fix rsyscall handler: must not clobber errno from signal context

[musl] / src / thread / pthread_create.c

diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index d2344f1..410eefc 100644 (file)
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -1,5 +1,11 @@
 #include "pthread_impl.h"
 
+static void dummy_1(pthread_t self)
+{
+}
+weak_alias(dummy_1, __pthread_tsd_run_dtors);
+weak_alias(dummy_1, __sigtimer_handler);
+
 #ifdef __pthread_unwind_next
 #undef __pthread_unwind_next
 #define __pthread_unwind_next __pthread_unwind_next_3
@@ -7,7 +13,6 @@
 
 void __pthread_unwind_next(struct __ptcb *cb)
 {
-       int i, j, not_finished;
        pthread_t self;
 
        if (cb->__next) longjmp((void *)cb->__next->__jb, 1);
@@ -16,18 +21,7 @@ void __pthread_unwind_next(struct __ptcb *cb)
 
        LOCK(&self->exitlock);
 
-       not_finished = self->tsd_used;
-       for (j=0; not_finished && j<PTHREAD_DESTRUCTOR_ITERATIONS; j++) {
-               not_finished = 0;
-               for (i=0; i<PTHREAD_KEYS_MAX; i++) {
-                       if (self->tsd[i] && libc.tsd_keys[i]) {
-                               void *tmp = self->tsd[i];
-                               self->tsd[i] = 0;
-                               libc.tsd_keys[i](tmp);
-                               not_finished = 1;
-                       }
-               }
-       }
+       __pthread_tsd_run_dtors(self);
 
        /* Mark this thread dead before decrementing count */
        self->dead = 1;
@@ -54,22 +48,28 @@ static void docancel(struct pthread *self)
 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
 {
        struct pthread *self = __pthread_self();
-       if (!self->cancel) {
-               if (si->si_code == SI_TIMER && libc.sigtimer)
-                       libc.sigtimer(sig, si, ctx);
-               return;
-       }
-       if (self->canceldisable) return;
-       if (self->cancelasync || (self->cancelpoint==1 && PC_AT_SYS(ctx)))
+       if (si->si_code == SI_TIMER) __sigtimer_handler(self);
+       if (self->cancel && !self->canceldisable &&
+           (self->cancelasync || (self->cancelpoint==1 && PC_AT_SYS(ctx))))
                docancel(self);
 }
 
 static void cancelpt(int x)
 {
        struct pthread *self = __pthread_self();
-       if (self->canceldisable) return;
-       if ((self->cancelpoint+=x)==1 && x>=0 && self->cancel)
-               docancel(self);
+       switch (x) {
+       case 1:
+               self->cancelpoint++;
+       case 0:
+               if (self->cancel && self->cancelpoint==1 && !self->canceldisable)
+                       docancel(self);
+               break;
+       case -1:
+               self->cancelpoint--;
+               break;
+       default:
+               self->canceldisable += x;
+       }
 }
 
 /* "rsyscall" is a mechanism by which a thread can synchronously force all
@@ -89,19 +89,20 @@ static struct {
 static void rsyscall_handler(int sig, siginfo_t *si, void *ctx)
 {
        struct pthread *self = __pthread_self();
+       long r;
 
-       if (si->si_code > 0 || si->si_pid != self->pid ||
-               rs.cnt == libc.threads_minus_1) return;
+       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) {
-               __wait(&rs.hold, 0, 1, 1);
+               sigfillset(&((ucontext_t *)ctx)->uc_sigmask);
                return;
        }
 
-       if (syscall(rs.nr, rs.arg[0], rs.arg[1], rs.arg[2],
-               rs.arg[3], rs.arg[4], rs.arg[5]) < 0 && !rs.err) rs.err=errno;
+       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);
@@ -128,9 +129,9 @@ static int rsyscall(int nr, long a, long b, long c, long d, long e, long f)
        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.hold = 1;
        rs.err = 0;
        rs.cnt = 0;
+       rs.hold = 1;
 
        /* Dispatch signals until all threads respond */
        for (i=libc.threads_minus_1; i; i--)
@@ -162,13 +163,18 @@ static void init_threads()
        libc.lockfile = __lockfile;
        libc.cancelpt = cancelpt;
        libc.rsyscall = rsyscall;
+
+       sigfillset(&sa.sa_mask);
+       sa.sa_sigaction = rsyscall_handler;
+       __libc_sigaction(SIGSYSCALL, &sa, 0);
+
+       sigemptyset(&sa.sa_mask);
        sa.sa_sigaction = cancel_handler;
        __libc_sigaction(SIGCANCEL, &sa, 0);
+
        sigaddset(&sa.sa_mask, SIGSYSCALL);
        sigaddset(&sa.sa_mask, SIGCANCEL);
-       sa.sa_sigaction = rsyscall_handler;
-       __libc_sigaction(SIGSYSCALL, &sa, 0);
-       sigprocmask(SIG_UNBLOCK, &sa.sa_mask, 0);
+       __libc_sigprocmask(SIG_UNBLOCK, &sa.sa_mask, 0);
 }
 
 static int start(void *p)
@@ -201,7 +207,7 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
        unsigned char *map, *stack, *tsd;
        static const pthread_attr_t default_attr;
 
-       if (!self) return errno = ENOSYS;
+       if (!self) return ENOSYS;
        if (!init && ++init) init_threads();
 
        if (!attr) attr = &default_attr;