DBD::SQLite: empty or comment-only statements shouldn't die. issue spotted by tokuhirom++

Changes

@@ -1,5 +1,9 @@
 Changes for Perl extension DBD-SQLite
 
+1.28_02 to be released
+    - Now empty (or comment only) statements won't cause segv
+      or "not an error" errors. Spotted by TOKUHIROM. (ISHIGAKI)
+
 1.28_01 Tue 22 Dec 2009
     - Updated to SQLite 3.6.21 (ISHIGAKI)
     - silence warnings on HP-UX (HMBRAND)

dbdimp.c

@@ -415,10 +415,12 @@ sqlite_st_prepare(SV *sth, imp_sth_t *imp_sth, char *statement, SV *attribs)
       return FALSE; /* -> undef in lib/DBD/SQLite.pm */
     }
 
+#if 0
     if (*statement == '\0') {
       sqlite_error(sth, -2, "attempt to prepare empty statement");
       return FALSE; /* -> undef in lib/DBD/SQLite.pm */
     }
+#endif
 
     sqlite_trace(sth, imp_sth, 3, form("prepare statement: %s", statement));
     imp_sth->nrow      = -1;
@@ -467,6 +469,8 @@ sqlite_st_execute(SV *sth, imp_sth_t *imp_sth)
         return -2; /* -> undef in SQLite.xsi */
     }
 
+    if (!imp_sth->stmt) return 0;
+
     croak_if_db_is_null();
     croak_if_stmt_is_null();
 
@@ -575,6 +579,7 @@ sqlite_st_execute(SV *sth, imp_sth_t *imp_sth)
             }
             sqlite_error(sth, imp_sth->retval, sqlite3_errmsg(imp_dbh->db));
             if (sqlite3_reset(imp_sth->stmt) != SQLITE_OK) {
+sqlite_trace(sth, imp_sth, 3, "RESET ERROR!");
                 sqlite_error(sth, imp_sth->retval, sqlite3_errmsg(imp_dbh->db));
             }
             return -5; /* -> undef in SQLite.xsi */

t/38_empty_statement.t

@@ -0,0 +1,45 @@
+#!/usr/bin/perl
+
+use strict;
+BEGIN {
+	$|  = 1;
+	$^W = 1;
+}
+
+use t::lib::Test qw/connect_ok/;
+use Test::More;
+use Test::NoWarnings;
+
+plan tests => 8;
+
+my $dbh = connect_ok( RaiseError => 1 );
+
+eval { $dbh->do("\n") };
+ok !$@, "empty statement does not spit a warning";
+diag $@ if $@;
+
+eval { $dbh->do("     ") };
+ok !$@, "empty statement does not spit a warning";
+diag $@ if $@;
+
+eval { $dbh->do("") };
+ok !$@, "empty statement does not spit a warning";
+diag $@ if $@;
+
+eval { $dbh->do("/* everything in a comment */") };
+ok !$@, "empty statement does not spit a warning";
+diag $@ if $@;
+
+eval { $dbh->do("-- everything in a comment") };
+ok !$@, "empty statement does not spit a warning";
+diag $@ if $@;
+
+{
+    # We know this causes "Use of uninitialized value
+    # in subroutine entry" warning, but anyway this
+    # shouldn't die, either.
+    local $SIG{__WARN__};
+    eval { $dbh->do(undef) };
+    ok !$@, "undef statement does spit a warning, but does not die anyway";
+    diag $@ if $@;
+}