syscall: allow for mksyscall_windows.go to be used outside of syscall

Fixes #8398.

LGTM=chines
R=golang-codereviews, chines, josharian
CC=golang-codereviews
https://golang.org/cl/114140043

diff --git a/src/pkg/syscall/mksyscall_windows.go b/src/pkg/syscall/mksyscall_windows.go
index 4225588de7126e6115e15dde4cce48f54b70029b..3b483ec87aa10cc887a5df6e646acc42588f61f7 100644 (file)
--- a/src/pkg/syscall/mksyscall_windows.go
+++ b/src/pkg/syscall/mksyscall_windows.go
@@ -47,6 +47,8 @@ import (
        "errors"
        "flag"
        "fmt"
+       "go/parser"
+       "go/token"
        "io"
        "log"
        "os"
@@ -61,6 +63,19 @@ func trim(s string) string {
        return strings.Trim(s, " \t")
 }
 
+var packageName string
+
+func packagename() string {
+       return packageName
+}
+
+func syscalldot() string {
+       if packageName == "syscall" {
+               return ""
+       }
+       return "syscall."
+}
+
 // Param is function parameter
 type Param struct {
        Name      string
@@ -243,20 +258,20 @@ func (r *Rets) useLongHandleErrorCode(retvar string) string {
                if e1 != 0 {
                        err = error(e1)
                } else {
-                       err = EINVAL
+                       err = %sEINVAL
                }
        }`
        cond := retvar + " == 0"
        if r.FailCond != "" {
                cond = strings.Replace(r.FailCond, "failretval", retvar, 1)
        }
-       return fmt.Sprintf(code, cond)
+       return fmt.Sprintf(code, cond, syscalldot())
 }
 
 // SetErrorCode returns source code that sets return parameters.
 func (r *Rets) SetErrorCode() string {
        const code = `if r0 != 0 {
-               %s = Errno(r0)
+               %s = %sErrno(r0)
        }`
        if r.Name == "" && !r.ReturnsError {
                return ""
@@ -265,7 +280,7 @@ func (r *Rets) SetErrorCode() string {
                return r.useLongHandleErrorCode("r1")
        }
        if r.Type == "error" {
-               return fmt.Sprintf(code, r.Name)
+               return fmt.Sprintf(code, r.Name, syscalldot())
        }
        s := ""
        if r.Type[0] == '*' {
@@ -475,9 +490,9 @@ func (f *Fn) SyscallParamCount() int {
 func (f *Fn) Syscall() string {
        c := f.SyscallParamCount()
        if c == 3 {
-               return "Syscall"
+               return syscalldot() + "Syscall"
        }
-       return "Syscall" + strconv.Itoa(c)
+       return syscalldot() + "Syscall" + strconv.Itoa(c)
 }
 
 // SyscallParamList returns source code for SyscallX parameters for function f.
@@ -502,9 +517,9 @@ func (f *Fn) IsUTF16() bool {
 // StrconvFunc returns name of Go string to OS string function for f.
 func (f *Fn) StrconvFunc() string {
        if f.IsUTF16() {
-               return "UTF16PtrFromString"
+               return syscalldot() + "UTF16PtrFromString"
        }
-       return "BytePtrFromString"
+       return syscalldot() + "BytePtrFromString"
 }
 
 // StrconvType returns Go type name used for OS string for f.
@@ -582,12 +597,29 @@ func (src *Source) ParseFile(path string) error {
                return err
        }
        src.Files = append(src.Files, path)
+
+       // get package name
+       fset := token.NewFileSet()
+       _, err = file.Seek(0, 0)
+       if err != nil {
+               return err
+       }
+       pkg, err := parser.ParseFile(fset, "", file, parser.PackageClauseOnly)
+       if err != nil {
+               return err
+       }
+       packageName = pkg.Name.Name
+
        return nil
 }
 
 // Generate output source file from a source set src.
 func (src *Source) Generate(w io.Writer) error {
-       t := template.Must(template.New("main").Parse(srcTemplate))
+       funcMap := template.FuncMap{
+               "syscalldot":  syscalldot,
+               "packagename": packagename,
+       }
+       t := template.Must(template.New("main").Funcs(funcMap).Parse(srcTemplate))
        err := t.Execute(w, src)
        if err != nil {
                return errors.New("Failed to execute template: " + err.Error())
@@ -623,9 +655,10 @@ const srcTemplate = `
 {{define "main"}}// go build mksyscall_windows.go && ./mksyscall_windows{{range .Files}} {{.}}{{end}}
 // MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
 
-package syscall
+package {{packagename}}
 
-import "unsafe"
+import "unsafe"{{if syscalldot}}
+import "syscall"{{end}}
 
 var (
 {{template "dlls" .}}
@@ -635,7 +668,7 @@ var (
 
 {{/* help functions */}}
 
-{{define "dlls"}}{{range .DLLs}}       mod{{.}} = NewLazyDLL("{{.}}.dll")
+{{define "dlls"}}{{range .DLLs}}       mod{{.}} = {{syscalldot}}NewLazyDLL("{{.}}.dll")
 {{end}}{{end}}
 
 {{define "funcnames"}}{{range .Funcs}} proc{{.DLLFuncName}} = mod{{.DLLName}}.NewProc("{{.DLLFuncName}}")