RE: [PATCH v3 1/4] poll() exits too early with EFAULT if 1st arg is NULL

If poll() is used as a milli-second sleep, like in help.c, by passing a NULL
in the 1st and a 0 in the 2nd arg, it exits with EFAULT.

As per Paolo Bonzini, the original author, this is a bug and to be fixed like
in this commit, which is not to exit if the 2nd arg is 0.

Signed-off-by: Joachim Schmitz <redacted>
---
 compat/win32/poll.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compat/win32/poll.c b/compat/win32/poll.c
index 403eaa7..9e7a25c 100644
--- a/compat/win32/poll.c
+++ b/compat/win32/poll.c

@@ -349,7 +349,7 @@ poll (struct pollfd *pfd, nfds_t nfd, int timeout)
 
   /* EFAULT is not necessary to implement, but let's do it in the
      simplest case. */
-  if (!pfd)
+  if (!pfd && nfd)
     {
       errno = EFAULT;
       return -1;

-- 
1.7.12

Joachim Schmitz wrote:

Actually this one is not needed for win32 (nor does win32 suffer from a 
similar bug), so should probably better get added after patch 2/2 (or as 
part of it), the move to compat/poll/.

Bye, Jojo

Joachim Schmitz wrote:

Joachim Schmitz wrote:

quoted

If poll() is used as a milli-second sleep, like in help.c, by passing
a NULL in the 1st and a 0 in the 2nd arg, it exits with EFAULT.

As per Paolo Bonzini, the original author, this is a bug and to be
fixed like in this commit, which is not to exit if the 2nd arg is 0.

Signed-off-by: Joachim Schmitz <redacted>
---
compat/win32/poll.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compat/win32/poll.c b/compat/win32/poll.c
index 403eaa7..9e7a25c 100644
--- a/compat/win32/poll.c
+++ b/compat/win32/poll.c

@@ -349,7 +349,7 @@ poll (struct pollfd *pfd, nfds_t nfd, int

timeout) 

  /* EFAULT is not necessary to implement, but let's do it in the
     simplest case. */
-  if (!pfd)
+  if (!pfd && nfd)
    {
      errno = EFAULT;
      return -1;

Actually this one is not needed for win32 (nor does win32 suffer from
a similar bug), so should probably better get added after patch 2/2
(or as part of it), the move to compat/poll/.

It just got added that was to gnulib, with a commit message of:

don't exit early if NULL is the 1st arg to poll(),
but nfd is 0.  In that case poll should behave like select.

Bye, Jojo