).
these functions are specified to write to stderr but not set its
orientation, presumably so that they can be used in programs operating
stderr in wide mode. also, they are not allowed to clobber errno on
success. save and restore to meet the requirement.
psiginfo is reduced to a think wrapper around psignal, since it
already behaved the same. if we want to add more detailed siginfo
printing at some point this will need refactoring.
if no output is produced, no underlying fwrite will ever be called,
but byte-oriented printf functions are still required to set the
orientation of the stream to byte-oriented. call __towrite explicitly
if the FILE is not already in write mode.
commit b5a8b28915 setup the write buffer
bound pointers for the temporary buffer manually to fix a buffer
overflow issue, but in doing so, caused vfprintf on unbuffered files
never to call __towrite, thereby failing to set the stream orientation
to byte-oriented, failing to clear any prior read mode, and failing to
produce an error when the stream is not writable.
revert the inline setup of the bounds pointers and instead zero them,
so that the underlying fwrite code will call __towrite to set them up.
commit 0b80a7b040 added the ability to
set application-provided stdio FILE buffers, adding the possibility
that stderr might be buffered at exit time, but __stdio_exit did not
have code to flush it.
this regression was not present in any release.
if __cp_cancel was reached via __syscall_cp, r12 will necessarily
still contain a GOT pointer (for libc.so or for the static-linked main
program) valid for entering __cancel. however, in the case of async
cancellation, r12 may contain any scratch value; it's not necessarily
even a valid GOT pointer for the code that was interrupted.
unlike in commit 0ec49dab67 where the
corresponding issue was fixed for powerpc64, there is fundamentally no
way for fdpic code to recompute its GOT pointer. so a new mechanism is
introduced for cancel_handler to write a GOT register value into the
interrupted context on archs where it is needed.
entering the local entry point for __cancel from __cp_cancel is valid
if __cp_cancel was reached from __syscall_cp, since both are in libc
and share the same TOC pointer, but it is not valid if __cp_cancel was
reached when cancel_handler rewrote the program counter for
asynchronous cancellation of code outside libc.
to ensure __cancel is entered with a valid TOC pointer, recompute the
correct value in a PC-relative manner before jumping.
- REALTIME_SIGNALS is supposed to be version-valued
- DELAYTIMER_MAX was wrongly using the min allowed max
- unavailable compilation environments wrongly used 0 instead of -1
Rich Felker