1 files changed, 64 insertions, 1 deletions
diff --git a/libgo/syscalls/syscall.go b/libgo/syscalls/syscall.go
index fa7d9d0..8c7a7ba 100644
--- a/libgo/syscalls/syscall.go
+++ b/libgo/syscalls/syscall.go
@@ -13,7 +13,10 @@
 // the manuals for the appropriate operating system.
 package syscall
 
-import "unsafe"
+import (
+	"sync"
+	"unsafe"
+)
 
 func libc_syscall32(trap int32, a1, a2, a3, a4, a5, a6 int32) int32 __asm__ ("syscall");
 func libc_syscall64(trap int64, a1, a2, a3, a4, a5, a6 int64) int64 __asm__ ("syscall");
@@ -46,3 +49,63 @@ func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
   }
   return r, 0, uintptr(GetErrno());
 }
+
+// Mmap manager, for use by operating system-specific implementations.
+
+type mmapper struct {
+	sync.Mutex
+	active map[*byte][]byte // active mappings; key is last byte in mapping
+	mmap   func(addr, length uintptr, prot, flags, fd int, offset int64) (uintptr, int)
+	munmap func(addr uintptr, length uintptr) int
+}
+
+func (m *mmapper) Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, errno int) {
+	if length <= 0 {
+		return nil, EINVAL
+	}
+
+	// Map the requested memory.
+	addr, errno := m.mmap(0, uintptr(length), prot, flags, fd, offset)
+	if errno != 0 {
+		return nil, errno
+	}
+
+	// Slice memory layout
+	var sl = struct {
+		addr uintptr
+		len  int
+		cap  int
+	}{addr, length, length}
+
+	// Use unsafe to turn sl into a []byte.
+	b := *(*[]byte)(unsafe.Pointer(&sl))
+
+	// Register mapping in m and return it.
+	p := &b[cap(b)-1]
+	m.Lock()
+	defer m.Unlock()
+	m.active[p] = b
+	return b, 0
+}
+
+func (m *mmapper) Munmap(data []byte) (errno int) {
+	if len(data) == 0 || len(data) != cap(data) {
+		return EINVAL
+	}
+
+	// Find the base of the mapping.
+	p := &data[cap(data)-1]
+	m.Lock()
+	defer m.Unlock()
+	b := m.active[p]
+	if b == nil || &b[0] != &data[0] {
+		return EINVAL
+	}
+
+	// Unmap the memory and update m.
+	if errno := m.munmap(uintptr(unsafe.Pointer(&b[0])), uintptr(len(b))); errno != 0 {
+		return errno
+	}
+	m.active[p] = nil, false
+	return 0
+}