X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;ds=sidebyside;f=src%2Fprocess%2Fposix_spawn.c;h=f675a13c37dbb59c2e912854ea854f35d0bc31c1;hb=8011614da008032642aa8292c3fd079bf7a8843d;hp=dd4501298cb545eaedcd8aa35c32688a91142a11;hpb=4862864fc1a6d162b297db09c216b136db83d7dd;p=musl

diff --git a/src/process/posix_spawn.c b/src/process/posix_spawn.c
index dd450129..f675a13c 100644
--- a/src/process/posix_spawn.c
+++ b/src/process/posix_spawn.c
@@ -10,12 +10,6 @@
 #include "fdop.h"
 #include "libc.h"
 
-static void dummy_0()
-{
-}
-weak_alias(dummy_0, __acquire_ptc);
-weak_alias(dummy_0, __release_ptc);
-
 struct args {
 	int p[2];
 	sigset_t oldmask;
@@ -26,29 +20,43 @@ struct args {
 	char *const *argv, *const *envp;
 };
 
+void __get_handler_set(sigset_t *);
+
 static int child(void *args_vp)
 {
 	int i, ret;
-	struct sigaction sa;
+	struct sigaction sa = {0};
 	struct args *args = args_vp;
 	int p = args->p[1];
 	const posix_spawn_file_actions_t *fa = args->fa;
 	const posix_spawnattr_t *restrict attr = args->attr;
+	sigset_t hset;
 
 	close(args->p[0]);
 
 	/* All signal dispositions must be either SIG_DFL or SIG_IGN
 	 * before signals are unblocked. Otherwise a signal handler
 	 * from the parent might get run in the child while sharing
-	 * memory, with unpredictable and dangerous results. */
+	 * memory, with unpredictable and dangerous results. To
+	 * reduce overhead, sigaction has tracked for us which signals
+	 * potentially have a signal handler. */
+	__get_handler_set(&hset);
 	for (i=1; i<_NSIG; i++) {
-		__libc_sigaction(i, 0, &sa);
-		if (sa.sa_handler!=SIG_DFL && (sa.sa_handler!=SIG_IGN ||
-		    ((attr->__flags & POSIX_SPAWN_SETSIGDEF)
-		     && sigismember(&attr->__def, i) ))) {
+		if ((attr->__flags & POSIX_SPAWN_SETSIGDEF)
+		     && sigismember(&attr->__def, i)) {
 			sa.sa_handler = SIG_DFL;
-			__libc_sigaction(i, &sa, 0);
+		} else if (sigismember(&hset, i)) {
+			if (i-32<3U) {
+				sa.sa_handler = SIG_IGN;
+			} else {
+				__libc_sigaction(i, 0, &sa);
+				if (sa.sa_handler==SIG_IGN) continue;
+				sa.sa_handler = SIG_DFL;
+			}
+		} else {
+			continue;
 		}
+		__libc_sigaction(i, &sa, 0);
 	}
 
 	if (attr->__flags & POSIX_SPAWN_SETPGROUP)
@@ -111,6 +119,7 @@ static int child(void *args_vp)
 		? &attr->__mask : &args->oldmask, 0);
 
 	args->exec(args->path, args->argv, args->envp);
+	ret = -errno;
 
 fail:
 	/* Since sizeof errno < PIPE_BUF, the write is atomic. */
@@ -144,11 +153,8 @@ int __posix_spawnx(pid_t *restrict res, const char *restrict path,
 	args.envp = envp;
 	pthread_sigmask(SIG_BLOCK, SIGALL_SET, &args.oldmask);
 
-	/* This lock prevents setuid/setgid operations while the parent
-	 * is sharing memory with the child. Situations where processes
-	 * with different permissions share VM are fundamentally unsafe. */
-	__acquire_ptc();
-	pid = __clone(child, stack+sizeof stack, CLONE_VM|SIGCHLD, &args);
+	pid = __clone(child, stack+sizeof stack,
+		CLONE_VM|CLONE_VFORK|SIGCHLD, &args);
 	close(args.p[1]);
 
 	if (pid > 0) {
@@ -158,12 +164,9 @@ int __posix_spawnx(pid_t *restrict res, const char *restrict path,
 		ec = -pid;
 	}
 
-	/* At this point, the child has either exited or successfully
-	 * performed exec, so the lock may be released. */
-	__release_ptc();
 	close(args.p[0]);
 
-	if (!ec) *res = pid;
+	if (!ec && res) *res = pid;
 
 	pthread_sigmask(SIG_SETMASK, &args.oldmask, 0);
 	pthread_setcancelstate(cs, 0);