Add fuse_getgroups (high level lib) and fuse_req_getgroups (low

level lib) functions to query the supplementary group IDs for the
current request.  Currently this is implemented on Linux by
reading from the /proc filesystem.

2 files changed, 41 insertions, 0 deletions

diff --git a/include/fuse.h b/include/fuse.h
index 6ded4f5..a58cd9f 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -624,6 +624,26 @@ int fuse_loop_mt(struct fuse *f);
 struct fuse_context *fuse_get_context(void);
 
 /**
+ * Get the current supplementary group IDs for the current request
+ *
+ * Similar to the getgroups(2) system call, except the return value is
+ * always the total number of group IDs, even if it is larger than the
+ * specified size.
+ *
+ * The current fuse kernel module in linux (as of 2.6.30) doesn't pass
+ * the group list to userspace, hence this function needs to parse
+ * "/proc/$TID/task/$TID/status" to get the group IDs.
+ *
+ * This feature may not be supported on all operating systems.  In
+ * such a case this function will return -ENOSYS.
+ *
+ * @param size size of given array
+ * @param list array of group IDs to be filled in
+ * @return the total number of supplementary group IDs or -errno on failure
+ */
+int fuse_getgroups(int size, gid_t list[]);
+
+/**
  * Check if the current request has already been interrupted
  *
  * @return 1 if the request has been interrupted, 0 otherwise
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 5ab2422..a495e15 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1175,6 +1175,27 @@ void *fuse_req_userdata(fuse_req_t req);
 const struct fuse_ctx *fuse_req_ctx(fuse_req_t req);
 
 /**
+ * Get the current supplementary group IDs for the specified request
+ *
+ * Similar to the getgroups(2) system call, except the return value is
+ * always the total number of group IDs, even if it is larger than the
+ * specified size.
+ *
+ * The current fuse kernel module in linux (as of 2.6.30) doesn't pass
+ * the group list to userspace, hence this function needs to parse
+ * "/proc/$TID/task/$TID/status" to get the group IDs.
+ *
+ * This feature may not be supported on all operating systems.  In
+ * such a case this function will return -ENOSYS.
+ *
+ * @param req request handle
+ * @param size size of given array
+ * @param list array of group IDs to be filled in
+ * @return the total number of supplementary group IDs or -errno on failure
+ */
+int fuse_req_getgroups(fuse_req_t req, int size, gid_t list[]);
+
+/**
  * Callback function for an interrupt
  *
  * @param req interrupted request