scm: Switch compel fd plugin onto common

Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

compel/plugins/fds/fds.c

+#include <errno.h>
+
 #include "uapi/plugins.h"
 
 #include "uapi/std/syscall.h"
@@ -5,22 +7,14 @@
 #include "uapi/plugin-fds.h"
 
 #include "std-priv.h"
+#include "log.h"
 
 #include "common/compiler.h"
+#include "common/bug.h"
 
 #define __sys(foo)	sys_##foo
-#define __std(foo)	std_##foo
-
-#include "../../src/shared/fds.c"
-
-int fds_send(int *fds, int nr_fds)
-{
-	return fds_send_via(std_ctl_sock(), fds, nr_fds);
-}
+#define __memcpy	std_memcpy
 
-int fds_recv(int *fds, int nr_fds)
-{
-	return fds_recv_via(std_ctl_sock(), fds, nr_fds);
-}
+#include "common/scm-code.c"
 
 PLUGIN_REGISTER_DUMMY(fds)

compel/plugins/include/uapi/plugin-fds.h

@@ -5,23 +5,11 @@
 #ifndef __COMPEL_PLUGIN_FDS_H__
 #define __COMPEL_PLUGIN_FDS_H__
 
-extern int fds_send(int *fds, int nr_fds);
-extern int fds_recv(int *fds, int nr_fds);
+#include "common/scm.h"
 
-static inline int fds_send_one(int fd)
+static inline int send_fd(int sock, struct sockaddr_un *saddr, int saddr_len, int fd)
 {
-	return fds_send(&fd, 1);
-}
-
-static inline int fds_recv_one(void)
-{
-	int fd, ret;
-
-	ret = fds_recv(&fd, 1);
-	if (ret)
-		fd = -1;
-
-	return fd;
+	return send_fds(sock, saddr, saddr_len, &fd, 1, false);
 }
 
 #endif /* __COMPEL_PLUGIN_FDS_H__ */

compel/src/shared/fds.c

-#include <sys/socket.h>
-#include <sys/un.h>
-
-/*
- * Because of kernel doing kmalloc for user data passed
- * in SCM messages, and there is kernel's SCM_MAX_FD as a limit
- * for descriptors passed at once we're trying to reduce
- * the pressue on kernel memory manager and use predefined
- * known to work well size of the message buffer.
- */
-#define CR_SCM_MSG_SIZE		(1024)
-#define CR_SCM_MAX_FD		(252)
-
-struct scm_fdset {
-	struct msghdr	hdr;
-	struct iovec	iov;
-	char		msg_buf[CR_SCM_MSG_SIZE];
-	char		f;
-};
-
-static void scm_fdset_init_chunk(struct scm_fdset *fdset, int nr_fds)
-{
-	struct cmsghdr *cmsg;
-
-	fdset->hdr.msg_controllen = CMSG_LEN(sizeof(int) * nr_fds);
-
-	cmsg		= CMSG_FIRSTHDR(&fdset->hdr);
-	cmsg->cmsg_len	= fdset->hdr.msg_controllen;
-}
-
-static int *scm_fdset_init(struct scm_fdset *fdset)
-{
-	struct cmsghdr *cmsg;
-
-	BUILD_BUG_ON(sizeof(fdset->msg_buf) < (CMSG_SPACE(sizeof(int) * CR_SCM_MAX_FD)));
-
-	fdset->iov.iov_base		= &fdset->f;
-	fdset->iov.iov_len		= 1;
-
-	fdset->hdr.msg_iov		= &fdset->iov;
-	fdset->hdr.msg_iovlen		= 1;
-	fdset->hdr.msg_name		= NULL;
-	fdset->hdr.msg_namelen		= 0;
-
-	fdset->hdr.msg_control		= &fdset->msg_buf;
-	fdset->hdr.msg_controllen	= CMSG_LEN(sizeof(int) * CR_SCM_MAX_FD);
-
-	cmsg				= CMSG_FIRSTHDR(&fdset->hdr);
-	cmsg->cmsg_len			= fdset->hdr.msg_controllen;
-	cmsg->cmsg_level		= SOL_SOCKET;
-	cmsg->cmsg_type			= SCM_RIGHTS;
-
-	return (int *)CMSG_DATA(cmsg);
-}
-
-int fds_send_via(int sock, int *fds, int nr_fds)
-{
-	struct scm_fdset fdset;
-	int i, min_fd, ret;
-	int *cmsg_data;
-
-	cmsg_data = scm_fdset_init(&fdset);
-
-	for (i = 0; i < nr_fds; i += min_fd) {
-		min_fd = min(CR_SCM_MAX_FD, nr_fds - i);
-		scm_fdset_init_chunk(&fdset, min_fd);
-		__std(memcpy(cmsg_data, &fds[i], sizeof(int) * min_fd));
-		ret = __sys(sendmsg(sock, &fdset.hdr, 0));
-		if (ret <= 0)
-			return ret ? : -1;
-	}
-
-	return 0;
-}
-
-int fds_recv_via(int sock, int *fds, int nr_fds)
-{
-	struct scm_fdset fdset;
-	struct cmsghdr *cmsg;
-	int *cmsg_data;
-	int ret;
-	int i, min_fd;
-
-	cmsg_data = scm_fdset_init(&fdset);
-	for (i = 0; i < nr_fds; i += min_fd) {
-		min_fd = min(CR_SCM_MAX_FD, nr_fds - i);
-		scm_fdset_init_chunk(&fdset, min_fd);
-
-		ret = __sys(recvmsg(sock, &fdset.hdr, 0));
-		if (ret <= 0)
-			return ret ? : -1;
-
-		cmsg = CMSG_FIRSTHDR(&fdset.hdr);
-		if (!cmsg || cmsg->cmsg_type != SCM_RIGHTS)
-			return -1;
-		if (fdset.hdr.msg_flags & MSG_CTRUNC)
-			return -2;
-
-		min_fd = (cmsg->cmsg_len - sizeof(struct cmsghdr)) / sizeof(int);
-		/*
-		 * In case if kernel screwed the recepient, most probably
-		 * the caller stack frame will be overwriten, just scream
-		 * and exit.
-		 */
-		if (unlikely(min_fd > CR_SCM_MAX_FD))
-			*(volatile unsigned long *)NULL = 0xdead0000 + __LINE__;
-		if (unlikely(min_fd <= 0))
-			return -1;
-		__std(memcpy(&fds[i], cmsg_data, sizeof(int) * min_fd));
-	}
-
-	return 0;
-}