On Mon, 2010-03-15, Paul Burba wrote:
> On Fri, Mar 12, 2010 at 12:59 PM, Julian Foad <julian.f...@wandisco.com> 
> wrote:
> > Hi Paul.
> >
> > I think we can tighten the validation of svn_merge_range_t to exclude
> > change number "r0" (RANGE->start == -1) as in the following patch.
> >
> > My reasoning is that a change numbered "r0" is not a valid concept in
> > any Subversion system because the state (tree-snapshot) numbered r0 is
> > by definition the beginning.  (It also happens to be empty by
> > definition, but that's not so relevant.)  We can say the same in a
> > different way: change "r0" would mean the change from "r(-1)" to "r0",
> > and "r(-1)" is not a valid concept.
> >
> > Makes sense?
> 
> Hi Julian,
> 
> It does make sense, but I can't apply this patch, seems to have a few
> problems, see below.

[...]
> > @@ -877,24 +877,27 @@ test_remove_rangelist(apr_pool_t *pool)
>                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Why is that all on one line?  Those offsets are supposed to be on
> their own line no?

I don't think this is the problem.  This is the diff format produced by
the "--show-c-function" ("-p") option to GNU diff or "svn diff".

> Also, test_remove_rangelist(apr_pool_t *pool) looks to be on line 706
> in 
> https://svn.apache.org/repos/asf/subversion/trunk/subversion/tests/libsvn_subr/mergeinfo-tes...@922300,
> so it seems your from-to headers are off.

That's just because the "--show-c-function" option is very dumb and just
intended as a guess.  It just shows (part of) the last line it saw
before the current hunk that looked like a line introducing a function.

[...]
> > @@ -943,12 +946,15 @@ test_rangelist_remove_randomly(apr_pool_
>                                                                 ^^^
> Again, all on one line and this time the line is truncated.

Yup, that's normal.

> Anyhow, could try attaching the patch again?

Certainly.  Attached v2, which in addition has a fix for one of the
places that generated an "r0" merge-range.

It's possible your patch application was marred by line-endings, or
maybe can't cope with 6 context lines (the default is 3), so I've
attached the patch this time, and cut the context lines back to 3.
(What patch-application program was it?)

- Julian

Tighten merge-range validation to not allow "change number r0" aka "revision
range -1:Y".

* subversion/libsvn_subr/mergeinfo.c
  (IS_VALID_FORWARD_RANGE): New macro.
  (get_type_of_intersection): Use IS_VALID_FORWARD_RANGE() for tighter
    validation of arguments than before: it previously accepted "change 0".
  (range_intersect, range_contains): Validate arguments. Add doc strings.

* subversion/tests/libsvn_subr/mergeinfo-test.c
  (randomly_fill_rev_array, rev_array_to_rangelist): Expand doc strings.
  (test_rangelist_remove_randomly, test_rangelist_intersect_randomly): Don't
    ever include change number r0 in a merge range.

* subversion/libsvn_client/mergeinfo.c
  (filter_log_entry_with_rangelist): Ignore revision 0 because that doesn't
    represent a mergeable change.
--This line, and those below, will be ignored--

Index: subversion/libsvn_client/mergeinfo.c
===================================================================
--- subversion/libsvn_client/mergeinfo.c	(revision 923165)
+++ subversion/libsvn_client/mergeinfo.c	(working copy)
@@ -1293,24 +1293,33 @@ struct filter_log_entry_baton_t
   void *log_receiver_baton;
 
   svn_client_ctx_t *ctx;
 };
 
 /* Implements the svn_log_entry_receiver_t interface.  BATON is a
-   `struct filter_log_entry_baton_t *' */
+   `struct filter_log_entry_baton_t *'.
+
+   Call the wrapped log receiver BATON->log_receiver (with
+   BATON->log_receiver_baton), only if the log entry falls within the
+   ranges in BATON->rangelist.
+ */
 static svn_error_t *
 filter_log_entry_with_rangelist(void *baton,
                                 svn_log_entry_t *log_entry,
                                 apr_pool_t *pool)
 {
   struct filter_log_entry_baton_t *fleb = baton;
   apr_array_header_t *intersection, *this_rangelist;
 
   if (fleb->ctx->cancel_func)
     SVN_ERR(fleb->ctx->cancel_func(fleb->ctx->cancel_baton));
 
+  /* Ignore r0 because there can be no "change 0" in a merge range. */
+  if (log_entry->revision == 0)
+    return SVN_NO_ERROR;
+
   this_rangelist = svn_rangelist__initialize(log_entry->revision - 1,
                                              log_entry->revision,
                                              TRUE, pool);
 
   /* Don't consider inheritance yet, see if LOG_ENTRY->REVISION is
      fully or partially represented in BATON->RANGELIST. */
@@ -1433,13 +1442,13 @@ filter_log_entry_with_rangelist(void *ba
             log_entry->non_inheritable = FALSE;
           else
             return SVN_NO_ERROR;
         }
     }
 
-  /* Call the wrapped log reveiver which this function is filtering for. */
+  /* Call the wrapped log receiver which this function is filtering for. */
   return fleb->log_receiver(fleb->log_receiver_baton, log_entry, pool);
 }
 
 static svn_error_t *
 logs_for_mergeinfo_rangelist(const char *source_url,
                              const apr_array_header_t *merge_source_paths,
Index: subversion/tests/libsvn_subr/mergeinfo-test.c
===================================================================
--- subversion/tests/libsvn_subr/mergeinfo-test.c	(revision 922300)
+++ subversion/tests/libsvn_subr/mergeinfo-test.c	(working copy)
@@ -877,24 +877,27 @@ test_remove_rangelist(apr_pool_t *pool)
 
 #define RANDOM_REV_ARRAY_LENGTH 100
 
 /* Random number seed. */
 static apr_uint32_t random_rev_array_seed;
 
-/* Fill 3/4 of the array with 1s. */
+/* Set a random 3/4-ish of the elements of array REVS[RANDOM_REV_ARRAY_LENGTH]
+ * to TRUE and the rest to FALSE. */
 static void
 randomly_fill_rev_array(svn_boolean_t *revs)
 {
   int i;
   for (i = 0; i < RANDOM_REV_ARRAY_LENGTH; i++)
     {
       apr_uint32_t next = svn_test_rand(&random_rev_array_seed);
       revs[i] = (next < 0x40000000) ? 0 : 1;
     }
 }
 
+/* Set *RANGELIST to a rangelist representing the revisions that are marked
+ * with TRUE in the array REVS[RANDOM_REV_ARRAY_LENGTH]. */
 static svn_error_t *
 rev_array_to_rangelist(apr_array_header_t **rangelist,
                        svn_boolean_t *revs,
                        apr_pool_t *pool)
 {
   svn_stringbuf_t *buf = svn_stringbuf_create("/trunk: ", pool);
@@ -943,12 +946,15 @@ test_rangelist_remove_randomly(apr_pool_
       int j;
 
       svn_pool_clear(iterpool);
 
       randomly_fill_rev_array(first_revs);
       randomly_fill_rev_array(second_revs);
+      /* There is no change numbered "r0" */
+      first_revs[0] = FALSE;
+      second_revs[0] = FALSE;
       for (j = 0; j < RANDOM_REV_ARRAY_LENGTH; j++)
         expected_revs[j] = second_revs[j] && !first_revs[j];
 
       SVN_ERR(rev_array_to_rangelist(&first_rangelist, first_revs, iterpool));
       SVN_ERR(rev_array_to_rangelist(&second_rangelist, second_revs, iterpool));
       SVN_ERR(rev_array_to_rangelist(&expected_rangelist, expected_revs,
@@ -998,12 +1004,15 @@ test_rangelist_intersect_randomly(apr_po
       int j;
 
       svn_pool_clear(iterpool);
 
       randomly_fill_rev_array(first_revs);
       randomly_fill_rev_array(second_revs);
+      /* There is no change numbered "r0" */
+      first_revs[0] = FALSE;
+      second_revs[0] = FALSE;
       for (j = 0; j < RANDOM_REV_ARRAY_LENGTH; j++)
         expected_revs[j] = second_revs[j] && first_revs[j];
 
       SVN_ERR(rev_array_to_rangelist(&first_rangelist, first_revs, iterpool));
       SVN_ERR(rev_array_to_rangelist(&second_rangelist, second_revs, iterpool));
       SVN_ERR(rev_array_to_rangelist(&expected_rangelist, expected_revs,
Index: subversion/libsvn_subr/mergeinfo.c
===================================================================
--- subversion/libsvn_subr/mergeinfo.c	(revision 922300)
+++ subversion/libsvn_subr/mergeinfo.c	(working copy)
@@ -112,12 +112,22 @@ parse_pathname(const char **input,
 
   *input = last_colon;
 
   return SVN_NO_ERROR;
 }
 
+/* Return TRUE iff (svn_merge_range_t *) RANGE describes a valid, forward
+ * revision range.
+ *
+ * Note: The smallest valid value of RANGE->start is 0 because it is an
+ * exclusive endpoint, being one less than the revision number of the first
+ * change described by the range, and the oldest possible change is "r1" as
+ * there cannot be a change "r0". */
+#define IS_VALID_FORWARD_RANGE(range) \
+  (SVN_IS_VALID_REVNUM((range)->start) && ((range)->start < (range)->end))
+
 /* Ways in which two svn_merge_range_t can intersect or adjoin, if at all. */
 typedef enum
 {
   /* Ranges don't intersect and don't adjoin. */
   svn__no_intersection,
 
@@ -141,22 +151,14 @@ static svn_error_t *
 get_type_of_intersection(const svn_merge_range_t *r1,
                          const svn_merge_range_t *r2,
                          intersection_type_t *intersection_type)
 {
   SVN_ERR_ASSERT(r1);
   SVN_ERR_ASSERT(r2);
-
-  /* Why not use SVN_IS_VALID_REVNUM here?  Because revision 0
-     is described START = -1, END = 0.  See svn_merge_range_t. */
-  SVN_ERR_ASSERT(r1->start >= -1);
-  SVN_ERR_ASSERT(r2->start >= -1);
-
-  SVN_ERR_ASSERT(SVN_IS_VALID_REVNUM(r1->end));
-  SVN_ERR_ASSERT(SVN_IS_VALID_REVNUM(r2->end));
-  SVN_ERR_ASSERT(r1->start < r1->end);
-  SVN_ERR_ASSERT(r2->start < r2->end);
+  SVN_ERR_ASSERT(IS_VALID_FORWARD_RANGE(r1));
+  SVN_ERR_ASSERT(IS_VALID_FORWARD_RANGE(r2));
 
   if (!(r1->start <= r2->end && r2->start <= r1->end))
     *intersection_type = svn__no_intersection;
   else if (r1->start == r2->start && r1->end == r2->end)
     *intersection_type = svn__equal_intersection;
   else if (r1->end == r2->start || r2->end == r1->start)
@@ -760,26 +762,37 @@ svn_rangelist_merge(apr_array_header_t *
     }
 
   *rangelist = output;
   return SVN_NO_ERROR;
 }
 
+/* Return TRUE iff the forward revision ranges FIRST and SECOND overlap and
+ * (if CONSIDER_INHERITANCE is TRUE) have the same inheritability. */
 static svn_boolean_t
 range_intersect(const svn_merge_range_t *first, const svn_merge_range_t *second,
                 svn_boolean_t consider_inheritance)
 {
+  SVN_ERR_ASSERT_NO_RETURN(IS_VALID_FORWARD_RANGE(first));
+  SVN_ERR_ASSERT_NO_RETURN(IS_VALID_FORWARD_RANGE(second));
+
   return (first->start + 1 <= second->end)
     && (second->start + 1 <= first->end)
     && (!consider_inheritance
         || (!(first->inheritable) == !(second->inheritable)));
 }
 
+/* Return TRUE iff the forward revision range FIRST wholly contains the
+ * forward revision range SECOND and (if CONSIDER_INHERITANCE is TRUE) has
+ * the same inheritability. */
 static svn_boolean_t
 range_contains(const svn_merge_range_t *first, const svn_merge_range_t *second,
                svn_boolean_t consider_inheritance)
 {
+  SVN_ERR_ASSERT_NO_RETURN(IS_VALID_FORWARD_RANGE(first));
+  SVN_ERR_ASSERT_NO_RETURN(IS_VALID_FORWARD_RANGE(second));
+
   return (first->start <= second->start) && (second->end <= first->end)
     && (!consider_inheritance
         || (!(first->inheritable) == !(second->inheritable)));
 }
 
 /* Swap start and end fields of RANGE. */

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