ref: 4f0bfe0fb8dc608a94fe429c5ddb12e58997e1ce
dir: /sys/src/cmd/aux/flashfs/errors.c/
char Edirnotempty[] = "directory not empty on deletion"; char Eexists[] = "file already exists"; char Enonexist[] = "file does not exist"; char Eisdir[] = "is a directory"; char Enotdir[] = "not a directory"; char Eperm[] = "permission denied"; char Erofs[] = "read only filesystem";