util: Add os_get_page_size query

No Apple/BSD implementation yet, I have no idea how to do that

Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7680>

src/util/os_misc.c

@@ -322,3 +322,34 @@ os_get_available_system_memory(uint64_t *size)
    return false;
 #endif
 }
+
+/**
+ * Return the size of a page
+ * \param size returns the size of a page
+ * \return true for success, or false on failure
+ */
+bool
+os_get_page_size(uint64_t *size)
+{
+#if DETECT_OS_LINUX || DETECT_OS_CYGWIN || DETECT_OS_SOLARIS || DETECT_OS_HURD
+   const long page_size = sysconf(_SC_PAGE_SIZE);
+
+   if (page_size <= 0)
+      return false;
+
+   *size = (uint64_t)page_size;
+   return true;
+#elif DETECT_OS_HAIKU
+   *size = (uint64_t)B_PAGE_SIZE;
+   return true;
+#elif DETECT_OS_WINDOWS
+   SYSTEM_INFO SysInfo;
+
+   GetSystemInfo(&SysInfo);
+   *size = SysInfo.dwPageSize;
+   return true;
+#else
+#error unexpected platform in os_sysinfo.c
+   return false;
+#endif
+}

src/util/os_misc.h

@@ -101,6 +101,12 @@ os_get_total_physical_memory(uint64_t *size);
 bool
 os_get_available_system_memory(uint64_t *size);
 
+/*
+ * Size of a page
+ */
+bool
+os_get_page_size(uint64_t *size);
+
 
 #ifdef	__cplusplus
 }