FF插件：如何在JavaScript中声明的C函数与fgets

问题描述

我正在开发的Firefox插件，我想用WINAPI读取文件。
我设法与WINAPI连接并正常工作。

I'm developing firefox plugin and I want to read file using WinApi.I manage to connect with WinApi and it works fine.

var lib = ctypes.open("user32.dll");
var msgBox = lib.declare("MessageBoxW",
                       ctypes.winapi_abi,
                       ctypes.int32_t,
                       ctypes.int32_t,
                       ctypes.jschar.ptr,
                       ctypes.jschar.ptr,
                       ctypes.int32_t);
var MB_OK = 0;
var ret = msgBox(0, "Hello world", "title", MB_OK);

现在我宣布的fopen ：

const FILE = new ctypes.StructType("FILE").ptr;
var fopen = libc.declare("fopen",                     // symbol name
                        ctypes.default_abi,           // cdecl calling convention
                        FILE,                         // return type (FILE*)
                        ctypes.char.ptr,              // first arg (const char*)
                        ctypes.char.ptr);             // second arg (const char*)

但我不声明与fgets 。我仍然无法弄清楚。我尝试做的：

but I fail to declare fgets. I still can't figure it out. I try to do:

var libc = ctypes.open("msvcrt.dll");
var fgets = libc.declare("fgets",
                        ctypes.default_abi,
                        ctypes.char.ptr,
                        ctypes.char.ptr,
                        ctypes.int32_t,
                        FILE);
// Call the function, and get a FILE* pointer object back.
console.log(LOG_FILTER, "Try to open file.");
var file1 = fopen("1.in", "r");

  var SIZE = 100;
  var line = ctypes.char(SIZE).ptr;
  line = fgets(line, SIZE, file1);`

我想我不要用错库，因为那时我会得到错误错误：在库中找不到函数符号，但我仍然得到类型错误：预期类型的​​指针，得到（无效0）

I think I don't use wrong library because then I would get error "Error: couldn't find function symbol in library" but I still get "TypeError: expected type pointer, got (void 0)"

推荐答案

因此​​，这里是我的解决方案。我决定用 GETC 函数代替与fgets 我设法读取文件。

So here is my solution. I decided to use getc function instead of fgets and I manage to read file.

Components.utils.import("resource://gre/modules/ctypes.jsm");
var libc = ctypes.open("msvcrt.dll");

// int getc(FILE *stream);
var getc = libc.declare("getc",
                        ctypes.default_abi,
                        ctypes.int32_t,
                        FILE);
var file = fopen("newfile.in", "w");
var readFile = readFileToString(file)

function readFileToString(file) {
  var result = '';
  var c = 0;
  while((c = getc(file)) != -1) {
    result += String.fromCharCode(c);
  }
  console.log("result = " + result);
  return result;
}

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