From: Sapan Bhatia <sapanb@cs.princeton.edu>
Date: Tue, 24 Mar 2009 18:14:59 +0000 (+0000)
Subject: Adding some scripts that implement fd passing
X-Git-Tag: 0.9-0~25
X-Git-Url: http://git.onelab.eu/?p=vsys-scripts.git;a=commitdiff_plain;h=ec680f4ee67d7026a97bb830e27af71a1764cfe2

Adding some scripts that implement fd passing
---

diff --git a/Makefile b/Makefile
index 8d4968d..9bb4e8a 100644
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,13 @@
 CC=gcc
 CFLAGS=-g -O2
 
-all: dcookie
+all: dcookie fd_bmsocket
 
 dcookie: dcookie.c
 	gcc dcookie.c -o exec/dcookie
 
+fd_bmsocket: fd_bmsocket.c
+	gcc fd_bmsocket.c -o exec/fd_bmsocket
+
 clean: 
 	rm -f exec/*
diff --git a/fdpass.c b/fdpass.c
new file mode 100644
index 0000000..5548064
--- /dev/null
+++ b/fdpass.c
@@ -0,0 +1,93 @@
+// Modified version of library functions in FUSE
+//
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mount.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+
+int send_fd(int sock_fd, int fd)
+{
+	int retval;
+	struct msghdr msg;
+	struct cmsghdr *p_cmsg;
+	struct iovec vec;
+	size_t cmsgbuf[CMSG_SPACE(sizeof(fd)) / sizeof(size_t)];
+	int *p_fds;
+	char sendchar = 0;
+
+	msg.msg_control = cmsgbuf;
+	msg.msg_controllen = sizeof(cmsgbuf);
+	p_cmsg = CMSG_FIRSTHDR(&msg);
+	p_cmsg->cmsg_level = SOL_SOCKET;
+	p_cmsg->cmsg_type = SCM_RIGHTS;
+	p_cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
+	p_fds = (int *) CMSG_DATA(p_cmsg);
+	*p_fds = fd;
+	msg.msg_controllen = p_cmsg->cmsg_len;
+	msg.msg_name = NULL;
+	msg.msg_namelen = 0;
+	msg.msg_iov = &vec;
+	msg.msg_iovlen = 1;
+	msg.msg_flags = 0;
+	/* "To pass file descriptors or credentials you need to send/read at
+	 * least one byte" (man 7 unix) */
+	vec.iov_base = &sendchar;
+	vec.iov_len = sizeof(sendchar);
+	while ((retval = sendmsg(sock_fd, &msg, 0)) == -1 && errno == EINTR);
+	if (retval != 1) {
+		perror("sending file descriptor");
+		return -1;
+	}
+	return 0;
+}
+
+
+/* return value:
+ * >= 0	 => fd
+ * -1	 => error
+ */
+int receive_fd(int fd)
+{
+	struct msghdr msg;
+	struct iovec iov;
+	char buf[1];
+	int rv;
+	size_t ccmsg[CMSG_SPACE(sizeof(int)) / sizeof(size_t)];
+	struct cmsghdr *cmsg;
+
+	iov.iov_base = buf;
+	iov.iov_len = 1;
+
+	msg.msg_name = 0;
+	msg.msg_namelen = 0;
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+	/* old BSD implementations should use msg_accrights instead of
+	 * msg_control; the interface is different. */
+	msg.msg_control = ccmsg;
+	msg.msg_controllen = sizeof(ccmsg);
+
+	while(((rv = recvmsg(fd, &msg, 0)) == -1) && errno == EINTR);
+	if (rv == -1) {
+		perror("recvmsg");
+		return -1;
+	}
+	if(!rv) {
+		/* EOF */
+		return -1;
+	}
+
+	cmsg = CMSG_FIRSTHDR(&msg);
+	if (!cmsg->cmsg_type == SCM_RIGHTS) {
+		fprintf(stderr, "got control message of unknown type %d\n",
+			cmsg->cmsg_type);
+		return -1;
+	}
+	return *(int*)CMSG_DATA(cmsg);
+}
+