Question

I’m writing an (un)archiving tool and the way it is designed it first creates a regular file from the archive before it examines the special attributes and may decide that this item is a symlink, in fact.

Note: Before more people misunderstand me for wanting to make a symlink of a file. No, I write the symlink data, i.e. its path, into the file, and then I want to tell the file system that this is a symlink

I’ve been developing this on OS X, where it’s possible to turn a regular file into a symlink by simply setting its Type and Creator codes accordingly.

Now I like to get this code working on Linux as well. So I like to find a similar way there.

I am aware that the normal way to create a symlink is to call the symlink() function, but I wonder if there is also a way to change a regular file into a symlink, just like it’s possible in OSX’s BSD system, so that I do not have to refactor my working code too much?

There is lstat(), which returns the file type in st_mode’s upmost bits. Now I wonder if there’s also an analogous setter function for this mode field.

Answer 1

I don’t believe there is a way in Linux to do this as you describe. IIRC, the filesystem stores symlink information in the inode table and not in a regular file so there’s no direct way of turning a file into a link.

If the symlink’s path is stored inside the file, why not read out the path, delete the file, and create a symlink in its place?