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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,53 +1,68 @@ | ||
| //go:build (linux || darwin) && (amd64 || arm64) | ||
| //go:build unix | ||
|
|
||
| package util | ||
|
|
||
| import ( | ||
| "math" | ||
| "syscall" | ||
| ) | ||
|
|
||
| type MmapedMemoryAllocator []byte | ||
| "github.com/tetratelabs/wazero/experimental" | ||
| "golang.org/x/sys/unix" | ||
| ) | ||
|
|
||
| func (m *MmapedMemoryAllocator) Make(min, cap, max uint64) []byte { | ||
| func mmappedAllocator(min, cap, max uint64) experimental.MemoryBuffer { | ||
| if max > math.MaxInt { | ||
| // This ensures int(max) overflows to a negative value, | ||
| // and syscall.Mmap returns EINVAL. | ||
| // and unix.Mmap returns EINVAL. | ||
| max = math.MaxUint64 | ||
| } | ||
| // Reserve the full max bytes of address space, to ensure we don't need to move it. | ||
| // A protected, private, anonymous mapping should not commit memory. | ||
| b, err := syscall.Mmap(-1, 0, int(max), syscall.PROT_NONE, syscall.MAP_PRIVATE|syscall.MAP_ANON) | ||
| b, err := unix.Mmap(-1, 0, int(max), unix.PROT_NONE, unix.MAP_PRIVATE|unix.MAP_ANON) | ||
| if err != nil { | ||
| panic(err) | ||
| } | ||
| // Commit the initial min bytes of memory. | ||
| err = syscall.Mprotect(b[:min], syscall.PROT_READ|syscall.PROT_WRITE) | ||
| // Commit the initial cap bytes of memory. | ||
| err = unix.Mprotect(b[:cap], unix.PROT_READ|unix.PROT_WRITE) | ||
| if err != nil { | ||
| syscall.Munmap(b) | ||
| unix.Munmap(b) | ||
| panic(err) | ||
| } | ||
| b = b[:min] | ||
| *m = b | ||
| return b | ||
| return &mmappedBuffer{ | ||
| buf: b[:cap], | ||
| cur: min, | ||
| } | ||
| } | ||
|
|
||
| // The slice covers the entire mmapped memory: | ||
| // - len(buf) is the already committed memory, | ||
| // - cap(buf) is the reserved address space, | ||
| // - cur is the already requested size. | ||
| type mmappedBuffer struct { | ||
| buf []byte | ||
| cur uint64 | ||
| } | ||
|
|
||
| func (m *mmappedBuffer) Buffer() []byte { | ||
| // Limit capacity because bytes beyond len(m.buf) | ||
| // have not yet been committed. | ||
| return m.buf[:m.cur:len(m.buf)] | ||
| } | ||
|
|
||
| func (m *MmapedMemoryAllocator) Grow(size uint64) []byte { | ||
| b := *m | ||
| func (m *mmappedBuffer) Grow(size uint64) []byte { | ||
| // Commit additional memory up to size bytes. | ||
| err := syscall.Mprotect(b[len(b):size], syscall.PROT_READ|syscall.PROT_WRITE) | ||
| err := unix.Mprotect(m.buf[len(m.buf):size], unix.PROT_READ|unix.PROT_WRITE) | ||
| if err != nil { | ||
| panic(err) | ||
| } | ||
| b = b[:size] | ||
| *m = b | ||
| return b | ||
| m.buf = m.buf[:size] | ||
| m.cur = size | ||
| return m.Buffer() | ||
| } | ||
|
|
||
| func (m *MmapedMemoryAllocator) Free() { | ||
| err := syscall.Munmap(*m) | ||
| func (m *mmappedBuffer) Free() { | ||
| err := unix.Munmap(m.buf) | ||
| if err != nil { | ||
| panic(err) | ||
| } | ||
| *m = nil | ||
| m.buf = nil | ||
| } |
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