Re: [PATCH v4 3/3] cat-file: add --follow-symlinks to --batch

On Mon, 2015-05-11 at 13:21 -0700, Junio C Hamano wrote:
dturner@twopensource.com writes:

quoted

+--follow-symlinks::
+	Follow symlinks inside the repository.  Instead of providing
+	output about the link itself, provide output about the linked-to
+	object.  This option requires --batch or --batch-check.  In the
+	event of a symlink loop (or more than 40 symlinks in a symlink
+	resolution chain), the file will be treated as missing.  If a
+	symlink points outside the repository (e.g. a link to /foo or a
+	root-level link to ../foo), the portion of the link which is
+	outside the repository will be printed.  Follow-symlinks will
+	be silently turned off if <object> specifies an object in the
+	index rather than one in the object database.

One thing that I found is missing from the above and other places in
the documents updated by this patch, when I pretend that I am an
end-user who never saw the discussion for the problem definition and
design of the solution on the list, is what "symlink" this refers
to and how I am expected to use this feature.

I'll send something like this when I re-roll:

Follow symlinks inside the repository when requesting objects with
extended SHA-1 expressions of the form tree-ish:path-in-tree. Instead of
providing output about the link itself, provide output about the
linked-to object.  This option requires --batch or	--batch-check.  In
the event of a symlink loop (or more than 40 symlinks in a symlink
resolution chain), the file will be treated as missing.  If a symlink
points outside the tree-ish (e.g. a link to /foo or a root-level link
to ../foo), the portion of the link which is outside the tree will be
printed. Follow-symlinks will be silently turned off if <object>
specifies an object in the index rather than one in the object database.

I could also provide some examples, if you think this would be useful.

+If --follow-symlinks is used, and a symlink in the repository points

quoted

+outside the repository, then `cat-file` will ignore any custom

format

quoted

+and print:
+
+------------
+symlink SP <size> LF <symlink> LF
+------------

A symlink contain LF, obviously, and we should use some quoting
convention.  Perhaps quote_c_style() on a string that needs it is
sufficient---most sane people do not put LF or literally '\' 'n' or
'"' in their symbolic links, so the ugly output is not visible for
them, and it is far better to be able to say "If you have funny
characters in your symlinks, they will be quoted" than "If you have
funny characters in your symlinks, you are SOL".

There is no need for quoting because <size> is sufficient to
disambiguate the parsing (just as is the case for blobs, which might
contain arbitrary characters).