os: stub out support for some more features

This is necessary for the following:

  - to make sure os/exec can be imported
  - to make sure internal/testenv can be imported

The internal/testenv package (which imports os/exec) is used by a lot of
tests. By adding support for it, more tests can be run.

This commit adds a bunch of new packages that now pass all tests.

12 files changed, 186 insertions, 12 deletions

diff --git a/Makefile b/Makefile
index 1a922f87d..3ed2a8951 100644
--- a/Makefile
+++ b/Makefile
@@ -200,31 +200,41 @@ test: wasi-libc
 
 TEST_PACKAGES = \
 	compress/bzip2 \
+	compress/flate \
+	compress/zlib \
 	container/heap \
 	container/list \
 	container/ring \
 	crypto/des \
 	crypto/dsa \
+	crypto/elliptic/internal/fiat \
+	crypto/internal/subtle \
 	crypto/md5 \
 	crypto/rc4 \
 	crypto/sha1 \
 	crypto/sha256 \
 	crypto/sha512 \
+	debug/macho \
 	encoding \
 	encoding/ascii85 \
 	encoding/base32 \
+	encoding/csv \
 	encoding/hex \
+	go/scanner \
 	hash \
 	hash/adler32 \
-	hash/fnv \
 	hash/crc64 \
+	hash/fnv \
 	html \
 	index/suffixarray \
 	internal/itoa \
+	internal/profile \
 	math \
 	math/cmplx \
+	net/http/internal/ascii \
 	net/mail \
 	os \
+	path \
 	reflect \
 	testing \
 	testing/iotest \
diff --git a/src/os/env.go b/src/os/env.go
index eac3072ac..585650e79 100644
--- a/src/os/env.go
+++ b/src/os/env.go
@@ -12,3 +12,7 @@ func Getenv(key string) string {
 func LookupEnv(key string) (string, bool) {
 	return syscall.Getenv(key)
 }
+
+func Environ() []string {
+	return syscall.Environ()
+}
diff --git a/src/os/exec.go b/src/os/exec.go
index 8bc544ba2..067be0de1 100644
--- a/src/os/exec.go
+++ b/src/os/exec.go
@@ -16,3 +16,36 @@ func Getpid() int {
 func Getppid() int {
 	return syscall.Getppid()
 }
+
+type ProcAttr struct {
+	Dir   string
+	Env   []string
+	Files []*File
+	Sys   *syscall.SysProcAttr
+}
+
+type ProcessState struct {
+}
+
+func (p *ProcessState) String() string {
+	return "" // TODO
+}
+func (p *ProcessState) Success() bool {
+	return false // TODO
+}
+
+type Process struct {
+	Pid int
+}
+
+func StartProcess(name string, argv []string, attr *ProcAttr) (*Process, error) {
+	return nil, &PathError{"fork/exec", name, ErrNotImplemented}
+}
+
+func (p *Process) Wait() (*ProcessState, error) {
+	return nil, ErrNotImplemented
+}
+
+func (p *Process) Kill() error {
+	return ErrNotImplemented
+}
diff --git a/src/os/file.go b/src/os/file.go
index 6af6a28f3..2af911229 100644
--- a/src/os/file.go
+++ b/src/os/file.go
@@ -52,6 +52,16 @@ func Remove(path string) error {
 	return nil
 }
 
+// Symlink is a stub, it is not implemented.
+func Symlink(oldname, newname string) error {
+	return ErrNotImplemented
+}
+
+// RemoveAll is a stub, it is not implemented.
+func RemoveAll(path string) error {
+	return ErrNotImplemented
+}
+
 // File represents an open file descriptor.
 type File struct {
 	handle FileHandle
@@ -187,6 +197,27 @@ func (e *PathError) Error() string {
 	return e.Op + " " + e.Path + ": " + e.Err.Error()
 }
 
+func (e *PathError) Unwrap() error {
+	return e.Err
+}
+
+// LinkError records an error during a link or symlink or rename system call and
+// the paths that caused it.
+type LinkError struct {
+	Op  string
+	Old string
+	New string
+	Err error
+}
+
+func (e *LinkError) Error() string {
+	return e.Op + " " + e.Old + " " + e.New + ": " + e.Err.Error()
+}
+
+func (e *LinkError) Unwrap() error {
+	return e.Err
+}
+
 const (
 	O_RDONLY int = syscall.O_RDONLY
 	O_WRONLY int = syscall.O_WRONLY
diff --git a/src/os/file_anyos.go b/src/os/file_anyos.go
index 4cf2a50eb..74637a1ea 100644
--- a/src/os/file_anyos.go
+++ b/src/os/file_anyos.go
@@ -21,6 +21,8 @@ var (
 	Stderr = &File{unixFileHandle(syscall.Stderr), "/dev/stderr"}
 )
 
+const DevNull = "/dev/null"
+
 // isOS indicates whether we're running on a real operating system with
 // filesystem support.
 const isOS = true
diff --git a/src/os/file_other.go b/src/os/file_other.go
index af885eddc..37f9675d5 100644
--- a/src/os/file_other.go
+++ b/src/os/file_other.go
@@ -48,3 +48,7 @@ func (f stdioFileHandle) Close() error {
 
 //go:linkname putchar runtime.putchar
 func putchar(c byte)
+
+func Pipe() (r *File, w *File, err error) {
+	return nil, nil, ErrNotImplemented
+}
diff --git a/src/os/file_unix.go b/src/os/file_unix.go
index 7ead108b0..64230fd39 100644
--- a/src/os/file_unix.go
+++ b/src/os/file_unix.go
@@ -2,4 +2,23 @@
 
 package os
 
+import "syscall"
+
 type syscallFd = int
+
+func Pipe() (r *File, w *File, err error) {
+	var p [2]int
+	err = handleSyscallError(syscall.Pipe2(p[:], syscall.O_CLOEXEC))
+	if err != nil {
+		return
+	}
+	r = &File{
+		handle: unixFileHandle(p[0]),
+		name:   "|0",
+	}
+	w = &File{
+		handle: unixFileHandle(p[1]),
+		name:   "|1",
+	}
+	return
+}
diff --git a/src/os/file_windows.go b/src/os/file_windows.go
index 11ae1e0d1..cf9703808 100644
--- a/src/os/file_windows.go
+++ b/src/os/file_windows.go
@@ -5,3 +5,20 @@ package os
 import "syscall"
 
 type syscallFd = syscall.Handle
+
+func Pipe() (r *File, w *File, err error) {
+	var p [2]syscall.Handle
+	e := handleSyscallError(syscall.Pipe(p[:]))
+	if e != nil {
+		return nil, nil, err
+	}
+	r = &File{
+		handle: unixFileHandle(p[0]),
+		name:   "|0",
+	}
+	w = &File{
+		handle: unixFileHandle(p[1]),
+		name:   "|1",
+	}
+	return
+}
diff --git a/src/syscall/syscall_libc.go b/src/syscall/syscall_libc.go
index f4f3578c6..77db38e24 100644
--- a/src/syscall/syscall_libc.go
+++ b/src/syscall/syscall_libc.go
@@ -81,6 +81,12 @@ func Kill(pid int, sig Signal) (err error) {
 	return ENOSYS // TODO
 }
 
+type SysProcAttr struct{}
+
+func Pipe2(p []int, flags int) (err error) {
+	return ENOSYS // TODO
+}
+
 func Getenv(key string) (value string, found bool) {
 	data := cstring(key)
 	raw := libc_getenv(&data[0])
@@ -115,6 +121,26 @@ func Mprotect(b []byte, prot int) (err error) {
 	return
 }
 
+func Environ() []string {
+	environ := libc_environ
+	var envs []string
+	for *environ != nil {
+		// Convert the C string to a Go string.
+		length := libc_strlen(*environ)
+		var envVar string
+		rawEnvVar := (*struct {
+			ptr    unsafe.Pointer
+			length uintptr
+		})(unsafe.Pointer(&envVar))
+		rawEnvVar.ptr = *environ
+		rawEnvVar.length = length
+		envs = append(envs, envVar)
+		// This is the Go equivalent of "environ++" in C.
+		environ = (*unsafe.Pointer)(unsafe.Pointer(uintptr(unsafe.Pointer(environ)) + unsafe.Sizeof(environ)))
+	}
+	return envs
+}
+
 // cstring converts a Go string to a C string.
 func cstring(s string) []byte {
 	data := make([]byte, len(s)+1)
@@ -128,6 +154,9 @@ func splitSlice(p []byte) (buf *byte, len uintptr) {
 	return slice.buf, slice.len
 }
 
+//export strlen
+func libc_strlen(ptr unsafe.Pointer) uintptr
+
 // ssize_t write(int fd, const void *buf, size_t count)
 //export write
 func libc_write(fd int32, buf *byte, count uint) int
@@ -167,3 +196,6 @@ func libc_rmdir(pathname *byte) int32
 // int unlink(const char *pathname);
 //export unlink
 func libc_unlink(pathname *byte) int32
+
+//go:extern environ
+var libc_environ *unsafe.Pointer
diff --git a/src/syscall/syscall_libc_darwin.go b/src/syscall/syscall_libc_darwin.go
index 6ca95f53b..481ba3830 100644
--- a/src/syscall/syscall_libc_darwin.go
+++ b/src/syscall/syscall_libc_darwin.go
@@ -36,18 +36,20 @@ func (e Errno) Is(target error) bool {
 	return false
 }
 
+// Source: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/sys/errno.h.auto.html
 const (
-	EPERM       Errno = 0x1
-	ENOENT      Errno = 0x2
-	EACCES      Errno = 0xd
-	EEXIST      Errno = 0x11
-	EINTR       Errno = 0x4
-	ENOTDIR     Errno = 0x14
-	EINVAL      Errno = 0x16
-	EMFILE      Errno = 0x18
-	EAGAIN      Errno = 0x23
-	ETIMEDOUT   Errno = 0x3c
-	ENOSYS      Errno = 0x4e
+	EPERM       Errno = 1
+	ENOENT      Errno = 2
+	EACCES      Errno = 13
+	EEXIST      Errno = 17
+	EINTR       Errno = 4
+	ENOTDIR     Errno = 20
+	EINVAL      Errno = 22
+	EMFILE      Errno = 24
+	EPIPE       Errno = 32
+	EAGAIN      Errno = 35
+	ETIMEDOUT   Errno = 60
+	ENOSYS      Errno = 78
 	EWOULDBLOCK Errno = EAGAIN
 )
 
@@ -77,6 +79,8 @@ const (
 	O_CREAT  = 0x200
 	O_TRUNC  = 0x400
 	O_EXCL   = 0x800
+
+	O_CLOEXEC = 0x01000000
 )
 
 // Source: https://opensource.apple.com/source/xnu/xnu-7195.81.3/bsd/sys/mman.h.auto.html
diff --git a/src/syscall/syscall_nonhosted.go b/src/syscall/syscall_nonhosted.go
index 885738e4a..0fd7ffc5b 100644
--- a/src/syscall/syscall_nonhosted.go
+++ b/src/syscall/syscall_nonhosted.go
@@ -67,6 +67,13 @@ func Getenv(key string) (value string, found bool) {
 	return "", false
 }
 
+func Environ() []string {
+	env := runtime_envs()
+	envCopy := make([]string, len(env))
+	copy(envCopy, env)
+	return envCopy
+}
+
 func Open(path string, mode int, perm uint32) (fd int, err error) {
 	return 0, ENOSYS
 }
diff --git a/testdata/env.go b/testdata/env.go
index 115da6d3d..79f4885ee 100644
--- a/testdata/env.go
+++ b/testdata/env.go
@@ -13,6 +13,17 @@ func main() {
 	}
 	println("ENV2:", v)
 
+	found := false
+	expected := "ENV1=" + os.Getenv("ENV1")
+	for _, envVar := range os.Environ() {
+		if envVar == expected {
+			found = true
+		}
+	}
+	if !found {
+		println("could not find " + expected + " in os.Environ()")
+	}
+
 	// Check for command line arguments.
 	// Argument 0 is skipped because it is the program name, which varies by
 	// test run.