// Copyright 2019 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.

// +build ignore

/*

This program reads a file containing function prototypes

(like syscall_aix.go) and generates system call bodies.

The prototypes are marked by lines beginning with "//sys"

and read like func declarations if //sys is replaced by func, but:

	* The parameter lists must give a name for each argument.

	  This includes return parameters.

	* The parameter lists must give a type for each argument:

	  the (x, y, z int) shorthand is not allowed.

	* If the return parameter is an error number, it must be named err.

	* If go func name needs to be different than its libc name,

	* or the function is not in libc, name could be specified

	* at the end, after "=" sign, like

	  //sys getsockopt(s int, level int, name int, val uintptr, vallen *_Socklen) (err error) = libsocket.getsockopt

*/

package main

import (

	"bufio"

	"flag"

	"fmt"

	"os"

	"regexp"

	"strings"

)

var (

	b32  = flag.Bool("b32", false, "32bit big-endian")

	l32  = flag.Bool("l32", false, "32bit little-endian")

	aix  = flag.Bool("aix", false, "aix")

	tags = flag.String("tags", "", "build tags")

)

// cmdLine returns this programs's commandline arguments

func cmdLine() string {

	return "go run mksyscall_aix_ppc.go " + strings.Join(os.Args[1:], " ")

}

// buildTags returns build tags

func buildTags() string {

	return *tags

}

// Param is function parameter

type Param struct {

	Name string

	Type string

}

// usage prints the program usage

func usage() {

	fmt.Fprintf(os.Stderr, "usage: go run mksyscall_aix_ppc.go [-b32 | -l32] [-tags x,y] [file ...]\n")

	os.Exit(1)

}

// parseParamList parses parameter list and returns a slice of parameters

func parseParamList(list string) []string {

	list = strings.TrimSpace(list)

	if list == "" {

		return []string{}

	}

	return regexp.MustCompile(`\s*,\s*`).Split(list, -1)

}

// parseParam splits a parameter into name and type

func parseParam(p string) Param {

	ps := regexp.MustCompile(`^(\S*) (\S*)$`).FindStringSubmatch(p)

	if ps == nil {

		fmt.Fprintf(os.Stderr, "malformed parameter: %s\n", p)

		os.Exit(1)

	}

	return Param{ps[1], ps[2]}

}

func main() {

	flag.Usage = usage

	flag.Parse()

	if len(flag.Args()) <= 0 {

		fmt.Fprintf(os.Stderr, "no files to parse provided\n")

		usage()

	}

	endianness := ""

	if *b32 {

		endianness = "big-endian"

	} else if *l32 {

		endianness = "little-endian"

	}

	pack := ""

	text := ""

	cExtern := "/*\n#include <stdint.h>\n#include <stddef.h>\n"

	for _, path := range flag.Args() {

		file, err := os.Open(path)

		if err != nil {

			fmt.Fprintf(os.Stderr, err.Error())

			os.Exit(1)

		}

		s := bufio.NewScanner(file)

		for s.Scan() {

			t := s.Text()

			t = strings.TrimSpace(t)

			t = regexp.MustCompile(`\s+`).ReplaceAllString(t, ` `)

			if p := regexp.MustCompile(`^package (\S+)$`).FindStringSubmatch(t); p != nil && pack == "" {

				pack = p[1]

			}

			nonblock := regexp.MustCompile(`^\/\/sysnb `).FindStringSubmatch(t)

			if regexp.MustCompile(`^\/\/sys `).FindStringSubmatch(t) == nil && nonblock == nil {

				continue

			}

			// Line must be of the form

			//	func Open(path string, mode int, perm int) (fd int, err error)

			// Split into name, in params, out params.

			f := regexp.MustCompile(`^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*(?:(\w*)\.)?(\w*))?$`).FindStringSubmatch(t)

			if f == nil {

				fmt.Fprintf(os.Stderr, "%s:%s\nmalformed //sys declaration\n", path, t)

				os.Exit(1)

			}

			funct, inps, outps, modname, sysname := f[2], f[3], f[4], f[5], f[6]

			// Split argument lists on comma.

			in := parseParamList(inps)

			out := parseParamList(outps)

			inps = strings.Join(in, ", ")

			outps = strings.Join(out, ", ")

			// Try in vain to keep people from editing this file.

			// The theory is that they jump into the middle of the file

			// without reading the header.

			text += "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n"

			// Check if value return, err return available

			errvar := ""

			retvar := ""

			rettype := ""

			for _, param := range out {

				p := parseParam(param)

				if p.Type == "error" {

					errvar = p.Name

				} else {

					retvar = p.Name

					rettype = p.Type

				}

			}

			// System call name.

			if sysname == "" {

				sysname = funct

			}

			sysname = regexp.MustCompile(`([a-z])([A-Z])`).ReplaceAllString(sysname, `${1}_$2`)

			sysname = strings.ToLower(sysname) // All libc functions are lowercase.

			cRettype := ""

			if rettype == "unsafe.Pointer" {

				cRettype = "uintptr_t"

			} else if rettype == "uintptr" {

				cRettype = "uintptr_t"

			} else if regexp.MustCompile(`^_`).FindStringSubmatch(rettype) != nil {

				cRettype = "uintptr_t"

			} else if rettype == "int" {

				cRettype = "int"

			} else if rettype == "int32" {

				cRettype = "int"

			} else if rettype == "int64" {

				cRettype = "long long"

			} else if rettype == "uint32" {

				cRettype = "unsigned int"

			} else if rettype == "uint64" {

				cRettype = "unsigned long long"

			} else {

				cRettype = "int"

			}

			if sysname == "exit" {

				cRettype = "void"

			}

			// Change p.Types to c

			var cIn []string

			for _, param := range in {

				p := parseParam(param)

				if regexp.MustCompile(`^\*`).FindStringSubmatch(p.Type) != nil {

					cIn = append(cIn, "uintptr_t")

				} else if p.Type == "string" {

					cIn = append(cIn, "uintptr_t")

				} else if regexp.MustCompile(`^\[\](.*)`).FindStringSubmatch(p.Type) != nil {

					cIn = append(cIn, "uintptr_t", "size_t")

				} else if p.Type == "unsafe.Pointer" {

					cIn = append(cIn, "uintptr_t")

				} else if p.Type == "uintptr" {

					cIn = append(cIn, "uintptr_t")

				} else if regexp.MustCompile(`^_`).FindStringSubmatch(p.Type) != nil {

					cIn = append(cIn, "uintptr_t")

				} else if p.Type == "int" {

					cIn = append(cIn, "int")

				} else if p.Type == "int32" {

					cIn = append(cIn, "int")

				} else if p.Type == "int64" {

					cIn = append(cIn, "long long")

				} else if p.Type == "uint32" {

					cIn = append(cIn, "unsigned int")

				} else if p.Type == "uint64" {

					cIn = append(cIn, "unsigned long long")

				} else {

					cIn = append(cIn, "int")

				}

			}

			if funct != "fcntl" && funct != "FcntlInt" && funct != "readlen" && funct != "writelen" {

				if sysname == "select" {

					// select is a keyword of Go. Its name is

					// changed to c_select.

					cExtern += "#define c_select select\n"

				}

				// Imports of system calls from libc

				cExtern += fmt.Sprintf("%s %s", cRettype, sysname)

				cIn := strings.Join(cIn, ", ")

				cExtern += fmt.Sprintf("(%s);\n", cIn)

			}

			// So file name.

			if *aix {

				if modname == "" {

					modname = "libc.a/shr_64.o"

				} else {

					fmt.Fprintf(os.Stderr, "%s: only syscall using libc are available\n", funct)

					os.Exit(1)

				}

			}

			strconvfunc := "C.CString"

			// Go function header.

			if outps != "" {

				outps = fmt.Sprintf(" (%s)", outps)

			}

			if text != "" {

				text += "\n"

			}

			text += fmt.Sprintf("func %s(%s)%s {\n", funct, strings.Join(in, ", "), outps)

			// Prepare arguments to Syscall.

			var args []string

			n := 0

			argN := 0

			for _, param := range in {

				p := parseParam(param)

				if regexp.MustCompile(`^\*`).FindStringSubmatch(p.Type) != nil {

					args = append(args, "C.uintptr_t(uintptr(unsafe.Pointer("+p.Name+")))")

				} else if p.Type == "string" && errvar != "" {

					text += fmt.Sprintf("\t_p%d := uintptr(unsafe.Pointer(%s(%s)))\n", n, strconvfunc, p.Name)

					args = append(args, fmt.Sprintf("C.uintptr_t(_p%d)", n))

					n++

				} else if p.Type == "string" {

					fmt.Fprintf(os.Stderr, path+":"+funct+" uses string arguments, but has no error return\n")

					text += fmt.Sprintf("\t_p%d := uintptr(unsafe.Pointer(%s(%s)))\n", n, strconvfunc, p.Name)

					args = append(args, fmt.Sprintf("C.uintptr_t(_p%d)", n))

					n++

				} else if m := regexp.MustCompile(`^\[\](.*)`).FindStringSubmatch(p.Type); m != nil {

					// Convert slice into pointer, length.

					// Have to be careful not to take address of &a[0] if len == 0:

					// pass nil in that case.

					text += fmt.Sprintf("\tvar _p%d *%s\n", n, m[1])

					text += fmt.Sprintf("\tif len(%s) > 0 {\n\t\t_p%d = &%s[0]\n\t}\n", p.Name, n, p.Name)

					args = append(args, fmt.Sprintf("C.uintptr_t(uintptr(unsafe.Pointer(_p%d)))", n))

					n++

					text += fmt.Sprintf("\tvar _p%d int\n", n)

					text += fmt.Sprintf("\t_p%d = len(%s)\n", n, p.Name)

					args = append(args, fmt.Sprintf("C.size_t(_p%d)", n))

					n++

				} else if p.Type == "int64" && endianness != "" {

					if endianness == "big-endian" {

						args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name))

					} else {

						args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name))

					}

					n++

				} else if p.Type == "bool" {

					text += fmt.Sprintf("\tvar _p%d uint32\n", n)

					text += fmt.Sprintf("\tif %s {\n\t\t_p%d = 1\n\t} else {\n\t\t_p%d = 0\n\t}\n", p.Name, n, n)

					args = append(args, fmt.Sprintf("_p%d", n))

				} else if regexp.MustCompile(`^_`).FindStringSubmatch(p.Type) != nil {

					args = append(args, fmt.Sprintf("C.uintptr_t(uintptr(%s))", p.Name))

				} else if p.Type == "unsafe.Pointer" {

					args = append(args, fmt.Sprintf("C.uintptr_t(uintptr(%s))", p.Name))

				} else if p.Type == "int" {

					if (argN == 2) && ((funct == "readlen") || (funct == "writelen")) {

						args = append(args, fmt.Sprintf("C.size_t(%s)", p.Name))

					} else if argN == 0 && funct == "fcntl" {

						args = append(args, fmt.Sprintf("C.uintptr_t(%s)", p.Name))

					} else if (argN == 2) && ((funct == "fcntl") || (funct == "FcntlInt")) {

						args = append(args, fmt.Sprintf("C.uintptr_t(%s)", p.Name))

					} else {

						args = append(args, fmt.Sprintf("C.int(%s)", p.Name))

					}

				} else if p.Type == "int32" {

					args = append(args, fmt.Sprintf("C.int(%s)", p.Name))

				} else if p.Type == "int64" {

					args = append(args, fmt.Sprintf("C.longlong(%s)", p.Name))

				} else if p.Type == "uint32" {

					args = append(args, fmt.Sprintf("C.uint(%s)", p.Name))

				} else if p.Type == "uint64" {

					args = append(args, fmt.Sprintf("C.ulonglong(%s)", p.Name))

				} else if p.Type == "uintptr" {

					args = append(args, fmt.Sprintf("C.uintptr_t(%s)", p.Name))

				} else {

					args = append(args, fmt.Sprintf("C.int(%s)", p.Name))

				}

				argN++

			}

			// Actual call.

			arglist := strings.Join(args, ", ")

			call := ""

			if sysname == "exit" {

				if errvar != "" {

					call += "er :="

				} else {

					call += ""

				}

			} else if errvar != "" {

				call += "r0,er :="

			} else if retvar != "" {

				call += "r0,_ :="

			} else {

				call += ""

			}

			if sysname == "select" {

				// select is a keyword of Go. Its name is

				// changed to c_select.

				call += fmt.Sprintf("C.c_%s(%s)", sysname, arglist)

			} else {

				call += fmt.Sprintf("C.%s(%s)", sysname, arglist)

			}

			// Assign return values.

			body := ""

			for i := 0; i < len(out); i++ {

				p := parseParam(out[i])

				reg := ""

				if p.Name == "err" {

					reg = "e1"

				} else {

					reg = "r0"

				}

				if reg != "e1" {

					body += fmt.Sprintf("\t%s = %s(%s)\n", p.Name, p.Type, reg)

				}

			}

			// verify return

			if sysname != "exit" && errvar != "" {

				if regexp.MustCompile(`^uintptr`).FindStringSubmatch(cRettype) != nil {

					body += "\tif (uintptr(r0) ==^uintptr(0) && er != nil) {\n"

					body += fmt.Sprintf("\t\t%s = er\n", errvar)

					body += "\t}\n"

				} else {

					body += "\tif (r0 ==-1 && er != nil) {\n"

					body += fmt.Sprintf("\t\t%s = er\n", errvar)

					body += "\t}\n"

				}

			} else if errvar != "" {

				body += "\tif (er != nil) {\n"

				body += fmt.Sprintf("\t\t%s = er\n", errvar)

				body += "\t}\n"

			}

			text += fmt.Sprintf("\t%s\n", call)

			text += body

			text += "\treturn\n"

			text += "}\n"

		}

		if err := s.Err(); err != nil {

			fmt.Fprintf(os.Stderr, err.Error())

			os.Exit(1)

		}

		file.Close()

	}

	imp := ""

	if pack != "unix" {

		imp = "import \"golang.org/x/sys/unix\"\n"

	}

	fmt.Printf(srcTemplate, cmdLine(), buildTags(), pack, cExtern, imp, text)

}

const srcTemplate = `// %s

// Code generated by the command above; see README.md. DO NOT EDIT.

// +build %s

package %s

%s

*/

import "C"

import (

	"unsafe"

)

%s

%s

`