1 /*

     2  * A type which wraps a pipe handle in message oriented mode

     3  *

     4  * pipe_connection.c

     5  *

     6  * Copyright (c) 2006-2008, R Oudkerk --- see COPYING.txt

     7  */

     8 

     9 #include "multiprocessing.h"

    10 

    11 #define CLOSE(h) CloseHandle(h)

    12 

    13 /*

    14  * Send string to the pipe; assumes in message oriented mode

    15  */

    16 

    17 static Py_ssize_t

    18 conn_send_string(ConnectionObject *conn, char *string, size_t length)

    19 {

    20 	DWORD amount_written;

    21 	BOOL ret;

    22 

    23 	Py_BEGIN_ALLOW_THREADS

    24 	ret = WriteFile(conn->handle, string, length, &amount_written, NULL);

    25 	Py_END_ALLOW_THREADS

    26 	return ret ? MP_SUCCESS : MP_STANDARD_ERROR;

    27 }

    28 

    29 /*

    30  * Attempts to read into buffer, or if buffer too small into *newbuffer.

    31  *

    32  * Returns number of bytes read.  Assumes in message oriented mode.

    33  */

    34 

    35 static Py_ssize_t

    36 conn_recv_string(ConnectionObject *conn, char *buffer, 

    37 		 size_t buflength, char **newbuffer, size_t maxlength)

    38 {

    39 	DWORD left, length, full_length, err;

    40 	BOOL ret;

    41 	*newbuffer = NULL;

    42 

    43 	Py_BEGIN_ALLOW_THREADS

    44 	ret = ReadFile(conn->handle, buffer, MIN(buflength, maxlength), 

    45 		      &length, NULL);

    46 	Py_END_ALLOW_THREADS

    47 	if (ret)

    48 		return length;

    49 

    50 	err = GetLastError();

    51 	if (err != ERROR_MORE_DATA) {

    52 		if (err == ERROR_BROKEN_PIPE)

    53 			return MP_END_OF_FILE;

    54 		return MP_STANDARD_ERROR;

    55 	}

    56 

    57 	if (!PeekNamedPipe(conn->handle, NULL, 0, NULL, NULL, &left))

    58 		return MP_STANDARD_ERROR;

    59 

    60 	full_length = length + left;

    61 	if (full_length > maxlength)

    62 		return MP_BAD_MESSAGE_LENGTH;

    63 

    64 	*newbuffer = PyMem_Malloc(full_length);

    65 	if (*newbuffer == NULL)

    66 		return MP_MEMORY_ERROR;

    67 

    68 	memcpy(*newbuffer, buffer, length);

    69 

    70 	Py_BEGIN_ALLOW_THREADS

    71 	ret = ReadFile(conn->handle, *newbuffer+length, left, &length, NULL);

    72 	Py_END_ALLOW_THREADS

    73 	if (ret) {

    74 		assert(length == left);

    75 		return full_length;

    76 	} else {

    77 		PyMem_Free(*newbuffer);

    78 		return MP_STANDARD_ERROR;

    79 	}

    80 }

    81 

    82 /*

    83  * Check whether any data is available for reading

    84  */

    85 

    86 #define conn_poll(conn, timeout) conn_poll_save(conn, timeout, _save)

    87 

    88 static int

    89 conn_poll_save(ConnectionObject *conn, double timeout, PyThreadState *_save)

    90 {

    91 	DWORD bytes, deadline, delay;

    92 	int difference, res;

    93 	BOOL block = FALSE;

    94 

    95 	if (!PeekNamedPipe(conn->handle, NULL, 0, NULL, &bytes, NULL))

    96 		return MP_STANDARD_ERROR;

    97 

    98 	if (timeout == 0.0)

    99 		return bytes > 0;

   100 

   101 	if (timeout < 0.0)

   102 		block = TRUE;

   103 	else

   104 		/* XXX does not check for overflow */

   105 		deadline = GetTickCount() + (DWORD)(1000 * timeout + 0.5);

   106 

   107 	Sleep(0);

   108 

   109 	for (delay = 1 ; ; delay += 1) {

   110 		if (!PeekNamedPipe(conn->handle, NULL, 0, NULL, &bytes, NULL))

   111 			return MP_STANDARD_ERROR;

   112 		else if (bytes > 0)

   113 			return TRUE;

   114 

   115 		if (!block) {

   116 			difference = deadline - GetTickCount();

   117 			if (difference < 0)

   118 				return FALSE;

   119 			if ((int)delay > difference)

   120 				delay = difference;

   121 		}

   122 

   123 		if (delay > 20)

   124 			delay = 20;

   125 

   126 		Sleep(delay);

   127 

   128 		/* check for signals */

   129 		Py_BLOCK_THREADS 

   130 		res = PyErr_CheckSignals();

   131 		Py_UNBLOCK_THREADS

   132 

   133 		if (res)

   134 			return MP_EXCEPTION_HAS_BEEN_SET;

   135 	}

   136 }

   137 

   138 /*

   139  * "connection.h" defines the PipeConnection type using the definitions above

   140  */

   141 

   142 #define CONNECTION_NAME "PipeConnection"

   143 #define CONNECTION_TYPE PipeConnectionType

   144 

   145 #include "connection.h"