Prevent psql from issuing BEGIN before ALTER SYSTEM when AUTOCOMMIT is off.

The autocommit-off mode works by issuing an implicit BEGIN just before
any command that is not already in a transaction block and is not itself
a BEGIN or other transaction-control command, nor a command that
cannot be executed inside a transaction block. This commit prevents psql
from issuing such an implicit BEGIN before ALTER SYSTEM because it's
not allowed inside a transaction block.

Backpatch to 9.4 where ALTER SYSTEM was added.

Report by Feike Steenbergen

diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index 60169a2a7dfae3213795f1aedcc9160b8951929e..c08c81366d11775381ce27e09d2a8b252aa5ca52 100644 (file)
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -1524,6 +1524,23 @@ command_no_begin(const char *query)
        return false;
    }
 
+   if (wordlen == 5 && pg_strncasecmp(query, "alter", 5) == 0)
+   {
+       query += wordlen;
+
+       query = skip_white_space(query);
+
+       wordlen = 0;
+       while (isalpha((unsigned char) query[wordlen]))
+           wordlen += PQmblen(&query[wordlen], pset.encoding);
+
+       /* ALTER SYSTEM isn't allowed in xacts */
+       if (wordlen == 6 && pg_strncasecmp(query, "system", 6) == 0)
+           return true;
+
+       return false;
+   }
+
    /*
     * Note: these tests will match DROP SYSTEM and REINDEX TABLESPACE, which
     * aren't really valid commands so we don't care much. The other four