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linux-user: fix wait* syscall status returns 

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>
This commit is contained in:
Alexander Graf 2011-11-24 00:44:43 +01:00 committed by Riku Voipio
parent 2a7e12455c
commit 5379557b8d
1 changed files with 2 additions and 2 deletions
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4
linux-user/syscall.c
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@ -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;