[Bug-tar] [PATCH] Refuse to create archive for non-existent members

[Connor Behan]

* src/create.c (dump_file0): Open archive when the existence check is
first passed.
(create_archive): Close archive if the existence check was passed at
least once.
---
 src/create.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/src/create.c b/src/create.c
index e14e13d..a56f28f 100644
--- a/src/create.c
+++ b/src/create.c
@@ -1327,9 +1327,6 @@ create_archive (void)
 
   trivial_link_count = name_count <= 1 && ! dereference_option;
 
-  open_archive (ACCESS_WRITE);
-  buffer_write_global_xheader ();
-
   if (incremental_option)
     {
       size_t buffer_size = 1000;
@@ -1405,11 +1402,15 @@ create_archive (void)
          dump_file (0, name, name);
     }
 
-  write_eot ();
-  close_archive ();
-  finish_deferred_unlinks ();
-  if (listed_incremental_option)
-    write_directory_file ();
+  /* If none of the passed files existed, the archive was never opened.  */
+  if (archive > 0)
+    {
+      write_eot ();
+      close_archive ();
+      finish_deferred_unlinks ();
+      if (listed_incremental_option)
+        write_directory_file ();
+    }
 }
 
 
@@ -1676,6 +1677,13 @@ dump_file0 (struct tar_stat_info *st, char const *name, 
char const *p)
       return;
     }
 
+  /* The archive should be opened when we first verify that it will not be 
empty.  */
+  if (archive <= 0)
+    {
+      open_archive (ACCESS_WRITE);
+      buffer_write_global_xheader ();
+    }
+
   st->archive_file_size = original_size = st->stat.st_size;
   st->atime = get_stat_atime (&st->stat);
   st->mtime = get_stat_mtime (&st->stat);
-- 
1.8.4