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.

2 files changed, 74 insertions, 0 deletions

diff --git a/osdep/io.c b/osdep/io.c
index 7c46dd47ab..e63509a4f8 100644
--- a/osdep/io.c
+++ b/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__
diff --git a/osdep/io.h b/osdep/io.h
index c3fc0cf9cb..0348d3d1a3 100644
--- a/osdep/io.h
+++ b/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