make runtime compatible with wasm

runtime/internal/clite/syscall/env_unix.go

@@ -0,0 +1,69 @@
+package syscall
+
+import (
+	"sync"
+	_ "unsafe"
+
+	c "github.com/goplus/llgo/runtime/internal/clite"
+)
+
+var (
+	envOnce sync.Once
+	envLock sync.RWMutex
+	env     map[string]int
+	envs    []string
+)
+
+//go:linkname c_environ environ
+var c_environ **c.Char
+
+//go:linkname c_getenv C.getenv
+func c_getenv(name *c.Char) *c.Char
+
+func copyenv() {
+	env = make(map[string]int)
+	p := c_environ
+	i := 0
+	for p != nil {
+		s := c.GoString(*p)
+		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
+			}
+		}
+		p = c.Advance(p, 1)
+		i++
+	}
+}
+
+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
+}