library patch: syscall, os environ

internal/lib/syscall/env_unix.go

@@ -0,0 +1,173 @@
+// Copyright 2010 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 unix || (js && wasm) || plan9 || wasip1
+
+// Unix environment variables.
+
+package syscall
+
+import (
+	"runtime"
+	"sync"
+
+	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/c/os"
+)
+
+var (
+	// envOnce guards initialization by copyenv, which populates env.
+	envOnce sync.Once
+
+	// envLock guards env and envs.
+	envLock sync.RWMutex
+
+	// env maps from an environment variable to its first occurrence in envs.
+	env map[string]int
+
+	// envs is provided by the runtime. elements are expected to
+	// be of the form "key=value". An empty string means deleted
+	// (or a duplicate to be ignored).
+	envs []string = runtimeEnvs()
+)
+
+func runtimeEnvs() []string {
+	ret := make([]string, 0, 8)
+	cenvs := os.Environ
+	i := 0
+	for {
+		ce := *c.Advance(cenvs, i)
+		if ce == nil {
+			return ret
+		}
+		ret = append(ret, c.GoString(ce))
+		i++
+	}
+}
+
+func copyenv() {
+	env = make(map[string]int)
+	for i, s := range envs {
+		for j := 0; j < len(s); j++ {
+			if s[j] == '=' {
+				key := s[:j]
+				if _, ok := env[key]; !ok {
+					env[key] = i // first mention of key
+				} else {
+					// Clear duplicate keys. This permits Unsetenv to
+					// safely delete only the first item without
+					// worrying about unshadowing a later one,
+					// which might be a security problem.
+					envs[i] = ""
+				}
+				break
+			}
+		}
+	}
+}
+
+func Unsetenv(key string) error {
+	envOnce.Do(copyenv)
+
+	envLock.Lock()
+	defer envLock.Unlock()
+
+	if i, ok := env[key]; ok {
+		envs[i] = ""
+		delete(env, key)
+	}
+	os.Unsetenv(c.AllocaCStr(key))
+	return nil
+}
+
+func Getenv(key string) (value string, found bool) {
+	envOnce.Do(copyenv)
+	if len(key) == 0 {
+		return "", false
+	}
+
+	envLock.RLock()
+	defer envLock.RUnlock()
+
+	i, ok := env[key]
+	if !ok {
+		return "", false
+	}
+	s := envs[i]
+	for i := 0; i < len(s); i++ {
+		if s[i] == '=' {
+			return s[i+1:], true
+		}
+	}
+	return "", false
+}
+
+/* TODO(xsw):
+func Getenv(key string) (value string, found bool) {
+	ret := os.Getenv(c.AllocaCStr(key))
+	if ret != nil {
+		return c.GoString(ret), true
+	}
+	return "", false
+}
+*/
+
+func Setenv(key, value string) error {
+	envOnce.Do(copyenv)
+	if len(key) == 0 {
+		return EINVAL
+	}
+	for i := 0; i < len(key); i++ {
+		if key[i] == '=' || key[i] == 0 {
+			return EINVAL
+		}
+	}
+	// On Plan 9, null is used as a separator, eg in $path.
+	if runtime.GOOS != "plan9" {
+		for i := 0; i < len(value); i++ {
+			if value[i] == 0 {
+				return EINVAL
+			}
+		}
+	}
+
+	envLock.Lock()
+	defer envLock.Unlock()
+
+	i, ok := env[key]
+	kv := key + "=" + value
+	if ok {
+		envs[i] = kv
+	} else {
+		i = len(envs)
+		envs = append(envs, kv)
+	}
+	env[key] = i
+	os.Setenv(c.AllocaCStr(key), c.AllocaCStr(value), 1)
+	return nil
+}
+
+func Clearenv() {
+	envOnce.Do(copyenv) // prevent copyenv in Getenv/Setenv
+
+	envLock.Lock()
+	defer envLock.Unlock()
+
+	os.Clearenv()
+	env = make(map[string]int)
+	envs = []string{}
+}
+
+func Environ() []string {
+	envOnce.Do(copyenv)
+	envLock.RLock()
+	defer envLock.RUnlock()
+	a := make([]string, 0, len(envs))
+	for _, env := range envs {
+		if env != "" {
+			a = append(a, env)
+		}
+	}
+	return a
+}

internal/lib/syscall/env_windows.go

@@ -0,0 +1,96 @@
+// Copyright 2010 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.
+
+// Windows environment variables.
+
+package syscall
+
+import (
+	"unsafe"
+)
+
+func Getenv(key string) (value string, found bool) {
+	keyp, err := UTF16PtrFromString(key)
+	if err != nil {
+		return "", false
+	}
+	n := uint32(100)
+	for {
+		b := make([]uint16, n)
+		n, err = GetEnvironmentVariable(keyp, &b[0], uint32(len(b)))
+		if n == 0 && err == ERROR_ENVVAR_NOT_FOUND {
+			return "", false
+		}
+		if n <= uint32(len(b)) {
+			return UTF16ToString(b[:n]), true
+		}
+	}
+}
+
+func Setenv(key, value string) error {
+	v, err := UTF16PtrFromString(value)
+	if err != nil {
+		return err
+	}
+	keyp, err := UTF16PtrFromString(key)
+	if err != nil {
+		return err
+	}
+	e := SetEnvironmentVariable(keyp, v)
+	if e != nil {
+		return e
+	}
+	runtimeSetenv(key, value)
+	return nil
+}
+
+func Unsetenv(key string) error {
+	keyp, err := UTF16PtrFromString(key)
+	if err != nil {
+		return err
+	}
+	e := SetEnvironmentVariable(keyp, nil)
+	if e != nil {
+		return e
+	}
+	runtimeUnsetenv(key)
+	return nil
+}
+
+func Clearenv() {
+	for _, s := range Environ() {
+		// Environment variables can begin with =
+		// so start looking for the separator = at j=1.
+		// https://devblogs.microsoft.com/oldnewthing/20100506-00/?p=14133
+		for j := 1; j < len(s); j++ {
+			if s[j] == '=' {
+				Unsetenv(s[0:j])
+				break
+			}
+		}
+	}
+}
+
+func Environ() []string {
+	envp, e := GetEnvironmentStrings()
+	if e != nil {
+		return nil
+	}
+	defer FreeEnvironmentStrings(envp)
+
+	r := make([]string, 0, 50) // Empty with room to grow.
+	const size = unsafe.Sizeof(*envp)
+	for *envp != 0 { // environment block ends with empty string
+		// find NUL terminator
+		end := unsafe.Pointer(envp)
+		for *(*uint16)(end) != 0 {
+			end = unsafe.Add(end, size)
+		}
+
+		entry := unsafe.Slice(envp, (uintptr(end)-uintptr(unsafe.Pointer(envp)))/size)
+		r = append(r, UTF16ToString(entry))
+		envp = (*uint16)(unsafe.Add(end, size))
+	}
+	return r
+}

internal/lib/syscall/syscall.go

@@ -73,14 +73,6 @@ func Getwd() (string, error) {
 	return "", Errno(os.Errno)
 }
 
-func Getenv(key string) (value string, found bool) {
-	ret := os.Getenv(c.AllocaCStr(key))
-	if ret != nil {
-		return c.GoString(ret), true
-	}
-	return "", false
-}
-
 func Getpid() (pid int) {
 	return int(os.Getpid())
 }