C++ WInApi ReadFile reads nothing and reports error 109 ERROR_BROKEN_PIPE

I have been trying to call adb from a C++ app and read its output, without success. adb is present on PATH.

The ReadFile call never reads anything, even if I wait.

GetLastError() returns 109 ERROR_BROKEN_PIPE.

I have tried all the solutions proposed in all existing StackOverflow questions on this matter, without any success.

Even trying to capture output from cmd /c echo Hello World doesn't work.

Code:

#include <array>
#include <string>
#include <windows.h>
int main() {
std::string adbConnectCommand = "adb connect localhost:5555";
STARTUPINFO startupInfo;
SECURITY_ATTRIBUTES secAttr;
PROCESS_INFORMATION procInfo;
HANDLE stdoutReadHandle = NULL;
HANDLE stdoutWriteHandle = NULL;
ZeroMemory(&secAttr, sizeof(secAttr));
secAttr.nLength = sizeof(SECURITY_ATTRIBUTES);
secAttr.bInheritHandle = TRUE;
secAttr.lpSecurityDescriptor = NULL;
// Create a pipe for the child process's STDOUT
if (!CreatePipe(&stdoutReadHandle, &stdoutWriteHandle, &secAttr, 0))
return 2; // error
// Ensure the read handle to the pipe for STDOUT is not inherited
if (!SetHandleInformation(stdoutReadHandle, HANDLE_FLAG_INHERIT, 0))
return 2; // error
ZeroMemory(&startupInfo, sizeof(startupInfo));
startupInfo.cb = sizeof(startupInfo);
startupInfo.hStdError = &stdoutWriteHandle;
startupInfo.hStdOutput = &stdoutWriteHandle;
startupInfo.dwFlags |= STARTF_USESTDHANDLES;
ZeroMemory(&procInfo, sizeof(procInfo));
// Start the child process
if (CreateProcessA(NULL,                // No module name (use command line)
(TCHAR*)adbConnectCommand.c_str(),  // Command line
NULL,                               // Process handle not inheritable
NULL,                               // Thread handle not inheritable
TRUE,                               // Set handle inheritance
0,                                  // No creation flags
NULL,                               // Use parent's environment block
NULL,                               // Use parent's starting directory 
&startupInfo,                       // Pointer to STARTUPINFO structure
&procInfo)                          // Pointer to PROCESS_INFORMATION structure
)
{
// Close the handles we don't need so we can read from stdoutReadHandle
CloseHandle(procInfo.hProcess);
CloseHandle(procInfo.hThread);
CloseHandle(stdoutWriteHandle);
std::array<char, 512> buffer;
std::string adbConnectOutput;
while(ReadFile(stdoutReadHandle, buffer.data(), buffer.size(), NULL, NULL))
adbConnectOutput += buffer.data();
CloseHandle(stdoutReadHandle);
if (adbConnectOutput.find("connected to localhost:5555") == std::string::npos)
return 1; // not found
m_Connected = true;
return 0; // success
}
return 2; // error
}
</details>
# 答案1
**得分**: 4
在这段代码中：
```c++
startupInfo.hStdError = &stdoutWriteHandle;
startupInfo.hStdOutput = &stdoutWriteHandle;

HANDLE 被定义为 void*，因此任何指针都可以赋值给它。但并不是每个指针都是有效的 HANDLE 值。在这种情况下，stdoutWriteHandle 是一个 HANDLE 变量，可以直接赋值给 hStdError 和 hStdOutput，所以你需要去掉 &，因为它们不应该出现在这里，例如：

startupInfo.hStdError = stdoutWriteHandle;
startupInfo.hStdOutput = stdoutWriteHandle;

另外，你的代码还存在其他问题。

在这段代码中：

// Start the child process
if (CreateProcessA(NULL,                // No module name (use command line)
    (TCHAR*)adbConnectCommand.c_str(),  // Command line
    ...

这里的类型转换 TCHAR* 是错误的。CreateProcessA() 期望的是 LPSTR（也就是 char*），但是 TCHAR* 可能是 char*，也可能不是，这取决于你的项目配置。所以应该使用正确的类型，例如：

CreateProcessA(NULL,
    (LPSTR)adbConnectCommand.c_str(),
    ...

然而，你应该使用 C++ 风格的 const_cast 而不是 C 风格的转换，例如：

CreateProcessA(NULL,
    const_cast<LPSTR>(adbConnectCommand.c_str()),
    ...

或者，使用 std::string::data()（C++17 及更高版本）或 std::string::operator[]，例如：

CreateProcessA(NULL,
    adbConnectCommand.data(),
    ...

CreateProcessA(NULL,
    &adbConnectCommand[0],
    ...

在这段代码中：

while(ReadFile(stdoutReadHandle, buffer.data(), buffer.size(), NULL, NULL))
    adbConnectOutput += buffer.data();

ReadFile() 写入到缓冲区的数据没有以空字符结尾，但是你却将一个以空字符结尾的 char* 指针追加到输出的 std::string 中。你需要注意 ReadFile() 实际报告给你的大小，特别是因为它不需要空字符结尾，并且可能比你请求的大小小，例如：

std::array<char, 512> buffer;
std::string adbConnectOutput;
DWORD dwNumRead;

while (ReadFile(stdoutReadHandle, buffer.data(), buffer.size(), &dwNumRead, NULL))
    adbConnectOutput.append(buffer.data(), dwNumRead);

startupInfo.hStdError = stdoutWriteHandle;
startupInfo.hStdOutput = stdoutWriteHandle;

CreateProcessA(NULL,
(LPSTR)adbConnectCommand.c_str(),
...

CreateProcessA(NULL,
const_cast<LPSTR>(adbConnectCommand.c_str()),
...

CreateProcessA(NULL,
adbConnectCommand.data(),
...

CreateProcessA(NULL,
&adbConnectCommand[0],
...

std::array<char, 512> buffer;
std::string adbConnectOutput;
DWORD dwNumRead;
while (ReadFile(stdoutReadHandle, buffer.data(), buffer.size(), &dwNumRead, NULL))
adbConnectOutput.append(buffer.data(), dwNumRead);