RE: malformed argument re-use in svn_client_url_from_path2

[Maximo, Andre (GE Global Research)]

Hi Bert,

  thanks for your prompt reply.  Here is the code:

void CVCS::svnURLPath(CString& urlPath, const CString &fullPath)
{
  apr_pool_t *local_pool = svn_pool_create(m_svn_pool);
  const char *url = NULL;
  svn_error_t *err = svn_client_url_from_path2(&url, fullPath, m_svn_ctx, 
m_svn_pool, local_pool);
  if (url != NULL)
    urlPath = CString(url);
  svn_pool_destroy(local_pool);
}

  Where “m_svn_ctx” and “m_svn_pool” are pointers to class member context and 
main pool.  What happens is that when I call this method for a valid fullPath 
it returns a valid urlPath. But, if I passed a non-existent fullPath, the code 
crashes at the “svn_client_url_from_path2”.

Best,
  Andre.

From: Bert Huijben [mailto:b...@qqmail.nl]
Sent: Thursday, October 24, 2013 4:03 PM
To: Maximo, Andre (GE Global Research); users@subversion.apache.org
Subject: Re: malformed argument re-use in svn_client_url_from_path2

Without more context I can't see what is wrong with the original code.

The second argument is passed by value and the local value is overwritten only 
in the function when the old pointer is never used again. This is valid in C 
and this code is tested by our testsuite as far as I can tell.

Do you have some example code that shows how it fails for you?
In most similar cases where I reviewed similar problems the cause was really a 
pool handling bug, either in Subversion (where old code often passes the same 
pool as scratch and result pool, so the wrong pool could be used somewhere) or 
in the user code.

Bert

Sent from Windows Mail

From: Maximo, Andre (GE Global Research)<mailto:max...@ge.com>
Sent: ‎Thursday‎, ‎October‎ ‎24‎, ‎2013 ‎1‎:‎51‎ ‎PM
To: users@subversion.apache.org<mailto:users@subversion.apache.org>

Hi,
  the function “svn_client_url_from_path2” in “libsvn_client/url.c” re-uses the 
const char* argument “path_or_url” as both output and input of the 
svn_dirent_get_absolute call and this causes the function to crash. The 
crashing line is:

  SVN_ERR(svn_dirent_get_absolute(&path_or_url, path_or_url, scratch_pool));

  The description of my developing environment is:

  O.S.: Windows 7
  Release: Subversion 1.8.3
  Compiler: MS Visual Studio 2010
  No modifications to SVN
  DB: FSFS
 Additional details: I replicate the problem using the same const char * 
variable in both arguments of the svn_dirent_get_absolute call (crashing in the 
same way) and made it to pass ok on this call by having another const char * as 
output. Replicated code snipet crashing:

  err = svn_dirent_get_absolute(&path, path, local_pool);

  And the ok code snipet:

  const char *local_path=NULL;
  err = svn_dirent_get_absolute(&local_path, path, local_pool);

  Should the function “svn_client_url_from_path2” have a “local_path_or_url” 
variable for output as all the other client functions that use 
“svn_dirent_get_absolute” have?

Thanks for your attention,

Andre Maximo, PhD
Information Visualization Researcher – Systems Integration
GE Global Research

T +55 21 3733 8190
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