/*
* call-seq:
* conn.trace( stream ) -> nil
*
* Enables tracing message passing between backend. The
* trace message will be written to the stream _stream_,
* which must implement a method +fileno+ that returns
* a writable file descriptor.
*/
static VALUE
pgconn_trace(VALUE self, VALUE stream)
{
VALUE fileno;
FILE *new_fp;
int old_fd, new_fd;
VALUE new_file;
if(rb_respond_to(stream,rb_intern("fileno")) == Qfalse)
rb_raise(rb_eArgError, "stream does not respond to method: fileno");
fileno = rb_funcall(stream, rb_intern("fileno"), 0);
if(fileno == Qnil)
rb_raise(rb_eArgError, "can't get file descriptor from stream");
/* Duplicate the file descriptor and re-open
* it. Then, make it into a ruby File object
* and assign it to an instance variable.
* This prevents a problem when the File
* object passed to this function is closed
* before the connection object is. */
old_fd = NUM2INT(fileno);
new_fd = dup(old_fd);
new_fp = fdopen(new_fd, "w");
if(new_fp == NULL)
rb_raise(rb_eArgError, "stream is not writable");
new_file = rb_funcall(rb_cIO, rb_intern("new"), 1, INT2NUM(new_fd));
rb_iv_set(self, "@trace_stream", new_file);
PQtrace(get_pgconn(self), new_fp);
return Qnil;
}