字符串到 char (*array)[]

Question

//file.go

func main() {

  message := "My Message :)"
  // I've tried this slice before.
  // tmpslice := (*[1 << 30]*C.char)(unsafe.Pointer(argv))[:length:length] 
  argv := make([]*C.char, len(message))
  for i, s := range str {
    cs := C.CString(string(s))
    defer C.free(unsafe.Pointer(cs))
    argv[i] = cs
  }

  C.notifyWebhook(&argv)

}

  //file.c
  void notiftWebhook(char (*message)[]) {
  printf("notiftWebhook executed | argv: %s \n", *message);
  char url[500];
  char data[200];


  int user_id = 0xdeadfeed;

  snprintf(url,500,"https://webhook.site/a6a8d1ae-6766-4d90-a4c8-87a9599bfbf0",token);
  snprintf(data,200,"user_id=%d&text=%s",user_id,*message);
  CURL *curl;
  //CURLcode res;

  //static const char *postthis = "moo mooo moo moo";

  curl_global_init(CURL_GLOBAL_ALL);
  curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, url);
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS,data);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
    curl_easy_perform(curl);
  }
  curl_global_cleanup();
}

编译器返回：

cgo-gcc-prolog:129:19: error: array size is negative

我编写了一个 webhook 函数，但触发了 notifyWebhook 函数并发送了错误的参数。为什么？我在哪里犯错？

Answer 1

string to char (*array)[]
cgo-gcc-prolog: error: array size is negative

使用垫片。例如，

so.go:

// string to char (*array)[]

package main

/*
#include <stdlib.h>
#include <stdio.h>

void notify(char (*message)[]) {
    printf("notify | argv: %1$p %1$s\n", *message);
}

void shimmy(char *message[]) {
    printf("shimmy | argv: %1$p %1$s\n", *message);
    notify((char (*)[])*message);
}
*/
import "C"

import (
    "fmt"
    "unsafe"
)

func main() {
    message := "My Message :)"
    cs := C.CString(message)
    defer C.free(unsafe.Pointer(cs))
    fmt.Printf("main   | argv: %p %s\n", cs, C.GoString(cs))
    C.shimmy(&cs)
}

输出：

$ go run so.go
main   | argv: 0x19cb820 My Message :)
shimmy | argv: 0x19cb820 My Message :)
notify | argv: 0x19cb820 My Message :)
$ 

$ go version
go version devel +4d5bb9c609 Fri Dec 20 23:07:52 2019 +0000 linux/amd64
$ go env CC
gcc
$ gcc --version
gcc (Ubuntu 9.2.1-9ubuntu2) 9.2.1 20191008
$

字符串到 char (*array)[]

string to char (*array)[]

go

cgo

gccgo