Re: [platform-core-dev] org.eclipse.core.runtime.Path issue with colons

[John Arthorne <John_Arthorne@xxxxxxxxxx>]

I was not the initial author, but I
will try to explain the design rationale of IPath. This is an abstract
data structure consisting of a device and a series of segments. While it
is largely used to represent file system paths, it can also represent network
paths, or other abstract paths in non file-system trees. To support these
requirements, it needed to reserve two characters: one for the device separator,
and one for the segment separator. Thus / and : are reserved, independent
of the operating system used (similarly, Unix reserves / and null characters).
Since Eclipse uses IPath as a lookup mechanism for the in-memory representation
of the workspace, these two limitations carry forward into Eclipse. Again,
these limitations were not introduced with any particular operating system
in mind. The Eclipse workspace (just one client of the abstract IPath data
structure) imposes further checking on resource paths depending on the
operating system, invalidating characters and strings that are not allowed
under that system.

We are aware of these limitations on
*nix platforms (worse on Mac which also allows '/' in filenames). While
a solution would be welcome, it is not as easy as changing the semantics
of IPath based on the underlying operating system, as this would break
other clients of the data structure. Also, the treatment of \ and / as
equivalent is not easy to change, since existing code may be using \ in
path names and expecting the conversion to happen for free.

Here is the bug report reference, if
you want to CC yourself or add further comments:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=24152
--

Ed Warnicke <eaw@xxxxxxxxx>
Sent by: platform-core-dev-admin@xxxxxxxxxxx

08/27/2004 07:09 PM

Please respond to
platform-core-dev

To	platform-core-dev@xxxxxxxxxxx
cc
Subject	[platform-core-dev] org.eclipse.core.runtime.Path issue with colons

I've been using CDT on an existing code base, and
have discovered that it
seems to have issues with colons in filenames.  I filed a bug with
regard to this
against CDT here:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=72718

I have since traced the issue down to issues in 
org.eclipse.core.runtime.Path.

It seems that there are significant 'Windowisms' in 
org.eclipse.core.runtime.Path
which render the characters ':' and '\\' both invalid characters in Path
Segments
(and thus filenames).  Both characters are perfectly legal characters
in 
Path Segments
(and filenames) under Unix/Linux (where I'm working).  The result
is 
that I simply
can't create projects.

I'm going to try to make changes (and submit a patch) to fix these problems.
What I would like to do is see to it that whatever behavior the original
author
was seeking under Windows still occurs, but that users on Unix/Linux 
systems
are not unnecessarily hamstrung.

In relation to this effort I have a few questions:
1)   What is the correct way to detect differences in the platform
being run
      on so that I can intelligently apply or not apply
this behavior 
appropriately?
2)   Can anyone give me any guidance on what the original author of
      this code was trying to acheive?  Some quick
research indicated 
that the
      quirks in legal filenames under Windows are much more
numerous than
      having ':' and '\\' be illegal characters for Path
Segments, so 
I'm confused as
      to why non-Windows systems were broken here for an
incomplete 
solution.

Ed

P.S. Specifically these are the places where there seem to be issues:

1)   Path.isValidSegment() returns false if it finds '/','\\'. or
':' in 
a segment.  This causes
      valid patch segments on Unix/Linux containing ':'
or '\\' to be 
rejected.
2)   Path.initialize() splits on ':' and effectively discards all
characters leading the colon
      (rolling them into the device attribute).  As
a result a filename 
like
      foo:bar.c would become resource bar.c... not the correct
behavior.
3)   Path.append() similarly seems to treat ':' (in the form of 
IPath.DEVICE_SEPARATOR)
      as a path seperator, which could cause all no end
of mischeif in 
the many, many
      other methods calling Path.append()
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