Fix for issue 816
* subversion/libsvn_client/log.c (svn_client_log): Tests added to 
ensure version numbers passed to it are between 0 and head inclusive
Throws SVN_ERR_CLIENT_BAD_REVISION if new tests fail. 
* subversion/include/svn_client.h (svn_client_log comment text):
amended to mention the new revision number tests. 

Index: subversion/libsvn_client/log.c
===================================================================
--- subversion/libsvn_client/log.c
+++ subversion/libsvn_client/log.c	Sat Jul 27 18:52:04 2002
@@ -62,9 +62,11 @@
   const char *URL;
   const char *base_name = NULL;
   apr_array_header_t *condensed_targets;
-  svn_revnum_t start_revnum, end_revnum;
+  svn_revnum_t start_revnum, end_revnum, head_revnum;
   svn_error_t *err;
+  svn_client_revision_t head;
 
+  head.kind = svn_client_revision_head;
   if ((start->kind == svn_client_revision_unspecified)
       || (end->kind == svn_client_revision_unspecified))
     {
@@ -73,7 +75,7 @@
          "svn_client_log: caller failed to supply revision");
     }
 
-  start_revnum = end_revnum = SVN_INVALID_REVNUM;
+  start_revnum = end_revnum = head_revnum = SVN_INVALID_REVNUM;
 
   path = (APR_ARRAY_IDX(targets, 0, const char *));
 
@@ -151,6 +153,51 @@
            (&start_revnum, ra_lib, session, start, base_name, pool));
   SVN_ERR (svn_client__get_revision_number
            (&end_revnum, ra_lib, session, end, base_name, pool));
+  SVN_ERR (svn_client__get_revision_number
+           (&head_revnum, ra_lib, session, &head, base_name, pool));
+
+  /* Here, we check that the versions input were valid.  If not, we
+     return an error */
+  if (start_revnum > head_revnum && end_revnum > head_revnum)
+    {
+      err = svn_error_createf(SVN_ERR_CLIENT_BAD_REVISION, 0, NULL, pool,
+                              "Both revision numbers too high: %"
+                              SVN_REVNUM_T_FMT " and %" SVN_REVNUM_T_FMT
+                              ".  Head is %" SVN_REVNUM_T_FMT ".",
+                              start_revnum, end_revnum, head_revnum);
+      return err;
+    }
+
+  if (start_revnum > head_revnum || end_revnum > head_revnum)
+    {
+      err = svn_error_createf(SVN_ERR_CLIENT_BAD_REVISION, 0, NULL, pool,
+                              "Revision number too high: %" SVN_REVNUM_T_FMT
+                              ".  Head is %" SVN_REVNUM_T_FMT ".",
+                              (start_revnum > end_revnum)? \
+                              start_revnum:end_revnum,
+                              head_revnum);
+      return err;
+    }
+
+  if (start_revnum < 0 && end_revnum < 0)
+    {
+      err = svn_error_createf(SVN_ERR_CLIENT_BAD_REVISION, 0, NULL, pool,
+                              "Both revision numbers are negative: %"
+                              SVN_REVNUM_T_FMT " and %" SVN_REVNUM_T_FMT
+                              ".  Negative revision number are not allowed.",
+                              start_revnum, end_revnum);
+      return err;
+    }
+
+  if (start_revnum < 0 || end_revnum < 0)
+    {
+      err = svn_error_createf(SVN_ERR_CLIENT_BAD_REVISION, 0, NULL, pool,
+                              "Revision number negative: %" SVN_REVNUM_T_FMT
+                              ".  Negative revision numbers are not allowed.",
+                              (start_revnum < end_revnum)? \
+                              start_revnum:end_revnum);
+      return err;
+    }
 
   err = ra_lib->get_log (session,
                          condensed_targets,
Index: subversion/include/svn_client.h
===================================================================
--- subversion/include/svn_client.h
+++ subversion/include/svn_client.h	Sat Jul 27 17:11:41 2002
@@ -556,6 +556,13 @@
    If START->kind or END->kind is svn_client_revision_unspecified,
    return the error SVN_ERR_CLIENT_BAD_REVISION.
 
+   If the version number returned after canonicalising either START or
+   FINISH is greater than that of head, return the error
+   SVN_ERR_CLIENT_BAD_REVISION
+
+   If the version number returned after canonicalising either START or
+   FINISH is negative, return the error SVN_ERR_CLIENT_BAD_REVISION
+
    Use POOL for any temporary allocation.
 
    Special case for repositories at revision 0: