X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=blobdiff_plain;f=src%2Fprocess%2Fsystem.c;h=ebe207f597f13edd3bba746115260b6894ce20c4;hp=0f1c07b55289ac1a3b44cab58eb0fb52d1c3095b;hb=599f97360389911c293e0ca4c5eb49e007377fba;hpb=0b44a0315b47dd8eced9f3b7f31580cf14bbfc01

diff --git a/src/process/system.c b/src/process/system.c
index 0f1c07b5..ebe207f5 100644
--- a/src/process/system.c
+++ b/src/process/system.c
@@ -3,43 +3,63 @@
 #include <signal.h>
 #include <sys/wait.h>
 #include <errno.h>
+#include "pthread_impl.h"
+#include "libc.h"
+
+static void dummy_0()
+{
+}
+weak_alias(dummy_0, __acquire_ptc);
+weak_alias(dummy_0, __release_ptc);
+
+pid_t __vfork(void);
 
 int system(const char *cmd)
 {
 	pid_t pid;
-	sigset_t old, new;
-	struct sigaction sa, oldint, oldquit;
-	int status;
+	sigset_t old;
+	struct sigaction sa = { .sa_handler = SIG_IGN }, oldint, oldquit;
+	int status = -1, i;
 
 	if (!cmd) return 1;
 
-	sa.sa_handler = SIG_IGN;
-	sigemptyset(&sa.sa_mask);
-	sa.sa_flags = 0;
-
 	sigaction(SIGINT, &sa, &oldint);
 	sigaction(SIGQUIT, &sa, &oldquit);
-	sigaddset(&sa.sa_mask, SIGCHLD);
-	sigprocmask(SIG_BLOCK, &new, &old);
+	sigprocmask(SIG_BLOCK, SIGALL_SET, &old);
+
+	__acquire_ptc();
+	pid = __vfork();
+
+	if (pid) __release_ptc();
 
-	pid = fork();
-	if (pid <= 0) {
+	if (pid > 0) {
+		sigset_t new = old;
+		sigaddset(&new, SIGCHLD);
+		sigprocmask(SIG_BLOCK, &new, 0);
+		while (waitpid(pid, &status, 0) && errno == EINTR);
+	}
+
+	if (pid) {
 		sigaction(SIGINT, &oldint, NULL);
 		sigaction(SIGQUIT, &oldquit, NULL);
 		sigprocmask(SIG_SETMASK, &old, NULL);
-		if (pid == 0) {
-			execl("/bin/sh", "sh", "-c", cmd, (char *)0);
-			_exit(127);
-		}
-		return -1;
+		return status;
 	}
-	while (waitpid(pid, &status, 0) == -1)
-		if (errno != EINTR) {
-			status = -1;
-			break;
+
+	/* Before we can unblock signals in the child, all signal
+	 * handlers must be eliminated -- even implementation-internal
+	 * ones. Otherwise, a signal handler could run in the child
+	 * and clobber the parent's memory (due to vfork). */
+	for (i=1; i<=8*__SYSCALL_SSLEN; i++) {
+		struct sigaction sa;
+		__libc_sigaction(i, 0, &sa);
+		if (sa.sa_handler!=SIG_IGN && sa.sa_handler!=SIG_DFL) {
+			sa.sa_handler = SIG_DFL;
+			__libc_sigaction(i, &sa, 0);
 		}
-	sigaction(SIGINT, &oldint, NULL);
-	sigaction(SIGQUIT, &oldquit, NULL);
+	}
+
 	sigprocmask(SIG_SETMASK, &old, NULL);
-	return status;
+	execl("/bin/sh", "sh", "-c", cmd, (char *)0);
+	_exit(127);
 }