diff options
Diffstat (limited to 'src/thread/__rsyscall.c')
| -rw-r--r-- | src/thread/__rsyscall.c | 114 | 
1 files changed, 0 insertions, 114 deletions
| diff --git a/src/thread/__rsyscall.c b/src/thread/__rsyscall.c deleted file mode 100644 index e885d9e7..00000000 --- a/src/thread/__rsyscall.c +++ /dev/null @@ -1,114 +0,0 @@ -#include "pthread_impl.h" - -/* "rsyscall" is a mechanism by which a thread can synchronously force all - * other threads to perform an arbitrary syscall. It is necessary to work - * around the non-conformant implementation of setuid() et al on Linux, - * which affect only the calling thread and not the whole process. This - * implementation performs some tricks with signal delivery to work around - * the fact that it does not keep any list of threads in userspace. */ - -static struct { -	volatile int lock, hold, blocks, cnt; -	unsigned long arg[6]; -	int nr; -	int err; -	int init; -} rs; - -static void rsyscall_handler(int sig, siginfo_t *si, void *ctx) -{ -	struct pthread *self = __pthread_self(); -	long r; - -	if (!rs.hold || rs.cnt == libc.threads_minus_1) return; - -	/* Threads which have already decremented themselves from the -	 * thread count must not increment rs.cnt or otherwise act. */ -	if (self->dead) { -		sigfillset(&((ucontext_t *)ctx)->uc_sigmask); -		return; -	} - -	r = __syscall(rs.nr, rs.arg[0], rs.arg[1], -		rs.arg[2], rs.arg[3], rs.arg[4], rs.arg[5]); -	if (r < 0) rs.err=-r; - -	a_inc(&rs.cnt); -	__wake(&rs.cnt, 1, 1); -	while(rs.hold) -		__wait(&rs.hold, 0, 1, 1); -	a_dec(&rs.cnt); -	if (!rs.cnt) __wake(&rs.cnt, 1, 1); -} - -int __rsyscall(int nr, long a, long b, long c, long d, long e, long f) -{ -	int i, ret; -	sigset_t set = { 0 }; -	struct pthread *self; - -	if (!libc.threads_minus_1) -		return syscall(nr, a, b, c, d, e, f); - -	self = __pthread_self(); - -	LOCK(&rs.lock); -	while ((i=rs.blocks)) -		__wait(&rs.blocks, 0, i, 1); - -	__syscall(SYS_rt_sigprocmask, SIG_BLOCK, (uint64_t[]){-1}, &set, 8); - -	if (!rs.init) { -		struct sigaction sa = { -			.sa_flags = SA_SIGINFO | SA_RESTART, -			.sa_sigaction = rsyscall_handler, -			.sa_mask = set -		}; -		sigfillset(&sa.sa_mask); -		sa.sa_sigaction = rsyscall_handler; -		__libc_sigaction(SIGSYSCALL, &sa, 0); -		rs.init = 1; -	} - -	rs.nr = nr; -	rs.arg[0] = a; rs.arg[1] = b; -	rs.arg[2] = c; rs.arg[3] = d; -	rs.arg[4] = d; rs.arg[5] = f; -	rs.err = 0; -	rs.cnt = 0; -	rs.hold = 1; - -	/* Dispatch signals until all threads respond */ -	for (i=libc.threads_minus_1; i; i--) -		sigqueue(self->pid, SIGSYSCALL, (union sigval){0}); -	while ((i=rs.cnt) < libc.threads_minus_1) { -		sigqueue(self->pid, SIGSYSCALL, (union sigval){0}); -		__wait(&rs.cnt, 0, i, 1); -	} - -	/* Handle any lingering signals with no-op */ -	__syscall(SYS_rt_sigprocmask, SIG_SETMASK, &set, &set, 8); - -	/* Resume other threads' signal handlers and wait for them */ -	rs.hold = 0; -	__wake(&rs.hold, -1, 0); -	while((i=rs.cnt)) __wait(&rs.cnt, 0, i, 1); - -	if (rs.err) errno = rs.err, ret = -1; -	else ret = syscall(nr, a, b, c, d, e, f); - -	UNLOCK(&rs.lock); -	return ret; -} - -void __rsyscall_lock() -{ -	a_inc(&rs.blocks); -	while (rs.lock) __wait(&rs.lock, 0, 1, 1); -} - -void __rsyscall_unlock() -{ -	a_dec(&rs.blocks); -	if (rs.lock) __wake(&rs.blocks, 1, 1); -} | 
