fix test & test for mremap

Author: anton-kuklin

unix/mremap_linux_test.go

@@ -13,14 +13,50 @@ import (
 )
 
 func TestMremap(t *testing.T) {
+	b, err := unix.Mmap(-1, 0, unix.Getpagesize()*2, unix.PROT_NONE, unix.MAP_ANON|unix.MAP_PRIVATE)
+	if err != nil {
+		t.Fatalf("Mmap: %v", err)
+	}
+	if err := unix.Mprotect(b, unix.PROT_READ|unix.PROT_WRITE); err != nil {
+		t.Fatalf("Mprotect: %v", err)
+	}
+
+	b[0] = 42
+	if err := unix.Msync(b, unix.MS_SYNC); err != nil {
+		t.Fatalf("Msync: %v", err)
+	}
+
+	bNew, err := unix.Mmap(-1, int64(unix.Getpagesize()*4), unix.Getpagesize(), unix.PROT_NONE, unix.MAP_ANON|unix.MAP_PRIVATE)
+	if err != nil {
+		t.Fatalf("Mmap: %v", err)
+	}
 
+	bRemapped, err := unix.Mremap(b, bNew, 0)
+	if err != nil {
+		t.Fatalf("Mremap: %v", err)
+	}
+	if &bRemapped[0] != &bNew[0] {
+		t.Fatal("bNew and bRemapped start at different pointers")
+	}
+	if bRemapped[0] != 42 {
+		t.Fatal("first element wasn't mapped")
+	}
+	if len(bNew) != len(bRemapped) {
+		t.Fatal("bNew len doesn't equal bRemapped len")
+	}
+	if cap(bNew) != cap(bRemapped) {
+		t.Fatal("bNew cap doesn't equal bRemapped len")
+	}
 }
 
 func TestMremap2(t *testing.T) {
 	b, err := unix.Mmap(-1, 0, unix.Getpagesize()*2, unix.PROT_NONE, unix.MAP_ANON|unix.MAP_PRIVATE)
 	if err != nil {
 		t.Fatalf("Mmap: %v", err)
 	}
+	if err := unix.Mprotect(b, unix.PROT_READ|unix.PROT_WRITE); err != nil {
+		t.Fatalf("Mprotect: %v", err)
+	}
 
 	b[0] = 42
 	if err := unix.Msync(b, unix.MS_SYNC); err != nil {
@@ -36,6 +72,9 @@ func TestMremap2(t *testing.T) {
 		t.Fatal("first element value was changed")
 	}
 	if len(bNew) != unix.Getpagesize() {
-		t.Fatal("first ")
+		t.Fatal("new memory len not equal to specified len")
+	}
+	if cap(bNew) != unix.Getpagesize() {
+		t.Fatal("new memory cap not equal to specified len")
 	}
 }

unix/syscall_unix.go

@@ -152,6 +152,7 @@ func (m *mmapper) Mremap(oldData []byte, newData []byte, flags int) (data []byte
 	if len(oldData) == 0 || len(oldData) != cap(oldData) || len(newData) == 0 || len(newData) != cap(newData) {
 		return nil, EINVAL
 	}
+	flags |= MREMAP_MAYMOVE | MREMAP_FIXED
 
 	pOld := &oldData[cap(oldData)-1]
 	m.Lock()