[11/19] linux-user: fix wait* syscall status returns

Submitted by riku.voipio@linaro.org on Jan. 31, 2012, 9:29 a.m.

Details

Message ID fc03f50f8691379a58f95c18a463d21e294b1b0a.1328001769.git.riku.voipio@linaro.org
State New
Headers show

Commit Message

riku.voipio@linaro.org Jan. 31, 2012, 9:29 a.m.
From: Alexander Graf <agraf@suse.de>

When calling wait4 or waitpid with a status pointer and WNOHANG, the
syscall can potentially not modify the status pointer input. Now if we
have guest code like:

  int status = 0;
  waitpid(pid, &status, WNOHANG);
  if (status)
     <breakage>

then we have to make sure that in case status did not change we actually
return the guest's initialized status variable instead of our own uninitialized.
We fail to do so today, as we proxy everything through an uninitialized status
variable which for me ended up always containing the last error code.

This patch fixes some test cases when building yast2-core in OBS for ARM.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
---
 linux-user/syscall.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

Patch hide | download patch | download mbox

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 29d92c4..06b19e0 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4867,7 +4867,7 @@  abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
         {
             int status;
             ret = get_errno(waitpid(arg1, &status, arg3));
-            if (!is_error(ret) && arg2
+            if (!is_error(ret) && arg2 && ret
                 && put_user_s32(host_to_target_waitstatus(status), arg2))
                 goto efault;
         }
@@ -6423,7 +6423,7 @@  abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
                 rusage_ptr = NULL;
             ret = get_errno(wait4(arg1, &status, arg3, rusage_ptr));
             if (!is_error(ret)) {
-                if (status_ptr) {
+                if (status_ptr && ret) {
                     status = host_to_target_waitstatus(status);
                     if (put_user_s32(status, status_ptr))
                         goto efault;