Make sure we close all database file descriptors.

Iterate through the names returned by sqlite3_db_name which will
include names given via "ATTACH DATABASE ... AS" and any temp
databases.

Author: flavorjones

ext/sqlite3/database.c

@@ -22,17 +22,20 @@ close_or_discard_db(sqlite3RubyPtr ctx)
         } else {
             // This is an open connection carried across a fork().
             // "Discard" it. See adr/2024-09-fork-safety.md
+            const char *db_name;
             sqlite3_file *sfile;
-            int status;
+            int status, j_db = 0;
 
             rb_warning("An open sqlite database connection was inherited from a forked process and "
                        "is being discarded. This is a memory leak. If possible, please close all sqlite "
                        "database connections before forking.");
 
-            // close the open file descriptors
-            status = sqlite3_file_control(ctx->db, NULL, SQLITE_FCNTL_FILE_POINTER, &sfile);
-            if (status == 0 && sfile->pMethods != NULL) {
-                sfile->pMethods->xClose(sfile);
+            while ((db_name = sqlite3_db_name(ctx->db, j_db)) != NULL) {
+                status = sqlite3_file_control(ctx->db, db_name, SQLITE_FCNTL_FILE_POINTER, &sfile);
+                if (status == 0 && sfile->pMethods != NULL) {
+                    sfile->pMethods->xClose(sfile);
+                }
+                j_db++;
             }
 
             status = sqlite3_file_control(ctx->db, NULL, SQLITE_FCNTL_JOURNAL_POINTER, &sfile);

test/test_database.rb

@@ -730,7 +730,9 @@ def test_discard_a_connection
         read, write = IO.pipe
 
         db = SQLite3::Database.new("test.db")
+        db.execute("attach database 'test.db' as 'foo';") # exercise sqlite3_db_name()
         Process.fork do
+          read.close
           $stderr = StringIO.new
 
           result = db.close
@@ -740,20 +742,23 @@ def test_discard_a_connection
           write.write($stderr.string)
 
           write.close
-          read.close
           exit!
         end
+        write.close
+
+        assert1, assert2, *stderr = *read.readlines
+        read.close
+
+        assert_equal("ok", assert1.chomp, "return value was not the database")
+        assert_equal("ok", assert2.chomp, "closed? did not return true")
 
-        assert_equal("ok", read.readline.chomp, "return value was not the database")
-        assert_equal("ok", read.readline.chomp, "closed? did not return true")
+        assert_equal(1, stderr.count, "unexpected output on stderr: #{stderr.inspect}")
         assert_match(
           /warning: An open sqlite database connection was inherited from a forked process/,
-          read.readline,
+          stderr.first,
           "expected warning was not emitted"
         )
 
-        write.close
-        read.close
       ensure
         db.close
         FileUtils.rm_f("test.db")