Add support for file read

To make 'cat /var/lib/lxcfs/cgroup/freezer/tasks' work, we also need for
getattr to actually give a file size.  So, do that.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

diff --git a/cgmanager.c b/cgmanager.c
index ac6225e4d836c201b54fbc4bc9c0f32da8564c2f..ce5680bceabdfa5f6cdcbc354441849c884eec52 100644 (file)
--- a/cgmanager.c
+++ b/cgmanager.c
@@ -203,3 +203,24 @@ bool cgm_escape_cgroup(void)
        cgm_dbus_disconnect();
        return true;
 }
+
+bool cgm_get_value(const char *controller, const char *cgroup, const char *file,
+               char **value)
+{
+       if (!cgm_dbus_connect()) {
+               return false;
+       }
+
+       if ( cgmanager_get_value_sync(NULL, cgroup_manager, controller, cgroup,
+                       file, value) != 0 ) {
+               NihError *nerr;
+               nerr = nih_error_get();
+               fprintf(stderr, "call to get_value failed: %s", nerr->message);
+               nih_free(nerr);
+               cgm_dbus_disconnect();
+               return false;
+       }
+
+       cgm_dbus_disconnect();
+       return true;
+}

diff --git a/cgmanager.h b/cgmanager.h
index e556f47006b9fe8236b44e66c95361b2ebfde776..a605a7cc7a35f3aa68c62bc3744cce98a2d38c2d 100644 (file)
--- a/cgmanager.h
+++ b/cgmanager.h
@@ -8,5 +8,7 @@ bool cgm_get_controllers(char ***contrls);
 bool cgm_list_keys(const char *controller, const char *cgroup, struct cgm_keys ***keys);
 bool cgm_list_children(const char *controller, const char *cgroup, char ***list);
 char *cgm_get_pid_cgroup(pid_t pid, const char *controller);
+bool cgm_get_value(const char *controller, const char *cgroup, const char *file,
+               char **value);
 
 bool cgm_escape_cgroup(void);

diff --git a/lxcfs.c b/lxcfs.c
index 58cc5163fa465d7537e7da358941296c9501cc8e..771deda7b75ffc1d0b7327f120d114945d5718e2 100644 (file)
--- a/lxcfs.c
+++ b/lxcfs.c
@@ -282,6 +282,15 @@ static void get_cgdir_and_path(const char *cg, char **dir, char **file)
        *p = '\0';
 }
 
+static size_t get_file_size(const char *contrl, const char *cg, const char *f)
+{
+       nih_local char *data = NULL;
+       size_t s;
+       if (!cgm_get_value(contrl, cg, f, &data))
+               return -EINVAL;
+       s = strlen(data);
+       return s;
+}
 /*
  * gettattr fn for anything under /cgroup
  */
@@ -367,6 +376,7 @@ static int cg_getattr(const char *path, struct stat *sb)
                sb->st_nlink = 1;
                sb->st_uid = k->uid;
                sb->st_gid = k->gid;
+               sb->st_size = get_file_size(controller, path1, path2);
                return 0;
        }
 
@@ -452,6 +462,99 @@ static int cg_releasedir(const char *path, struct fuse_file_info *fi)
        return 0;
 }
 
+static int cg_open(const char *path, struct fuse_file_info *fi)
+{
+       nih_local char *controller = NULL;
+       const char *cgroup;
+       char *fpath = NULL, *path1, *path2;
+       nih_local char * cgdir = NULL;
+       nih_local struct cgm_keys *k = NULL;
+       struct fuse_context *fc = fuse_get_context();
+
+       if (!fc)
+               return -EIO;
+
+       controller = pick_controller_from_path(fc, path);
+       if (!controller)
+               return -EIO;
+       cgroup = find_cgroup_in_path(path);
+       if (!cgroup)
+               return -EINVAL;
+
+       get_cgdir_and_path(cgroup, &cgdir, &fpath);
+       if (!fpath) {
+               path1 = "/";
+               path2 = cgdir;
+       } else {
+               path1 = cgdir;
+               path2 = fpath;
+       }
+
+       if ((k = get_cgroup_key(controller, path1, path2)) != NULL) {
+               if (!fc_may_access(fc, controller, path1, path2, fi->flags))
+                       return -EPERM;
+
+               /* TODO - we want to cache this info for read/write */
+               return 0;
+       }
+
+       return -EINVAL;
+}
+
+static int cg_read(const char *path, char *buf, size_t size, off_t offset,
+               struct fuse_file_info *fi)
+{
+       nih_local char *controller = NULL;
+       const char *cgroup;
+       char *fpath = NULL, *path1, *path2;
+       struct fuse_context *fc = fuse_get_context();
+       nih_local char * cgdir = NULL;
+       nih_local struct cgm_keys *k = NULL;
+
+       if (offset)
+               return -EIO;
+
+       if (!fc)
+               return -EIO;
+
+       controller = pick_controller_from_path(fc, path);
+       if (!controller)
+               return -EIO;
+       cgroup = find_cgroup_in_path(path);
+       if (!cgroup)
+               return -EINVAL;
+
+       get_cgdir_and_path(cgroup, &cgdir, &fpath);
+       if (!fpath) {
+               path1 = "/";
+               path2 = cgdir;
+       } else {
+               path1 = cgdir;
+               path2 = fpath;
+       }
+
+       if ((k = get_cgroup_key(controller, path1, path2)) != NULL) {
+               nih_local char *data = NULL;
+               int s;
+
+               if (!fc_may_access(fc, controller, path1, path2, fi->flags))
+                       return -EPERM;
+
+               if (!cgm_get_value(controller, path1, path2, &data))
+                       return -EINVAL;
+
+               s = strlen(data);
+               if (s > size)
+                       s = size;
+               memcpy(buf, data, s);
+
+fprintf(stderr, "cg_read: returning %d: %s\n", s, buf);
+               return s;
+       }
+
+       return -EINVAL;
+}
+
 /*
  * So far I'm not actually using cg_ops and proc_ops, but listing them
  * here makes it clearer who is supporting what.  Still I prefer to 
@@ -472,8 +575,8 @@ const struct fuse_operations cg_ops = {
        .chown = NULL,
        .truncate = NULL,
        .utime = NULL,
-       .open = NULL,
-       .read = NULL,
+       .open = cg_open,
+       .read = cg_read,
        .write = NULL,
        .statfs = NULL,
        .flush = NULL,
@@ -600,9 +703,38 @@ static int lxcfs_releasedir(const char *path, struct fuse_file_info *fi)
        return -EINVAL;
 }
 
-void *bb_init(struct fuse_conn_info *conn)
+static int lxcfs_open(const char *path, struct fuse_file_info *fi)
+{
+       if (strncmp(path, "/cgroup", 7) == 0) {
+               return cg_open(path, fi);
+       }
+
+       return -EINVAL;
+}
+
+static int lxcfs_read(const char *path, char *buf, size_t size, off_t offset,
+               struct fuse_file_info *fi)
+{
+       if (strncmp(path, "/cgroup", 7) == 0) {
+               return cg_read(path, buf, size, offset, fi);
+       }
+
+       return -EINVAL;
+}
+
+static int lxcfs_flush(const char *path, struct fuse_file_info *fi)
+{
+       return 0;
+}
+
+static int lxcfs_release(const char *path, struct fuse_file_info *fi)
 {
-       return LXCFS_DATA;
+       return 0;
+}
+
+static int lxcfs_fsync(const char *path, int datasync, struct fuse_file_info *fi)
+{
+       return 0;
 }
 
 const struct fuse_operations lxcfs_ops = {
@@ -620,13 +752,15 @@ const struct fuse_operations lxcfs_ops = {
        .chown = NULL,
        .truncate = NULL,
        .utime = NULL,
-       .open = NULL,
-       .read = NULL,
+
+       .open = lxcfs_open,
+       .read = lxcfs_read,
+       .release = lxcfs_release,
        .write = NULL,
+
        .statfs = NULL,
-       .flush = NULL,
-       .release = NULL,
-       .fsync = NULL,
+       .flush = lxcfs_flush,
+       .fsync = lxcfs_fsync,
 
        .setxattr = NULL,
        .getxattr = NULL,
@@ -646,7 +780,7 @@ const struct fuse_operations lxcfs_ops = {
        .fgetattr = NULL,
 };
 
-void usage(const char *me)
+static void usage(const char *me)
 {
        fprintf(stderr, "Usage:\n");
        fprintf(stderr, "\n");
@@ -654,7 +788,7 @@ void usage(const char *me)
        exit(1);
 }
 
-bool is_help(char *w)
+static bool is_help(char *w)
 {
        if (strcmp(w, "-h") == 0 ||
                        strcmp(w, "--help") == 0 ||