svn commit: r1925664 - in /subversion/trunk/subversion: include/svn_io.h libsvn_client/blame.c libsvn_subr/stream.c libsvn_subr/subst.c

Author: brane
Date: Sun May 18 11:36:06 2025
New Revision: 1925664

URL: http://svn.apache.org/viewvc?rev=1925664&view=rev
Log:
When wrapping streams, set only those handlers on the wrapper that are
supported by the source stream, otherwise the svn_stream_supports_*()
predicates do not work as expected. And for consistency, expose the "stream
supports seek" predicate explicitly in the streams API instead of hiding it
behind "supports reset".

* subversion/include/svn_io.h
  (svn_stream_supports_seek): New function.
* subversion/libsvn_subr/stream.c
  (svn_stream_supports_seek): Implemented here.
  (svn_stream_supports_reset): This is now just a wrapper for the above.
  (svn_stream_disown): Add the partial read, mark and seek handlers only
   if the original wrapped stream supports them.
  (svn_stream_checksummed2): Likewise.

* subversion/libsvn_subr/subst.c
  (stream_translated): Use separate checks to decide when to add the
   mark and seek stream handlers.

* subversion/libsvn_client/blame.c
  (file_rev_handler): Let's just agree to not disown NULL streams, shall we?
   We have a perfectly good empty stream that can be disowned without
   dereferencing a null pointer.

Modified:
    subversion/trunk/subversion/include/svn_io.h
    subversion/trunk/subversion/libsvn_client/blame.c
    subversion/trunk/subversion/libsvn_subr/stream.c
    subversion/trunk/subversion/libsvn_subr/subst.c

Modified: subversion/trunk/subversion/include/svn_io.h
URL: http://svn.apache.org/viewvc/subversion/trunk/subversion/include/svn_io.h?rev=1925664&r1=1925663&r2=1925664&view=diff
==============================================================================
--- subversion/trunk/subversion/include/svn_io.h (original)
+++ subversion/trunk/subversion/include/svn_io.h Sun May 18 11:36:06 2025
@@ -1385,6 +1385,14 @@ svn_stream_reset(svn_stream_t *stream);
 svn_boolean_t
 svn_stream_supports_mark(svn_stream_t *stream);
 
+/** Returns @c TRUE if the generic @a stream supports svn_stream_seek().
+ *
+ * @see svn_stream_seek()
+ * @since New in 1.15.
+ */
+svn_boolean_t
+svn_stream_supports_seek(svn_stream_t *stream);
+
 /** Returns @c TRUE if the generic @a stream supports svn_stream_reset().
  *
  * @see svn_stream_reset()

Modified: subversion/trunk/subversion/libsvn_client/blame.c
URL: http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_client/blame.c?rev=1925664&r1=1925663&r2=1925664&view=diff
==============================================================================
--- subversion/trunk/subversion/libsvn_client/blame.c (original)
+++ subversion/trunk/subversion/libsvn_client/blame.c Sun May 18 11:36:06 2025
@@ -499,8 +499,7 @@ file_rev_handler(void *baton, const char
     SVN_ERR(svn_stream_open_readonly(&delta_baton->source_stream, frb->last_filename,
                                      frb->currpool, pool));
   else
-    /* Means empty stream below. */
-    delta_baton->source_stream = NULL;
+    delta_baton->source_stream = svn_stream_empty(pool);
   last_stream = svn_stream_disown(delta_baton->source_stream, pool);
 
   if (frb->include_merged_revisions && !merged_revision)

Modified: subversion/trunk/subversion/libsvn_subr/stream.c
URL: http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_subr/stream.c?rev=1925664&r1=1925663&r2=1925664&view=diff
==============================================================================
--- subversion/trunk/subversion/libsvn_subr/stream.c (original)
+++ subversion/trunk/subversion/libsvn_subr/stream.c Sun May 18 11:36:06 2025
@@ -236,11 +236,17 @@ svn_stream_supports_mark(svn_stream_t *s
 }
 
 svn_boolean_t
-svn_stream_supports_reset(svn_stream_t *stream)
+svn_stream_supports_seek(svn_stream_t *stream)
 {
   return stream->seek_fn != NULL;
 }
 
+svn_boolean_t
+svn_stream_supports_reset(svn_stream_t *stream)
+{
+  return svn_stream_supports_seek(stream);
+}
+
 svn_error_t *
 svn_stream_mark(svn_stream_t *stream, svn_stream_mark_t **mark,
                 apr_pool_t *pool)
@@ -658,12 +664,16 @@ svn_stream_t *
 svn_stream_disown(svn_stream_t *stream, apr_pool_t *pool)
 {
   svn_stream_t *s = svn_stream_create(stream, pool);
+  const svn_read_fn_t read_handler =
+    svn_stream_supports_partial_read(stream) ? read_handler_disown : NULL;
 
-  svn_stream_set_read2(s, read_handler_disown, read_full_handler_disown);
+  svn_stream_set_read2(s, read_handler, read_full_handler_disown);
   svn_stream_set_skip(s, skip_handler_disown);
   svn_stream_set_write(s, write_handler_disown);
-  svn_stream_set_mark(s, mark_handler_disown);
-  svn_stream_set_seek(s, seek_handler_disown);
+  if (svn_stream_supports_mark(stream))
+    svn_stream_set_mark(s, mark_handler_disown);
+  if (svn_stream_supports_seek(stream))
+    svn_stream_set_seek(s, seek_handler_disown);
   svn_stream_set_data_available(s, data_available_disown);
   svn_stream_set_readline(s, readline_handler_disown);
 
@@ -1490,6 +1500,8 @@ svn_stream_checksummed2(svn_stream_t *st
 {
   svn_stream_t *s;
   struct checksum_stream_baton *baton;
+  const svn_read_fn_t read_handler =
+    svn_stream_supports_partial_read(stream) ? read_handler_checksum : NULL;
 
   if (read_checksum == NULL && write_checksum == NULL)
     return stream;
@@ -1512,7 +1524,7 @@ svn_stream_checksummed2(svn_stream_t *st
   baton->pool = pool;
 
   s = svn_stream_create(baton, pool);
-  svn_stream_set_read2(s, read_handler_checksum, read_full_handler_checksum);
+  svn_stream_set_read2(s, read_handler, read_full_handler_checksum);
   svn_stream_set_write(s, write_handler_checksum);
   svn_stream_set_data_available(s, data_available_handler_checksum);
   svn_stream_set_close(s, close_handler_checksum);

Modified: subversion/trunk/subversion/libsvn_subr/subst.c
URL: http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_subr/subst.c?rev=1925664&r1=1925663&r2=1925664&view=diff
==============================================================================
--- subversion/trunk/subversion/libsvn_subr/subst.c (original)
+++ subversion/trunk/subversion/libsvn_subr/subst.c Sun May 18 11:36:06 2025
@@ -1542,10 +1542,9 @@ stream_translated(svn_stream_t *stream,
       svn_stream_set_write(s, translated_stream_write);
       svn_stream_set_close(s, translated_stream_close);
       if (svn_stream_supports_mark(stream))
-        {
-          svn_stream_set_mark(s, translated_stream_mark);
-          svn_stream_set_seek(s, translated_stream_seek);
-        }
+        svn_stream_set_mark(s, translated_stream_mark);
+      if (svn_stream_supports_seek(stream))
+        svn_stream_set_seek(s, translated_stream_seek);
 
       return s;
     }