[pypy-commit] pypy py3.5-noninherit: Implement the basics

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: py3.5-noninherit
Changeset: r86552:6ba4a5df9526
Date: 2016-08-26 14:15 +0200
http://bitbucket.org/pypy/pypy/changeset/6ba4a5df9526/

Log:	Implement the basics

diff --git a/rpython/rlib/rposix.py b/rpython/rlib/rposix.py
--- a/rpython/rlib/rposix.py
+++ b/rpython/rlib/rposix.py
@@ -2080,13 +2080,45 @@
 
 eci_inheritable = eci.merge(ExternalCompilationInfo(
     separate_module_sources=["""
+#include <errno.h>
+
 RPY_EXTERN
 int rpy_set_inheritable(int fd, int inheritable)
 {
-    /* XXX minimal impl. XXX */
-    int request = inheritable ? FIONCLEX : FIOCLEX;
-    return ioctl(fd, request, NULL);
+    static int ioctl_works = -1;
+    int flags;
+
+    if (ioctl_works != 0) {
+        int request = inheritable ? FIONCLEX : FIOCLEX;
+        int err = ioctl(fd, request, NULL);
+        if (!err) {
+            ioctl_works = 1;
+            return 0;
+        }
+
+        if (errno != ENOTTY && errno != EACCES) {
+            return -1;
+        }
+        else {
+            /* ENOTTY: The ioctl is declared but not supported by the
+               kernel.  EACCES: SELinux policy, this can be the case on
+               Android. */
+            ioctl_works = 0;
+        }
+        /* fallback to fcntl() if ioctl() does not work */
+    }
+
+    flags = fcntl(fd, F_GETFD);
+    if (flags < 0)
+        return -1;
+
+    if (inheritable)
+        flags &= ~FD_CLOEXEC;
+    else
+        flags |= FD_CLOEXEC;
+    return fcntl(fd, F_SETFD, flags);
 }
+
 RPY_EXTERN
 int rpy_get_inheritable(int fd)
 {
@@ -2106,10 +2138,25 @@
                              compilation_info=eci_inheritable)
 
 def set_inheritable(fd, inheritable):
-    error = c_set_inheritable(fd, inheritable)
-    handle_posix_error('set_inheritable', error)
+    result = c_set_inheritable(fd, inheritable)
+    handle_posix_error('set_inheritable', result)
 
 def get_inheritable(fd):
     res = c_get_inheritable(fd)
     res = handle_posix_error('get_inheritable', res)
     return res != 0
+
+class SetNonInheritableCache(object):
+    """Make one prebuilt instance of this for each path that creates
+    file descriptors, where you don't necessarily know if that function
+    returns inheritable or non-inheritable file descriptors.
+    """
+    _immutable_fields_ = ['cached_inheritable?']
+    cached_inheritable = -1    # -1 = don't know yet; 0 = off; 1 = on
+
+    def set_non_inheritable(self, fd):
+        if self.cached_inheritable == -1:
+            self.cached_inheritable = get_inheritable(fd)
+        if self.cached_inheritable == 1:
+            # 'fd' is inheritable; we must manually turn it off
+            set_inheritable(fd, False)
diff --git a/rpython/rlib/test/test_rposix.py b/rpython/rlib/test/test_rposix.py
--- a/rpython/rlib/test/test_rposix.py
+++ b/rpython/rlib/test/test_rposix.py
@@ -589,3 +589,18 @@
     assert rposix.get_inheritable(fd1) == False
     os.close(fd1)
     os.close(fd2)
+
+def test_SetNonInheritableCache():
+    cache = rposix.SetNonInheritableCache()
+    fd1, fd2 = os.pipe()
+    assert rposix.get_inheritable(fd1) == True
+    assert rposix.get_inheritable(fd1) == True
+    assert cache.cached_inheritable == -1
+    cache.set_non_inheritable(fd1)
+    assert cache.cached_inheritable == 1
+    cache.set_non_inheritable(fd2)
+    assert cache.cached_inheritable == 1
+    assert rposix.get_inheritable(fd1) == False
+    assert rposix.get_inheritable(fd1) == False
+    os.close(fd1)
+    os.close(fd2)