ENH: Windows implementation of process pipeline.

Process.h.in

@@ -89,10 +89,21 @@ kwsysEXPORT void kwsysProcess_Delete(kwsysProcess* cp);
 /**
  * Set the command line to be executed.  Argument is an array of
  * pointers to the command and each argument.  Ths array must end with
- * a NULL pointer.
+ * a NULL pointer.  Any previous command lines are removed.  Returns
+ * 1 for success and 0 otherwise.
  */
-kwsysEXPORT void kwsysProcess_SetCommand(kwsysProcess* cp,
-                                         char const* const* command);
+kwsysEXPORT int kwsysProcess_SetCommand(kwsysProcess* cp,
+                                        char const* const* command);
+
+/**
+ * Add a command line to be executed.  Argument is an array of
+ * pointers to the command and each argument.  Ths array must end with
+ * a NULL pointer.  If this is not the first command added, its
+ * standard input will be connected to the standard output of the
+ * previous command.  Returns 1 for success and 0 otherwise.
+ */
+kwsysEXPORT int kwsysProcess_AddCommand(kwsysProcess* cp,
+                                        char const* const* command);
 
 /**
  * Set the timeout for the child process.  The timeout period begins

ProcessFwd9x.c

@@ -27,6 +27,8 @@ PURPOSE.  See the above copyright notices for more information.
 #include <windows.h>
 #include <stdio.h>
 
+void ReportLastError(HANDLE errorPipe);
+
 int main()
 {
   /* Process startup information for the real child.  */
@@ -49,6 +51,11 @@ int main()
   /* Handle to the error reporting pipe provided by the parent.  This
      is parsed off the command line.  */
   HANDLE errorPipe = 0;
+  HANDLE errorPipeOrig = 0;
+
+  /* Handle to the event the parent uses to tell us to resume the child.
+     This is parsed off the command line.  */
+  HANDLE resumeEvent = 0;
 
   /* Handle to the event the parent uses to tell us to kill the child.
      This is parsed off the command line.  */
@@ -75,7 +82,12 @@ int main()
 
   /* Parse the error pipe handle.  */
   while(*cmdLine && *cmdLine == ' ') { ++cmdLine; }
-  sscanf(cmdLine, "%p", &errorPipe);
+  sscanf(cmdLine, "%p", &errorPipeOrig);
+
+  /* Parse the resume event handle.  */
+  while(*cmdLine && *cmdLine != ' ') { ++cmdLine; }
+  while(*cmdLine && *cmdLine == ' ') { ++cmdLine; }
+  sscanf(cmdLine, "%p", &resumeEvent);
 
   /* Parse the kill event handle.  */
   while(*cmdLine && *cmdLine != ' ') { ++cmdLine; }
@@ -91,6 +103,22 @@ int main()
   while(*cmdLine && *cmdLine != ' ') { ++cmdLine; }
   while(*cmdLine && *cmdLine == ' ') { ++cmdLine; }
 
+  /* Create a non-inherited copy of the error pipe.  We do not want
+     the child to get it.  */
+  if(DuplicateHandle(GetCurrentProcess(), errorPipeOrig,
+                     GetCurrentProcess(), &errorPipe,
+                     0, FALSE, DUPLICATE_SAME_ACCESS))
+    {
+    /* Have a non-inherited duplicate.  Close the inherited one.  */
+    CloseHandle(errorPipeOrig);
+    }
+  else
+    {
+    /* Could not duplicate handle.  Report the error.  */
+    ReportLastError(errorPipeOrig);
+    return 1;
+    }
+
   /* Create the subprocess.  */
   ZeroMemory(&si, sizeof(si));
   ZeroMemory(&pi, sizeof(pi));
@@ -100,32 +128,23 @@ int main()
   si.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
   si.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
   si.hStdError = GetStdHandle(STD_ERROR_HANDLE);
-  if(!CreateProcess(0, cmdLine, 0, 0, TRUE, 0, 0, 0, &si, &pi))
+  if(CreateProcess(0, cmdLine, 0, 0, TRUE, CREATE_SUSPENDED, 0, 0, &si, &pi))
+    {
+    /* Process created successfully.  Close the error reporting pipe
+       to notify the parent of success.  */
+    CloseHandle(errorPipe);
+    }
+  else
     {
     /* Error creating the process.  Report the error to the parent
        process through the special error reporting pipe.  */
-    LPVOID lpMsgBuf;
-    DWORD n;
-    FormatMessage( 
-      FORMAT_MESSAGE_ALLOCATE_BUFFER | 
-      FORMAT_MESSAGE_FROM_SYSTEM | 
-      FORMAT_MESSAGE_IGNORE_INSERTS,
-      NULL,
-      GetLastError(),
-      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
-      (LPTSTR) &lpMsgBuf,
-      0,
-      NULL 
-      );
-    WriteFile(errorPipe, lpMsgBuf, strlen(lpMsgBuf)+1, &n, 0);
-    LocalFree( lpMsgBuf );
+    ReportLastError(errorPipe);
     return 1;
     }
-  CloseHandle(pi.hThread);  
 
-  /* Wait for subprocess to exit or for kill event from parent.  */
+  /* Wait for resume or kill event from parent.  */
   waitHandles[0] = killEvent;
-  waitHandles[1] = pi.hProcess;
+  waitHandles[1] = resumeEvent;
   waitResult = WaitForMultipleObjects(2, waitHandles, 0, INFINITE);
 
   /* Check what happened.  */
@@ -135,22 +154,54 @@ int main()
     TerminateProcess(pi.hProcess, 255);
     WaitForSingleObject(pi.hProcess, INFINITE);
     CloseHandle(pi.hProcess);
+    CloseHandle(pi.hThread);  
     return 1;
     }
-  else if(GetExitCodeProcess(pi.hProcess, &retVal))
+  else
+    {
+    /* We were asked to resume the child.  */
+    ResumeThread(pi.hThread);
+    CloseHandle(pi.hThread);
+    }
+
+  /* Wait for subprocess to exit or for kill event from parent.  */
+  waitHandles[0] = killEvent;
+  waitHandles[1] = pi.hProcess;
+  waitResult = WaitForMultipleObjects(2, waitHandles, 0, INFINITE);
+
+  /* Check what happened.  */
+  if(waitResult == WAIT_OBJECT_0)
     {
-    /* The child exited and we could get the return code.  */
+    /* We were asked to kill the child.  */
+    TerminateProcess(pi.hProcess, 255);
+    WaitForSingleObject(pi.hProcess, INFINITE);
     CloseHandle(pi.hProcess);
-    return retVal;
+    return 1;
     }
   else
     {
-    /* The child exited and we could not get the return code.  Report
-       the problem to the parent process.  */
-    DWORD n;
-    const char* msg = "Failed to get process return code.";
-    WriteFile(errorPipe, msg, strlen(msg)+1, &n, 0);
+    /* The child exited.  Get the return code.  */
+    GetExitCodeProcess(pi.hProcess, &retVal);
     CloseHandle(pi.hProcess);
-    return -1;
+    return retVal;
     }
 }
+
+void ReportLastError(HANDLE errorPipe)
+{
+  LPVOID lpMsgBuf;
+  DWORD n;
+  FormatMessage( 
+    FORMAT_MESSAGE_ALLOCATE_BUFFER | 
+    FORMAT_MESSAGE_FROM_SYSTEM | 
+    FORMAT_MESSAGE_IGNORE_INSERTS,
+    NULL,
+    GetLastError(),
+    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
+    (LPTSTR) &lpMsgBuf,
+    0,
+    NULL 
+    );
+  WriteFile(errorPipe, lpMsgBuf, strlen(lpMsgBuf)+1, &n, 0);
+  LocalFree( lpMsgBuf );
+}