Mercurial > public > mercurial-scm > hg

diff mercurial/cext/osutil.c @ 49275:c6a3243567b6

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chg: replace mercurial.util.recvfds() by simpler pure Python implementation On Python 3, we have socket.socket.recvmsg(). This makes it possible to receive FDs in pure Python code. The new code behaves like the previous implementations, except that it?s more strict about the format of the ancillary data. This works because we know in which format the FDs are passed. Because the code is (and always has been) specific to chg (payload is 1 byte, number of passed FDs is limited) and we now have only one implementation and the code is very short, I decided to stop exposing a function in mercurial.util. Note on terminology: The SCM_RIGHTS mechanism is used to share open file descriptions to another process over a socket. The sending side passes an array of file descriptors and the receiving side receives an array of file descriptors. The file descriptors are different in general on both sides but refer to the same open file descriptions. The two terms are often conflated, even in the official documentation. That?s why I used ?FD? above, which could mean both ?file descriptor? and ?file description?.
author Manuel Jacob <me@manueljacob.de>
date Thu, 02 Jun 2022 23:57:56 +0200
parents 2ef3b7d30cc1
children b619ba39d10a
line wrap: on
line diff
--- a/mercurial/cext/osutil.c	Mon Jun 06 13:58:32 2022 +0400
+++ b/mercurial/cext/osutil.c	Thu Jun 02 23:57:56 2022 +0200
@@ -685,75 +685,6 @@
 	return NULL;
 }
 
-/*
- * recvfds() simply does not release GIL during blocking io operation because
- * command server is known to be single-threaded.
- *
- * Old systems such as Solaris don't provide CMSG_LEN, msg_control, etc.
- * Currently, recvfds() is not supported on these platforms.
- */
-#ifdef CMSG_LEN
-
-static ssize_t recvfdstobuf(int sockfd, int **rfds, void *cbuf, size_t cbufsize)
-{
-	char dummy[1];
-	struct iovec iov = {dummy, sizeof(dummy)};
-	struct msghdr msgh = {0};
-	struct cmsghdr *cmsg;
-
-	msgh.msg_iov = &iov;
-	msgh.msg_iovlen = 1;
-	msgh.msg_control = cbuf;
-	msgh.msg_controllen = (socklen_t)cbufsize;
-	if (recvmsg(sockfd, &msgh, 0) < 0)
-		return -1;
-
-	for (cmsg = CMSG_FIRSTHDR(&msgh); cmsg;
-	     cmsg = CMSG_NXTHDR(&msgh, cmsg)) {
-		if (cmsg->cmsg_level != SOL_SOCKET ||
-		    cmsg->cmsg_type != SCM_RIGHTS)
-			continue;
-		*rfds = (int *)CMSG_DATA(cmsg);
-		return (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
-	}
-
-	*rfds = cbuf;
-	return 0;
-}
-
-static PyObject *recvfds(PyObject *self, PyObject *args)
-{
-	int sockfd;
-	int *rfds = NULL;
-	ssize_t rfdscount, i;
-	char cbuf[256];
-	PyObject *rfdslist = NULL;
-
-	if (!PyArg_ParseTuple(args, "i", &sockfd))
-		return NULL;
-
-	rfdscount = recvfdstobuf(sockfd, &rfds, cbuf, sizeof(cbuf));
-	if (rfdscount < 0)
-		return PyErr_SetFromErrno(PyExc_OSError);
-
-	rfdslist = PyList_New(rfdscount);
-	if (!rfdslist)
-		goto bail;
-	for (i = 0; i < rfdscount; i++) {
-		PyObject *obj = PyLong_FromLong(rfds[i]);
-		if (!obj)
-			goto bail;
-		PyList_SET_ITEM(rfdslist, i, obj);
-	}
-	return rfdslist;
-
-bail:
-	Py_XDECREF(rfdslist);
-	return NULL;
-}
-
-#endif /* CMSG_LEN */
-
 /* allow disabling setprocname via compiler flags */
 #ifndef SETPROCNAME_USE_NONE
 #if defined(HAVE_SETPROCTITLE)
@@ -1285,10 +1216,6 @@
 	{"statfiles", (PyCFunction)statfiles, METH_VARARGS | METH_KEYWORDS,
 	 "stat a series of files or symlinks\n"
 "Returns None for non-existent entries and entries of other types.\n"},
-#ifdef CMSG_LEN
-	{"recvfds", (PyCFunction)recvfds, METH_VARARGS,
-	 "receive list of file descriptors via socket\n"},
-#endif
 #ifndef SETPROCNAME_USE_NONE
 	{"setprocname", (PyCFunction)setprocname, METH_VARARGS,
 	 "set process title (best-effort)\n"},