WASI & darwin: support basic file io based on libc

Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>

src/syscall/errno_other.go

@@ -0,0 +1,5 @@
+// +build !wasi,!darwin
+
+package syscall
+
+func (e Errno) Is(target error) bool { return false }

src/syscall/syscall_libc.go

@@ -13,12 +13,15 @@ type sliceHeader struct {
 }
 
 func Close(fd int) (err error) {
-	return ENOSYS // TODO
+	if libc_close(fd) < 0 {
+		err = getErrno()
+	}
+	return
 }
 
 func Write(fd int, p []byte) (n int, err error) {
 	buf, count := splitSlice(p)
-	n = libc_write(int32(fd), buf, uint(count))
+	n = libc_write(fd, buf, uint(count))
 	if n < 0 {
 		err = getErrno()
 	}
@@ -26,15 +29,25 @@ func Write(fd int, p []byte) (n int, err error) {
 }
 
 func Read(fd int, p []byte) (n int, err error) {
-	return 0, ENOSYS // TODO
+	buf, count := splitSlice(p)
+	n = libc_read(fd, buf, uint(count))
+	if n < 0 {
+		err = getErrno()
+	}
+	return
 }
 
 func Seek(fd int, offset int64, whence int) (off int64, err error) {
 	return 0, ENOSYS // TODO
 }
 
-func Open(path string, mode int, perm uint32) (fd int, err error) {
-	return 0, ENOSYS // TODO
+func Open(path string, flag int, mode uint32) (fd int, err error) {
+	data := append([]byte(path), 0)
+	fd = libc_open(&data[0], flag, mode)
+	if fd < 0 {
+		err = getErrno()
+	}
+	return
 }
 
 func Mkdir(path string, mode uint32) (err error) {
@@ -78,8 +91,20 @@ func splitSlice(p []byte) (buf *byte, len uintptr) {
 
 // ssize_t write(int fd, const void *buf, size_t count)
 //export write
-func libc_write(fd int32, buf *byte, count uint) int
+func libc_write(fd int, buf *byte, count uint) int
 
 // char *getenv(const char *name);
 //export getenv
 func libc_getenv(name *byte) *byte
+
+// ssize_t read(int fd, void *buf, size_t count);
+//export read
+func libc_read(fd int, buf *byte, count uint) int
+
+// int open(const char *pathname, int flags, mode_t mode);
+//export open
+func libc_open(pathname *byte, flags int, mode uint32) int
+
+// int close(int fd)
+//export close
+func libc_close(fd int) int

src/syscall/syscall_libc_darwin.go

@@ -1,3 +1,5 @@
+// +build darwin
+
 package syscall
 
 // This file defines errno and constants to match the darwin libsystem ABI.
@@ -22,10 +24,25 @@ func getErrno() Errno {
 	return Errno(uintptr(*errptr))
 }
 
+func (e Errno) Is(target error) bool {
+	switch target.Error() {
+	case "permission denied":
+		return e == EACCES || e == EPERM
+	case "file already exists":
+		return e == EEXIST
+	case "file does not exist":
+		return e == ENOENT
+	}
+	return false
+}
+
 const (
+	EPERM       Errno = 0x1
 	ENOENT      Errno = 0x2
+	EACCES      Errno = 0xd
 	EEXIST      Errno = 0x11
 	EINTR       Errno = 0x4
+	ENOTDIR     Errno = 0x14
 	EMFILE      Errno = 0x18
 	EAGAIN      Errno = 0x23
 	ETIMEDOUT   Errno = 0x3c

src/syscall/syscall_libc_nintendoswitch.go

@@ -2,8 +2,6 @@
 
 package syscall
 
-import "errors"
-
 // A Signal is a number describing a process signal.
 // It implements the os.Signal interface.
 type Signal int
@@ -32,7 +30,6 @@ const (
 	O_RDWR   = 2
 
 	O_CREAT  = 0100
-	O_CREATE = O_CREAT
 	O_TRUNC  = 01000
 	O_APPEND = 02000
 	O_EXCL   = 0200
@@ -41,8 +38,9 @@ const (
 	O_CLOEXEC = 0
 )
 
-var dummyError = errors.New("unknown syscall error")
+//go:extern errno
+var libcErrno uintptr
 
 func getErrno() error {
-	return dummyError
+	return Errno(libcErrno)
 }

src/syscall/syscall_libc_wasi.go

@@ -33,7 +33,6 @@ const (
 	O_RDWR   = O_RDONLY | O_WRONLY
 
 	O_CREAT  = __WASI_OFLAGS_CREAT << 12
-	O_CREATE = O_CREAT
 	O_TRUNC  = __WASI_OFLAGS_TRUNC << 12
 	O_APPEND = __WASI_FDFLAGS_APPEND
 	O_EXCL   = __WASI_OFLAGS_EXCL << 12
@@ -48,3 +47,95 @@ var libcErrno uintptr
 func getErrno() error {
 	return Errno(libcErrno)
 }
+
+func (e Errno) Is(target error) bool {
+	switch target.Error() {
+	case "permission denied":
+		return e == EACCES || e == EPERM || e == ENOTCAPABLE // ENOTCAPABLE is unique in WASI
+	case "file already exists":
+		return e == EEXIST || e == ENOTEMPTY
+	case "file does not exist":
+		return e == ENOENT
+	}
+	return false
+}
+
+// https://github.com/WebAssembly/wasi-libc/blob/main/libc-bottom-half/headers/public/__errno.h
+const (
+	E2BIG           Errno = 1      /* Argument list too long */
+	EACCES          Errno = 2      /* Permission denied */
+	EADDRINUSE      Errno = 3      /* Address already in use */
+	EADDRNOTAVAIL   Errno = 4      /* Address not available */
+	EAFNOSUPPORT    Errno = 5      /* Address family not supported by protocol family */
+	EAGAIN          Errno = 6      /* Try again */
+	EWOULDBLOCK     Errno = EAGAIN /* Operation would block */
+	EALREADY        Errno = 7      /* Socket already connected */
+	EBADF           Errno = 8      /* Bad file number */
+	EBADMSG         Errno = 9      /* Trying to read unreadable message */
+	EBUSY           Errno = 10     /* Device or resource busy */
+	ECANCELED       Errno = 11     /* Operation canceled. */
+	ECHILD          Errno = 12     /* No child processes */
+	ECONNABORTED    Errno = 13     /* Connection aborted */
+	ECONNREFUSED    Errno = 14     /* Connection refused */
+	ECONNRESET      Errno = 15     /* Connection reset by peer */
+	EDEADLK         Errno = 16     /* Deadlock condition */
+	EDESTADDRREQ    Errno = 17     /* Destination address required */
+	EDOM            Errno = 18     /* Math arg out of domain of func */
+	EDQUOT          Errno = 19     /* Quota exceeded */
+	EEXIST          Errno = 20     /* File exists */
+	EFAULT          Errno = 21     /* Bad address */
+	EFBIG           Errno = 22     /* File too large */
+	EHOSTUNREACH    Errno = 23     /* Host is unreachable */
+	EIDRM           Errno = 24     /* Identifier removed */
+	EILSEQ          Errno = 25
+	EINPROGRESS     Errno = 26 /* Connection already in progress */
+	EINTR           Errno = 27 /* Interrupted system call */
+	EINVAL          Errno = 28 /* Invalid argument */
+	EIO             Errno = 29 /* I/O error */
+	EISCONN         Errno = 30 /* Socket is already connected */
+	EISDIR          Errno = 31 /* Is a directory */
+	ELOOP           Errno = 32 /* Too many symbolic links */
+	EMFILE          Errno = 33 /* Too many open files */
+	EMLINK          Errno = 34 /* Too many links */
+	EMSGSIZE        Errno = 35 /* Message too long */
+	EMULTIHOP       Errno = 36 /* Multihop attempted */
+	ENAMETOOLONG    Errno = 37 /* File name too long */
+	ENETDOWN        Errno = 38 /* Network interface is not configured */
+	ENETRESET       Errno = 39
+	ENETUNREACH     Errno = 40         /* Network is unreachable */
+	ENFILE          Errno = 41         /* File table overflow */
+	ENOBUFS         Errno = 42         /* No buffer space available */
+	ENODEV          Errno = 43         /* No such device */
+	ENOENT          Errno = 44         /* No such file or directory */
+	ENOEXEC         Errno = 45         /* Exec format error */
+	ENOLCK          Errno = 46         /* No record locks available */
+	ENOLINK         Errno = 47         /* The link has been severed */
+	ENOMEM          Errno = 48         /* Out of memory */
+	ENOMSG          Errno = 49         /* No message of desired type */
+	ENOPROTOOPT     Errno = 50         /* Protocol not available */
+	ENOSPC          Errno = 51         /* No space left on device */
+	ENOSYS          Errno = 52         /* Function not implemented */
+	ENOTCONN        Errno = 53         /* Socket is not connected */
+	ENOTDIR         Errno = 54         /* Not a directory */
+	ENOTEMPTY       Errno = 55         /* Directory not empty */
+	ENOTSOCK        Errno = 57         /* Socket operation on non-socket */
+	ESOCKTNOSUPPORT Errno = 58         /* Socket type not supported */
+	EOPNOTSUPP      Errno = 58         /* Operation not supported on transport endpoint */
+	ENOTSUP         Errno = EOPNOTSUPP /* Not supported */
+	ENOTTY          Errno = 59         /* Not a typewriter */
+	ENXIO           Errno = 60         /* No such device or address */
+	EOVERFLOW       Errno = 61         /* Value too large for defined data type */
+	EPERM           Errno = 63         /* Operation not permitted */
+	EPIPE           Errno = 64         /* Broken pipe */
+	EPROTO          Errno = 65         /* Protocol error */
+	EPROTONOSUPPORT Errno = 66         /* Unknown protocol */
+	EPROTOTYPE      Errno = 67         /* Protocol wrong type for socket */
+	ERANGE          Errno = 68         /* Math result not representable */
+	EROFS           Errno = 69         /* Read-only file system */
+	ESPIPE          Errno = 70         /* Illegal seek */
+	ESRCH           Errno = 71         /* No such process */
+	ESTALE          Errno = 72
+	ETIMEDOUT       Errno = 73 /* Connection timed out */
+	EXDEV           Errno = 75 /* Cross-device link */
+	ENOTCAPABLE     Errno = 76 /* Extension: Capabilities insufficient. */
+)

src/syscall/tables_baremetal.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build baremetal nintendoswitch wasi
+// +build baremetal nintendoswitch
 
 package syscall