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2018-09-15improve error handling of ttyname_r and isattyBenjamin Peterson-2/+6
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.
2018-09-12remove spurious inclusion of libc.h for LFS64 ABI aliasesRich Felker-14/+7
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.
2018-09-12reduce spurious inclusion of libc.hRich Felker-9/+0
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.
2018-09-12move and deduplicate declarations of __procfdname to make it checkableRich Felker-6/+1
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.
2018-05-01avoid excessive stack usage in getcwdRich Felker-2/+2
to support the GNU extension of allocating a buffer for getcwd's result when a null pointer is passed without incurring a link dependency on free, we use a PATH_MAX-sized buffer on the stack and only duplicate it to allocated storage after the operation succeeds. unfortunately this imposed excessive stack usage on all callers, including those not making use of the GNU extension. instead, use a VLA to make stack allocation conditional.
2018-04-19fix out of bounds write for zero length buffer in gethostnameMarc André Tanner-1/+1
2018-04-17fix return value of nice functionRich Felker-5/+9
the Linux SYS_nice syscall is unusable because it does not return the newly set priority. always use SYS_setpriority. also avoid overflows in addition of inc by handling large inc values directly without examining the old nice value.
2018-02-07make getcwd fail if it cannot obtain an absolute pathDmitry V. Levin-1/+7
Currently getcwd(3) can succeed without returning an absolute path because the underlying getcwd syscall, starting with linux commit v2.6.36-rc1~96^2~2, may succeed without returning an absolute path. This is a conformance issue because "The getcwd() function shall place an absolute pathname of the current working directory in the array pointed to by buf, and return buf". Fix this by checking the path returned by syscall and failing with ENOENT if the path is not absolute. The error code is chosen for consistency with the case when the current directory is unlinked. Similar issue was fixed in glibc recently, see https://sourceware.org/bugzilla/show_bug.cgi?id=22679
2018-02-05revert regression in faccessat AT_EACCESS robustnessRich Felker-21/+14
commit f9fb20b42da0e755d93de229a5a737d79a0e8f60 switched from using a pipe for the result to conveying it via the child process exit status. Alexander Monakov pointed out that the latter could fail if the application is not expecting faccessat to produce a child and performs a wait operation with __WCLONE or __WALL, and that it is not clear whether it's guaranteed to work when SIGCHLD's disposition has been set to SIG_IGN. in addition, that commit introduced a bug that caused EACCES to be produced instead of EBUSY due to an exit path that was overlooked when the error channel was changed, and introduced a spurious retry loop around the wait operation.
2017-05-27fix fchown fallback on arches without chown(2)Samuel Holland-1/+1
The flags argument was missing, causing uninitalized data to be passed to fchownat(2). The correct value of flags should match the fallback for chown(3).
2017-04-21make ttyname[_r] return ENODEV rather than ENOENTRich Felker-1/+1
commit 0a950dcf15bb9f7274c804dca490e9e20e475f3e added checking that the pathname a tty device was opened with actually matches the device, which can fail to hold when a container inherits a tty from outside the container. the error code added at the time was ENOENT; however, discussions between affected applications and glibc developers resulted in glibc adopting ENODEV as the error for this condition, and this has now been documented in the man pages project as well. adopt the same error code for consistency. patch by Christian Brauner.
2016-08-30verify that ttyname refers to the same file as the fdSzabolcs Nagy-4/+11
linux containers use separate mount namespace so the /proc symlink might not point to the right device if the fd was opened in the parent namespace, in this case return ENOENT.
2016-08-11fix pread/pwrite syscall calling convention on shRich Felker-2/+2
despite sh not generally using register-pair alignment for 64-bit syscall arguments, there are arch-specific versions of the syscall entry points for pread and pwrite which include a dummy argument for alignment before the 64-bit offset argument.
2016-04-18add mips n32 port (ILP32 ABI for mips64)Rich Felker-0/+19
based on patch submitted by Jaydeep Patil, with minor changes.
2016-03-06add mips64 portRich Felker-0/+19
patch by Mahesh Bodapati and Jaydeep Patil of Imagination Technologies.
2015-06-16switch to using trap number 31 for syscalls on shRich Felker-1/+1
nominally the low bits of the trap number on sh are the number of syscall arguments, but they have never been used by the kernel, and some code making syscalls does not even know the number of arguments and needs to pass an arbitrary high number anyway. sh3/sh4 traditionally used the trap range 16-31 for syscalls, but part of this range overlapped with hardware exceptions/interrupts on sh2 hardware, so an incompatible range 32-47 was chosen for sh2. using trap number 31 everywhere, since it's in the existing sh3/sh4 range and does not conflict with sh2 hardware, is a proposed unification of the kernel syscall convention that will allow binaries to be shared between sh2 and sh3/sh4. if this is not accepted into the kernel, we can refit the sh2 target with runtime selection mechanisms for the trap number, but doing so would be invasive and would entail non-trivial overhead.
2015-02-23fix possible isatty false positives and unwanted device state changesRich Felker-3/+4
the equivalent checks for newly opened stdio output streams, used to determine buffering mode, are also fixed. on most archs, the TCGETS ioctl command shares a value with SNDCTL_TMR_TIMEBASE, part of the OSS sound API which was apparently used with certain MIDI and timer devices. for file descriptors referring to such a device, TCGETS will not fail with ENOTTY as expected; it may produce a different error, or may succeed, and if it succeeds it changes the mode of the device. while it's unlikely that such devices are in use, this is in principle very harmful behavior for an operation which is supposed to do nothing but query whether the fd refers to a tty. TIOCGWINSZ, used to query logical window size for a terminal, was chosen as an alternate ioctl to perform the isatty check. it does not share a value with any other ioctl commands, and it succeeds on any tty device. this change also cleans up strace output to be less ugly and misleading.
2015-02-20map interruption of close by signal to success rather than EINPROGRESSRich Felker-1/+1
commit 82dc1e2e783815e00a90cd3f681436a80d54a314 addressed the resolution of Austin Group issue 529, which requires close to leave the fd open when failing with EINTR, by returning the newly defined error code EINPROGRESS. this turns out to be a bad idea, though, since legacy applications not aware of the new specification are likely to interpret any error from close except EINTR as a hard failure.
2015-02-13overhaul aio implementation for correctnessRich Felker-0/+8
previously, aio operations were not tracked by file descriptor; each operation was completely independent. this resulted in non-conforming behavior for non-seekable/append-mode writes (which are required to be ordered) and made it impossible to implement aio_cancel, which in turn made closing file descriptors with outstanding aio operations unsafe. the new implementation is significantly heavier (roughly twice the size, and seems to be slightly slower) and presently aims mainly at correctness, not performance. most of the public interfaces have been moved into a single file, aio.c, because there is little benefit to be had from splitting them. whenever any aio functions are used, aio_cancel and the internal queue lifetime management and fd-to-queue mapping code must be linked, and these functions make up the bulk of the code size. the close function's interaction with aio is implemented with weak alias magic, to avoid pulling in heavy aio cancellation code in programs that don't use aio, and the expensive cancellation path (which includes signal blocking) is optimized out when there are no active aio queues.
2015-01-30make fsync, fdatasync, and msync cancellation pointsTrutz Behn-2/+2
these are mandatory cancellation points per POSIX, so their omission was a conformance bug.
2015-01-15for multithreaded set*id/setrlimit, handle case where callback does not runRich Felker-1/+1
in the current version of __synccall, the callback is always run, so failure to handle this case did not matter. however, the upcoming overhaul of __synccall will have failure cases, in which case the callback does not run and errno is already set. the changes being committed now are in preparation for that.
2015-01-12remove rlimit hacks from multi-threaded set*id() codeRich Felker-23/+15
the code being removed was introduced to work around "partial failure" of multi-threaded set*id() operations, where some threads would succeed in changing their ids but an RLIMIT_NPROC setting would prevent the rest from succeeding, leaving the process in an inconsistent and dangerous state. however, the workaround code did not handle important usage cases like swapping real and effective uids then restoring their original values, and the wrongful kernel enforcement of RLIMIT_NPROC at setuid time was removed in Linux 3.1, making the workaround obsolete. since the partial failure still is dangerous on old kernels, and could in principle happen on post-fix kernels as well if set*id() syscalls fail for another spurious reason such as resource-related failures, new code is added to detect and forcibly kill the process if/when such a situation arises. future documentation releases should be updated to reflect that setting RLIMIT_NPROC to RLIM_INFINITY is necessary to avoid this forced-kill on old kernels. ideally, at some point the kernel will get proper multi-threaded set*id() syscalls capable of performing their actions atomically, and all of the userspace code to emulate them can be treated as a fallback for outdated kernels.
2015-01-12simplify ctermidRich Felker-14/+2
opening /dev/tty then using ttyname_r on it does not produce a canonical terminal name; it simply yields "/dev/tty". it would be possible to make ctermid determine the actual controlling terminal device via field 7 of /proc/self/stat, but doing so would introduce a buffer overflow into applications built with L_ctermid==9, which glibc defines, adversely affecting the quality of ABI compat.
2014-05-29support linux kernel apis (new archs) with old syscalls removedRich Felker-1/+69
such archs are expected to omit definitions of the SYS_* macros for syscalls their kernels lack from arch/$ARCH/bits/syscall.h. the preprocessor is then able to select the an appropriate implementation for affected functions. two basic strategies are used on a case-by-case basis: where the old syscalls correspond to deprecated library-level functions, the deprecated functions have been converted to wrappers for the modern function, and the modern function has fallback code (omitted at the preprocessor level on new archs) to make use of the old syscalls if the new syscall fails with ENOSYS. this also improves functionality on older kernels and eliminates the incentive to program with deprecated library-level functions for the sake of compatibility with older kernels. in other situations where the old syscalls correspond to library-level functions which are not deprecated but merely lack some new features, such as the *at functions, the old syscalls are still used on archs which support them. this may change at some point in the future if or when fallback code is added to the new functions to make them usable (possibly with reduced functionality) on old kernels.
2014-02-27rename superh port to "sh" for consistencyRich Felker-0/+0
linux, gcc, etc. all use "sh" as the name for the superh arch. there was already some inconsistency internally in musl: the dynamic linker was searching for "ld-musl-sh.path" as its path file despite its own name being "ld-musl-superh.so.1". there was some sentiment in both directions as to how to resolve the inconsistency, but overall "sh" was favored.
2014-02-23superh portBobby Bingham-0/+27
2013-12-19fix failure of fchmod, fstat, fchdir, and fchown to produce EBADFRich Felker-2/+6
the workaround/fallback code for supporting O_PATH file descriptors when the kernel lacks support for performing these operations on them caused EBADF to get replaced by ENOENT (due to missing entry in /proc/self/fd). this is unlikely to affect real-world code (calls that might yield EBADF are generally unsafe, especially in library code) but it was breaking some test cases. the fix I've applied is something of a tradeoff: it adds one syscall to these operations on kernels where the workaround is needed. the alternative would be to catch ENOENT from the /proc lookup and translate it to EBADF, but I want to avoid doing that in the interest of not touching/depending on /proc at all in these functions as long as the kernel correctly supports the operations. this is following the general principle of isolating hacks to code paths that are taken on broken systems, and keeping the code for correct systems completely hack-free.
2013-12-12include cleanups: remove unused headers and add feature test macrosSzabolcs Nagy-6/+1
2013-12-06add posix_close, accepted for inclusion in the next issue of POSIXRich Felker-0/+6
this is purely a wrapper for close since Linux does not support EINTR semantics for the close syscall.
2013-11-01simplify faccessat AT_EACCESS path and eliminate resource dependenceRich Felker-14/+21
now that we're waiting for the exit status of the child process, the result can be conveyed in the exit status rather than via a pipe. since the error value might not fit in 7 bits, a table is used to translate possible meaningful error values to small integers.
2013-11-01fix faccessat AT_EACCESS path not to leave zombie processesRich Felker-2/+6
I mistakenly assumed that clone without a signal produced processes that would not become zombies; however, waitpid with __WCLONE is required to release their pids.
2013-10-18in faccessat slow path, add close-on-exec to pipe fdsRich Felker-1/+1
as usual, this is needed to avoid fd leaks. as a better solution, the use of fds could possibly be replaced with mmap and a futex.
2013-10-12fix uid/gid-setting error in faccessat with AT_EACCESS flagRich Felker-2/+2
this fixes an issue reported by Daniel Thau whereby faccessat with the AT_EACCESS flag did not work in cases where the process is running suid or sgid but without root privileges. per POSIX, when the process does not have "appropriate privileges", setuid changes the euid, not the real uid, and the target uid must be equal to the current real or saved uid; if this condition is not met, EPERM results. this caused the faccessat child process to fail. using the setreuid syscall rather than setuid works. POSIX leaves it unspecified whether setreuid can set the real user id to the effective user id on processes without "appropriate privileges", but Linux allows this; if it's not allowed, there would be no way for this function to work.
2013-10-08fix errno value for getcwd when size argument is zeroRich Felker-1/+7
based on patch by Michael Forney. at the same time, I've changed the if branch to be more clear, avoiding the comma operator. the underlying issue is that Linux always returns ERANGE when size is too short, even when it's zero, rather than returning EINVAL for the special case of zero as required by POSIX.
2013-08-31fix missing return value warning in faccessat, minor cleanupRich Felker-1/+1
clone will pass the return value of the start function to SYS_exit anyway; there's no need to call the syscall directly.
2013-08-09block all signals, even implementation-internal ones, in faccessat childRich Felker-1/+1
the child process's stack may be insufficient size to support a signal frame, and there is no reason these signal handlers should run in the child anyway.
2013-08-03fix faccessat to support AT_EACCESS flagRich Felker-1/+46
this is another case of the kernel syscall failing to support flags where it needs to, leading to horrible workarounds in userspace. this time the workaround requires changing uid/gid, and that's not safe to do in the current process. in the worst case, kernel resource limits might prevent recovering the original values, and then there would be no way to safely return. so, use the safe but horribly inefficient alternative: forking. clone is used instead of fork to suppress signals from the child. fortunately this worst-case code is only needed when effective and real ids mismatch, which mainly happens in suid programs.
2013-08-02make fchdir, fchmod, fchown, and fstat support O_PATH file descriptorsRich Felker-2/+18
on newer kernels, fchdir and fstat work anyway. this same fix should be applied to any other syscalls that are similarly affected. with this change, the current definitions of O_SEARCH and O_EXEC as O_PATH are mostly conforming to POSIX requirements. the main remaining issue is that O_NOFOLLOW has different semantics.
2013-08-02debloat code that depends on /proc/self/fd/%d with shared functionRich Felker-1/+3
I intend to add more Linux workarounds that depend on using these pathnames, and some of them will be in "syscall" functions that, from an anti-bloat standpoint, should not depend on the whole snprintf framework.
2013-07-09fix bogus lazy allocation in ctermid and missing malloc failure checkRich Felker-10/+7
also clean up, optimize, and simplify the code, removing branches by simply pre-setting the result string to an empty string, which will be preserved if other operations fail.
2013-07-09fix fd leak on races and cancellation in ctermidRich Felker-2/+3
2013-03-25in pipe2, use pipe() rather than __syscall(SYS_pipe, ...) for fallbackRich Felker-3/+3
SYS_pipe is not usable directly in general, since mips has a very broken calling convention for the pipe syscall. instead, just call the function, so that the mips-specific ugliness is isolated in mips/pipe.s and not copied elsewhere.
2013-02-03streamline old-kernel fallback path of pipe2 to use syscalls directlyRich Felker-4/+4
also, don't waste code/time on F_GETFL since pipes always have blank flags initially (at least on old kernels, which are all this fallback code matters for).
2012-12-11fix double errno-decoding in the old-kernel fallback path of pipe2Rich Felker-1/+1
this bug seems to have caused any failure by pipe2 on such systems to set errno to 1, rather than the proper error code.
2012-10-24greatly improve freopen behaviorRich Felker-2/+13
1. don't open /dev/null just as a basis to copy flags; use shared __fmodeflags function to get the right file flags for the mode. 2. handle the case (probably invalid, but whatever) case where the original stream's file descriptor was closed; previously, the logic re-closed it. 3. accept the "e" mode flag for close-on-exec; update dup3 to fallback to using dup2 so we can simply call __dup3 instead of putting fallback logic in freopen itself.
2012-10-18overhaul system() and popen() to use vfork; fix various related bugsRich Felker-3/+17
since we target systems without overcommit, special care should be taken that system() and popen(), like posix_spawn(), do not fail in processes whose commit charges are too high to allow ordinary forking. this in turn requires special precautions to ensure that the parent process's signal handlers do not end up running in the shared-memory child, where they could corrupt the state of the parent process. popen has also been updated to use pipe2, so it does not have a fd-leak race in multi-threaded programs. since pipe2 is missing on older kernels, (non-atomic) emulation has been added. some silly bugs in the old code should be gone too.
2012-09-29move accept4, dup3, and pipe2 to non-linux-specific locationsRich Felker-0/+18
these interfaces have been adopted by the Austin Group for inclusion in the next version of POSIX.
2012-09-29fix some indention-with-spaces that crept inRich Felker-1/+1
2012-09-24fix handling of EINTR during close()Rich Felker-1/+4
austin group interpretation for defect #529 (http://austingroupbugs.net/view.php?id=529) tightens the requirements on close such that, if it returns with EINTR, the file descriptor must not be closed. the linux kernel developers vehemently disagree with this, and will not change it. we catch and remap EINTR to EINPROGRESS, which the standard allows close() to return when the operation was not finished but the file descriptor has been closed.
2012-09-09fix up lfs64 junk for preadv/pwritevRich Felker-2/+2