From 9ded490806368ee6c6aaf5f84a6e02b97f49eb23 Mon Sep 17 00:00:00 2001
From: Bill Currie <bill@taniwha.org>
Date: Thu, 1 Apr 2021 18:20:56 +0900
Subject: [PATCH] [util] Add Sys_PageSize

Eliminate that particular problem once and for all.
---
 include/QF/sys.h |  1 +
 libs/util/cmem.c | 12 ++++++------
 libs/util/sys.c  | 37 +++++++++++++++++++++----------------
 3 files changed, 28 insertions(+), 22 deletions(-)

diff --git a/include/QF/sys.h b/include/QF/sys.h
index eb0f25e00..e1ed1a057 100644
--- a/include/QF/sys.h
+++ b/include/QF/sys.h
@@ -120,6 +120,7 @@ void Sys_Init_Cvars (void);
 //
 void Sys_MakeCodeWriteable (uintptr_t startaddr, size_t length);
 void Sys_PageIn (void *ptr, size_t size);
+long Sys_PageSize (void);
 void *Sys_Alloc (size_t size);
 
 //
diff --git a/libs/util/cmem.c b/libs/util/cmem.c
index 651f94993..02f78bb0e 100644
--- a/libs/util/cmem.c
+++ b/libs/util/cmem.c
@@ -24,20 +24,20 @@
 		Boston, MA  02111-1307, USA
 
 */
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
 #include <unistd.h>
 #include <malloc.h>
 
 #include "QF/alloc.h"
 #include "QF/cmem.h"
+#include "QF/sys.h"
 
 #ifdef _WIN32
 #define cmem_alloc(align, size) _aligned_malloc(size, align)
 #define cmem_free(mem) _aligned_free(mem)
-#define _SC_PAGESIZE 1
-static size_t sysconf (int key)
-{
-	return 4096;
-}
 #else
 #define cmem_alloc(align, size) aligned_alloc(align, size)
 #define cmem_free(mem) free(mem)
@@ -58,7 +58,7 @@ new_memsuper (void)
 {
 	memsuper_t *super = cmem_alloc (MEM_LINE_SIZE, sizeof (*super));
 	memset (super, 0, sizeof (*super));
-	super->page_size = sysconf (_SC_PAGESIZE);
+	super->page_size = Sys_PageSize ();
 	super->page_mask = (super->page_size - 1);
 	return super;
 }
diff --git a/libs/util/sys.c b/libs/util/sys.c
index f448a6f55..cada787f2 100644
--- a/libs/util/sys.c
+++ b/libs/util/sys.c
@@ -442,20 +442,10 @@ Sys_MakeCodeWriteable (uintptr_t startaddr, size_t length)
 #else
 # ifdef HAVE_MPROTECT
 	int         r;
+	long        psize = Sys_PageSize ();
 	unsigned long endaddr = startaddr + length;
-#  ifdef HAVE__SC_PAGESIZE
-	long		psize = sysconf (_SC_PAGESIZE);
-
-	startaddr &= ~(psize - 1);
-	endaddr = (endaddr + psize - 1) & ~(psize -1);
-#  else
-#   ifdef HAVE_GETPAGESIZE
-	int         psize = getpagesize ();
-
 	startaddr &= ~(psize - 1);
 	endaddr = (endaddr + psize - 1) & ~(psize - 1);
-#   endif
-#  endif
 	// systems with mprotect but not getpagesize (or similar) probably don't
 	// need to page align the arguments to mprotect (eg, QNX)
 	r = mprotect ((char *) startaddr, endaddr - startaddr,
@@ -619,18 +609,33 @@ Sys_PageIn (void *ptr, size_t size)
 //#endif
 }
 
+VISIBLE long
+Sys_PageSize (void)
+{
+#ifdef _WIN32
+	SYSTEM_INFO si;
+	GetSystemInfo (&si);
+	return si.dwPageSize;
+#else
+# ifdef HAVE__SC_PAGESIZE
+	return sysconf (_SC_PAGESIZE);
+# else
+#  ifdef HAVE_GETPAGESIZE
+	return getpagesize ();
+#  endif
+# endif
+#endif
+}
+
 VISIBLE void *
 Sys_Alloc (size_t size)
 {
-#ifdef _WIN32
-	size_t      page_size = 4096;
+	size_t      page_size = Sys_PageSize ();
 	size_t      page_mask = page_size - 1;
 	size = (size + page_mask) & ~page_mask;
+#ifdef _WIN32
 	return VirtualAlloc (0, size, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
 #else
-	size_t      page_size = sysconf (_SC_PAGESIZE);
-	size_t      page_mask = page_size - 1;
-	size = (size + page_mask) & ~page_mask;
 	return mmap (0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS,
 				 -1, 0);
 #endif