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Support non-blocking i/o across platforms

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This change introduces new tests for `O_NONBLOCK` and `SOCK_NONBLOCK` to
confirm that non-blocking i/o is now working on all supported platforms,
including Windows. For example, you can now say on Windows, MacOS, etc.:

    socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);

To create a non-blocking IPv4 TCP socket. Or you can enable non-blocking
i/o on an existing socket / pipe / etc. file descriptor by calling fcntl

    fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);

This functionality is polyfilled on older Linux kernels too, e.g. RHEL5.
Now that fcntl() support is much better the FIOCLEX / FIONCLEX polyfills
for ioctl() have been removed since they're ugly non-POSIX diameond APIs

This change fixes a weakness in kprintf() that was causing Windows trace
tools to frequently crash.
This commit is contained in:
Justine Tunney 2023-07-23 02:56:47 -07:00
parent 5c9e03e3e0
commit 1d4eb08fa1
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
102 changed files with 678 additions and 331 deletions
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59
third_party/python/Python/fileutils.c vendored
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@ -446,8 +446,18 @@ _Py_get_inheritable(int fd)
static int
set_inheritable(int fd, int inheritable, int raise, int *atomic_flag_works)
{
#ifdef MS_WINDOWS
HANDLE handle;
DWORD flags;
#else
#if defined(HAVE_SYS_IOCTL_H) && defined(FIOCLEX) && defined(FIONCLEX)
static int ioctl_works = -1;
int res, err, flags, new_flags;
int request;
int err;
#endif
int flags, new_flags;
int res;
#endif
/* atomic_flag_works can only be used to make the file descriptor
non-inheritable */
@ -460,22 +470,49 @@ set_inheritable(int fd, int inheritable, int raise, int *atomic_flag_works)
return -1;
*atomic_flag_works = !isInheritable;
}
if (*atomic_flag_works)
return 0;
}
#ifdef MS_WINDOWS
_Py_BEGIN_SUPPRESS_IPH
handle = (HANDLE)_get_osfhandle(fd);
_Py_END_SUPPRESS_IPH
if (handle == INVALID_HANDLE_VALUE) {
if (raise)
PyErr_SetFromErrno(PyExc_OSError);
return -1;
}
if (inheritable)
flags = HANDLE_FLAG_INHERIT;
else
flags = 0;
if (!SetHandleInformation(handle, HANDLE_FLAG_INHERIT, flags)) {
if (raise)
PyErr_SetFromWindowsErr(0);
return -1;
}
return 0;
#else
#if defined(HAVE_SYS_IOCTL_H) && defined(FIOCLEX) && defined(FIONCLEX)
if (ioctl_works != 0 && raise != 0) {
/* fast-path: ioctl() only requires one syscall */
/* caveat: raise=0 is an indicator that we must be async-signal-safe
* thus avoid using ioctl() so we skip the fast-path. */
if (inheritable)
err = ioctl(fd, FIONCLEX, NULL);
request = FIONCLEX;
else
err = ioctl(fd, FIOCLEX, NULL);
request = FIOCLEX;
err = ioctl(fd, request, NULL);
if (!err) {
ioctl_works = 1;
return 0;
}
if (errno != ENOTTY && errno != EACCES) {
if (raise)
PyErr_SetFromErrno(PyExc_OSError);
@ -483,18 +520,19 @@ set_inheritable(int fd, int inheritable, int raise, int *atomic_flag_works)
}
else {
/* Issue #22258: Here, ENOTTY means "Inappropriate ioctl for
device". The ioctl is declared but not supported by the
kernel. Remember that ioctl() doesn't work. It is the
case on Illumos-based OS for example.
device". The ioctl is declared but not supported by the kernel.
Remember that ioctl() doesn't work. It is the case on
Illumos-based OS for example.
Issue #27057: When SELinux policy disallows ioctl it will
fail with EACCES. While FIOCLEX is safe operation it may
be unavailable because ioctl was denied altogether. This
can be the case on Android. */
Issue #27057: When SELinux policy disallows ioctl it will fail
with EACCES. While FIOCLEX is safe operation it may be
unavailable because ioctl was denied altogether.
This can be the case on Android. */
ioctl_works = 0;
}
/* fallback to fcntl() if ioctl() does not work */
}
#endif
/* slow-path: fcntl() requires two syscalls */
flags = fcntl(fd, F_GETFD);
@ -523,6 +561,7 @@ set_inheritable(int fd, int inheritable, int raise, int *atomic_flag_works)
return -1;
}
return 0;
#endif
}
/* Make the file descriptor non-inheritable.