Don’t UTF8-flag PVs that aren’t valid UTF-8.

Issue #78

dbdimp.c

@@ -272,7 +272,7 @@ stacked_sv_from_sqlite3_value(pTHX_ sqlite3_value *value, int is_unicode)
         len = sqlite3_value_bytes(value);
         sv = newSVpvn((const char *)sqlite3_value_text(value), len);
         if (is_unicode) {
-            SvUTF8_on(sv);
+            DBD_SQLITE_UTF8_DECODE(sv);
         }
         return sv_2mortal(sv);
     case SQLITE_BLOB:
@@ -1229,7 +1229,7 @@ sqlite_st_fetch(SV *sth, imp_sth_t *imp_sth)
                 }
                 sv_setpvn(AvARRAY(av)[i], val, len);
                 if (imp_dbh->unicode) {
-                    SvUTF8_on(AvARRAY(av)[i]);
+                    DBD_SQLITE_UTF8_DECODE(AvARRAY(av)[i]);
                 } else {
                     SvUTF8_off(AvARRAY(av)[i]);
                 }
@@ -1405,7 +1405,7 @@ sqlite_st_FETCH_attrib(SV *sth, imp_sth_t *imp_sth, SV *keysv)
                 /*    fieldname = ++dot;     */
                 SV *sv_fieldname = newSVpv(fieldname, 0);
                 if (imp_dbh->unicode)
-                    SvUTF8_on(sv_fieldname);
+                    DBD_SQLITE_UTF8_DECODE(sv_fieldname);
                 av_store(av, n, sv_fieldname);
             }
         }
@@ -2125,9 +2125,9 @@ sqlite_db_collation_dispatcher_utf8(void *func, int len1, const void *string1,
     SAVETMPS;
     PUSHMARK(SP);
     sv1 = newSVpvn(string1, len1);
-    SvUTF8_on(sv1);
+    DBD_SQLITE_UTF8_DECODE(sv1);
     sv2 = newSVpvn(string2, len2);
-    SvUTF8_on(sv2);
+    DBD_SQLITE_UTF8_DECODE(sv2);
     XPUSHs( sv_2mortal( sv1 ) );
     XPUSHs( sv_2mortal( sv2 ) );
     PUTBACK;

dbdimp.h

@@ -22,6 +22,12 @@ typedef struct {
 #define sqlite3_int64 sqlite_int64
 #endif
 
+#define DBD_SQLITE_UTF8_DECODE(sv) ( \
+    is_utf8_string((U8*) SvPVX(sv), SvCUR(sv)) \
+        ? SvUTF8_on(sv) \
+        : warn("Received invalid UTF-8 from SQLite; cannot decode!") \
+)
+
 /* A linked list of statements prepared by this module */
 typedef struct stmt_list_s stmt_list_s;
 

t/69_unicode_no_invalid_utf8.t

@@ -0,0 +1,49 @@
+# This is a test for correct handling of upgraded strings without
+# the sqlite_unicode parameter.
+
+use strict;
+use warnings;
+use lib "t/lib";
+use SQLiteTest;
+use Test::More;
+use if -d ".git", "Test::FailWarnings";
+
+{
+    my $dbh = connect_ok(
+        dbfile => 'foo',
+        RaiseError => 1,
+    );
+
+    my $tbl_name = "\xe9p\xe9e";
+    my $str = "CREATE TABLE $tbl_name ( col1 TEXT )";
+    $dbh->do($str);
+
+    $dbh->{'sqlite_unicode'} = 1;
+
+    my @warnings;
+    my $master_ar = do {
+        local $SIG{'__WARN__'} = sub { push @warnings, @_ };
+        $dbh->selectall_arrayref('SELECT * FROM sqlite_master', { Slice => {} });
+    };
+
+    for my $key ( sort keys %{ $master_ar->[0] } ) {
+        ok(
+            utf8::valid($master_ar->[0]{$key}),
+            "$key is utf8::valid",
+        );
+    }
+
+    is(
+        $master_ar->[0]{'name'},
+        $tbl_name,
+        '`name`',
+    );
+
+    like(
+        $warnings[0],
+        qr<UTF-8>,
+        'warning about invalid UTF-8',
+    );
+}
+
+done_testing;