9a4a372642
This renames the internal writefs package to syscallfs as it is largely dependent on syscall signatures. This also implements utimes in gojs. WASI will be a follow-up change as it requires more infrastructure. Notably, we also need non-TinyGo tests because TinyGo doesn't yet support os.Chtimes or corresponding syscalls. Signed-off-by: Adrian Cole <adrian@tetrate.io>
115 lines
3.3 KiB
Go
115 lines
3.3 KiB
Go
package platform
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import (
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"fmt"
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"io"
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"reflect"
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"syscall"
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"unsafe"
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)
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var (
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kernel32 = syscall.NewLazyDLL("kernel32.dll")
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procVirtualAlloc = kernel32.NewProc("VirtualAlloc")
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procVirtualProtect = kernel32.NewProc("VirtualProtect")
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procVirtualFree = kernel32.NewProc("VirtualFree")
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)
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const (
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windows_MEM_COMMIT uintptr = 0x00001000
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windows_MEM_RELEASE uintptr = 0x00008000
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windows_PAGE_READWRITE uintptr = 0x00000004
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windows_PAGE_EXECUTE_READ uintptr = 0x00000020
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windows_PAGE_EXECUTE_READWRITE uintptr = 0x00000040
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)
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func munmapCodeSegment(code []byte) error {
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return freeMemory(code)
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}
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// allocateMemory commits the memory region via the "VirtualAlloc" function.
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// See https://docs.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-virtualalloc
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func allocateMemory(size uintptr, protect uintptr) (uintptr, error) {
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address := uintptr(0) // TODO: document why zero
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alloctype := windows_MEM_COMMIT
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if r, _, err := procVirtualAlloc.Call(address, size, alloctype, protect); r == 0 {
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return 0, fmt.Errorf("compiler: VirtualAlloc error: %w", ensureErr(err))
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} else {
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return r, nil
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}
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}
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// freeMemory releases the memory region via the "VirtualFree" function.
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// See https://docs.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-virtualfree
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func freeMemory(code []byte) error {
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address := uintptr(unsafe.Pointer(&code[0]))
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size := uintptr(0) // size must be 0 because we're using MEM_RELEASE.
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freetype := windows_MEM_RELEASE
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if r, _, err := procVirtualFree.Call(address, size, freetype); r == 0 {
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return fmt.Errorf("compiler: VirtualFree error: %w", ensureErr(err))
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}
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return nil
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}
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func virtualProtect(address, size, newprotect uintptr, oldprotect *uint32) error {
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if r, _, err := procVirtualProtect.Call(address, size, newprotect, uintptr(unsafe.Pointer(oldprotect))); r == 0 {
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return fmt.Errorf("compiler: VirtualProtect error: %w", ensureErr(err))
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}
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return nil
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}
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func mmapCodeSegmentAMD64(code io.Reader, size int) ([]byte, error) {
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p, err := allocateMemory(uintptr(size), windows_PAGE_EXECUTE_READWRITE)
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if err != nil {
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return nil, err
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}
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var mem []byte
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sh := (*reflect.SliceHeader)(unsafe.Pointer(&mem))
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sh.Data = p
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sh.Len = size
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sh.Cap = size
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w := &bufWriter{underlying: mem}
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_, err = io.CopyN(w, code, int64(size))
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return mem, err
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}
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func mmapCodeSegmentARM64(code io.Reader, size int) ([]byte, error) {
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p, err := allocateMemory(uintptr(size), windows_PAGE_READWRITE)
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if err != nil {
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return nil, err
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}
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var mem []byte
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sh := (*reflect.SliceHeader)(unsafe.Pointer(&mem))
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sh.Data = p
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sh.Len = size
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sh.Cap = size
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w := &bufWriter{underlying: mem}
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_, err = io.CopyN(w, code, int64(size))
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if err != nil {
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return nil, err
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}
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old := uint32(windows_PAGE_READWRITE)
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err = virtualProtect(p, uintptr(size), windows_PAGE_EXECUTE_READ, &old)
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if err != nil {
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return nil, err
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}
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return mem, nil
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}
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// ensureErr returns syscall.EINVAL when the input error is nil.
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//
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// We are supposed to use "GetLastError" which is more precise, but it is not safe to execute in goroutines. While
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// "GetLastError" is thread-local, goroutines are not pinned to threads.
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//
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// See https://docs.microsoft.com/en-us/windows/win32/api/errhandlingapi/nf-errhandlingapi-getlasterror
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func ensureErr(err error) error {
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if err != nil {
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return err
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}
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return syscall.EINVAL
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}
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