Merge branch 'bug4991_v2'

33 files changed, 198 insertions, 203 deletions

diff --git a/changes/win32macro b/changes/win32macro
new file mode 100644
index 0000000000..402bb99b3a
--- /dev/null
+++ b/changes/win32macro
@@ -0,0 +1,4 @@
+  o Code simplifications and refactoring:
+    - Use the _WIN32 macro throughout our code to detect Windows.
+      (Previously we had used the obsolete 'WIN32' and the
+      idiosyncratic 'MS_WINDOWS'.)
diff --git a/configure.in b/configure.in
index ddb682379d..ef571b84d6 100644
--- a/configure.in
+++ b/configure.in
@@ -224,12 +224,12 @@ AC_ARG_WITH(tor-group,
 AC_SUBST(TORGROUP)
 
 
-dnl If WIN32 is defined and non-zero, we are building for win32
+dnl If _WIN32 is defined and non-zero, we are building for win32
 AC_MSG_CHECKING([for win32])
 AC_RUN_IFELSE([AC_LANG_SOURCE([
 int main(int c, char **v) {
-#ifdef WIN32
-#if WIN32
+#ifdef _WIN32
+#if _WIN32
   return 0;
 #else
   return 1;
@@ -246,7 +246,7 @@ bwin32=cross; AC_MSG_RESULT([cross])
 if test "$bwin32" = cross; then
 AC_MSG_CHECKING([for win32 (cross)])
 AC_COMPILE_IFELSE([AC_LANG_SOURCE([
-#ifdef WIN32
+#ifdef _WIN32
 int main(int c, char **v) {return 0;}
 #else
 #error
@@ -257,9 +257,6 @@ bwin32=true; AC_MSG_RESULT([yes]),
 bwin32=false; AC_MSG_RESULT([no]))
 fi
 
-if test "$bwin32" = true; then
-AC_DEFINE(MS_WINDOWS, 1, [Define to 1 if we are building for Windows.])
-fi
 AM_CONDITIONAL(BUILD_NT_SERVICES, test x$bwin32 = xtrue)
 
 dnl Enable C99 when compiling with MIPSpro
@@ -380,19 +377,19 @@ if test "$enable_static_libevent" = "yes"; then
 fi
 
 TOR_SEARCH_LIBRARY(libevent, $trylibeventdir, [-levent $STATIC_LIBEVENT_FLAGS $TOR_LIB_WS32], [
-#ifdef WIN32
+#ifdef _WIN32
 #include <winsock2.h>
 #endif
 #include <stdlib.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <event.h>], [
-#ifdef WIN32
+#ifdef _WIN32
 #include <winsock2.h>
 #endif
 void exit(int); void *event_init(void);],
     [
-#ifdef WIN32
+#ifdef _WIN32
 {WSADATA d; WSAStartup(0x101,&d); }
 #endif
 event_init(); exit(0);
@@ -573,7 +570,7 @@ if test "$natpmp" = "true"; then
     AC_DEFINE(NAT_PMP, 1, [Define to 1 if we are building with nat-pmp.])
     TOR_SEARCH_LIBRARY(libnatpmp, $trylibnatpmpdir, [-lnatpmp $TOR_LIB_WS32 $TOR_LIB_IPHLPAPI],
         [#include <natpmp.h>],
-        [#ifdef MS_WINDOWS
+        [#ifdef _WIN32
          #define STATICLIB
          #endif
          #include <natpmp.h>],
@@ -772,7 +769,7 @@ AC_CHECK_TYPES([struct in6_addr, struct sockaddr_in6, sa_family_t], , ,
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define WIN32_WINNT 0x400
 #define _WIN32_WINNT 0x400
 #define WIN32_LEAN_AND_MEAN
@@ -797,7 +794,7 @@ AC_CHECK_MEMBERS([struct in6_addr.s6_addr32, struct in6_addr.s6_addr16, struct s
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define WIN32_WINNT 0x400
 #define _WIN32_WINNT 0x400
 #define WIN32_LEAN_AND_MEAN
diff --git a/src/common/address.c b/src/common/address.c
index e18ef95469..17cda42cb7 100644
--- a/src/common/address.c
+++ b/src/common/address.c
@@ -15,7 +15,7 @@
 #include "torlog.h"
 #include "container.h"
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #include <process.h>
 #include <windows.h>
 #include <winsock2.h>
@@ -275,7 +275,7 @@ tor_addr_lookup(const char *name, uint16_t family, tor_addr_t *addr)
     ent = err ? NULL : &hent;
 #else
     ent = gethostbyname(name);
-#ifdef MS_WINDOWS
+#ifdef _WIN32
     err = WSAGetLastError();
 #else
     err = h_errno;
@@ -291,7 +291,7 @@ tor_addr_lookup(const char *name, uint16_t family, tor_addr_t *addr)
       }
       return 0;
     }
-#ifdef MS_WINDOWS
+#ifdef _WIN32
     return (err == WSATRY_AGAIN) ? 1 : -1;
 #else
     return (err == TRY_AGAIN) ? 1 : -1;
@@ -1101,7 +1101,7 @@ tor_addr_port_lookup(const char *s, tor_addr_t *addr_out, uint16_t *port_out)
   return -1;
 }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 typedef ULONG (WINAPI *GetAdaptersAddresses_fn_t)(
               ULONG, ULONG, PVOID, PIP_ADAPTER_ADDRESSES, PULONG);
 #endif
@@ -1140,7 +1140,7 @@ get_interface_addresses_raw(int severity)
 
   freeifaddrs(ifa);
   return result;
-#elif defined(MS_WINDOWS)
+#elif defined(_WIN32)
   /* Windows XP began to provide GetAdaptersAddresses. Windows 2000 had a
      "GetAdaptersInfo", but that's deprecated; let's just try
      GetAdaptersAddresses and fall back to connect+getsockname.
diff --git a/src/common/compat.c b/src/common/compat.c
index cd112035c6..64c06681da 100644
--- a/src/common/compat.c
+++ b/src/common/compat.c
@@ -21,7 +21,7 @@
 
 #include "compat.h"
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #include <process.h>
 #include <windows.h>
 #include <sys/locking.h>
@@ -205,7 +205,7 @@ tor_munmap_file(tor_mmap_t *handle)
   munmap((char*)handle->data, handle->mapping_size);
   tor_free(handle);
 }
-#elif defined(MS_WINDOWS)
+#elif defined(_WIN32)
 tor_mmap_t *
 tor_mmap_file(const char *filename)
 {
@@ -341,7 +341,7 @@ tor_vsnprintf(char *str, size_t size, const char *format, va_list args)
     return -1; /* no place for the NUL */
   if (size > SIZE_T_CEILING)
     return -1;
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   r = _vsnprintf(str, size, format, args);
 #else
   r = vsnprintf(str, size, format, args);
@@ -570,7 +570,7 @@ tor_strtok_r_impl(char *str, const char *sep, char **lasts)
   return start;
 }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 /** Take a filename and return a pointer to its final element.  This
  * function is called on __FILE__ to fix a MSVC nit where __FILE__
  * contains the full path to the file.  This is bad, because it
@@ -670,7 +670,7 @@ set_uint64(void *cp, uint64_t v)
 int
 replace_file(const char *from, const char *to)
 {
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   return rename(from,to);
 #else
   switch (file_status(to))
@@ -739,7 +739,7 @@ tor_lockfile_lock(const char *filename, int blocking, int *locked_out)
     return NULL;
   }
 
-#ifdef WIN32
+#ifdef _WIN32
   _lseek(fd, 0, SEEK_SET);
   if (_locking(fd, blocking ? _LK_LOCK : _LK_NBLCK, 1) < 0) {
     if (errno != EACCES && errno != EDEADLOCK)
@@ -788,7 +788,7 @@ tor_lockfile_unlock(tor_lockfile_t *lockfile)
   tor_assert(lockfile);
 
   log_info(LD_FS, "Unlocking \"%s\"", lockfile->filename);
-#ifdef WIN32
+#ifdef _WIN32
   _lseek(lockfile->fd, 0, SEEK_SET);
   if (_locking(lockfile->fd, _LK_UNLCK, 1) < 0) {
     log_warn(LD_FS,"Error unlocking \"%s\": %s", lockfile->filename,
@@ -824,7 +824,7 @@ tor_lockfile_unlock(tor_lockfile_t *lockfile)
 off_t
 tor_fd_getpos(int fd)
 {
-#ifdef WIN32
+#ifdef _WIN32
   return (off_t) _lseek(fd, 0, SEEK_CUR);
 #else
   return (off_t) lseek(fd, 0, SEEK_CUR);
@@ -835,7 +835,7 @@ tor_fd_getpos(int fd)
 int
 tor_fd_seekend(int fd)
 {
-#ifdef WIN32
+#ifdef _WIN32
   return _lseek(fd, 0, SEEK_END) < 0 ? -1 : 0;
 #else
   return lseek(fd, 0, SEEK_END) < 0 ? -1 : 0;
@@ -888,7 +888,7 @@ tor_close_socket(tor_socket_t s)
    * tor_close_socket to close sockets, and always using close() on
    * files.
    */
-#if defined(MS_WINDOWS)
+#if defined(_WIN32)
   r = closesocket(s);
 #else
   r = close(s);
@@ -909,7 +909,7 @@ tor_close_socket(tor_socket_t s)
   } else {
     int err = tor_socket_errno(-1);
     log_info(LD_NET, "Close returned an error: %s", tor_socket_strerror(err));
-#ifdef WIN32
+#ifdef _WIN32
     if (err != WSAENOTSOCK)
       --n_sockets_open;
 #else
@@ -1016,7 +1016,7 @@ get_n_open_sockets(void)
 void
 set_socket_nonblocking(tor_socket_t socket)
 {
-#if defined(MS_WINDOWS)
+#if defined(_WIN32)
   unsigned long nonblocking = 1;
   ioctlsocket(socket, FIONBIO, (unsigned long*) &nonblocking);
 #else
@@ -1045,7 +1045,7 @@ int
 tor_socketpair(int family, int type, int protocol, tor_socket_t fd[2])
 {
 //don't use win32 socketpairs (they are always bad)
-#if defined(HAVE_SOCKETPAIR) && !defined(MS_WINDOWS)
+#if defined(HAVE_SOCKETPAIR) && !defined(_WIN32)
   int r;
 #ifdef SOCK_CLOEXEC
   type |= SOCK_CLOEXEC;
@@ -1089,7 +1089,7 @@ tor_socketpair(int family, int type, int protocol, tor_socket_t fd[2])
         || family != AF_UNIX
 #endif
         ) {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
       return -WSAEAFNOSUPPORT;
 #else
       return -EAFNOSUPPORT;
@@ -1149,7 +1149,7 @@ tor_socketpair(int family, int type, int protocol, tor_socket_t fd[2])
     return 0;
 
   abort_tidy_up_and_fail:
-#ifdef MS_WINDOWS
+#ifdef _WIN32
     saved_errno = WSAECONNABORTED;
 #else
     saved_errno = ECONNABORTED; /* I hope this is portable and appropriate.  */
@@ -1191,7 +1191,7 @@ set_max_file_descriptors(rlim_t limit, int *max_out)
 #if defined(CYGWIN) || defined(__CYGWIN__)
   const char *platform = "Cygwin";
   const unsigned long MAX_CONNECTIONS = 3200;
-#elif defined(MS_WINDOWS)
+#elif defined(_WIN32)
   const char *platform = "Windows";
   const unsigned long MAX_CONNECTIONS = 15000;
 #else
@@ -1274,7 +1274,7 @@ set_max_file_descriptors(rlim_t limit, int *max_out)
   return 0;
 }
 
-#ifndef MS_WINDOWS
+#ifndef _WIN32
 /** Log details of current user and group credentials. Return 0 on
  * success. Logs and return -1 on failure.
  */
@@ -1380,7 +1380,7 @@ log_credential_status(void)
 int
 switch_id(const char *user)
 {
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   struct passwd *pw = NULL;
   uid_t old_uid;
   gid_t old_gid;
@@ -1591,7 +1591,7 @@ get_parent_directory(char *fname)
   char *cp;
   int at_end = 1;
   tor_assert(fname);
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   /* If we start with, say, c:, then don't consider that the start of the path
    */
   if (fname[0] && fname[1] == ':') {
@@ -1608,7 +1608,7 @@ get_parent_directory(char *fname)
   at_end = 1;
   while (--cp > fname) {
     int is_sep = (*cp == '/'
-#ifdef MS_WINDOWS
+#ifdef _WIN32
                   || *cp == '\\'
 #endif
                   );
@@ -1628,7 +1628,7 @@ get_parent_directory(char *fname)
 char *
 make_path_absolute(char *fname)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   char *absfname_malloced = _fullpath(NULL, fname, 1);
 
   /* We don't want to assume that tor_free can free a string allocated
@@ -1900,7 +1900,7 @@ tor_lookup_hostname(const char *name, uint32_t *addr)
 void
 tor_init_weak_random(unsigned seed)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   srand(seed);
 #else
   srandom(seed);
@@ -1913,7 +1913,7 @@ tor_init_weak_random(unsigned seed)
 long
 tor_weak_random(void)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   return rand();
 #else
   return random();
@@ -1942,7 +1942,7 @@ get_uname(void)
     } else
 #endif
       {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
         OSVERSIONINFOEX info;
         int i;
         const char *plat = NULL;
@@ -2144,7 +2144,7 @@ spawn_exit(void)
 static int
 compute_num_cpus_impl(void)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   SYSTEM_INFO info;
   memset(&info, 0, sizeof(info));
   GetSystemInfo(&info);
@@ -2192,7 +2192,7 @@ compute_num_cpus(void)
 void
 tor_gettimeofday(struct timeval *timeval)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   /* Epoch bias copied from perl: number of units between windows epoch and
    * Unix epoch. */
 #define EPOCH_BIAS U64_LITERAL(116444736000000000)
@@ -2237,7 +2237,7 @@ tor_gettimeofday(struct timeval *timeval)
   return;
 }
 
-#if defined(TOR_IS_MULTITHREADED) && !defined(MS_WINDOWS)
+#if defined(TOR_IS_MULTITHREADED) && !defined(_WIN32)
 /** Defined iff we need to add locks when defining fake versions of reentrant
  * versions of time-related functions. */
 #define TIME_FNS_NEED_LOCKS
@@ -2781,7 +2781,7 @@ in_main_thread(void)
  * should call tor_socket_errno <em>at most once</em> on the failing
  * socket to get the error.
  */
-#if defined(MS_WINDOWS)
+#if defined(_WIN32)
 int
 tor_socket_errno(tor_socket_t sock)
 {
@@ -2797,7 +2797,7 @@ tor_socket_errno(tor_socket_t sock)
 }
 #endif
 
-#if defined(MS_WINDOWS)
+#if defined(_WIN32)
 #define E(code, s) { code, (s " [" #code " ]") }
 struct { int code; const char *msg; } windows_socket_errors[] = {
   E(WSAEINTR, "Interrupted function call"),
@@ -2879,7 +2879,7 @@ tor_socket_strerror(int e)
 int
 network_init(void)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   /* This silly exercise is necessary before windows will allow
    * gethostbyname to work. */
   WSADATA WSAData;
@@ -2901,7 +2901,7 @@ network_init(void)
   return 0;
 }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 /** Return a newly allocated string describing the windows system error code
  * <b>err</b>.  Note that error codes are different from errno.  Error codes
  * come from GetLastError() when a winapi call fails.  errno is set only when
diff --git a/src/common/compat.h b/src/common/compat.h
index 4329d45369..fa1ef90eb7 100644
--- a/src/common/compat.h
+++ b/src/common/compat.h
@@ -8,7 +8,7 @@
 
 #include "orconfig.h"
 #include "torint.h"
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #ifndef WIN32_WINNT
 #define WIN32_WINNT 0x400
 #endif
@@ -35,7 +35,7 @@
 #ifdef HAVE_STRING_H
 #include <string.h>
 #endif
-#if defined(HAVE_PTHREAD_H) && !defined(MS_WINDOWS)
+#if defined(HAVE_PTHREAD_H) && !defined(_WIN32)
 #include <pthread.h>
 #endif
 #include <stdarg.h>
@@ -89,7 +89,7 @@
 #endif
 
 /* inline is __inline on windows. */
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define INLINE __inline
 #else
 #define INLINE inline
@@ -196,7 +196,7 @@ extern INLINE double U64_TO_DBL(uint64_t x) {
 #endif
 
 /* ===== String compatibility */
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 /* Windows names string functions differently from most other platforms. */
 #define strncasecmp _strnicmp
 #define strcasecmp _stricmp
@@ -249,7 +249,7 @@ typedef struct tor_mmap_t {
 #ifdef HAVE_SYS_MMAN_H
   size_t mapping_size; /**< Size of the actual mapping. (This is this file
                         * size, rounded up to the nearest page.) */
-#elif defined MS_WINDOWS
+#elif defined _WIN32
   HANDLE file_handle;
   HANDLE mmap_handle;
 #endif
@@ -307,7 +307,7 @@ char *tor_strtok_r_impl(char *str, const char *sep, char **lasts);
 #define tor_strtok_r(str, sep, lasts) tor_strtok_r_impl(str, sep, lasts)
 #endif
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define _SHORT_FILE_ (tor_fix_source_file(__FILE__))
 const char *tor_fix_source_file(const char *fname);
 #else
@@ -386,7 +386,7 @@ void tor_lockfile_unlock(tor_lockfile_t *lockfile);
 off_t tor_fd_getpos(int fd);
 int tor_fd_seekend(int fd);
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define PATH_SEPARATOR "\\"
 #else
 #define PATH_SEPARATOR "/"
@@ -398,7 +398,7 @@ int tor_fd_seekend(int fd);
 typedef int socklen_t;
 #endif
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 /* XXX Actually, this should arguably be SOCKET; we use intptr_t here so that
  * any inadvertant checks for the socket being <= 0 or > 0 will probably
  * still work. */
@@ -499,7 +499,7 @@ int network_init(void);
  * errnos against expected values, and use tor_socket_errno to find
  * the actual errno after a socket operation fails.
  */
-#if defined(MS_WINDOWS)
+#if defined(_WIN32)
 /** Return true if e is EAGAIN or the local equivalent. */
 #define ERRNO_IS_EAGAIN(e)           ((e) == EAGAIN || (e) == WSAEWOULDBLOCK)
 /** Return true if e is EINPROGRESS or the local equivalent. */
@@ -584,7 +584,7 @@ char *make_path_absolute(char *fname);
 int spawn_func(void (*func)(void *), void *data);
 void spawn_exit(void) ATTR_NORETURN;
 
-#if defined(ENABLE_THREADS) && defined(MS_WINDOWS)
+#if defined(ENABLE_THREADS) && defined(_WIN32)
 #define USE_WIN32_THREADS
 #define TOR_IS_MULTITHREADED 1
 #elif (defined(ENABLE_THREADS) && defined(HAVE_PTHREAD_H) && \
@@ -666,14 +666,14 @@ void tor_cond_signal_all(tor_cond_t *cond);
 #endif
 
 /* Platform-specific helpers. */
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 char *format_win32_error(DWORD err);
 #endif
 
 /*for some reason my compiler doesn't have these version flags defined
   a nice homework assignment for someone one day is to define the rest*/
 //these are the values as given on MSDN
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 
 #ifndef VER_SUITE_EMBEDDEDNT
 #define VER_SUITE_EMBEDDEDNT 0x00000040
diff --git a/src/common/compat_libevent.c b/src/common/compat_libevent.c
index 0cedef8d5e..70e3baf9dd 100644
--- a/src/common/compat_libevent.c
+++ b/src/common/compat_libevent.c
@@ -205,7 +205,7 @@ tor_libevent_initialize(tor_libevent_cfg *torcfg)
     cfg = event_config_new();
     tor_assert(cfg);
 
-#if defined(MS_WINDOWS) && defined(USE_BUFFEREVENTS)
+#if defined(_WIN32) && defined(USE_BUFFEREVENTS)
     if (! torcfg->disable_iocp) {
       evthread_use_windows_threads();
       event_config_set_flag(cfg, EVENT_BASE_FLAG_STARTUP_IOCP);
@@ -241,7 +241,7 @@ tor_libevent_initialize(tor_libevent_cfg *torcfg)
       /* This could be a socketpair() failure, which can happen sometimes on
        * windows boxes with obnoxious firewall rules.  Downgrade and try
        * again. */
-#if defined(MS_WINDOWS) && defined(USE_BUFFEREVENTS)
+#if defined(_WIN32) && defined(USE_BUFFEREVENTS)
       if (torcfg->disable_iocp == 0) {
         log_warn(LD_GENERAL, "Unable to initialize Libevent. Trying again "
                  "with IOCP disabled.");
diff --git a/src/common/crypto.c b/src/common/crypto.c
index 6bc54fc44f..380dcf0abc 100644
--- a/src/common/crypto.c
+++ b/src/common/crypto.c
@@ -12,7 +12,7 @@
 
 #include "orconfig.h"
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #ifndef WIN32_WINNT
 #define WIN32_WINNT 0x400
 #endif
@@ -2409,7 +2409,7 @@ crypto_seed_rng(int startup)
   int rand_poll_status = 0;
 
   /* local variables */
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   unsigned char buf[ADD_ENTROPY];
   static int provider_set = 0;
   static HCRYPTPROV provider;
@@ -2431,7 +2431,7 @@ crypto_seed_rng(int startup)
       log_warn(LD_CRYPTO, "RAND_poll() failed.");
   }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   if (!provider_set) {
     if (!CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
                              CRYPT_VERIFYCONTEXT)) {
diff --git a/src/common/procmon.c b/src/common/procmon.c
index 5c10e9a22b..85d2a2fe3f 100644
--- a/src/common/procmon.c
+++ b/src/common/procmon.c
@@ -21,7 +21,7 @@
 #include <errno.h>
 #endif
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #include <windows.h>
 
 /* Windows does not define pid_t, but _getpid() returns an int. */
@@ -91,7 +91,7 @@ struct tor_process_monitor_t {
    * polls. */
   pid_t pid;
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   /** Windows-only: Should we poll hproc?  If false, poll pid
    * instead. */
   int poll_hproc;
@@ -192,7 +192,7 @@ tor_process_monitor_new(struct event_base *base,
 
   procmon->pid = ppspec.pid;
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   procmon->hproc = OpenProcess(PROCESS_QUERY_INFORMATION | SYNCHRONIZE,
                                FALSE,
                                procmon->pid);
@@ -246,7 +246,7 @@ tor_process_monitor_poll_cb(evutil_socket_t unused1, short unused2,
 
   tor_assert(procmon != NULL);
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   if (procmon->poll_hproc) {
     DWORD exit_code;
     if (!GetExitCodeProcess(procmon->hproc, &exit_code)) {
@@ -323,7 +323,7 @@ tor_process_monitor_free(tor_process_monitor_t *procmon)
   if (procmon == NULL)
     return;
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   if (procmon->hproc != NULL)
     CloseHandle(procmon->hproc);
 #endif
diff --git a/src/common/tortls.c b/src/common/tortls.c
index 570dd005fd..26d37145a3 100644
--- a/src/common/tortls.c
+++ b/src/common/tortls.c
@@ -21,7 +21,7 @@
 #endif
 
 #include <assert.h>
-#ifdef MS_WINDOWS /*wrkard for dtls1.h >= 0.9.8m of "#include <winsock.h>"*/
+#ifdef _WIN32 /*wrkard for dtls1.h >= 0.9.8m of "#include <winsock.h>"*/
  #ifndef WIN32_WINNT
  #define WIN32_WINNT 0x400
  #endif
@@ -333,7 +333,7 @@ tls_log_errors(tor_tls_t *tls, int severity, int domain, const char *doing)
 static int
 tor_errno_to_tls_error(int e)
 {
-#if defined(MS_WINDOWS)
+#if defined(_WIN32)
   switch (e) {
     case WSAECONNRESET: // most common
       return TOR_TLS_ERROR_CONNRESET;
diff --git a/src/common/util.c b/src/common/util.c
index 40efff0518..52fea2186a 100644
--- a/src/common/util.c
+++ b/src/common/util.c
@@ -26,7 +26,7 @@
 #include "container.h"
 #include "address.h"
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #include <io.h>
 #include <direct.h>
 #include <process.h>
@@ -915,7 +915,7 @@ tor_parse_uint64(const char *s, int base, uint64_t min,
 
 #ifdef HAVE_STRTOULL
   r = (uint64_t)strtoull(s, &endptr, base);
-#elif defined(MS_WINDOWS)
+#elif defined(_WIN32)
 #if defined(_MSC_VER) && _MSC_VER < 1300
   tor_assert(base <= 10);
   r = (uint64_t)_atoi64(s);
@@ -1731,7 +1731,7 @@ read_all(tor_socket_t fd, char *buf, size_t count, int isSocket)
 static void
 clean_name_for_stat(char *name)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   size_t len = strlen(name);
   if (!len)
     return;
@@ -1790,7 +1790,7 @@ check_private_dir(const char *dirname, cpd_check_t check,
   int r;
   struct stat st;
   char *f;
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   int mask;
   struct passwd *pw = NULL;
   uid_t running_uid;
@@ -1812,7 +1812,7 @@ check_private_dir(const char *dirname, cpd_check_t check,
     }
     if (check & CPD_CREATE) {
       log_info(LD_GENERAL, "Creating directory %s", dirname);
-#if defined (MS_WINDOWS) && !defined (WINCE)
+#if defined (_WIN32) && !defined (WINCE)
       r = mkdir(dirname);
 #else
       r = mkdir(dirname, 0700);
@@ -1834,7 +1834,7 @@ check_private_dir(const char *dirname, cpd_check_t check,
     log_warn(LD_FS, "%s is not a directory", dirname);
     return -1;
   }
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   if (effective_user) {
     /* Look up the user and group information.
      * If we have a problem, bail out. */
@@ -1921,7 +1921,7 @@ check_private_dir(const char *dirname, cpd_check_t check,
 int
 write_str_to_file(const char *fname, const char *str, int bin)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   if (!bin && strchr(str, '\r')) {
     log_warn(LD_BUG,
              "We're writing a text string that already contains a CR.");
@@ -2263,7 +2263,7 @@ read_file_to_str(const char *filename, int flags, struct stat *stat_out)
   }
   string[r] = '\0'; /* NUL-terminate the result. */
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   if (!bin && strchr(string, '\r')) {
     log_debug(LD_FS, "We didn't convert CRLF to LF as well as we hoped "
               "when reading %s. Coping.",
@@ -2544,7 +2544,7 @@ char *
 expand_filename(const char *filename)
 {
   tor_assert(filename);
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   return tor_strdup(filename);
 #else
   if (*filename == '~') {
@@ -2780,7 +2780,7 @@ smartlist_t *
 tor_listdir(const char *dirname)
 {
   smartlist_t *result;
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   char *pattern=NULL;
   TCHAR tpattern[MAX_PATH] = {0};
   char name[MAX_PATH] = {0};
@@ -2843,7 +2843,7 @@ path_is_relative(const char *filename)
 {
   if (filename && filename[0] == '/')
     return 0;
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   else if (filename && filename[0] == '\\')
     return 0;
   else if (filename && strlen(filename)>3 && TOR_ISALPHA(filename[0]) &&
@@ -2858,7 +2858,7 @@ path_is_relative(const char *filename)
  * Process helpers
  * ===== */
 
-#ifndef MS_WINDOWS
+#ifndef _WIN32
 /* Based on code contributed by christian grothoff */
 /** True iff we've called start_daemon(). */
 static int start_daemon_called = 0;
@@ -2972,7 +2972,7 @@ finish_daemon(const char *desired_cwd)
   close(daemon_filedes[1]);
 }
 #else
-/* defined(MS_WINDOWS) */
+/* defined(_WIN32) */
 void
 start_daemon(void)
 {
@@ -2995,7 +2995,7 @@ write_pidfile(char *filename)
     log_warn(LD_FS, "Unable to open \"%s\" for writing: %s", filename,
              strerror(errno));
   } else {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
     fprintf(pidfile, "%d\n", (int)_getpid());
 #else
     fprintf(pidfile, "%d\n", (int)getpid());
@@ -3004,7 +3004,7 @@ write_pidfile(char *filename)
   }
 }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 HANDLE
 load_windows_system_library(const TCHAR *library_name)
 {
@@ -3191,7 +3191,7 @@ format_helper_exit_status(unsigned char child_state, int saved_errno,
 int
 tor_terminate_process(process_handle_t *process_handle)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   if (tor_get_exit_code(process_handle, 0, NULL) == PROCESS_EXIT_RUNNING) {
     HANDLE handle;
     /* If the signal is outside of what GenerateConsoleCtrlEvent can use,
@@ -3217,14 +3217,14 @@ tor_terminate_process(process_handle_t *process_handle)
 int
 tor_process_get_pid(process_handle_t *process_handle)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   return (int) process_handle->pid.dwProcessId;
 #else
   return (int) process_handle->pid;
 #endif
 }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 HANDLE
 tor_process_get_stdout_pipe(process_handle_t *process_handle)
 {
@@ -3243,7 +3243,7 @@ process_handle_new(void)
 {
   process_handle_t *out = tor_malloc_zero(sizeof(process_handle_t));
 
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   out->stdout_pipe = -1;
   out->stderr_pipe = -1;
 #endif
@@ -3284,14 +3284,14 @@ process_handle_new(void)
  */
 int
 tor_spawn_background(const char *const filename, const char **argv,
-#ifdef MS_WINDOWS
+#ifdef _WIN32
                      LPVOID envp,
 #else
                      const char **envp,
 #endif
                      process_handle_t **process_handle_out)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   HANDLE stdout_pipe_read = NULL;
   HANDLE stdout_pipe_write = NULL;
   HANDLE stderr_pipe_read = NULL;
@@ -3393,7 +3393,7 @@ tor_spawn_background(const char *const filename, const char **argv,
   /* TODO: Close pipes on exit */
   *process_handle_out = process_handle;
   return status;
-#else // MS_WINDOWS
+#else // _WIN32
   pid_t pid;
   int stdout_pipe[2];
   int stderr_pipe[2];
@@ -3574,7 +3574,7 @@ tor_spawn_background(const char *const filename, const char **argv,
 
   *process_handle_out = process_handle;
   return process_handle->status;
-#endif // MS_WINDOWS
+#endif // _WIN32
 }
 
 /** Destroy all resources allocated by the process handle in
@@ -3600,7 +3600,7 @@ tor_process_handle_destroy(process_handle_t *process_handle,
 
   process_handle->status = PROCESS_STATUS_NOTRUNNING;
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   if (process_handle->stdout_pipe)
     CloseHandle(process_handle->stdout_pipe);
 
@@ -3632,7 +3632,7 @@ int
 tor_get_exit_code(const process_handle_t *process_handle,
                   int block, int *exit_code)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   DWORD retval;
   BOOL success;
 
@@ -3687,12 +3687,12 @@ tor_get_exit_code(const process_handle_t *process_handle,
 
   if (exit_code != NULL)
     *exit_code = WEXITSTATUS(stat_loc);
-#endif // MS_WINDOWS
+#endif // _WIN32
 
   return PROCESS_EXIT_EXITED;
 }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 /** Read from a handle <b>h</b> into <b>buf</b>, up to <b>count</b> bytes.  If
  * <b>hProcess</b> is NULL, the function will return immediately if there is
  * nothing more to read. Otherwise <b>hProcess</b> should be set to the handle
@@ -3814,7 +3814,7 @@ ssize_t
 tor_read_all_from_process_stdout(const process_handle_t *process_handle,
                                  char *buf, size_t count)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   return tor_read_all_handle(process_handle->stdout_pipe, buf, count,
                              process_handle);
 #else
@@ -3828,7 +3828,7 @@ ssize_t
 tor_read_all_from_process_stderr(const process_handle_t *process_handle,
                                  char *buf, size_t count)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   return tor_read_all_handle(process_handle->stderr_pipe, buf, count,
                              process_handle);
 #else
@@ -3890,7 +3890,7 @@ tor_split_lines(smartlist_t *sl, char *buf, int len)
   return smartlist_len(sl);
 }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 /** Read from stream, and send lines to log at the specified log level.
  * Returns -1 if there is a error reading, and 0 otherwise.
  * If the generated stream is flushed more often than on new lines, or
@@ -4103,7 +4103,7 @@ tor_check_port_forwarding(const char *filename, int dir_port, int or_port,
       child_handle = NULL;
     }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
     /* Passing NULL as lpApplicationName makes Windows search for the .exe */
     status = tor_spawn_background(NULL, argv, NULL, &child_handle);
 #else
@@ -4126,7 +4126,7 @@ tor_check_port_forwarding(const char *filename, int dir_port, int or_port,
   if (child_handle && PROCESS_STATUS_RUNNING == child_handle->status) {
     /* Read from stdout/stderr and log result */
     retval = 0;
-#ifdef MS_WINDOWS
+#ifdef _WIN32
     stdout_status = log_from_handle(child_handle->stdout_pipe, LOG_INFO);
     stderr_status = log_from_handle(child_handle->stderr_pipe, LOG_WARN);
     /* If we got this far (on Windows), the process started */
@@ -4146,7 +4146,7 @@ tor_check_port_forwarding(const char *filename, int dir_port, int or_port,
     if (-1 == stdout_status || -1 == stderr_status)
       /* There was a failure */
       retval = -1;
-#ifdef MS_WINDOWS
+#ifdef _WIN32
     else if (!child_handle || tor_get_exit_code(child_handle, 0, NULL) !=
              PROCESS_EXIT_RUNNING) {
       /* process has exited or there was an error */
diff --git a/src/common/util.h b/src/common/util.h
index b15b1ea56a..1bad24bf72 100644
--- a/src/common/util.h
+++ b/src/common/util.h
@@ -364,7 +364,7 @@ void tor_check_port_forwarding(const char *filename,
 
 typedef struct process_handle_t process_handle_t;
 int tor_spawn_background(const char *const filename, const char **argv,
-#ifdef MS_WINDOWS
+#ifdef _WIN32
                          LPVOID envp,
 #else
                          const char **envp,
@@ -373,7 +373,7 @@ int tor_spawn_background(const char *const filename, const char **argv,
 
 #define SPAWN_ERROR_MESSAGE "ERR: Failed to spawn background process - code "
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 HANDLE load_windows_system_library(const TCHAR *library_name);
 #endif
 
@@ -388,7 +388,7 @@ HANDLE load_windows_system_library(const TCHAR *library_name);
 /*DOCDOC*/
 struct process_handle_t {
   int status;
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   HANDLE stdout_pipe;
   HANDLE stderr_pipe;
   PROCESS_INFORMATION pid;
@@ -398,7 +398,7 @@ struct process_handle_t {
   FILE *stdout_handle;
   FILE *stderr_handle;
   pid_t pid;
-#endif // MS_WINDOWS
+#endif // _WIN32
 };
 #endif
 
@@ -409,7 +409,7 @@ struct process_handle_t {
 int tor_get_exit_code(const process_handle_t *process_handle,
                       int block, int *exit_code);
 int tor_split_lines(struct smartlist_t *sl, char *buf, int len);
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 ssize_t tor_read_all_handle(HANDLE h, char *buf, size_t count,
                             const process_handle_t *process);
 #else
@@ -424,7 +424,7 @@ ssize_t tor_read_all_from_process_stderr(
 char *tor_join_win_cmdline(const char *argv[]);
 
 int tor_process_get_pid(process_handle_t *process_handle);
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 HANDLE tor_process_get_stdout_pipe(process_handle_t *process_handle);
 #else
 FILE *tor_process_get_stdout_pipe(process_handle_t *process_handle);
diff --git a/src/or/buffers.c b/src/or/buffers.c
index dbecf125c9..d4fc44ba9f 100644
--- a/src/or/buffers.c
+++ b/src/or/buffers.c
@@ -633,7 +633,7 @@ read_to_chunk(buf_t *buf, chunk_t *chunk, tor_socket_t fd, size_t at_most,
   if (read_result < 0) {
     int e = tor_socket_errno(fd);
     if (!ERRNO_IS_EAGAIN(e)) { /* it's a real error */
-#ifdef MS_WINDOWS
+#ifdef _WIN32
       if (e == WSAENOBUFS)
         log_warn(LD_NET,"recv() failed: WSAENOBUFS. Not enough ram?");
 #endif
@@ -790,7 +790,7 @@ flush_chunk(tor_socket_t s, buf_t *buf, chunk_t *chunk, size_t sz,
   if (write_result < 0) {
     int e = tor_socket_errno(s);
     if (!ERRNO_IS_EAGAIN(e)) { /* it's a real error */
-#ifdef MS_WINDOWS
+#ifdef _WIN32
       if (e == WSAENOBUFS)
         log_warn(LD_NET,"write() failed: WSAENOBUFS. Not enough ram?");
 #endif
diff --git a/src/or/config.c b/src/or/config.c
index 4b21b6c513..d341d63095 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -36,7 +36,7 @@
 #include "util.h"
 #include "routerlist.h"
 #include "transports.h"
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #include <shlobj.h>
 #endif
 
@@ -289,7 +289,7 @@ static config_var_t _option_vars[] = {
   V(FetchHidServDescriptors,     BOOL,     "1"),
   V(FetchUselessDescriptors,     BOOL,     "0"),
   V(FetchV2Networkstatus,        BOOL,     "0"),
-#ifdef WIN32
+#ifdef _WIN32
   V(GeoIPFile,                   FILENAME, "<default>"),
 #else
   V(GeoIPFile,                   FILENAME,
@@ -573,7 +573,7 @@ typedef struct {
                *(uint32_t*)STRUCT_VAR_P(cfg,fmt->magic_offset));        \
   STMT_END
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 static char *get_windows_conf_root(void);
 #endif
 static void config_line_append(config_line_t **lst,
@@ -1644,7 +1644,7 @@ options_act(const or_options_t *old_options)
      * understand prefixes somehow. -NM */
     /* XXXX023 Reload GeoIPFile on SIGHUP. -NM */
     char *actual_fname = tor_strdup(options->GeoIPFile);
-#ifdef WIN32
+#ifdef _WIN32
     if (!strcmp(actual_fname, "<default>")) {
       const char *conf_root = get_windows_conf_root();
       tor_free(actual_fname);
@@ -3357,7 +3357,7 @@ options_validate(or_options_t *old_options, or_options_t *options,
       REJECT("Failed to resolve/guess local address. See logs for details.");
   }
 
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   if (options->RunAsDaemon && torrc_fname && path_is_relative(torrc_fname))
     REJECT("Can't use a relative path to torrc when RunAsDaemon is set.");
 #endif
@@ -4247,7 +4247,7 @@ options_transition_affects_descriptor(const or_options_t *old_options,
   return 0;
 }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 /** Return the directory on windows where we expect to find our application
  * data. */
 static char *
@@ -4310,7 +4310,7 @@ get_windows_conf_root(void)
 static const char *
 get_default_conf_file(int defaults_file)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   if (defaults_file) {
     static char defaults_path[MAX_PATH+1];
     tor_snprintf(defaults_path, MAX_PATH, "%s\\torrc-defaults",
@@ -4400,7 +4400,7 @@ find_torrc_filename(int argc, char **argv,
     if (dflt && file_status(dflt) == FN_FILE) {
       fname = tor_strdup(dflt);
     } else {
-#ifndef MS_WINDOWS
+#ifndef _WIN32
       char *fn = NULL;
       if (!defaults_file)
         fn = expand_filename("~/.torrc");
@@ -4789,7 +4789,7 @@ options_init_logs(or_options_t *options, int validate_only)
   int ok;
   smartlist_t *elts;
   int daemon =
-#ifdef MS_WINDOWS
+#ifdef _WIN32
                0;
 #else
                options->RunAsDaemon;
@@ -5964,7 +5964,7 @@ check_server_ports(const smartlist_t *ports,
     } else {
       continue;
     }
-#ifndef MS_WINDOWS
+#ifndef _WIN32
     if (!port->no_advertise && port->port < 1024)
       ++n_low_port;
 #endif
@@ -6041,7 +6041,7 @@ get_first_advertised_port_by_type_af(int listener_type, int address_family)
 static int
 normalize_data_directory(or_options_t *options)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   char *p;
   if (options->DataDirectory)
     return 0; /* all set */
diff --git a/src/or/connection.c b/src/or/connection.c
index c51e7fbeff..bf65e8e81b 100644
--- a/src/or/connection.c
+++ b/src/or/connection.c
@@ -837,7 +837,7 @@ check_location_for_unix_socket(const or_options_t *options, const char *path)
 static void
 make_socket_reuseable(tor_socket_t sock)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   (void) sock;
 #else
   int one=1;
@@ -1317,7 +1317,7 @@ connection_connect(connection_t *conn, const char *address,
      * Warn if we do, and refuse to make the connection. */
     static ratelim_t disablenet_violated = RATELIM_INIT(30*60);
     char *m;
-#ifdef MS_WINDOWS
+#ifdef _WIN32
     *socket_error = WSAENETUNREACH;
 #else
     *socket_error = ENETUNREACH;
diff --git a/src/or/control.c b/src/or/control.c
index b7c46e92b0..9a07777a72 100644
--- a/src/or/control.c
+++ b/src/or/control.c
@@ -34,7 +34,7 @@
 #include "routerlist.h"
 #include "routerparse.h"
 
-#ifndef MS_WINDOWS
+#ifndef _WIN32
 #include <pwd.h>
 #include <sys/resource.h>
 #endif
@@ -542,7 +542,7 @@ control_ports_write_to_file(void)
     log_warn(LD_CONTROL, "Writing %s failed: %s",
              options->ControlPortWriteToFile, strerror(errno));
   }
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   if (options->ControlPortFileGroupReadable) {
     if (chmod(options->ControlPortWriteToFile, 0640)) {
       log_warn(LD_FS,"Unable to make %s group-readable.",
@@ -1392,7 +1392,7 @@ getinfo_helper_misc(control_connection_t *conn, const char *question,
   } else if (!strcmp(question, "process/pid")) {
     int myPid = -1;
 
-    #ifdef MS_WINDOWS
+    #ifdef _WIN32
       myPid = _getpid();
     #else
       myPid = getpid();
@@ -1400,14 +1400,14 @@ getinfo_helper_misc(control_connection_t *conn, const char *question,
 
     tor_asprintf(answer, "%d", myPid);
   } else if (!strcmp(question, "process/uid")) {
-    #ifdef MS_WINDOWS
+    #ifdef _WIN32
       *answer = tor_strdup("-1");
     #else
       int myUid = geteuid();
       tor_asprintf(answer, "%d", myUid);
     #endif
   } else if (!strcmp(question, "process/user")) {
-    #ifdef MS_WINDOWS
+    #ifdef _WIN32
       *answer = tor_strdup("");
     #else
       int myUid = geteuid();
@@ -1435,7 +1435,7 @@ getinfo_helper_misc(control_connection_t *conn, const char *question,
       }
     #elif defined(CYGWIN) || defined(__CYGWIN__)
       *answer = tor_strdup("3200");
-    #elif defined(MS_WINDOWS)
+    #elif defined(_WIN32)
       *answer = tor_strdup("15000");
     #else
       *answer = tor_strdup("15000");
@@ -4231,7 +4231,7 @@ init_cookie_authentication(int enabled)
     tor_free(fname);
     return -1;
   }
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   if (get_options()->CookieAuthFileGroupReadable) {
     if (chmod(fname, 0640)) {
       log_warn(LD_FS,"Unable to make %s group-readable.", escaped(fname));
diff --git a/src/or/dns.c b/src/or/dns.c
index ddf9841447..2b7d3e3506 100644
--- a/src/or/dns.c
+++ b/src/or/dns.c
@@ -1183,7 +1183,7 @@ configure_nameservers(int force)
   int r;
   options = get_options();
   conf_fname = options->ServerDNSResolvConfFile;
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   if (!conf_fname)
     conf_fname = "/etc/resolv.conf";
 #endif
@@ -1251,7 +1251,7 @@ configure_nameservers(int force)
     if (nameservers_configured)
       evdns_base_resume(the_evdns_base);
   }
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   else {
     if (nameservers_configured) {
       evdns_base_search_clear(the_evdns_base);
diff --git a/src/or/eventdns.c b/src/or/eventdns.c
index 7cd5d80afb..61a28361ab 100644
--- a/src/or/eventdns.c
+++ b/src/or/eventdns.c
@@ -96,7 +96,7 @@
 
 #include "eventdns.h"
 
-#ifdef WIN32
+#ifdef _WIN32
 #include <windows.h>
 #include <winsock2.h>
 #include <iphlpapi.h>
@@ -110,7 +110,7 @@
 #include <netinet/in6.h>
 #endif
 
-#ifdef WIN32
+#ifdef _WIN32
 typedef int socklen_t;
 #endif
 
@@ -343,7 +343,7 @@ static void server_port_ready_callback(int fd, short events, void *arg);
 
 static int strtoint(const char *const str);
 
-#ifdef WIN32
+#ifdef _WIN32
 static int
 last_error(int sock)
 {
@@ -432,7 +432,7 @@ _evdns_log(int warn, const char *fmt, ...)
 	if (!evdns_log_fn)
 		return;
 	va_start(args,fmt);
-#ifdef WIN32
+#ifdef _WIN32
 	_vsnprintf(buf, sizeof(buf), fmt, args);
 #else
 	vsnprintf(buf, sizeof(buf), fmt, args);
@@ -2298,7 +2298,7 @@ _evdns_nameserver_add_impl(const struct sockaddr *address,
 
 	ns->socket = tor_open_socket(address->sa_family, SOCK_DGRAM, 0);
 	if (ns->socket < 0) { err = 1; goto out1; }
-#ifdef WIN32
+#ifdef _WIN32
 	{
 		u_long nonblocking = 1;
 		ioctlsocket(ns->socket, FIONBIO, &nonblocking);
@@ -3101,7 +3101,7 @@ out1:
 	return err;
 }
 
-#ifdef WIN32
+#ifdef _WIN32
 /* Add multiple nameservers from a space-or-comma-separated list. */
 static int
 evdns_nameserver_ip_add_line(const char *ips) {
@@ -3309,7 +3309,7 @@ int
 evdns_init(void)
 {
 		int res = 0;
-#ifdef WIN32
+#ifdef _WIN32
 		evdns_config_windows_nameservers();
 #else
 		res = evdns_resolv_conf_parse(DNS_OPTIONS_ALL, "/etc/resolv.conf");
diff --git a/src/or/eventdns.h b/src/or/eventdns.h
index 3ff8bba4b6..1c130b2a12 100644
--- a/src/or/eventdns.h
+++ b/src/or/eventdns.h
@@ -273,7 +273,7 @@ int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_ty
 int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr);
 int evdns_set_option(const char *option, const char *val, int flags);
 int evdns_resolv_conf_parse(int flags, const char *);
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 int evdns_config_windows_nameservers(void);
 #endif
 void evdns_search_clear(void);
diff --git a/src/or/eventdns_tor.h b/src/or/eventdns_tor.h
index 6a178938b6..c75cff2d1f 100644
--- a/src/or/eventdns_tor.h
+++ b/src/or/eventdns_tor.h
@@ -9,16 +9,11 @@ typedef unsigned int uint;
 #ifndef HAVE_U_CHAR
 typedef unsigned char u_char;
 #endif
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define inline __inline
 #endif
 #include "torint.h"
 
-#if defined(MS_WINDOWS) && !defined(WIN32)
-/* How did _this_ happen? */
-#define WIN32
-#endif
-
 /* These are for debugging possible memory leaks. */
 #include "util.h"
 #include "compat.h"
diff --git a/src/or/main.c b/src/or/main.c
index e2480dcdbc..7ef14aaa76 100644
--- a/src/or/main.c
+++ b/src/or/main.c
@@ -196,7 +196,7 @@ free_old_inbuf(connection_t *conn)
 }
 #endif
 
-#if defined(MS_WINDOWS) && defined(USE_BUFFEREVENTS)
+#if defined(_WIN32) && defined(USE_BUFFEREVENTS)
 /** Remove the kernel-space send and receive buffers for <b>s</b>. For use
  * with IOCP only. */
 static int
@@ -237,7 +237,7 @@ connection_add_impl(connection_t *conn, int is_connecting)
   if (connection_type_uses_bufferevent(conn)) {
     if (SOCKET_OK(conn->s) && !conn->linked) {
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
       if (tor_libevent_using_iocp_bufferevents() &&
           get_options()->UserspaceIOCPBuffers) {
         set_buffer_lengths_to_zero(conn->s);
@@ -701,7 +701,7 @@ conn_read_callback(evutil_socket_t fd, short event, void *_conn)
 
   if (connection_handle_read(conn) < 0) {
     if (!conn->marked_for_close) {
-#ifndef MS_WINDOWS
+#ifndef _WIN32
       log_warn(LD_BUG,"Unhandled error on read for %s connection "
                "(fd %d); removing",
                conn_type_to_string(conn->type), (int)conn->s);
@@ -1689,7 +1689,7 @@ refill_callback(periodic_timer_t *timer, void *arg)
 }
 #endif
 
-#ifndef MS_WINDOWS
+#ifndef _WIN32
 /** Called when a possibly ignorable libevent error occurs; ensures that we
  * don't get into an infinite loop by ignoring too many errors from
  * libevent. */
@@ -1908,7 +1908,7 @@ do_main_loop(void)
     if (nt_service_is_stopping())
       return 0;
 
-#ifndef MS_WINDOWS
+#ifndef _WIN32
     /* Make it easier to tell whether libevent failure is our fault or not. */
     errno = 0;
 #endif
@@ -1932,7 +1932,7 @@ do_main_loop(void)
         log_err(LD_NET,"libevent call with %s failed: %s [%d]",
                 tor_libevent_get_method(), tor_socket_strerror(e), e);
         return -1;
-#ifndef MS_WINDOWS
+#ifndef _WIN32
       } else if (e == EINVAL) {
         log_warn(LD_NET, "EINVAL from libevent: should you upgrade libevent?");
         if (got_libevent_error())
@@ -1951,7 +1951,7 @@ do_main_loop(void)
   }
 }
 
-#ifndef MS_WINDOWS /* Only called when we're willing to use signals */
+#ifndef _WIN32 /* Only called when we're willing to use signals */
 /** Libevent callback: invoked when we get a signal.
  */
 static void
@@ -2168,7 +2168,7 @@ exit_function(void)
 {
   /* NOTE: If we ever daemonize, this gets called immediately.  That's
    * okay for now, because we only use this on Windows.  */
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   WSACleanup();
 #endif
 }
@@ -2177,7 +2177,7 @@ exit_function(void)
 void
 handle_signals(int is_parent)
 {
-#ifndef MS_WINDOWS /* do signal stuff only on Unix */
+#ifndef _WIN32 /* do signal stuff only on Unix */
   int i;
   static const int signals[] = {
     SIGINT,  /* do a controlled slow shutdown */
@@ -2300,7 +2300,7 @@ tor_init(int argc, char *argv[])
     return -1;
   }
 
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   if (geteuid()==0)
     log_warn(LD_GENERAL,"You are running Tor as root. You don't need to, "
              "and you probably shouldn't.");
@@ -2342,7 +2342,7 @@ try_locking(const or_options_t *options, int err_if_locked)
         log_warn(LD_GENERAL, "It looks like another Tor process is running "
                  "with the same data directory.  Waiting 5 seconds to see "
                  "if it goes away.");
-#ifndef WIN32
+#ifndef _WIN32
         sleep(5);
 #else
         Sleep(5000);
@@ -2578,7 +2578,7 @@ tor_main(int argc, char *argv[])
   }
 #endif
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   /* Call SetProcessDEPPolicy to permanently enable DEP.
      The function will not resolve on earlier versions of Windows,
      and failure is not dangerous. */
diff --git a/src/or/ntmain.h b/src/or/ntmain.h
index acd0e1d7eb..6d95a0987d 100644
--- a/src/or/ntmain.h
+++ b/src/or/ntmain.h
@@ -12,7 +12,7 @@
 #ifndef _TOR_NTMAIN_H
 #define _TOR_NTMAIN_H
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #if !defined (WINCE)
 #define NT_SERVICE
 #endif
diff --git a/src/or/or.h b/src/or/or.h
index 9ac8717ed2..33324f50b5 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -22,7 +22,7 @@
 #endif
 #endif
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #ifndef WIN32_WINNT
 #define WIN32_WINNT 0x400
 #endif
@@ -79,7 +79,7 @@
 #include <time.h>
 #endif
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #include <io.h>
 #include <process.h>
 #include <direct.h>
diff --git a/src/or/reasons.c b/src/or/reasons.c
index 319e6c055a..bcf15ff8f4 100644
--- a/src/or/reasons.c
+++ b/src/or/reasons.c
@@ -143,7 +143,7 @@ stream_end_reason_to_socks5_response(int reason)
  * E_CASE is for errors where windows has both a EFOO and a WSAEFOO
  * version, and S_CASE is for errors where windows has only a WSAEFOO
  * version.  (The E is for 'error', the S is for 'socket'). */
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define E_CASE(s) case s: case WSA ## s
 #define S_CASE(s) case WSA ## s
 #else
diff --git a/src/or/transports.c b/src/or/transports.c
index 0bc67ba98c..3e5501e0e1 100644
--- a/src/or/transports.c
+++ b/src/or/transports.c
@@ -91,7 +91,7 @@
 #include "util.h"
 #include "router.h"
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 static void set_managed_proxy_environment(LPVOID *envp,
                                           const managed_proxy_t *mp);
 #else
@@ -263,7 +263,7 @@ launch_managed_proxy(managed_proxy_t *mp)
 {
   int retval;
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 
   LPVOID envp=NULL;
 
@@ -349,7 +349,7 @@ pt_configure_remaining_proxies(void)
   } SMARTLIST_FOREACH_END(mp);
 }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 
 /** Attempt to continue configuring managed proxy <b>mp</b>. */
 static void
@@ -406,7 +406,7 @@ configure_proxy(managed_proxy_t *mp)
     smartlist_free(lines);
 }
 
-#else /* MS_WINDOWS */
+#else /* _WIN32 */
 
 /** Attempt to continue configuring managed proxy <b>mp</b>. */
 static void
@@ -451,7 +451,7 @@ configure_proxy(managed_proxy_t *mp)
   }
 }
 
-#endif /* MS_WINDOWS */
+#endif /* _WIN32 */
 
 /** Register server managed proxy <b>mp</b> transports to state */
 static void
@@ -941,7 +941,7 @@ get_bindaddr_for_server_proxy(const managed_proxy_t *mp)
   return bindaddr_result;
 }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 
 /** Prepare the environment <b>envp</b> of managed proxy <b>mp</b>.
  *  <b>envp</b> is allocated on the heap and should be freed by the
@@ -1043,7 +1043,7 @@ set_managed_proxy_environment(LPVOID *envp, const managed_proxy_t *mp)
   smartlist_free(envs);
 }
 
-#else /* MS_WINDOWS */
+#else /* _WIN32 */
 
 /** Prepare the environment <b>envp</b> of managed proxy <b>mp</b>.
  *  <b>envp</b> is allocated on the heap and should be freed by the
@@ -1104,7 +1104,7 @@ set_managed_proxy_environment(char ***envp, const managed_proxy_t *mp)
   return r;
 }
 
-#endif /* MS_WINDOWS */
+#endif /* _WIN32 */
 
 /** Create and return a new managed proxy for <b>transport</b> using
  *  <b>proxy_argv</b>. If <b>is_server</b> is true, it's a server
diff --git a/src/test/test-child.c b/src/test/test-child.c
index 1b9c5e3d57..b57d8caa90 100644
--- a/src/test/test-child.c
+++ b/src/test/test-child.c
@@ -1,6 +1,6 @@
 #include <stdio.h>
 #include "orconfig.h"
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define WINDOWS_LEAN_AND_MEAN
 #include <windows.h>
 #else
@@ -23,13 +23,13 @@ main(int argc, char **argv)
      succeed. Otherwise ReadFile() will get the entire output in one */
   // XXX: Can we make stdio flush on newline?
   fflush(stdout);
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   Sleep(1000);
 #else
   sleep(1);
 #endif
   fprintf(stdout, "DONE\n");
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   Sleep(1000);
 #else
   sleep(1);
diff --git a/src/test/test.c b/src/test/test.c
index 9d369c04d2..2ecf6ff6c9 100644
--- a/src/test/test.c
+++ b/src/test/test.c
@@ -19,7 +19,7 @@ const char tor_git_revision[] = "";
 #include <fcntl.h>
 #endif
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 /* For mkdir() */
 #include <direct.h>
 #else
@@ -83,7 +83,7 @@ setup_directory(void)
   int r;
   if (is_setup) return;
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   {
     char buf[MAX_PATH];
     const char *tmp = buf;
diff --git a/src/test/test_microdesc.c b/src/test/test_microdesc.c
index dcc6f9c169..9326c035fe 100644
--- a/src/test/test_microdesc.c
+++ b/src/test/test_microdesc.c
@@ -9,7 +9,7 @@
 
 #include "test.h"
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 /* For mkdir() */
 #include <direct.h>
 #else
@@ -66,7 +66,7 @@ test_md_cache(void *data)
   /* Possibly, turn this into a test setup/cleanup pair */
   tor_free(options->DataDirectory);
   options->DataDirectory = tor_strdup(get_fname("md_datadir_test"));
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   tt_int_op(0, ==, mkdir(options->DataDirectory));
 #else
   tt_int_op(0, ==, mkdir(options->DataDirectory, 0700));
diff --git a/src/test/test_util.c b/src/test/test_util.c
index 670d87d07b..508c15596d 100644
--- a/src/test/test_util.c
+++ b/src/test/test_util.c
@@ -530,7 +530,7 @@ test_util_threads(void)
   char *s1 = NULL, *s2 = NULL;
   int done = 0, timedout = 0;
   time_t started;
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   struct timeval tv;
   tv.tv_sec=0;
   tv.tv_usec=10;
@@ -564,7 +564,7 @@ test_util_threads(void)
       timedout = done = 1;
     }
     tor_mutex_release(_thread_test_mutex);
-#ifndef MS_WINDOWS
+#ifndef _WIN32
     /* Prevent the main thread from starving the worker threads. */
     select(0, NULL, NULL, NULL, &tv);
 #endif
@@ -735,7 +735,7 @@ test_util_mmap(void)
   test_assert(mapping);
   test_eq(mapping->size, strlen("Short file."));
   test_streq(mapping->data, "Short file.");
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   tor_munmap_file(mapping);
   mapping = NULL;
   test_assert(unlink(fname1) == 0);
@@ -1260,7 +1260,7 @@ test_util_parent_dir(void *ptr)
   tor_free(cp);
 }
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 static void
 test_util_load_win_lib(void *ptr)
 {
@@ -1312,7 +1312,7 @@ test_util_exit_status(void *ptr)
   ;
 }
 
-#ifndef MS_WINDOWS
+#ifndef _WIN32
 /** Check that fgets waits until a full line, and not return a partial line, on
  * a EAGAIN with a non-blocking pipe */
 static void
@@ -1412,7 +1412,7 @@ run_util_spawn_background(const char *argv[], const char *expected_out,
   int status;
 
   /* Start the program */
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   status = tor_spawn_background(NULL, argv, NULL, &process_handle);
 #else
   status = tor_spawn_background(argv[0], argv, NULL, &process_handle);
@@ -1459,7 +1459,7 @@ run_util_spawn_background(const char *argv[], const char *expected_out,
 static void
 test_util_spawn_background_ok(void *ptr)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   const char *argv[] = {"test-child.exe", "--test", NULL};
   const char *expected_out = "OUT\r\n--test\r\nSLEEPING\r\nDONE\r\n";
   const char *expected_err = "ERR\r\n";
@@ -1483,7 +1483,7 @@ test_util_spawn_background_fail(void *ptr)
   const char *expected_err = "";
   char expected_out[1024];
   char code[32];
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   const int expected_status = PROCESS_STATUS_ERROR;
 #else
   /* TODO: Once we can signal failure to exec, set this to be
@@ -1515,7 +1515,7 @@ test_util_spawn_background_partial_read(void *ptr)
   process_handle_t *process_handle=NULL;
   int status;
   char stdout_buf[100], stderr_buf[100];
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   const char *argv[] = {"test-child.exe", "--test", NULL};
   const char *expected_out[] = { "OUT\r\n--test\r\nSLEEPING\r\n",
                                  "DONE\r\n",
@@ -1533,7 +1533,7 @@ test_util_spawn_background_partial_read(void *ptr)
   (void)ptr;
 
   /* Start the program */
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   status = tor_spawn_background(NULL, argv, NULL, &process_handle);
 #else
   status = tor_spawn_background(argv[0], argv, NULL, &process_handle);
@@ -1544,7 +1544,7 @@ test_util_spawn_background_partial_read(void *ptr)
 
   /* Check stdout */
   for (expected_out_ctr = 0; expected_out[expected_out_ctr] != NULL;) {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
     pos = tor_read_all_handle(process_handle->stdout_pipe, stdout_buf,
                               sizeof(stdout_buf) - 1, NULL);
 #else
@@ -1567,7 +1567,7 @@ test_util_spawn_background_partial_read(void *ptr)
   }
 
   /* The process should have exited without writing more */
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   pos = tor_read_all_handle(process_handle->stdout_pipe, stdout_buf,
                             sizeof(stdout_buf) - 1,
                             process_handle);
@@ -1881,11 +1881,11 @@ struct testcase_t util_tests[] = {
   UTIL_TEST(asprintf, 0),
   UTIL_TEST(listdir, 0),
   UTIL_TEST(parent_dir, 0),
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   UTIL_TEST(load_win_lib, 0),
 #endif
   UTIL_TEST(exit_status, 0),
-#ifndef MS_WINDOWS
+#ifndef _WIN32
   UTIL_TEST(fgets_eagain, TT_SKIP),
 #endif
   UTIL_TEST(spawn_background_ok, 0),
diff --git a/src/tools/tor-fw-helper/tor-fw-helper-natpmp.c b/src/tools/tor-fw-helper/tor-fw-helper-natpmp.c
index a3a52d1037..ed79fd2521 100644
--- a/src/tools/tor-fw-helper/tor-fw-helper-natpmp.c
+++ b/src/tools/tor-fw-helper/tor-fw-helper-natpmp.c
@@ -9,14 +9,14 @@
 
 #include "orconfig.h"
 #ifdef NAT_PMP
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define STATICLIB
 #endif
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
-#ifndef MS_WINDOWS
+#ifndef _WIN32
 #include <arpa/inet.h>
 #endif
 
diff --git a/src/tools/tor-fw-helper/tor-fw-helper-upnp.c b/src/tools/tor-fw-helper/tor-fw-helper-upnp.c
index c4b14a84e2..442eae514e 100644
--- a/src/tools/tor-fw-helper/tor-fw-helper-upnp.c
+++ b/src/tools/tor-fw-helper/tor-fw-helper-upnp.c
@@ -9,7 +9,7 @@
 
 #include "orconfig.h"
 #ifdef MINIUPNPC
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #define STATICLIB
 #endif
 #include <stdint.h>
diff --git a/src/tools/tor-fw-helper/tor-fw-helper.c b/src/tools/tor-fw-helper/tor-fw-helper.c
index 002239745a..ea5ae7ffad 100644
--- a/src/tools/tor-fw-helper/tor-fw-helper.c
+++ b/src/tools/tor-fw-helper/tor-fw-helper.c
@@ -21,7 +21,7 @@
 #include <time.h>
 #include <string.h>
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #include <winsock2.h>
 #endif
 
@@ -229,7 +229,7 @@ tor_fw_add_dir_port(tor_fw_options_t *tor_fw_options,
 static int
 network_init(void)
 {
-#ifdef MS_WINDOWS
+#ifdef _WIN32
   /* This silly exercise is necessary before windows will allow
    * gethostbyname to work. */
   WSADATA WSAData;
diff --git a/src/tools/tor-resolve.c b/src/tools/tor-resolve.c
index f1220d9d88..73352feac7 100644
--- a/src/tools/tor-resolve.c
+++ b/src/tools/tor-resolve.c
@@ -32,7 +32,7 @@
 #include <errno.h>
 #endif
 
-#ifdef MS_WINDOWS
+#ifdef _WIN32
 #if defined(_MSC_VER) && (_MSC_VER <= 1300)
 #include <winsock.h>
 #else
diff --git a/src/win32/orconfig.h b/src/win32/orconfig.h
index 9891c8e4c8..bf33c8102f 100644
--- a/src/win32/orconfig.h
+++ b/src/win32/orconfig.h
@@ -3,8 +3,7 @@
  */
 
 /* Windows-only defines. */
-#define MS_WINDOWS
-#define MS_WIN32
+#define _WIN32
 #define CONFDIR ""
 
 /* Define to 1 if you have the <arpa/inet.h> header file. */