include cleanups: remove unused headers and add feature test macros

[musl] / src / process / posix_spawn.c

diff --git a/src/process/posix_spawn.c b/src/process/posix_spawn.c
index dd45012..eb98f9f 100644 (file)
--- 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) {
@@ -158,9 +164,6 @@ 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;