Win32 support for av_file_map()

Originally committed as revision 26221 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1040,6 +1040,7 @@ HAVE_LIST="
     machine_ioctl_bt848_h
     machine_ioctl_meteor_h
     malloc_h
+    MapViewOfFile
     memalign
     mkstemp
     mmap
@@ -2687,6 +2688,7 @@ check_func_headers io.h setmode
 check_func_headers lzo/lzo1x.h lzo1x_999_compress
 check_lib2 "windows.h psapi.h" GetProcessMemoryInfo -lpsapi
 check_func_headers windows.h GetProcessTimes
+check_func_headers windows.h MapViewOfFile
 check_func_headers windows.h VirtualAlloc
 
 check_header conio.h

libavutil/file.c

@@ -22,6 +22,9 @@
 #include <unistd.h>
 #if HAVE_MMAP
 #include <sys/mman.h>
+#elif HAVE_MAPVIEWOFFILE
+#include <io.h>
+#include <windows.h>
 #endif
 
 typedef struct {
@@ -81,6 +84,27 @@ int av_file_map(const char *filename, uint8_t **bufptr, size_t *size,
         return err;
     }
     *bufptr = ptr;
+#elif HAVE_MAPVIEWOFFILE
+    {
+        HANDLE mh, fh = (HANDLE)_get_osfhandle(fd);
+
+        mh = CreateFileMapping(fh, NULL, PAGE_READONLY, 0, 0, NULL);
+        if (!mh) {
+            av_log(&file_log_ctx, AV_LOG_ERROR, "Error occurred in CreateFileMapping()\n");
+            close(fd);
+            return -1;
+        }
+
+        ptr = MapViewOfFile(mh, FILE_MAP_READ, 0, 0, *size);
+        CloseHandle(mh);
+        if (!ptr) {
+            av_log(&file_log_ctx, AV_LOG_ERROR, "Error occurred in MapViewOfFile()\n");
+            close(fd);
+            return -1;
+        }
+
+        *bufptr = ptr;
+    }
 #else
     *bufptr = av_malloc(*size);
     if (!*bufptr) {
@@ -99,6 +123,8 @@ void av_file_unmap(uint8_t *bufptr, size_t size)
 {
 #if HAVE_MMAP
     munmap(bufptr, size);
+#elif HAVE_MAPVIEWOFFILE
+    UnmapViewOfFile(bufptr);
 #else
     av_free(bufptr);
 #endif