pg_upgrade: suppress creation of delete script

Suppress creation of the pg_upgrade delete script when the new data
directory is inside the old data directory.

Reported-by: IRC
Backpatch-through: 9.3, where delete script tests were added

diff --git a/contrib/pg_upgrade/check.c b/contrib/pg_upgrade/check.c
index d6afb53e2a2503bc512570889807d337c0eb012d..0e1a1605a024ba3af1c0cf6a79c9b36a09eaad68 100644 (file)
--- a/contrib/pg_upgrade/check.c
+++ b/contrib/pg_upgrade/check.c
@@ -263,9 +263,10 @@ output_completion_banner(char *analyze_script_file_name,
               deletion_script_file_name);
    else
        pg_log(PG_REPORT,
-              "Could not create a script to delete the old cluster's data\n"
-         "files because user-defined tablespaces exist in the old cluster\n"
-       "directory.  The old cluster's contents must be deleted manually.\n");
+         "Could not create a script to delete the old cluster's data files\n"
+         "because user-defined tablespaces or the new cluster's data directory\n"
+         "exist in the old cluster directory.  The old cluster's contents must\n"
+         "be deleted manually.\n");
 }
 
 
@@ -656,17 +657,34 @@ create_script_for_old_cluster_deletion(char **deletion_script_file_name)
 {
    FILE       *script = NULL;
    int         tblnum;
-   char        old_cluster_pgdata[MAXPGPATH];
+   char        old_cluster_pgdata[MAXPGPATH], new_cluster_pgdata[MAXPGPATH];
 
    *deletion_script_file_name = psprintf("delete_old_cluster.%s", SCRIPT_EXT);
 
+   strlcpy(old_cluster_pgdata, old_cluster.pgdata, MAXPGPATH);
+   canonicalize_path(old_cluster_pgdata);
+
+   strlcpy(new_cluster_pgdata, new_cluster.pgdata, MAXPGPATH);
+   canonicalize_path(new_cluster_pgdata);
+
+   /* Some people put the new data directory inside the old one. */
+   if (path_is_prefix_of_path(old_cluster_pgdata, new_cluster_pgdata))
+   {
+       pg_log(PG_WARNING,
+          "\nWARNING:  new data directory should not be inside the old data directory, e.g. %s\n", old_cluster_pgdata);
+
+       /* Unlink file in case it is left over from a previous run. */
+       unlink(*deletion_script_file_name);
+       pg_free(*deletion_script_file_name);
+       *deletion_script_file_name = NULL;
+       return;
+   }
+
    /*
     * Some users (oddly) create tablespaces inside the cluster data
     * directory.  We can't create a proper old cluster delete script in that
     * case.
     */
-   strlcpy(old_cluster_pgdata, old_cluster.pgdata, MAXPGPATH);
-   canonicalize_path(old_cluster_pgdata);
    for (tblnum = 0; tblnum < os_info.num_old_tablespaces; tblnum++)
    {
        char        old_tablespace_dir[MAXPGPATH];