path: root/src/process/system.c
AgeCommit message (Collapse)AuthorLines
2018-09-12reduce spurious inclusion of libc.hRich Felker-1/+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.
2018-08-28fix return value of system on failure to spawn child processRich Felker-1/+1
the value 0x7f00 (as if by _exit(127)) is specified only for the case where the child is created but then fails to exec the shell, since traditional fork+exec implementations do not admit reporting an error via errno in this case without additional machinery. it's unclear whether an implementation not subject to this failure mode needs to emulate it; one could read the standard as requiring that. if so, additional code will need to be added to map posix_spawn errors into the form system is expected to return. but for now, returning -1 to indicate an error is significantly better behavior than always reporting failures as if the shell failed to exec after fork.
2013-12-12include cleanups: remove unused headers and add feature test macrosSzabolcs Nagy-1/+1
2013-03-24remove cruft from pre-posix_spawn version of the system functionRich Felker-6/+0
2013-02-17consistently use the internal name __environ for environRich Felker-2/+2
patch by Jens Gustedt. previously, the intended policy was to use __environ in code that must conform to the ISO C namespace requirements, and environ elsewhere. this policy was not followed in practice anyway, making things confusing. on top of that, Jens reported that certain combinations of link-time optimization options were breaking with the inconsistent references; this seems to be a compiler or linker bug, but having it go away is a nice side effect of the changes made here.
2013-02-03base system() on posix_spawnRich Felker-41/+26
this avoids duplicating the fragile logic for executing an external program without fork.
2012-10-28system is a cancellation pointRich Felker-0/+3
ideally, system would also be cancellable while running the external command, but I cannot find any way to make that work without either leaking zombie processes or introducing behavior that is far outside what the standard specifies. glibc handles cancellation by killing the child process with SIGKILL, but this could be unsafe in that it could leave the data being manipulated by the command in an inconsistent state.
2012-10-19fix usage of locks with vforkRich Felker-1/+2
__release_ptc() is only valid in the parent; if it's performed in the child, the lock will be unlocked early then double-unlocked later, corrupting the lock state.
2012-10-18overhaul system() and popen() to use vfork; fix various related bugsRich Felker-23/+42
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.
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+45