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Re: Bug: IP address bogusly interpreted as peg revision

From: Troy Curtis Jr <troycurtisjr_at_gmail.com>
Date: Sun, 25 May 2008 21:45:56 -0500

On Sun, May 25, 2008 at 8:39 PM, Karl Fogel <kfogel_at_red-bean.com> wrote:
> "Troy Curtis Jr" <troycurtisjr_at_gmail.com> writes:
>> You know after thinking about it I could "fix" this behavior. I'm
>> working on my revised patch right now and I think the trailing slash
>> workaround would work if I returned "@" for no peg revision found
>> instead of "" in my new fangled svn_opt__split_arg_at_peg_revision()
>> function. This would mean that every single target coming out of the
>> svn_client_args_to_target_array() would have a peg revision, but some
>> of them would be blank.
> What's the connection betweening return "@" instead of "" and making
> trailing slashes prevent peg-revision interpretation?
> I'd hate to see an improvement to our peg revision interpretation affect
> APIs that way. Why can't we say "anything appearing before the last
> slash in a path is not a peg revision" without having the API effect you
> describe above?

The issue is where the canonicalization happens and when the peg
revision is actually parsed. When the paths are canonicalization
happens the peg revision is split off, the path is canonicallized and
the peg is stuck back on for later processing. Unfortunately a
trailing slash is removed during canonicallization, so during the
later peg processing it is not there to 'escape' the non-peg '@' sign.

For all later interpretation a trailing '@' symbol and no @ symbol at
all mean the same thing, no specified peg revision. By having
svn_opt__split_arg_at_peg_revision() return "@" for an empty peg
revision (instead of the empty string) you can always get the desired
behavior. In the case of a trailing slash on a target, you are
effectively replacing the trailing slash "escaping" method (which is
not canonical) with the "real" trailing '@' escaping method. But you
do guarantee that all targets will have an '@' specifier, but most of
them will not have anything following them.

Taking the some of the paths from the test_args_to_target_array() function in
subversion/tests/libsvn_client/client-test.c and adding a couple more:

Current behavior:
"." ""
"._at_BASE" "@BASE"
"foo///bar" "foo/bar"
"http://a//b////" "http://a/b"
"http://a///b@27" "http://a/b@27"
"http://a/b//@COMMITTED" "http://a/b@COMMITTED"
"foo@///bar" "foo@/bar"
"foo_at_HEAD///bar" "foo_at_HEAD/bar"
"svn+ssh://svn@" "svn+ssh://svn@"
"svn+ssh://svn@" "svn+ssh://svn@"
"svn+ssh://svn@" "svn+ssh://svn@"

Behavior if we always use '@' for no peg specified:
"." "@"
"._at_BASE" "@BASE"
"foo///bar" "foo/bar@"
"http://a//b////" "http://a/b@"
"http://a///b@27" "http://a/b@27"
"http://a/b//@COMMITTED" "http://a/b@COMMITTED"
"foo///@bar_at_HEAD" "foo/@bar_at_HEAD"
"foo@///bar" "foo@/bar@"
"foo_at_HEAD///bar" "foo_at_HEAD/bar@"
"svn+ssh://svn@" "svn+ssh://svn@"
"svn+ssh://svn@" "svn+ssh://svn@"
"svn+ssh://svn@" "svn+ssh://svn@"

All of the downstream APIs don't have to change and in fact don't have to know
about this modification. A trailing '@' IS a valid peg revision. If it is
there the APIs can take it. If not, it is handled just the same, unspecified.

This isn't really a change in our specification at the APIs, just in how we
interpret the user specified args. It is probably valid for a user to believe
a trailing slash should tell Subversion that the characters before it are a
target and NOT a peg revision, despite any '@' symbols that may be in it.


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Received on 2008-05-26 04:46:19 CEST

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