guest agent: add guest agent RPCs/commands

This adds the initial set of QMP/QAPI commands provided by the guest
agent:

guest-sync
guest-ping
guest-info
guest-shutdown
guest-file-open
guest-file-read
guest-file-write
guest-file-seek
guest-file-flush
guest-file-close
guest-fsfreeze-freeze
guest-fsfreeze-thaw
guest-fsfreeze-status

The input/output specification for these commands are documented in the
schema.

Example usage:

  host:
    qemu -device virtio-serial \
         -chardev socket,path=/tmp/vs0.sock,server,nowait,id=qga0 \
         -device virtserialport,chardev=qga0,name=org.qemu.quest_agent.0
         ...

    echo "{'execute':'guest-info'}" | socat stdio unix-connect:/tmp/qga0.sock

  guest:
    qemu-ga -m virtio-serial -p /dev/virtio-ports/org.qemu.guest_agent.0 \
            -p /var/run/qemu-guest-agent.pid -d

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Luiz Capitulino <lcapitulino@gmail.com>

2 files changed, 520 insertions, 0 deletions

diff --git a/qga/guest-agent-commands.c b/qga/guest-agent-commands.c
new file mode 100644
index 0000000..8c0d67e
--- /dev/null
+++ b/qga/guest-agent-commands.c
@@ -0,0 +1,518 @@
+/*
+ * QEMU Guest Agent commands
+ *
+ * Copyright IBM Corp. 2011
+ *
+ * Authors:
+ *  Michael Roth      <mdroth@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include <glib.h>
+#include <mntent.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <linux/fs.h>
+#include "qga/guest-agent-core.h"
+#include "qga-qmp-commands.h"
+#include "qerror.h"
+#include "qemu-queue.h"
+
+static GAState *ga_state;
+
+static void disable_logging(void)
+{
+    ga_disable_logging(ga_state);
+}
+
+static void enable_logging(void)
+{
+    ga_enable_logging(ga_state);
+}
+
+/* Note: in some situations, like with the fsfreeze, logging may be
+ * temporarilly disabled. if it is necessary that a command be able
+ * to log for accounting purposes, check ga_logging_enabled() beforehand,
+ * and use the QERR_QGA_LOGGING_DISABLED to generate an error
+ */
+static void slog(const char *fmt, ...)
+{
+    va_list ap;
+
+    va_start(ap, fmt);
+    g_logv("syslog", G_LOG_LEVEL_INFO, fmt, ap);
+    va_end(ap);
+}
+
+int64_t qmp_guest_sync(int64_t id, Error **errp)
+{
+    return id;
+}
+
+void qmp_guest_ping(Error **err)
+{
+    slog("guest-ping called");
+}
+
+struct GuestAgentInfo *qmp_guest_info(Error **err)
+{
+    GuestAgentInfo *info = qemu_mallocz(sizeof(GuestAgentInfo));
+
+    info->version = g_strdup(QGA_VERSION);
+
+    return info;
+}
+
+void qmp_guest_shutdown(bool has_mode, const char *mode, Error **err)
+{
+    int ret;
+    const char *shutdown_flag;
+
+    slog("guest-shutdown called, mode: %s", mode);
+    if (!has_mode || strcmp(mode, "powerdown") == 0) {
+        shutdown_flag = "-P";
+    } else if (strcmp(mode, "halt") == 0) {
+        shutdown_flag = "-H";
+    } else if (strcmp(mode, "reboot") == 0) {
+        shutdown_flag = "-r";
+    } else {
+        error_set(err, QERR_INVALID_PARAMETER_VALUE, "mode",
+                  "halt|powerdown|reboot");
+        return;
+    }
+
+    ret = fork();
+    if (ret == 0) {
+        /* child, start the shutdown */
+        setsid();
+        fclose(stdin);
+        fclose(stdout);
+        fclose(stderr);
+
+        ret = execl("/sbin/shutdown", "shutdown", shutdown_flag, "+0",
+                    "hypervisor initiated shutdown", (char*)NULL);
+        if (ret) {
+            slog("guest-shutdown failed: %s", strerror(errno));
+        }
+        exit(!!ret);
+    } else if (ret < 0) {
+        error_set(err, QERR_UNDEFINED_ERROR);
+    }
+}
+
+typedef struct GuestFileHandle {
+    uint64_t id;
+    FILE *fh;
+    QTAILQ_ENTRY(GuestFileHandle) next;
+} GuestFileHandle;
+
+static struct {
+    QTAILQ_HEAD(, GuestFileHandle) filehandles;
+} guest_file_state;
+
+static void guest_file_handle_add(FILE *fh)
+{
+    GuestFileHandle *gfh;
+
+    gfh = qemu_mallocz(sizeof(GuestFileHandle));
+    gfh->id = fileno(fh);
+    gfh->fh = fh;
+    QTAILQ_INSERT_TAIL(&guest_file_state.filehandles, gfh, next);
+}
+
+static GuestFileHandle *guest_file_handle_find(int64_t id)
+{
+    GuestFileHandle *gfh;
+
+    QTAILQ_FOREACH(gfh, &guest_file_state.filehandles, next)
+    {
+        if (gfh->id == id) {
+            return gfh;
+        }
+    }
+
+    return NULL;
+}
+
+int64_t qmp_guest_file_open(const char *path, bool has_mode, const char *mode, Error **err)
+{
+    FILE *fh;
+    int fd;
+    int64_t ret = -1;
+
+    if (!has_mode) {
+        mode = "r";
+    }
+    slog("guest-file-open called, filepath: %s, mode: %s", path, mode);
+    fh = fopen(path, mode);
+    if (!fh) {
+        error_set(err, QERR_OPEN_FILE_FAILED, path);
+        return -1;
+    }
+
+    /* set fd non-blocking to avoid common use cases (like reading from a
+     * named pipe) from hanging the agent
+     */
+    fd = fileno(fh);
+    ret = fcntl(fd, F_GETFL);
+    ret = fcntl(fd, F_SETFL, ret | O_NONBLOCK);
+    if (ret == -1) {
+        error_set(err, QERR_QGA_COMMAND_FAILED, "fcntl() failed");
+        fclose(fh);
+        return -1;
+    }
+
+    guest_file_handle_add(fh);
+    slog("guest-file-open, handle: %d", fd);
+    return fd;
+}
+
+void qmp_guest_file_close(int64_t handle, Error **err)
+{
+    GuestFileHandle *gfh = guest_file_handle_find(handle);
+    int ret;
+
+    slog("guest-file-close called, handle: %ld", handle);
+    if (!gfh) {
+        error_set(err, QERR_FD_NOT_FOUND, "handle");
+        return;
+    }
+
+    ret = fclose(gfh->fh);
+    if (ret == -1) {
+        error_set(err, QERR_QGA_COMMAND_FAILED, "fclose() failed");
+        return;
+    }
+
+    QTAILQ_REMOVE(&guest_file_state.filehandles, gfh, next);
+    qemu_free(gfh);
+}
+
+struct GuestFileRead *qmp_guest_file_read(int64_t handle, bool has_count,
+                                          int64_t count, Error **err)
+{
+    GuestFileHandle *gfh = guest_file_handle_find(handle);
+    GuestFileRead *read_data = NULL;
+    guchar *buf;
+    FILE *fh;
+    size_t read_count;
+
+    if (!gfh) {
+        error_set(err, QERR_FD_NOT_FOUND, "handle");
+        return NULL;
+    }
+
+    if (!has_count) {
+        count = QGA_READ_COUNT_DEFAULT;
+    } else if (count < 0) {
+        error_set(err, QERR_INVALID_PARAMETER, "count");
+        return NULL;
+    }
+
+    fh = gfh->fh;
+    buf = qemu_mallocz(count+1);
+    read_count = fread(buf, 1, count, fh);
+    if (ferror(fh)) {
+        slog("guest-file-read failed, handle: %ld", handle);
+        error_set(err, QERR_QGA_COMMAND_FAILED, "fread() failed");
+    } else {
+        buf[read_count] = 0;
+        read_data = qemu_mallocz(sizeof(GuestFileRead));
+        read_data->count = read_count;
+        read_data->eof = feof(fh);
+        if (read_count) {
+            read_data->buf_b64 = g_base64_encode(buf, read_count);
+        }
+    }
+    qemu_free(buf);
+    clearerr(fh);
+
+    return read_data;
+}
+
+GuestFileWrite *qmp_guest_file_write(int64_t handle, const char *buf_b64,
+                                     bool has_count, int64_t count, Error **err)
+{
+    GuestFileWrite *write_data = NULL;
+    guchar *buf;
+    gsize buf_len;
+    int write_count;
+    GuestFileHandle *gfh = guest_file_handle_find(handle);
+    FILE *fh;
+
+    if (!gfh) {
+        error_set(err, QERR_FD_NOT_FOUND, "handle");
+        return NULL;
+    }
+
+    fh = gfh->fh;
+    buf = g_base64_decode(buf_b64, &buf_len);
+
+    if (!has_count) {
+        count = buf_len;
+    } else if (count < 0 || count > buf_len) {
+        qemu_free(buf);
+        error_set(err, QERR_INVALID_PARAMETER, "count");
+        return NULL;
+    }
+
+    write_count = fwrite(buf, 1, count, fh);
+    if (ferror(fh)) {
+        slog("guest-file-write failed, handle: %ld", handle);
+        error_set(err, QERR_QGA_COMMAND_FAILED, "fwrite() error");
+    } else {
+        write_data = qemu_mallocz(sizeof(GuestFileWrite));
+        write_data->count = write_count;
+        write_data->eof = feof(fh);
+    }
+    qemu_free(buf);
+    clearerr(fh);
+
+    return write_data;
+}
+
+struct GuestFileSeek *qmp_guest_file_seek(int64_t handle, int64_t offset,
+                                          int64_t whence, Error **err)
+{
+    GuestFileHandle *gfh = guest_file_handle_find(handle);
+    GuestFileSeek *seek_data = NULL;
+    FILE *fh;
+    int ret;
+
+    if (!gfh) {
+        error_set(err, QERR_FD_NOT_FOUND, "handle");
+        return NULL;
+    }
+
+    fh = gfh->fh;
+    ret = fseek(fh, offset, whence);
+    if (ret == -1) {
+        error_set(err, QERR_QGA_COMMAND_FAILED, strerror(errno));
+    } else {
+        seek_data = qemu_mallocz(sizeof(GuestFileRead));
+        seek_data->position = ftell(fh);
+        seek_data->eof = feof(fh);
+    }
+    clearerr(fh);
+
+    return seek_data;
+}
+
+void qmp_guest_file_flush(int64_t handle, Error **err)
+{
+    GuestFileHandle *gfh = guest_file_handle_find(handle);
+    FILE *fh;
+    int ret;
+
+    if (!gfh) {
+        error_set(err, QERR_FD_NOT_FOUND, "handle");
+        return;
+    }
+
+    fh = gfh->fh;
+    ret = fflush(fh);
+    if (ret == EOF) {
+        error_set(err, QERR_QGA_COMMAND_FAILED, strerror(errno));
+    }
+}
+
+static void guest_file_init(void)
+{
+    QTAILQ_INIT(&guest_file_state.filehandles);
+}
+
+typedef struct GuestFsfreezeMount {
+    char *dirname;
+    char *devtype;
+    QTAILQ_ENTRY(GuestFsfreezeMount) next;
+} GuestFsfreezeMount;
+
+struct {
+    GuestFsfreezeStatus status;
+    QTAILQ_HEAD(, GuestFsfreezeMount) mount_list;
+} guest_fsfreeze_state;
+
+/*
+ * Walk the mount table and build a list of local file systems
+ */
+static int guest_fsfreeze_build_mount_list(void)
+{
+    struct mntent *ment;
+    GuestFsfreezeMount *mount, *temp;
+    char const *mtab = MOUNTED;
+    FILE *fp;
+
+    QTAILQ_FOREACH_SAFE(mount, &guest_fsfreeze_state.mount_list, next, temp) {
+        QTAILQ_REMOVE(&guest_fsfreeze_state.mount_list, mount, next);
+        qemu_free(mount->dirname);
+        qemu_free(mount->devtype);
+        qemu_free(mount);
+    }
+
+    fp = setmntent(mtab, "r");
+    if (!fp) {
+        g_warning("fsfreeze: unable to read mtab");
+        return -1;
+    }
+
+    while ((ment = getmntent(fp))) {
+        /*
+         * An entry which device name doesn't start with a '/' is
+         * either a dummy file system or a network file system.
+         * Add special handling for smbfs and cifs as is done by
+         * coreutils as well.
+         */
+        if ((ment->mnt_fsname[0] != '/') ||
+            (strcmp(ment->mnt_type, "smbfs") == 0) ||
+            (strcmp(ment->mnt_type, "cifs") == 0)) {
+            continue;
+        }
+
+        mount = qemu_mallocz(sizeof(GuestFsfreezeMount));
+        mount->dirname = qemu_strdup(ment->mnt_dir);
+        mount->devtype = qemu_strdup(ment->mnt_type);
+
+        QTAILQ_INSERT_TAIL(&guest_fsfreeze_state.mount_list, mount, next);
+    }
+
+    endmntent(fp);
+
+    return 0;
+}
+
+/*
+ * Return status of freeze/thaw
+ */
+GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **err)
+{
+    return guest_fsfreeze_state.status;
+}
+
+/*
+ * Walk list of mounted file systems in the guest, and freeze the ones which
+ * are real local file systems.
+ */
+int64_t qmp_guest_fsfreeze_freeze(Error **err)
+{
+    int ret = 0, i = 0;
+    struct GuestFsfreezeMount *mount, *temp;
+    int fd;
+    char err_msg[512];
+
+    slog("guest-fsfreeze called");
+
+    if (guest_fsfreeze_state.status == GUEST_FSFREEZE_STATUS_FROZEN) {
+        return 0;
+    }
+
+    ret = guest_fsfreeze_build_mount_list();
+    if (ret < 0) {
+        return ret;
+    }
+
+    /* cannot risk guest agent blocking itself on a write in this state */
+    disable_logging();
+
+    QTAILQ_FOREACH_SAFE(mount, &guest_fsfreeze_state.mount_list, next, temp) {
+        fd = qemu_open(mount->dirname, O_RDONLY);
+        if (fd == -1) {
+            sprintf(err_msg, "failed to open %s, %s", mount->dirname, strerror(errno));
+            error_set(err, QERR_QGA_COMMAND_FAILED, err_msg);
+            goto error;
+        }
+
+        /* we try to cull filesytems we know won't work in advance, but other
+         * filesytems may not implement fsfreeze for less obvious reasons.
+         * these will report EOPNOTSUPP, so we simply ignore them. when
+         * thawing, these filesystems will return an EINVAL instead, due to
+         * not being in a frozen state. Other filesystem-specific
+         * errors may result in EINVAL, however, so the user should check the
+         * number * of filesystems returned here against those returned by the
+         * thaw operation to determine whether everything completed
+         * successfully
+         */
+        ret = ioctl(fd, FIFREEZE);
+        if (ret < 0 && errno != EOPNOTSUPP) {
+            sprintf(err_msg, "failed to freeze %s, %s", mount->dirname, strerror(errno));
+            error_set(err, QERR_QGA_COMMAND_FAILED, err_msg);
+            close(fd);
+            goto error;
+        }
+        close(fd);
+
+        i++;
+    }
+
+    guest_fsfreeze_state.status = GUEST_FSFREEZE_STATUS_FROZEN;
+    return i;
+
+error:
+    if (i > 0) {
+        qmp_guest_fsfreeze_thaw(NULL);
+    }
+    return 0;
+}
+
+/*
+ * Walk list of frozen file systems in the guest, and thaw them.
+ */
+int64_t qmp_guest_fsfreeze_thaw(Error **err)
+{
+    int ret;
+    GuestFsfreezeMount *mount, *temp;
+    int fd, i = 0;
+    bool has_error = false;
+
+    QTAILQ_FOREACH_SAFE(mount, &guest_fsfreeze_state.mount_list, next, temp) {
+        fd = qemu_open(mount->dirname, O_RDONLY);
+        if (fd == -1) {
+            has_error = true;
+            continue;
+        }
+        ret = ioctl(fd, FITHAW);
+        if (ret < 0 && errno != EOPNOTSUPP && errno != EINVAL) {
+            has_error = true;
+            close(fd);
+            continue;
+        }
+        close(fd);
+        i++;
+    }
+
+    if (has_error) {
+        guest_fsfreeze_state.status = GUEST_FSFREEZE_STATUS_ERROR;
+    } else {
+        guest_fsfreeze_state.status = GUEST_FSFREEZE_STATUS_THAWED;
+    }
+    enable_logging();
+    return i;
+}
+
+static void guest_fsfreeze_init(void)
+{
+    guest_fsfreeze_state.status = GUEST_FSFREEZE_STATUS_THAWED;
+    QTAILQ_INIT(&guest_fsfreeze_state.mount_list);
+}
+
+static void guest_fsfreeze_cleanup(void)
+{
+    int64_t ret;
+    Error *err = NULL;
+
+    if (guest_fsfreeze_state.status == GUEST_FSFREEZE_STATUS_FROZEN) {
+        ret = qmp_guest_fsfreeze_thaw(&err);
+        if (ret < 0 || err) {
+            slog("failed to clean up frozen filesystems");
+        }
+    }
+}
+
+/* register init/cleanup routines for stateful command groups */
+void ga_command_state_init(GAState *s, GACommandState *cs)
+{
+    ga_state = s;
+    ga_command_state_add(cs, guest_fsfreeze_init, guest_fsfreeze_cleanup);
+    ga_command_state_add(cs, guest_file_init, NULL);
+}
diff --git a/qga/guest-agent-core.h b/qga/guest-agent-core.h
index 66d1729..e42b91d 100644
--- a/qga/guest-agent-core.h
+++ b/qga/guest-agent-core.h
@@ -14,10 +14,12 @@
 #include "qemu-common.h"
 
 #define QGA_VERSION "1.0"
+#define QGA_READ_COUNT_DEFAULT 4 << 10
 
 typedef struct GAState GAState;
 typedef struct GACommandState GACommandState;
 
+void ga_command_state_init(GAState *s, GACommandState *cs);
 void ga_command_state_add(GACommandState *cs,
                           void (*init)(void),
                           void (*cleanup)(void));