win32: add mmap() emulation

Makes all of overlay_add work on windows/mingw.

Since we now don't explicitly check for mmap() anymore (it's always
present), this also requires us to make af_export.c compile, but I
haven't tested it.

DOCS/man/input.rst

@@ -504,11 +504,6 @@ Input Commands that are Possibly Subject to Change
     Passing the wrong thing here will crash the player. The ``offset`` parameter
     is not used and must be 0. This mode might be useful for use with libmpv.
 
-    On Windows, currently only raw memory addresses work. File mapping is not
-    implemented because a ``mmap`` compatibility layer is missing, and because
-    this kind of shared memory method would perhaps not be overly useful on
-    Windows.
-
     ``offset`` is the offset of the first pixel in the source file. It is
     passed directly to ``mmap`` and is subject to certain restrictions
     (see ``man mmap`` for details). In particular, this value has to be a

audio/filter/af.c

@@ -70,9 +70,7 @@ static const struct af_info *const filter_list[] = {
     &af_info_pan,
     &af_info_surround,
     &af_info_sub,
-#if HAVE_SYS_MMAN_H
     &af_info_export,
-#endif
     &af_info_drc,
     &af_info_extrastereo,
     &af_info_lavcac3enc,

audio/filter/af_export.c

@@ -34,7 +34,6 @@
 #include "config.h"
 
 #include <sys/types.h>
-#include <sys/mman.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>

old-configure

@@ -963,7 +963,6 @@ cat > $TMPC << EOF
 #define HAVE_DOS_PATHS 0
 #define HAVE_PRIORITY 0
 #define HAVE_GLOB 1
-#define HAVE_SYS_MMAN_H 1
 #define HAVE_NANOSLEEP 1
 #define HAVE_SDL1 0
 #define HAVE_WAIO 0

osdep/io.c

@@ -19,6 +19,7 @@
  */
 #include <unistd.h>
 #include <errno.h>
+#include <assert.h>
 
 #include "talloc.h"
 
@@ -445,4 +446,62 @@ off_t mp_lseek(int fd, off_t offset, int whence)
     return _lseeki64(fd, offset, whence);
 }
 
+// Limited mmap() wrapper, inspired by:
+// http://code.google.com/p/mman-win32/source/browse/trunk/mman.c
+
+void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
+{
+    assert(addr == NULL); // not implemented
+    assert(flags == MAP_SHARED); // not implemented
+
+    HANDLE osf = (HANDLE)_get_osfhandle(fd);
+    if (!osf) {
+        errno = EBADF;
+        return MAP_FAILED;
+    }
+
+    DWORD protect = 0;
+    DWORD access = 0;
+    if (prot & PROT_WRITE) {
+        protect = PAGE_READWRITE;
+        access = FILE_MAP_WRITE;
+    } else if (prot & PROT_READ) {
+        protect = PAGE_READONLY;
+        access = FILE_MAP_READ;
+    }
+
+    DWORD l_low = (uint32_t)length;
+    DWORD l_high = ((uint64_t)length) >> 32;
+    HANDLE map = CreateFileMapping(osf, NULL, protect, l_high, l_low, NULL);
+
+    if (!map) {
+        errno = EACCES; // something random
+        return MAP_FAILED;
+    }
+
+    DWORD o_low = (uint32_t)offset;
+    DWORD o_high = ((uint64_t)offset) >> 32;
+    void *p = MapViewOfFile(map, access, o_high, o_low, length);
+
+    CloseHandle(map);
+
+    if (!p) {
+        errno = EINVAL;
+        return MAP_FAILED;
+    }
+    return p;
+}
+
+int munmap(void *addr, size_t length)
+{
+    UnmapViewOfFile(addr);
+    return 0;
+}
+
+int msync(void *addr, size_t length, int flags)
+{
+    FlushViewOfFile(addr, length);
+    return 0;
+}
+
 #endif // __MINGW32__

osdep/io.h

@@ -135,6 +135,17 @@ void mp_globfree(mp_glob_t *pglob);
 #undef fstat
 #define fstat(...) mp_fstat(__VA_ARGS__)
 
+void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset);
+int munmap(void *addr, size_t length);
+int msync(void *addr, size_t length, int flags);
+#define PROT_READ 1
+#define PROT_WRITE 2
+#define MAP_SHARED 1
+#define MAP_FAILED ((void *)-1)
+#define MS_ASYNC 1
+#define MS_SYNC 2
+#define MS_INVALIDATE 4
+
 #ifndef GLOB_NOMATCH
 #define GLOB_NOMATCH 3
 #endif
@@ -143,6 +154,10 @@ void mp_globfree(mp_glob_t *pglob);
 #define glob(...) mp_glob(__VA_ARGS__)
 #define globfree(...) mp_globfree(__VA_ARGS__)
 
+#else /* __MINGW32__ */
+
+#include <sys/mman.h>
+
 #endif /* __MINGW32__ */
 
 #endif

player/command.c

@@ -60,9 +60,6 @@
 #include "audio/decode/dec_audio.h"
 #include "options/path.h"
 #include "screenshot.h"
-#if HAVE_SYS_MMAN_H
-#include <sys/mman.h>
-#endif
 #ifndef __MINGW32__
 #include <sys/wait.h>
 #endif
@@ -3825,13 +3822,9 @@ static void replace_overlay(struct MPContext *mpctx, int id, struct overlay *new
     *ptr = *new;
     recreate_overlays(mpctx);
 
-#if HAVE_SYS_MMAN_H
     // Do this afterwards, so we never unmap while the OSD is using it.
     if (old.osd.bitmap && old.map_size)
         munmap(old.osd.bitmap, old.map_size);
-#else
-    (void)old;
-#endif
 }
 
 static int overlay_add(struct MPContext *mpctx, int id, int x, int y,
@@ -3878,10 +3871,8 @@ static int overlay_add(struct MPContext *mpctx, int id, int x, int y,
         fd = open(file, O_RDONLY | O_BINARY | O_CLOEXEC);
     }
     if (fd >= 0) {
-#if HAVE_SYS_MMAN_H
         overlay.map_size = h * stride;
         p = mmap(NULL, overlay.map_size, PROT_READ, MAP_SHARED, fd, offset);
-#endif
         if (close_fd)
             close(fd);
     }

wscript

@@ -110,8 +110,8 @@ main_dependencies = [
         'name': 'posix',
         'desc': 'POSIX environment',
         # This should be good enough.
-        'func': check_statement(['poll.h', 'unistd.h'],
-                    'struct pollfd pfd; poll(&pfd, 1, 0); fork(); int f[2]; pipe(f)'),
+        'func': check_statement(['poll.h', 'unistd.h', 'sys/mman.h'],
+            'struct pollfd pfd; poll(&pfd, 1, 0); fork(); int f[2]; pipe(f); munmap(f,0)'),
     }, {
         'name': 'posix-or-mingw',
         'desc': 'programming environment',
@@ -196,10 +196,6 @@ iconv support use --disable-iconv.",
         'desc': 'shm',
         'func': check_statement(['sys/types.h', 'sys/ipc.h', 'sys/shm.h'],
             'shmget(0, 0, 0); shmat(0, 0, 0); shmctl(0, 0, 0)')
-    }, {
-        'name': 'sys-mman-h',
-        'desc': 'mman.h',
-        'func': check_statement('sys/mman.h', 'mmap(0, 0, 0, 0, 0, 0)')
     }, {
         'name': 'nanosleep',
         'desc': 'nanosleep',

wscript_build.py

@@ -103,7 +103,7 @@ def build(ctx):
         ( "audio/filter/af_drc.c" ),
         ( "audio/filter/af_dummy.c" ),
         ( "audio/filter/af_equalizer.c" ),
-        ( "audio/filter/af_export.c",            "sys-mman-h" ),
+        ( "audio/filter/af_export.c" ),
         ( "audio/filter/af_extrastereo.c" ),
         ( "audio/filter/af_forcespeed.c" ),
         ( "audio/filter/af_format.c" ),