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// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build wasip1
package syscall
import (
"runtime"
"unsafe"
)
func init() {
// Try to set stdio to non-blocking mode before the os package
// calls NewFile for each fd. NewFile queries the non-blocking flag
// but doesn't change it, even if the runtime supports non-blocking
// stdio. Since WebAssembly modules are single-threaded, blocking
// system calls temporarily halt execution of the module. If the
// runtime supports non-blocking stdio, the Go runtime is able to
// use the WASI net poller to poll for read/write readiness and is
// able to schedule goroutines while waiting.
SetNonblock(0, true)
SetNonblock(1, true)
SetNonblock(2, true)
}
type uintptr32 = uint32
type size = uint32
type fdflags = uint32
type filesize = uint64
type filetype = uint8
type lookupflags = uint32
type oflags = uint32
type rights = uint64
type timestamp = uint64
type dircookie = uint64
type filedelta = int64
type fstflags = uint32
type iovec struct {
buf uintptr32
bufLen size
}
const (
LOOKUP_SYMLINK_FOLLOW = 0x00000001
)
const (
OFLAG_CREATE = 0x0001
OFLAG_DIRECTORY = 0x0002
OFLAG_EXCL = 0x0004
OFLAG_TRUNC = 0x0008
)
const (
FDFLAG_APPEND = 0x0001
FDFLAG_DSYNC = 0x0002
FDFLAG_NONBLOCK = 0x0004
FDFLAG_RSYNC = 0x0008
FDFLAG_SYNC = 0x0010
)
const (
RIGHT_FD_DATASYNC = 1 << iota
RIGHT_FD_READ
RIGHT_FD_SEEK
RIGHT_FDSTAT_SET_FLAGS
RIGHT_FD_SYNC
RIGHT_FD_TELL
RIGHT_FD_WRITE
RIGHT_FD_ADVISE
RIGHT_FD_ALLOCATE
RIGHT_PATH_CREATE_DIRECTORY
RIGHT_PATH_CREATE_FILE
RIGHT_PATH_LINK_SOURCE
RIGHT_PATH_LINK_TARGET
RIGHT_PATH_OPEN
RIGHT_FD_READDIR
RIGHT_PATH_READLINK
RIGHT_PATH_RENAME_SOURCE
RIGHT_PATH_RENAME_TARGET
RIGHT_PATH_FILESTAT_GET
RIGHT_PATH_FILESTAT_SET_SIZE
RIGHT_PATH_FILESTAT_SET_TIMES
RIGHT_FD_FILESTAT_GET
RIGHT_FD_FILESTAT_SET_SIZE
RIGHT_FD_FILESTAT_SET_TIMES
RIGHT_PATH_SYMLINK
RIGHT_PATH_REMOVE_DIRECTORY
RIGHT_PATH_UNLINK_FILE
RIGHT_POLL_FD_READWRITE
RIGHT_SOCK_SHUTDOWN
RIGHT_SOCK_ACCEPT
)
const (
WHENCE_SET = 0
WHENCE_CUR = 1
WHENCE_END = 2
)
const (
FILESTAT_SET_ATIM = 0x0001
FILESTAT_SET_ATIM_NOW = 0x0002
FILESTAT_SET_MTIM = 0x0004
FILESTAT_SET_MTIM_NOW = 0x0008
)
const (
// Despite the rights being defined as a 64 bits integer in the spec,
// wasmtime crashes the program if we set any of the upper 32 bits.
fullRights = rights(^uint32(0))
readRights = rights(RIGHT_FD_READ | RIGHT_FD_READDIR)
writeRights = rights(RIGHT_FD_DATASYNC | RIGHT_FD_WRITE | RIGHT_FD_ALLOCATE | RIGHT_PATH_FILESTAT_SET_SIZE)
// Some runtimes have very strict expectations when it comes to which
// rights can be enabled on files opened by path_open. The fileRights
// constant is used as a mask to retain only bits for operations that
// are supported on files.
fileRights rights = RIGHT_FD_DATASYNC |
RIGHT_FD_READ |
RIGHT_FD_SEEK |
RIGHT_FDSTAT_SET_FLAGS |
RIGHT_FD_SYNC |
RIGHT_FD_TELL |
RIGHT_FD_WRITE |
RIGHT_FD_ADVISE |
RIGHT_FD_ALLOCATE |
RIGHT_PATH_CREATE_DIRECTORY |
RIGHT_PATH_CREATE_FILE |
RIGHT_PATH_LINK_SOURCE |
RIGHT_PATH_LINK_TARGET |
RIGHT_PATH_OPEN |
RIGHT_FD_READDIR |
RIGHT_PATH_READLINK |
RIGHT_PATH_RENAME_SOURCE |
RIGHT_PATH_RENAME_TARGET |
RIGHT_PATH_FILESTAT_GET |
RIGHT_PATH_FILESTAT_SET_SIZE |
RIGHT_PATH_FILESTAT_SET_TIMES |
RIGHT_FD_FILESTAT_GET |
RIGHT_FD_FILESTAT_SET_SIZE |
RIGHT_FD_FILESTAT_SET_TIMES |
RIGHT_PATH_SYMLINK |
RIGHT_PATH_REMOVE_DIRECTORY |
RIGHT_PATH_UNLINK_FILE |
RIGHT_POLL_FD_READWRITE
// Runtimes like wasmtime and wasmedge will refuse to open directories
// if the rights requested by the application exceed the operations that
// can be performed on a directory.
dirRights rights = RIGHT_FD_SEEK |
RIGHT_FDSTAT_SET_FLAGS |
RIGHT_FD_SYNC |
RIGHT_PATH_CREATE_DIRECTORY |
RIGHT_PATH_CREATE_FILE |
RIGHT_PATH_LINK_SOURCE |
RIGHT_PATH_LINK_TARGET |
RIGHT_PATH_OPEN |
RIGHT_FD_READDIR |
RIGHT_PATH_READLINK |
RIGHT_PATH_RENAME_SOURCE |
RIGHT_PATH_RENAME_TARGET |
RIGHT_PATH_FILESTAT_GET |
RIGHT_PATH_FILESTAT_SET_SIZE |
RIGHT_PATH_FILESTAT_SET_TIMES |
RIGHT_FD_FILESTAT_GET |
RIGHT_FD_FILESTAT_SET_TIMES |
RIGHT_PATH_SYMLINK |
RIGHT_PATH_REMOVE_DIRECTORY |
RIGHT_PATH_UNLINK_FILE
)
// https://github.com/WebAssembly/WASI/blob/a2b96e81c0586125cc4dc79a5be0b78d9a059925/legacy/preview1/docs.md#-fd_closefd-fd---result-errno
//
//go:wasmimport wasi_snapshot_preview1 fd_close
//go:noescape
func fd_close(fd int32) Errno
// https://github.com/WebAssembly/WASI/blob/a2b96e81c0586125cc4dc79a5be0b78d9a059925/legacy/preview1/docs.md#-fd_filestat_set_sizefd-fd-size-filesize---result-errno
//
//go:wasmimport wasi_snapshot_preview1 fd_filestat_set_size
//go:noescape
func fd_filestat_set_size(fd int32, set_size filesize) Errno
// https://github.com/WebAssembly/WASI/blob/a2b96e81c0586125cc4dc79a5be0b78d9a059925/legacy/preview1/docs.md#-fd_preadfd-fd-iovs-iovec_array-offset-filesize---resultsize-errno
//
//go:wasmimport wasi_snapshot_preview1 fd_pread
//go:noescape
func fd_pread(fd int32, iovs unsafe.Pointer, iovsLen size, offset filesize, nread unsafe.Pointer) Errno
//go:wasmimport wasi_snapshot_preview1 fd_pwrite
//go:noescape
func fd_pwrite(fd int32, iovs unsafe.Pointer, iovsLen size, offset filesize, nwritten unsafe.Pointer) Errno
//go:wasmimport wasi_snapshot_preview1 fd_read
//go:noescape
func fd_read(fd int32, iovs unsafe.Pointer, iovsLen size, nread unsafe.Pointer) Errno
//go:wasmimport wasi_snapshot_preview1 fd_readdir
//go:noescape
func fd_readdir(fd int32, buf unsafe.Pointer, bufLen size, cookie dircookie, nwritten unsafe.Pointer) Errno
//go:wasmimport wasi_snapshot_preview1 fd_seek
//go:noescape
func fd_seek(fd int32, offset filedelta, whence uint32, newoffset unsafe.Pointer) Errno
// https://github.com/WebAssembly/WASI/blob/a2b96e81c0586125cc4dc79a5be0b78d9a059925/legacy/preview1/docs.md#-fd_fdstat_set_rightsfd-fd-fs_rights_base-rights-fs_rights_inheriting-rights---result-errno
//
//go:wasmimport wasi_snapshot_preview1 fd_fdstat_set_rights
//go:noescape
func fd_fdstat_set_rights(fd int32, rightsBase rights, rightsInheriting rights) Errno
//go:wasmimport wasi_snapshot_preview1 fd_filestat_get
//go:noescape
func fd_filestat_get(fd int32, buf unsafe.Pointer) Errno
//go:wasmimport wasi_snapshot_preview1 fd_write
//go:noescape
func fd_write(fd int32, iovs unsafe.Pointer, iovsLen size, nwritten unsafe.Pointer) Errno
//go:wasmimport wasi_snapshot_preview1 fd_sync
//go:noescape
func fd_sync(fd int32) Errno
//go:wasmimport wasi_snapshot_preview1 path_create_directory
//go:noescape
func path_create_directory(fd int32, path unsafe.Pointer, pathLen size) Errno
//go:wasmimport wasi_snapshot_preview1 path_filestat_get
//go:noescape
func path_filestat_get(fd int32, flags lookupflags, path unsafe.Pointer, pathLen size, buf unsafe.Pointer) Errno
//go:wasmimport wasi_snapshot_preview1 path_filestat_set_times
//go:noescape
func path_filestat_set_times(fd int32, flags lookupflags, path unsafe.Pointer, pathLen size, atim timestamp, mtim timestamp, fstflags fstflags) Errno
//go:wasmimport wasi_snapshot_preview1 path_link
//go:noescape
func path_link(oldFd int32, oldFlags lookupflags, oldPath unsafe.Pointer, oldPathLen size, newFd int32, newPath unsafe.Pointer, newPathLen size) Errno
//go:wasmimport wasi_snapshot_preview1 path_readlink
//go:noescape
func path_readlink(fd int32, path unsafe.Pointer, pathLen size, buf unsafe.Pointer, bufLen size, nwritten unsafe.Pointer) Errno
//go:wasmimport wasi_snapshot_preview1 path_remove_directory
//go:noescape
func path_remove_directory(fd int32, path unsafe.Pointer, pathLen size) Errno
//go:wasmimport wasi_snapshot_preview1 path_rename
//go:noescape
func path_rename(oldFd int32, oldPath unsafe.Pointer, oldPathLen size, newFd int32, newPath unsafe.Pointer, newPathLen size) Errno
//go:wasmimport wasi_snapshot_preview1 path_symlink
//go:noescape
func path_symlink(oldPath unsafe.Pointer, oldPathLen size, fd int32, newPath unsafe.Pointer, newPathLen size) Errno
//go:wasmimport wasi_snapshot_preview1 path_unlink_file
//go:noescape
func path_unlink_file(fd int32, path unsafe.Pointer, pathLen size) Errno
//go:wasmimport wasi_snapshot_preview1 path_open
//go:noescape
func path_open(rootFD int32, dirflags lookupflags, path unsafe.Pointer, pathLen size, oflags oflags, fsRightsBase rights, fsRightsInheriting rights, fsFlags fdflags, fd unsafe.Pointer) Errno
//go:wasmimport wasi_snapshot_preview1 random_get
//go:noescape
func random_get(buf unsafe.Pointer, bufLen size) Errno
// https://github.com/WebAssembly/WASI/blob/a2b96e81c0586125cc4dc79a5be0b78d9a059925/legacy/preview1/docs.md#-fdstat-record
// fdflags must be at offset 2, hence the uint16 type rather than the
// fdflags (uint32) type.
type fdstat struct {
filetype filetype
fdflags uint16
rightsBase rights
rightsInheriting rights
}
//go:wasmimport wasi_snapshot_preview1 fd_fdstat_get
//go:noescape
func fd_fdstat_get(fd int32, buf unsafe.Pointer) Errno
//go:wasmimport wasi_snapshot_preview1 fd_fdstat_set_flags
//go:noescape
func fd_fdstat_set_flags(fd int32, flags fdflags) Errno
func fd_fdstat_get_flags(fd int) (uint32, error) {
var stat fdstat
errno := fd_fdstat_get(int32(fd), unsafe.Pointer(&stat))
return uint32(stat.fdflags), errnoErr(errno)
}
func fd_fdstat_get_type(fd int) (uint8, error) {
var stat fdstat
errno := fd_fdstat_get(int32(fd), unsafe.Pointer(&stat))
return stat.filetype, errnoErr(errno)
}
type preopentype = uint8
const (
preopentypeDir preopentype = iota
)
type prestatDir struct {
prNameLen size
}
type prestat struct {
typ preopentype
dir prestatDir
}
//go:wasmimport wasi_snapshot_preview1 fd_prestat_get
//go:noescape
func fd_prestat_get(fd int32, prestat unsafe.Pointer) Errno
//go:wasmimport wasi_snapshot_preview1 fd_prestat_dir_name
//go:noescape
func fd_prestat_dir_name(fd int32, path unsafe.Pointer, pathLen size) Errno
type opendir struct {
fd int32
name string
}
// List of preopen directories that were exposed by the runtime. The first one
// is assumed to the be root directory of the file system, and others are seen
// as mount points at sub paths of the root.
var preopens []opendir
// Current working directory. We maintain this as a string and resolve paths in
// the code because wasmtime does not allow relative path lookups outside of the
// scope of a directory; a previous approach we tried consisted in maintaining
// open a file descriptor to the current directory so we could perform relative
// path lookups from that location, but it resulted in breaking path resolution
// from the current directory to its parent.
var cwd string
func init() {
dirNameBuf := make([]byte, 256)
// We start looking for preopens at fd=3 because 0, 1, and 2 are reserved
// for standard input and outputs.
for preopenFd := int32(3); ; preopenFd++ {
var prestat prestat
errno := fd_prestat_get(preopenFd, unsafe.Pointer(&prestat))
if errno == EBADF {
break
}
if errno == ENOTDIR || prestat.typ != preopentypeDir {
continue
}
if errno != 0 {
panic("fd_prestat: " + errno.Error())
}
if int(prestat.dir.prNameLen) > len(dirNameBuf) {
dirNameBuf = make([]byte, prestat.dir.prNameLen)
}
errno = fd_prestat_dir_name(preopenFd, unsafe.Pointer(&dirNameBuf[0]), prestat.dir.prNameLen)
if errno != 0 {
panic("fd_prestat_dir_name: " + errno.Error())
}
preopens = append(preopens, opendir{
fd: preopenFd,
name: string(dirNameBuf[:prestat.dir.prNameLen]),
})
}
if cwd, _ = Getenv("PWD"); cwd != "" {
cwd = joinPath("/", cwd)
} else if len(preopens) > 0 {
cwd = preopens[0].name
}
}
// Provided by package runtime.
func now() (sec int64, nsec int32)
//go:nosplit
func appendCleanPath(buf []byte, path string, lookupParent bool) ([]byte, bool) {
i := 0
for i < len(path) {
for i < len(path) && path[i] == '/' {
i++
}
j := i
for j < len(path) && path[j] != '/' {
j++
}
s := path[i:j]
i = j
switch s {
case "":
continue
case ".":
continue
case "..":
if !lookupParent {
k := len(buf)
for k > 0 && buf[k-1] != '/' {
k--
}
for k > 1 && buf[k-1] == '/' {
k--
}
buf = buf[:k]
if k == 0 {
lookupParent = true
} else {
s = ""
continue
}
}
default:
lookupParent = false
}
if len(buf) > 0 && buf[len(buf)-1] != '/' {
buf = append(buf, '/')
}
buf = append(buf, s...)
}
return buf, lookupParent
}
// joinPath concatenates dir and file paths, producing a cleaned path where
// "." and ".." have been removed, unless dir is relative and the references
// to parent directories in file represented a location relative to a parent
// of dir.
//
// This function is used for path resolution of all wasi functions expecting
// a path argument; the returned string is heap allocated, which we may want
// to optimize in the future. Instead of returning a string, the function
// could append the result to an output buffer that the functions in this
// file can manage to have allocated on the stack (e.g. initializing to a
// fixed capacity). Since it will significantly increase code complexity,
// we prefer to optimize for readability and maintainability at this time.
func joinPath(dir, file string) string {
buf := make([]byte, 0, len(dir)+len(file)+1)
if isAbs(dir) {
buf = append(buf, '/')
}
buf, lookupParent := appendCleanPath(buf, dir, false)
buf, _ = appendCleanPath(buf, file, lookupParent)
// The appendCleanPath function cleans the path so it does not inject
// references to the current directory. If both the dir and file args
// were ".", this results in the output buffer being empty so we handle
// this condition here.
if len(buf) == 0 {
buf = append(buf, '.')
}
// If the file ended with a '/' we make sure that the output also ends
// with a '/'. This is needed to ensure that programs have a mechanism
// to represent dereferencing symbolic links pointing to directories.
if buf[len(buf)-1] != '/' && isDir(file) {
buf = append(buf, '/')
}
return unsafe.String(&buf[0], len(buf))
}
func isAbs(path string) bool {
return hasPrefix(path, "/")
}
func isDir(path string) bool {
return hasSuffix(path, "/")
}
func hasPrefix(s, p string) bool {
return len(s) >= len(p) && s[:len(p)] == p
}
func hasSuffix(s, x string) bool {
return len(s) >= len(x) && s[len(s)-len(x):] == x
}
// preparePath returns the preopen file descriptor of the directory to perform
// path resolution from, along with the pair of pointer and length for the
// relative expression of path from the directory.
//
// If the path argument is not absolute, it is first appended to the current
// working directory before resolution.
func preparePath(path string) (int32, unsafe.Pointer, size) {
var dirFd = int32(-1)
var dirName string
dir := "/"
if !isAbs(path) {
dir = cwd
}
path = joinPath(dir, path)
for _, p := range preopens {
if len(p.name) > len(dirName) && hasPrefix(path, p.name) {
dirFd, dirName = p.fd, p.name
}
}
path = path[len(dirName):]
for isAbs(path) {
path = path[1:]
}
if len(path) == 0 {
path = "."
}
return dirFd, stringPointer(path), size(len(path))
}
func Open(path string, openmode int, perm uint32) (int, error) {
if path == "" {
return -1, EINVAL
}
dirFd, pathPtr, pathLen := preparePath(path)
var oflags oflags
if (openmode & O_CREATE) != 0 {
oflags |= OFLAG_CREATE
}
if (openmode & O_TRUNC) != 0 {
oflags |= OFLAG_TRUNC
}
if (openmode & O_EXCL) != 0 {
oflags |= OFLAG_EXCL
}
var rights rights
switch openmode & (O_RDONLY | O_WRONLY | O_RDWR) {
case O_RDONLY:
rights = fileRights & ^writeRights
case O_WRONLY:
rights = fileRights & ^readRights
case O_RDWR:
rights = fileRights
}
var fdflags fdflags
if (openmode & O_APPEND) != 0 {
fdflags |= FDFLAG_APPEND
}
if (openmode & O_SYNC) != 0 {
fdflags |= FDFLAG_SYNC
}
var fd int32
errno := path_open(
dirFd,
LOOKUP_SYMLINK_FOLLOW,
pathPtr,
pathLen,
oflags,
rights,
fileRights,
fdflags,
unsafe.Pointer(&fd),
)
if errno == EISDIR && oflags == 0 && fdflags == 0 && ((rights & writeRights) == 0) {
// wasmtime and wasmedge will error if attempting to open a directory
// because we are asking for too many rights. However, we cannot
// determine ahread of time if the path we are about to open is a
// directory, so instead we fallback to a second call to path_open with
// a more limited set of rights.
//
// This approach is subject to a race if the file system is modified
// concurrently, so we also inject OFLAG_DIRECTORY to ensure that we do
// not accidentally open a file which is not a directory.
errno = path_open(
dirFd,
LOOKUP_SYMLINK_FOLLOW,
pathPtr,
pathLen,
oflags|OFLAG_DIRECTORY,
rights&dirRights,
fileRights,
fdflags,
unsafe.Pointer(&fd),
)
}
return int(fd), errnoErr(errno)
}
func Close(fd int) error {
errno := fd_close(int32(fd))
return errnoErr(errno)
}
func CloseOnExec(fd int) {
// nothing to do - no exec
}
func Mkdir(path string, perm uint32) error {
if path == "" {
return EINVAL
}
dirFd, pathPtr, pathLen := preparePath(path)
errno := path_create_directory(dirFd, pathPtr, pathLen)
return errnoErr(errno)
}
func ReadDir(fd int, buf []byte, cookie dircookie) (int, error) {
var nwritten size
errno := fd_readdir(int32(fd), unsafe.Pointer(&buf[0]), size(len(buf)), cookie, unsafe.Pointer(&nwritten))
return int(nwritten), errnoErr(errno)
}
type Stat_t struct {
Dev uint64
Ino uint64
Filetype uint8
Nlink uint64
Size uint64
Atime uint64
Mtime uint64
Ctime uint64
Mode int
// Uid and Gid are always zero on wasip1 platforms
Uid uint32
Gid uint32
}
func Stat(path string, st *Stat_t) error {
if path == "" {
return EINVAL
}
dirFd, pathPtr, pathLen := preparePath(path)
errno := path_filestat_get(dirFd, LOOKUP_SYMLINK_FOLLOW, pathPtr, pathLen, unsafe.Pointer(st))
setDefaultMode(st)
return errnoErr(errno)
}
func Lstat(path string, st *Stat_t) error {
if path == "" {
return EINVAL
}
dirFd, pathPtr, pathLen := preparePath(path)
errno := path_filestat_get(dirFd, 0, pathPtr, pathLen, unsafe.Pointer(st))
setDefaultMode(st)
return errnoErr(errno)
}
func Fstat(fd int, st *Stat_t) error {
errno := fd_filestat_get(int32(fd), unsafe.Pointer(st))
setDefaultMode(st)
return errnoErr(errno)
}
func setDefaultMode(st *Stat_t) {
// WASI does not support unix-like permissions, but Go programs are likely
// to expect the permission bits to not be zero so we set defaults to help
// avoid breaking applications that are migrating to WASM.
if st.Filetype == FILETYPE_DIRECTORY {
st.Mode = 0700
} else {
st.Mode = 0600
}
}
func Unlink(path string) error {
if path == "" {
return EINVAL
}
dirFd, pathPtr, pathLen := preparePath(path)
errno := path_unlink_file(dirFd, pathPtr, pathLen)
return errnoErr(errno)
}
func Rmdir(path string) error {
if path == "" {
return EINVAL
}
dirFd, pathPtr, pathLen := preparePath(path)
errno := path_remove_directory(dirFd, pathPtr, pathLen)
return errnoErr(errno)
}
func Chmod(path string, mode uint32) error {
var stat Stat_t
return Stat(path, &stat)
}
func Fchmod(fd int, mode uint32) error {
var stat Stat_t
return Fstat(fd, &stat)
}
func Chown(path string, uid, gid int) error {
return ENOSYS
}
func Fchown(fd int, uid, gid int) error {
return ENOSYS
}
func Lchown(path string, uid, gid int) error {
return ENOSYS
}
func UtimesNano(path string, ts []Timespec) error {
// UTIME_OMIT value must match internal/syscall/unix/at_wasip1.go
const UTIME_OMIT = -0x2
if path == "" {
return EINVAL
}
dirFd, pathPtr, pathLen := preparePath(path)
atime := TimespecToNsec(ts[0])
mtime := TimespecToNsec(ts[1])
if ts[0].Nsec == UTIME_OMIT || ts[1].Nsec == UTIME_OMIT {
var st Stat_t
if err := Stat(path, &st); err != nil {
return err
}
if ts[0].Nsec == UTIME_OMIT {
atime = int64(st.Atime)
}
if ts[1].Nsec == UTIME_OMIT {
mtime = int64(st.Mtime)
}
}
errno := path_filestat_set_times(
dirFd,
LOOKUP_SYMLINK_FOLLOW,
pathPtr,
pathLen,
timestamp(atime),
timestamp(mtime),
FILESTAT_SET_ATIM|FILESTAT_SET_MTIM,
)
return errnoErr(errno)
}
func Rename(from, to string) error {
if from == "" || to == "" {
return EINVAL
}
oldDirFd, oldPathPtr, oldPathLen := preparePath(from)
newDirFd, newPathPtr, newPathLen := preparePath(to)
errno := path_rename(
oldDirFd,
oldPathPtr,
oldPathLen,
newDirFd,
newPathPtr,
newPathLen,
)
return errnoErr(errno)
}
func Truncate(path string, length int64) error {
if path == "" {
return EINVAL
}
fd, err := Open(path, O_WRONLY, 0)
if err != nil {
return err
}
defer Close(fd)
return Ftruncate(fd, length)
}
func Ftruncate(fd int, length int64) error {
errno := fd_filestat_set_size(int32(fd), filesize(length))
return errnoErr(errno)
}
const ImplementsGetwd = true
func Getwd() (string, error) {
return cwd, nil
}
func Chdir(path string) error {
if path == "" {
return EINVAL
}
dir := "/"
if !isAbs(path) {
dir = cwd
}
path = joinPath(dir, path)
var stat Stat_t
dirFd, pathPtr, pathLen := preparePath(path)
errno := path_filestat_get(dirFd, LOOKUP_SYMLINK_FOLLOW, pathPtr, pathLen, unsafe.Pointer(&stat))
if errno != 0 {
return errnoErr(errno)
}
if stat.Filetype != FILETYPE_DIRECTORY {
return ENOTDIR
}
cwd = path
return nil
}
func Readlink(path string, buf []byte) (n int, err error) {
if path == "" {
return 0, EINVAL
}
if len(buf) == 0 {
return 0, nil
}
dirFd, pathPtr, pathLen := preparePath(path)
var nwritten size
errno := path_readlink(
dirFd,
pathPtr,
pathLen,
unsafe.Pointer(&buf[0]),
size(len(buf)),
unsafe.Pointer(&nwritten),
)
// For some reason wasmtime returns ERANGE when the output buffer is
// shorter than the symbolic link value. os.Readlink expects a nil
// error and uses the fact that n is greater or equal to the buffer
// length to assume that it needs to try again with a larger size.
// This condition is handled in os.Readlink.
return int(nwritten), errnoErr(errno)
}
func Link(path, link string) error {
if path == "" || link == "" {
return EINVAL
}
oldDirFd, oldPathPtr, oldPathLen := preparePath(path)
newDirFd, newPathPtr, newPathLen := preparePath(link)
errno := path_link(
oldDirFd,
0,
oldPathPtr,
oldPathLen,
newDirFd,
newPathPtr,
newPathLen,
)
return errnoErr(errno)
}
func Symlink(path, link string) error {
if path == "" || link == "" {
return EINVAL
}
dirFd, pathPtr, pathlen := preparePath(link)
errno := path_symlink(
stringPointer(path),
size(len(path)),
dirFd,
pathPtr,
pathlen,
)
return errnoErr(errno)
}
func Fsync(fd int) error {
errno := fd_sync(int32(fd))
return errnoErr(errno)
}
func bytesPointer(b []byte) unsafe.Pointer {
return unsafe.Pointer(unsafe.SliceData(b))
}
func stringPointer(s string) unsafe.Pointer {
return unsafe.Pointer(unsafe.StringData(s))
}
func makeIOVec(b []byte) unsafe.Pointer {
return unsafe.Pointer(&iovec{
buf: uintptr32(uintptr(bytesPointer(b))),
bufLen: size(len(b)),
})
}
func Read(fd int, b []byte) (int, error) {
var nread size
errno := fd_read(int32(fd), makeIOVec(b), 1, unsafe.Pointer(&nread))
runtime.KeepAlive(b)
return int(nread), errnoErr(errno)
}
func Write(fd int, b []byte) (int, error) {
var nwritten size
errno := fd_write(int32(fd), makeIOVec(b), 1, unsafe.Pointer(&nwritten))
runtime.KeepAlive(b)
return int(nwritten), errnoErr(errno)
}
func Pread(fd int, b []byte, offset int64) (int, error) {
var nread size
errno := fd_pread(int32(fd), makeIOVec(b), 1, filesize(offset), unsafe.Pointer(&nread))
runtime.KeepAlive(b)
return int(nread), errnoErr(errno)
}
func Pwrite(fd int, b []byte, offset int64) (int, error) {
var nwritten size
errno := fd_pwrite(int32(fd), makeIOVec(b), 1, filesize(offset), unsafe.Pointer(&nwritten))
runtime.KeepAlive(b)
return int(nwritten), errnoErr(errno)
}
func Seek(fd int, offset int64, whence int) (int64, error) {
var newoffset filesize
errno := fd_seek(int32(fd), filedelta(offset), uint32(whence), unsafe.Pointer(&newoffset))
return int64(newoffset), errnoErr(errno)
}
func Dup(fd int) (int, error) {
return 0, ENOSYS
}
func Dup2(fd, newfd int) error {
return ENOSYS
}
func Pipe(fd []int) error {
return ENOSYS
}
func RandomGet(b []byte) error {
errno := random_get(bytesPointer(b), size(len(b)))
return errnoErr(errno)
}