cmd/sharefs: allocate sharefs_private early

This also removes global state used by sharefs_init.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/sharefs/fuse-operations.h

@@ -13,7 +13,11 @@
 
 /* sharefs_private is populated by sharefs_init and contains process-wide context */
 struct sharefs_private {
-    int dirfd; /* source dirfd opened during sharefs_init */
+    int dirfd;               /* source dirfd opened during sharefs_init */
+    bool init_failed;        /* whether sharefs_init failed */
+    uintptr_t source_handle; /* cgo handle of pathname to open for dirfd, freed during sharefs_init */
+    uintptr_t setuid;        /* uid to set by sharefs_init when running as root */
+    uintptr_t setgid;        /* gid to set by sharefs_init when running as root */
 };
 
 int sharefs_getattr(const char *pathname, struct stat *statbuf, struct fuse_file_info *fi);