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 <olaf@aepfle.de> and Dan Carpenter <dan.carpenter@oracle.com>

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 <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 195 insertions, 0 deletions

diff --git a/tools/hv/hv_fcopy_daemon.c b/tools/hv/hv_fcopy_daemon.c
new file mode 100644
index 000000000000..4ecc4fd0bc1b
--- /dev/null
+++ b/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);
+                }
+        }
+}