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diff --git a/lib/libc/stdlib/system.c b/lib/libc/stdlib/system.c
--- a/lib/libc/stdlib/system.c
+++ b/lib/libc/stdlib/system.c
@@ -32,21 +32,22 @@
#include "namespace.h"
#include <sys/types.h>
#include <sys/wait.h>
+
+#include <errno.h>
+#include <paths.h>
#include <signal.h>
-#include <stdlib.h>
#include <stddef.h>
+#include <stdlib.h>
#include <string.h>
#include <unistd.h>
-#include <paths.h>
-#include <errno.h>
#include "un-namespace.h"
#include "libc_private.h"
+#include "spinlock.h"
#pragma weak system
int
system(const char *command)
{
-
return (((int (*)(const char *))
__libc_interposing[INTERPOS_system])(command));
}
@@ -54,54 +55,78 @@
int
__libc_system(const char *command)
{
- pid_t pid, savedpid;
- int pstat;
- struct sigaction ign, intact, quitact;
- sigset_t newsigblock, oldsigblock;
+ static spinlock_t lock = _SPINLOCK_INITIALIZER;
+ static unsigned long concurrent;
+ static struct sigaction ointact, oquitact;
+ static sigset_t osigblock;
+ struct sigaction ign;
+ sigset_t sigblock;
+ int pstat = -1, serrno = 0;
+ pid_t pid;
- if (!command) /* just checking... */
- return(1);
+ if (command == NULL) /* just checking... */
+ return (1);
- (void)sigemptyset(&newsigblock);
- (void)sigaddset(&newsigblock, SIGCHLD);
- (void)sigaddset(&newsigblock, SIGINT);
- (void)sigaddset(&newsigblock, SIGQUIT);
- (void)__libc_sigprocmask(SIG_BLOCK, &newsigblock, &oldsigblock);
- switch(pid = vfork()) {
/*
- * In the child, use unwrapped syscalls. libthr is in
- * undefined state after vfork().
+ * If we are the first concurrent instance, ignore SIGINT and
+ * SIGQUIT and block SIGCHLD.
*/
- case -1: /* error */
- (void)__libc_sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
- return (-1);
- case 0: /* child */
+ _SPINLOCK(&lock);
+ if (concurrent++ == 0) {
+ memset(&ign, 0, sizeof(ign));
+ ign.sa_handler = SIG_IGN;
+ sigemptyset(&ign.sa_mask);
+ (void)__libc_sigaction(SIGINT, &ign, &ointact);
+ (void)__libc_sigaction(SIGQUIT, &ign, &oquitact);
+ sigemptyset(&sigblock);
+ sigaddset(&sigblock, SIGCHLD);
+ (void)__libc_sigprocmask(SIG_BLOCK, &sigblock, &osigblock);
+ }
+ _SPINUNLOCK(&lock);
+
+ /*
+ * Fork the child process.
+ */
+ if ((pid = fork()) < 0) { /* error */
+ serrno = errno;
+ } else if (pid == 0) { /* child */
/*
- * Restore original signal dispositions and exec the command.
+ * Restore original signal dispositions.
*/
- (void)__sys_sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
- execl(_PATH_BSHELL, "sh", "-c", command, (char *)NULL);
+ (void)__libc_sigaction(SIGINT, &ointact, NULL);
+ (void)__libc_sigaction(SIGQUIT, &oquitact, NULL);
+ (void)__sys_sigprocmask(SIG_SETMASK, &osigblock, NULL);
+ /*
+ * Exec the command.
+ */
+ execl(_PATH_BSHELL, "sh", "-c", command, NULL);
_exit(127);
+ } else { /* parent */
+ /*
+ * Wait for the child to terminate.
+ */
+ while (_wait4(pid, &pstat, 0, NULL) < 0) {
+ if (errno != EINTR) {
+ serrno = errno;
+ break;
+ }
+ }
}
- /*
- * If we are running means that the child has either completed
- * its execve, or has failed.
- * Block SIGINT/QUIT because sh -c handles it and wait for
- * it to clean up.
+
+ /*
+ * If we are the last concurrent instance, restore original signal
+ * dispositions.
*/
- memset(&ign, 0, sizeof(ign));
- ign.sa_handler = SIG_IGN;
- (void)sigemptyset(&ign.sa_mask);
- (void)__libc_sigaction(SIGINT, &ign, &intact);
- (void)__libc_sigaction(SIGQUIT, &ign, &quitact);
- savedpid = pid;
- do {
- pid = _wait4(savedpid, &pstat, 0, (struct rusage *)0);
- } while (pid == -1 && errno == EINTR);
- (void)__libc_sigaction(SIGINT, &intact, NULL);
- (void)__libc_sigaction(SIGQUIT, &quitact, NULL);
- (void)__libc_sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
- return (pid == -1 ? -1 : pstat);
+ _SPINLOCK(&lock);
+ if (--concurrent == 0) {
+ (void)__libc_sigaction(SIGINT, &ointact, NULL);
+ (void)__libc_sigaction(SIGQUIT, &oquitact, NULL);
+ (void)__libc_sigprocmask(SIG_SETMASK, &osigblock, NULL);
+ }
+ _SPINUNLOCK(&lock);
+ if (serrno != 0)
+ errno = serrno;
+ return (pstat);
}
__weak_reference(__libc_system, __system);

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