C.GoString()仅返回首字符：Python调用Go c-shared库字符串传参异常

Python3 的 ctypes 库做跨语言调用时，默认会将 Python 原生的 str 类型转换为宽字符指针 c_wchar_p，每个字符占用2字节（小端序存储下ASCII字符的高位为0值）。而Go侧定义的入参是单字节的C字符串指针 *C.char，读取字符串时会以第一个0值作为结束标识，因此只能识别到第一个有效字符。

你只需要在Python侧显式指定函数的参数类型，并将传入的字符串编码为UTF-8字节格式即可：

import ctypes
from ctypes import cdll, c_char_p, c_void_p

website = "https://draftss.com"
domain = "draftss.com"
website_ip = "23.xxx.xxx.xxx"

website_tech_finder_lib = cdll.LoadLibrary("website_tech_finder/builds/websiteTechFinder.so")

# 1. 显式声明函数的参数类型和返回值类型
website_tech_finder_lib.FetchAllData.argtypes = [c_char_p, c_char_p, c_char_p]
website_tech_finder_lib.FetchAllData.restype = c_char_p

# 2. 字符串编码为utf-8字节后传入
result_json_bytes = website_tech_finder_lib.FetchAllData(
    website.encode('utf-8'),
    domain.encode('utf-8'),
    website_ip.encode('utf-8')
)

# 将返回的C字节串转为Python字符串
result_json_string = result_json_bytes.decode('utf-8')

• Go侧通过C.CString创建的返回值字符串内存不属于Go的GC管理范围，你需要额外导出一个释放内存的Go函数，在Python侧使用完返回值后调用释放，避免内存泄漏：

  //export FreeMemory
  func FreeMemory(p *C.char) {
      C.free(unsafe.Pointer(p))
  }
  

  Python侧使用完返回值后调用：

  website_tech_finder_lib.FreeMemory.argtypes = [c_void_p]
  website_tech_finder_lib.FreeMemory(result_json_bytes)
  

内容的提问来源于stack exchange，提问作者Arun Nair