[macOS, UNIX] prefer _SC_PAGESIZE over (partially) deprecated getpagesize() (#1891)

Add a reusable `psutil_getpagesize()` utility common to all UNIXes.

Related to #1885 (`getpagesize()` is deprecated on recent macOS, POSIX.1-2001 and possibly other UNIXes).

The problem emerged on macOS but `getpagesize()` is also used in FreeBSD, NetBSD, OpenBSD and AIX, so it makes sense to do this in one place only, similarly to Windows which also provide a `psutil_getpagesize()` utility.

Follow cPython's `mmapmodule.c` and `resourcemodule.c` lead and rely on `sysconf(_SC_PAGESIZE)` instead, but leave `getpagesize()` in place as last resort/attempt for systems where it's not deprecated and/or they still legitimately rely on it.

Also provide a python wrapper so we can test the return value of this C function against Python's stdlib modules.

Signed-off-by: Giampaolo Rodola <g.rodola@gmail.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/psutil/_psutil_posix.c b/psutil/_psutil_posix.c
index b41c6dec..305cec76 100644
--- a/psutil/_psutil_posix.c
+++ b/psutil/_psutil_posix.c
@@ -15,6 +15,7 @@
 #include <sys/socket.h>
 #include <sys/ioctl.h>
 #include <net/if.h>
+#include <unistd.h>
 
 #ifdef PSUTIL_SUNOS10
     #include "arch/solaris/v10/ifaddrs.h"
@@ -50,6 +51,38 @@
 
 #include "_psutil_common.h"
 
+
+// ====================================================================
+// --- Utils
+// ====================================================================
+
+
+/*
+ * From "man getpagesize" on Linux, https://linux.die.net/man/2/getpagesize:
+ *
+ * > In SUSv2 the getpagesize() call is labeled LEGACY, and in POSIX.1-2001
+ * > it has been dropped.
+ * > Portable applications should employ sysconf(_SC_PAGESIZE) instead
+ * > of getpagesize().
+ * > Most systems allow the synonym _SC_PAGE_SIZE for _SC_PAGESIZE.
+ * > Whether getpagesize() is present as a Linux system call depends on the
+ * > architecture.
+ */
+long
+psutil_getpagesize(void) {
+#ifdef _SC_PAGESIZE
+    // recommended POSIX
+    return sysconf(_SC_PAGESIZE);
+#elif _SC_PAGE_SIZE
+    // alias
+    return sysconf(_SC_PAGE_SIZE);
+#else
+    // legacy
+    return (long) getpagesize();
+#endif
+}
+
+
 /*
  * Check if PID exists. Return values:
  * 1: exists
@@ -123,6 +156,18 @@ psutil_raise_for_pid(long pid, char *syscall) {
 }
 
 
+// ====================================================================
+// --- Python wrappers
+// ====================================================================
+
+
+// Exposed so we can test it against Python's stdlib.
+static PyObject *
+psutil_getpagesize_pywrapper(PyObject *self, PyObject *args) {
+    return Py_BuildValue("l", psutil_getpagesize());
+}
+
+
 /*
  * Given a PID return process priority as a Python integer.
  */
@@ -629,6 +674,8 @@ static PyMethodDef mod_methods[] = {
      "Retrieve NIC MTU"},
     {"net_if_is_running", psutil_net_if_is_running, METH_VARARGS,
      "Return True if the NIC is running."},
+    {"getpagesize", psutil_getpagesize_pywrapper, METH_VARARGS,
+     "Return memory page size."},
 #if defined(PSUTIL_BSD) || defined(PSUTIL_OSX)
     {"net_if_duplex_speed", psutil_net_if_duplex_speed, METH_VARARGS,
      "Return NIC stats."},