Drivers: hv: Implement the file copy service

Implement the file copy service for Linux guests on Hyper-V. This permits the
host to copy a file (over VMBUS) into the guest. This facility is part of
"guest integration services" supported on the Windows platform.
Here is a link that provides additional details on this functionality:

http://technet.microsoft.com/en-us/library/dn464282.aspx

In V1 version of the patch I have addressed comments from
Olaf Hering <[email protected]> and Dan Carpenter <[email protected]>

In V2 version of this patch I did some minor cleanup (making some globals
static). In V4 version of the patch I have addressed all of Olaf's
most recent set of comments/concerns.

In V5 version of the patch I had addressed Greg's most recent comments.
I would like to thank Greg for suggesting that I use misc device; it has
significantly simplified the code.

In V6 version of the patch I have cleaned up error message based on Olaf's
comments. I have also rebased the patch based on the current tip.

In this version of the patch, I have addressed the latest comments from Greg.

Signed-off-by: K. Y. Srinivasan <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

tools/hv/hv_fcopy_daemon.c

@@ -0,0 +1,195 @@
+/*
+ * An implementation of host to guest copy functionality for Linux.
+ *
+ * Copyright (C) 2014, Microsoft, Inc.
+ *
+ * Author : K. Y. Srinivasan <kys@microsoft.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ */
+
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/poll.h>
+#include <linux/types.h>
+#include <linux/kdev_t.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <ctype.h>
+#include <errno.h>
+#include <linux/hyperv.h>
+#include <syslog.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <dirent.h>
+
+static int target_fd;
+static char target_fname[W_MAX_PATH];
+
+static int hv_start_fcopy(struct hv_start_fcopy *smsg)
+{
+	int error = HV_E_FAIL;
+	char *q, *p;
+
+	/*
+	 * If possile append a path seperator to the path.
+	 */
+	if (strlen((char *)smsg->path_name) < (W_MAX_PATH - 2))
+		strcat((char *)smsg->path_name, "/");
+
+	p = (char *)smsg->path_name;
+	snprintf(target_fname, sizeof(target_fname), "%s/%s",
+		(char *)smsg->path_name, smsg->file_name);
+
+	syslog(LOG_INFO, "Target file name: %s", target_fname);
+	/*
+	 * Check to see if the path is already in place; if not,
+	 * create if required.
+	 */
+	while ((q = strchr(p, '/')) != NULL) {
+		if (q == p) {
+			p++;
+			continue;
+		}
+		*q = '\0';
+		if (access((char *)smsg->path_name, F_OK)) {
+			if (smsg->copy_flags & CREATE_PATH) {
+				if (mkdir((char *)smsg->path_name, 0755)) {
+					syslog(LOG_ERR, "Failed to create %s",
+						(char *)smsg->path_name);
+					goto done;
+				}
+			} else {
+				syslog(LOG_ERR, "Invalid path: %s",
+					(char *)smsg->path_name);
+				goto done;
+			}
+		}
+		p = q + 1;
+		*q = '/';
+	}
+
+	if (!access(target_fname, F_OK)) {
+		syslog(LOG_INFO, "File: %s exists", target_fname);
+		if (!smsg->copy_flags & OVER_WRITE)
+			goto done;
+	}
+
+	target_fd = open(target_fname, O_RDWR | O_CREAT | O_CLOEXEC, 0744);
+	if (target_fd == -1) {
+		syslog(LOG_INFO, "Open Failed: %s", strerror(errno));
+		goto done;
+	}
+
+	error = 0;
+done:
+	return error;
+}
+
+static int hv_copy_data(struct hv_do_fcopy *cpmsg)
+{
+	ssize_t bytes_written;
+
+	bytes_written = pwrite(target_fd, cpmsg->data, cpmsg->size,
+				cpmsg->offset);
+
+	if (bytes_written != cpmsg->size)
+		return HV_E_FAIL;
+
+	return 0;
+}
+
+static int hv_copy_finished(void)
+{
+	close(target_fd);
+	return 0;
+}
+static int hv_copy_cancel(void)
+{
+	close(target_fd);
+	unlink(target_fname);
+	return 0;
+
+}
+
+int main(void)
+{
+	int fd, fcopy_fd, len;
+	int error;
+	int version = FCOPY_CURRENT_VERSION;
+	char *buffer[4096 * 2];
+	struct hv_fcopy_hdr *in_msg;
+
+	if (daemon(1, 0)) {
+		syslog(LOG_ERR, "daemon() failed; error: %s", strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	openlog("HV_FCOPY", 0, LOG_USER);
+	syslog(LOG_INFO, "HV_FCOPY starting; pid is:%d", getpid());
+
+	fcopy_fd = open("/dev/vmbus/hv_fcopy", O_RDWR);
+
+	if (fcopy_fd < 0) {
+		syslog(LOG_ERR, "open /dev/vmbus/hv_fcopy failed; error: %d %s",
+			errno, strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	/*
+	 * Register with the kernel.
+	 */
+	if ((write(fcopy_fd, &version, sizeof(int))) != sizeof(int)) {
+		syslog(LOG_ERR, "Registration failed: %s", strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	while (1) {
+		/*
+		 * In this loop we process fcopy messages after the
+		 * handshake is complete.
+		 */
+		len = pread(fcopy_fd, buffer, (4096 * 2), 0);
+		if (len < 0) {
+			syslog(LOG_ERR, "pread failed: %s", strerror(errno));
+			exit(EXIT_FAILURE);
+		}
+		in_msg = (struct hv_fcopy_hdr *)buffer;
+
+		switch (in_msg->operation) {
+		case START_FILE_COPY:
+			error = hv_start_fcopy((struct hv_start_fcopy *)in_msg);
+			break;
+		case WRITE_TO_FILE:
+			error = hv_copy_data((struct hv_do_fcopy *)in_msg);
+			break;
+		case COMPLETE_FCOPY:
+			error = hv_copy_finished();
+			break;
+		case CANCEL_FCOPY:
+			error = hv_copy_cancel();
+			break;
+
+		default:
+			syslog(LOG_ERR, "Unknown operation: %d",
+				in_msg->operation);
+
+		}
+
+		if (pwrite(fcopy_fd, &error, sizeof(int), 0) != sizeof(int)) {
+			syslog(LOG_ERR, "pwrite failed: %s", strerror(errno));
+			exit(EXIT_FAILURE);
+		}
+	}
+}