问题描述
我有一个很难破译MSDN文档有关的来，如果读（的char []，的Int32，Int32）方法阻止或没有。我的理解是，它不应该阻止，但似乎像它当我设置RedirectStandardInput为true。
I'm having a hard time deciphering the MSDN doc about Process.StandardOutpout as to if the Read(Char[], Int32, Int32) method blocks or not. My understanding is that it shouldn't block, but it seems like it does when I set RedirectStandardInput to true.
是否有人有这方面的经验;或者我在对问题的一些解释呢？
Does anybody have experience with this; or some explanation for the issue I'm having?
这里的背景是，我不想等待一个完整的线（即带行结束符），或为进程读取标准输出之前退出。此外，我不希望使用回调。 我想读的StdOut同步的过程写吧。
The context here is that I don't want to wait for a full line (ie with a line terminator), or for the process to exit before reading standard output. Also I don't want to use callbacks. I want to read StdOut synchronously as the process writes to it.
下面是我的code的简化版本：
Here is a simplified version of my code:
string command = @"C:\flex_sdks\flex_sdk_4.5.1.21328\bin\fcsh.exe";
Process p = new Process();
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardInput = false; # <-- if I set this to true, then
# the program hangs on
# p.StandardOutput.Read later on
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.CreateNoWindow = true;
p.StartInfo.FileName = command;
p.Start();
StringBuilder sb_stdout = new StringBuilder(1024);
char[] buffer = new char[64];
int nb_bytes_read;
while (true) {
do {
nb_bytes_read = p.StandardOutput.Read(buffer, 0, buffer.Length);
sb_stdout.Append(new string(buffer, 0, nb_bytes_read));
} while (nb_bytes_read > 0);
if (sb_stdout.ToString().EndsWith("\n(fcsh) "))
break;
Thread.Sleep(20);
}
更新
根据我的（可能是坏的）假设Process.StandardOutput坏时使用：
Update
Based on my (probably bad) assumption that Process.StandardOutput is broken when used:
- 在标准输入重定向;和
- 而读别的东西比标准输出或标准错误终止线，
我决定尝试直接使用Windows的API。我说这样的code答案;它工作正常（至少目前如此）。
I decided to try using Windows' API directly. I added an answer with such code; it works fine (at least for now).
我创建了一个博客条目与code我现在用的。
I created a blog entry with the code I now use.
推荐答案
讨论这一点与本福格特后，我决定实现与不使用的System.Diagnostics.Process的进程通信。这是我想出了现在，它的伟大工程，即它每次都能正常工作，并没有什么块或挂起。
After discussing this a bit with Ben Voigt, I decided to implement communicating with the process without using System.Diagnostics.Process. This is what I came up with for now and it works great, ie it works consistently every time, and nothing blocks or hangs.
我张贴此，因为这可能会帮助任何人都需要从标准输出/标准错误读取和写入的一些创建过程标准输入，而没有的System.Diagnostics.Process做的事情。
I'm posting this as this might help anyone needing to read from stdout/stderr and to write to stdin of some created process while doing without System.Diagnostics.Process.
const UInt32 STARTF_USESTDHANDLES = 0x00000100;
const int HANDLE_FLAG_INHERIT = 1;
struct PROCESS_INFORMATION
{
public IntPtr hProcess;
public IntPtr hThread;
public uint dwProcessId;
public uint dwThreadId;
}
struct STARTUPINFO
{
public uint cb;
public string lpReserved;
public string lpDesktop;
public string lpTitle;
public uint dwX;
public uint dwY;
public uint dwXSize;
public uint dwYSize;
public uint dwXCountChars;
public uint dwYCountChars;
public uint dwFillAttribute;
public uint dwFlags;
public short wShowWindow;
public short cbReserved2;
public IntPtr lpReserved2;
public IntPtr hStdInput;
public IntPtr hStdOutput;
public IntPtr hStdError;
}
struct SECURITY_ATTRIBUTES
{
public int length;
public IntPtr lpSecurityDescriptor;
[MarshalAs(UnmanagedType.Bool)]
public bool bInheritHandle;
}
[DllImport("kernel32.dll")]
static extern bool CreateProcess(string lpApplicationName,
string lpCommandLine,
IntPtr lpProcessAttributes,
IntPtr lpThreadAttributes,
bool bInheritHandles,
uint dwCreationFlags,
IntPtr lpEnvironment,
string lpCurrentDirectory,
ref STARTUPINFO lpStartupInfo,
out PROCESS_INFORMATION lpProcessInformation);
[DllImport("kernel32.dll", SetLastError = true)]
static extern bool CloseHandle(IntPtr hObject);
[DllImport("kernel32.dll", SetLastError = true)]
static extern bool CreatePipe(out IntPtr hReadPipe,
out IntPtr hWritePipe,
ref SECURITY_ATTRIBUTES lpPipeAttributes,
uint nSize);
[DllImport("kernel32", SetLastError = true)]
static extern unsafe bool ReadFile(IntPtr hFile,
void* pBuffer,
int NumberOfBytesToRead,
int* pNumberOfBytesRead,
IntPtr lpOverlapped);
[DllImport("kernel32.dll")]
static extern unsafe bool WriteFile(IntPtr hFile,
void* pBuffer,
int nNumberOfBytesToWrite,
int* lpNumberOfBytesWritten,
IntPtr lpOverlapped);
[DllImport("kernel32.dll")]
static extern bool SetHandleInformation(IntPtr hObject, int dwMask, uint dwFlags);
void OpenAndCloseFcsh()
{
STARTUPINFO si = new STARTUPINFO();
SECURITY_ATTRIBUTES sa = new SECURITY_ATTRIBUTES();
PROCESS_INFORMATION pi = new PROCESS_INFORMATION();
sa.bInheritHandle = true;
sa.lpSecurityDescriptor = IntPtr.Zero;
sa.length = Marshal.SizeOf(typeof(SECURITY_ATTRIBUTES));
sa.lpSecurityDescriptor = IntPtr.Zero;
IntPtr h_stdout_r, h_stdout_w;
if (!CreatePipe(out h_stdout_r, out h_stdout_w, ref sa, 0))
throw new Exception("bad");
if (!SetHandleInformation(h_stdout_r, HANDLE_FLAG_INHERIT, 0))
throw new Exception("bad");
IntPtr h_stdin_r, h_stdin_w;
if (!CreatePipe(out h_stdin_r, out h_stdin_w, ref sa, 0))
throw new Exception("bad");
if (!SetHandleInformation(h_stdin_w, HANDLE_FLAG_INHERIT, 0))
throw new Exception("bad");
si.wShowWindow = 0;
si.cb = (uint)Marshal.SizeOf(si);
si.dwFlags |= STARTF_USESTDHANDLES;
si.hStdOutput = h_stdout_w;
si.hStdError = h_stdout_w;
si.hStdInput = h_stdin_r;
string command = @"C:\flex_sdks\flex_sdk_4.5.1.21328_trimmed\bin\fcsh.exe";
if (!CreateProcess(command, null, IntPtr.Zero, IntPtr.Zero, true, 0, IntPtr.Zero, null, ref si, out pi))
throw new Exception("bad");
Console.WriteLine("Process ID (PID): " + pi.dwProcessId);
Console.WriteLine("Process Handle : " + pi.hProcess);
// ****************************************************
// let's interact with our process
// first read to the prompt
Console.WriteLine("read this from fcsh.exe:\r\n" + ReadTillPrompt(h_stdout_r));
// write "help" to stdin
byte[] bytes_to_write = Encoding.UTF8.GetBytes("help\r\n");
Write(h_stdin_w, bytes_to_write, 0, bytes_to_write.Length);
// then read to the prompt again
Console.WriteLine("read this from fcsh.exe:\r\n" + ReadTillPrompt(h_stdout_r));
// write "quit" to stdin
bytes_to_write = Encoding.UTF8.GetBytes("quit\r\n");
Write(h_stdin_w, bytes_to_write, 0, bytes_to_write.Length);
// ****************************************************
if (!CloseHandle(pi.hProcess))
throw new Exception("bad");
if (!CloseHandle(pi.hThread))
throw new Exception("bad");
if (!CloseHandle(h_stdout_w))
throw new Exception("bad");
if (!CloseHandle(h_stdin_w))
throw new Exception("bad");
}
public string ReadTillPrompt(IntPtr h_stdout_r)
{
StringBuilder sb = new StringBuilder(1024);
byte[] buffer = new byte[128];
int nb_bytes_read;
while (true) {
nb_bytes_read = Read(h_stdout_r, buffer, 0, buffer.Length);
sb.Append(Encoding.UTF8.GetString(buffer, 0, nb_bytes_read));
if (sb.ToString().EndsWith("\n(fcsh) "))
break;
Thread.Sleep(20);
}
return sb.ToString();
}
public unsafe int Read(IntPtr h, byte[] buffer, int index, int count)
{
int n = 0;
fixed (byte* p = buffer) {
if (!ReadFile(h, p + index, count, &n, IntPtr.Zero))
throw new Exception("bad");
}
return n;
}
public unsafe int Write(IntPtr h, byte[] buffer, int index, int count)
{
int n = 0;
fixed (byte* p = buffer) {
if (!WriteFile(h, p + index, count, &n, IntPtr.Zero))
throw new Exception("bad");
}
return n;
}
这篇关于为什么StandardOutput.Read（）块时StartInfo.RedirectStandardInput设置为true？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！