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-rw-r--r--src/process/system.c65
1 files changed, 42 insertions, 23 deletions
diff --git a/src/process/system.c b/src/process/system.c
index 0f1c07b5..c8f26008 100644
--- a/src/process/system.c
+++ b/src/process/system.c
@@ -3,43 +3,62 @@
#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();
+ __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);
}