refactor setxid return path to use __syscall_ret

this avoids some spurious negation and duplicated errno logic, and
brings the code in line with the newly-added multithreaded setgroups.

diff --git a/src/unistd/setxid.c b/src/unistd/setxid.c
index 0239f8a..487c1a1 100644 (file)
--- a/src/unistd/setxid.c
+++ b/src/unistd/setxid.c
@@ -1,20 +1,19 @@
 #include <unistd.h>
-#include <errno.h>
+#include <signal.h>
 #include "syscall.h"
 #include "libc.h"
-#include "pthread_impl.h"
 
 struct ctx {
        int id, eid, sid;
-       int nr, err;
+       int nr, ret;
 };
 
 static void do_setxid(void *p)
 {
        struct ctx *c = p;
-       if (c->err>0) return;
-       int ret = -__syscall(c->nr, c->id, c->eid, c->sid);
-       if (ret && !c->err) {
+       if (c->ret<0) return;
+       int ret = __syscall(c->nr, c->id, c->eid, c->sid);
+       if (ret && !c->ret) {
                /* If one thread fails to set ids after another has already
                 * succeeded, forcibly killing the process is the only safe
                 * thing to do. State is inconsistent and dangerous. Use
@@ -22,18 +21,14 @@ static void do_setxid(void *p)
                __block_all_sigs(0);
                __syscall(SYS_kill, __syscall(SYS_getpid), SIGKILL);
        }
-       c->err = ret;
+       c->ret = ret;
 }
 
 int __setxid(int nr, int id, int eid, int sid)
 {
-       /* err is initially nonzero so that failure of the first thread does not
+       /* ret is initially nonzero so that failure of the first thread does not
         * trigger the safety kill above. */
-       struct ctx c = { .nr = nr, .id = id, .eid = eid, .sid = sid, .err = -1 };
+       struct ctx c = { .nr = nr, .id = id, .eid = eid, .sid = sid, .ret = 1 };
        __synccall(do_setxid, &c);
-       if (c.err) {
-               if (c.err>0) errno = c.err;
-               return -1;
-       }
-       return 0;
+       return __syscall_ret(c.ret);
 }