add mmap()/munmap() implementation for Windows

1 files changed, 100 insertions, 0 deletions

diff --git a/utils/mmap-windows.c b/utils/mmap-windows.c
new file mode 100644
index 000000000..1799392f0
--- /dev/null
+++ b/utils/mmap-windows.c
@@ -0,0 +1,100 @@
+/* mmap() replacement for Windows
+ *
+ * Author: Mike Frysinger <vapier@gentoo.org>
+ * Placed into the public domain
+ */
+
+/* References:
+ * CreateFileMapping: http://msdn.microsoft.com/en-us/library/aa366537(VS.85).aspx
+ * CloseHandle:       http://msdn.microsoft.com/en-us/library/ms724211(VS.85).aspx
+ * MapViewOfFile:     http://msdn.microsoft.com/en-us/library/aa366761(VS.85).aspx
+ * UnmapViewOfFile:   http://msdn.microsoft.com/en-us/library/aa366882(VS.85).aspx
+ */
+
+#include <io.h>
+#include <windows.h>
+#include <sys/types.h>
+
+#define PROT_READ     0x1
+#define PROT_WRITE    0x2
+/* This flag is only available in WinXP+ */
+#ifdef FILE_MAP_EXECUTE
+#define PROT_EXEC     0x4
+#else
+#define PROT_EXEC        0x0
+#define FILE_MAP_EXECUTE 0
+#endif
+
+#define MAP_SHARED    0x01
+#define MAP_PRIVATE   0x02
+#define MAP_ANONYMOUS 0x20
+#define MAP_ANON      MAP_ANONYMOUS
+#define MAP_FAILED    ((void *) -1)
+
+#ifdef __USE_FILE_OFFSET64
+# define DWORD_HI(x) (x >> 32)
+# define DWORD_LO(x) ((x) & 0xffffffff)
+#else
+# define DWORD_HI(x) (0)
+# define DWORD_LO(x) (x)
+#endif
+
+static void *mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset)
+{
+	if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC))
+		return MAP_FAILED;
+	if (fd == -1) {
+		if (!(flags & MAP_ANON) || offset)
+			return MAP_FAILED;
+	} else if (flags & MAP_ANON)
+		return MAP_FAILED;
+
+	DWORD flProtect;
+	if (prot & PROT_WRITE) {
+		if (prot & PROT_EXEC)
+			flProtect = PAGE_EXECUTE_READWRITE;
+		else
+			flProtect = PAGE_READWRITE;
+	} else if (prot & PROT_EXEC) {
+		if (prot & PROT_READ)
+			flProtect = PAGE_EXECUTE_READ;
+		else if (prot & PROT_EXEC)
+			flProtect = PAGE_EXECUTE;
+	} else
+		flProtect = PAGE_READONLY;
+
+	off_t end = length + offset;
+	HANDLE mmap_fd, h;
+	if (fd == -1)
+		mmap_fd = INVALID_HANDLE_VALUE;
+	else
+		mmap_fd = (HANDLE)_get_osfhandle(fd);
+	h = CreateFileMapping(mmap_fd, NULL, flProtect, DWORD_HI(end), DWORD_LO(end), NULL);
+	if (h == NULL)
+		return MAP_FAILED;
+
+	DWORD dwDesiredAccess;
+	if (prot & PROT_WRITE)
+		dwDesiredAccess = FILE_MAP_WRITE;
+	else
+		dwDesiredAccess = FILE_MAP_READ;
+	if (prot & PROT_EXEC)
+		dwDesiredAccess |= FILE_MAP_EXECUTE;
+	if (flags & MAP_PRIVATE)
+		dwDesiredAccess |= FILE_MAP_COPY;
+	void *ret = MapViewOfFile(h, dwDesiredAccess, DWORD_HI(offset), DWORD_LO(offset), length);
+	if (ret == NULL) {
+		CloseHandle(h);
+		ret = MAP_FAILED;
+	}
+	return ret;
+}
+
+static void munmap(void *addr, size_t length)
+{
+	UnmapViewOfFile(addr);
+	/* ruh-ro, we leaked handle from CreateFileMapping() ... */
+}
+
+#undef DWORD_HI
+#undef DWORD_LO