英文:
How to cast bytes to struct(c struct) in go?
问题
package main
/*
#define _GNU_SOURCE 1
#include <stdio.h>
#include <stdlib.h>
#include <utmpx.h>
#include <fcntl.h>
#include <unistd.h>
char *path_utmpx = _PATH_UTMPX;
typedef struct utmpx utmpx;
*/
import "C"
import (
"fmt"
"io/ioutil"
)
type Record C.utmpx
func main() {
path := C.GoString(C.path_utmpx)
content, err := ioutil.ReadFile(path)
handleError(err)
var records []Record
// 现在我们有了字节(content)和结构体(Record/C.utmpx)
// 我们如何将字节转换为结构体？
}
func handleError(err error) {
if err != nil {
panic("bad")
}
}
我正在尝试将content读入Record中。
我已经提出了一些相关的问题。
https://stackoverflow.com/q/44036358/5819540
https://stackoverflow.com/q/45300938/5819540
我已经阅读了一些文章和帖子，但仍然无法找到解决方法。
英文:
package main
/*
#define _GNU_SOURCE 1
#include <stdio.h>
#include <stdlib.h>
#include <utmpx.h>
#include <fcntl.h>
#include <unistd.h>
char *path_utmpx = _PATH_UTMPX;
typedef struct utmpx utmpx;
*/
import "C"
import (
"fmt"
"io/ioutil"
)
type Record C.utmpx
func main() {
path := C.GoString(C.path_utmpx)
content, err := ioutil.ReadFile(path)
handleError(err)
var records []Record
// now we have the bytes(content), the struct(Record/C.utmpx)
// how can I cast bytes to struct ?
}
func handleError(err error) {
if err != nil {
panic("bad")
}
}
I'm trying to read content into Record
I have asked a few related questions.
https://stackoverflow.com/q/44036358/5819540
https://stackoverflow.com/q/45300938/5819540
I have read some articles and posts but still cannot figure out a way to do this.
答案1
得分: 1
我认为你的方法不对。如果你想使用C库，你应该使用C库来读取文件。
不要仅仅为了有结构定义而使用cgo，你应该自己在Go中创建这些结构。然后，你可以编写适当的编组/解组代码来从原始字节中读取。
快速搜索显示，有人已经完成了将相关的C库转换为Go所需的工作。请参考utmp存储库。
以下是如何使用的简短示例：
package main
import (
"bytes"
"fmt"
"log"
"github.com/ericlagergren/go-gnulib/utmp"
)
func handleError(err error) {
if err != nil {
log.Fatal(err)
}
}
func byteToStr(b []byte) string {
i := bytes.IndexByte(b, 0)
if i == -1 {
i = len(b)
}
return string(b[:i])
}
func main() {
list, err := utmp.ReadUtmp(utmp.UtmpxFile, 0)
handleError(err)
for _, u := range list {
fmt.Println(byteToStr(u.User[:]))
}
}
你可以查看utmp包的GoDoc获取更多信息。
英文:
I think you're going about this the wrong way. If you were wanting to use the C library, you would use the C library to read the file.
Don't use cgo purely to have struct definitions, you should create these in Go yourself. You could then write the appropriate marshal / unmarshal code to read from the raw bytes.
A quick Google shows that someone has already done the work required to convert a look of the relevant C library to Go. See the utmp repository.
A short example of how this could be used is:
package main
import (
"bytes"
"fmt"
"log"
"github.com/ericlagergren/go-gnulib/utmp"
)
func handleError(err error) {
if err != nil {
log.Fatal(err)
}
}
func byteToStr(b []byte) string {
i := bytes.IndexByte(b, 0)
if i == -1 {
i = len(b)
}
return string(b[:i])
}
func main() {
list, err := utmp.ReadUtmp(utmp.UtmpxFile, 0)
handleError(err)
for _, u := range list {
fmt.Println(byteToStr(u.User[:]))
}
}
You can view the GoDoc for the utmp package for more information.
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论