libsysprof: add a SysprofTracefdConsumer

This is meant to simplify the proxying of data from a tracefd into the
destination capture.

src/libsysprof/sysprof-tracefd-consumer.c

@@ -0,0 +1,116 @@
+/* sysprof-tracefd-consumer.c
+ *
+ * Copyright 2023 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "config.h"
+
+#include <glib/gstdio.h>
+
+#include "sysprof-instrument-private.h"
+#include "sysprof-recording-private.h"
+#include "sysprof-tracefd-consumer.h"
+
+struct _SysprofTracefdConsumer
+{
+  SysprofInstrument parent_instance;
+  int trace_fd;
+};
+
+struct _SysprofTracefdConsumerClass
+{
+  SysprofInstrumentClass parent_class;
+};
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC (SysprofCaptureReader, sysprof_capture_reader_unref)
+
+G_DEFINE_FINAL_TYPE (SysprofTracefdConsumer, sysprof_tracefd_consumer, SYSPROF_TYPE_INSTRUMENT)
+
+static DexFuture *
+sysprof_tracefd_consumer_augment (SysprofInstrument *instrument,
+                                  SysprofRecording  *recording)
+{
+  SysprofTracefdConsumer *self = (SysprofTracefdConsumer *)instrument;
+  g_autoptr(SysprofCaptureReader) reader = NULL;
+  SysprofCaptureWriter *writer;
+
+  g_assert (SYSPROF_IS_TRACEFD_CONSUMER (self));
+  g_assert (SYSPROF_IS_RECORDING (recording));
+
+  if (self->trace_fd == -1)
+    return dex_future_new_for_boolean (TRUE);
+
+  writer = _sysprof_recording_writer (recording);
+
+  lseek (self->trace_fd, 0, SEEK_SET);
+
+  if ((reader = sysprof_capture_reader_new_from_fd (g_steal_fd (&self->trace_fd))))
+    sysprof_capture_writer_cat (writer, reader);
+
+  return dex_future_new_for_boolean (TRUE);
+}
+
+static void
+sysprof_tracefd_consumer_finalize (GObject *object)
+{
+  SysprofTracefdConsumer *self = (SysprofTracefdConsumer *)object;
+
+  g_clear_fd (&self->trace_fd, NULL);
+
+  G_OBJECT_CLASS (sysprof_tracefd_consumer_parent_class)->finalize (object);
+}
+
+static void
+sysprof_tracefd_consumer_class_init (SysprofTracefdConsumerClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  SysprofInstrumentClass *instrument_class = SYSPROF_INSTRUMENT_CLASS (klass);
+
+  object_class->finalize = sysprof_tracefd_consumer_finalize;
+
+  instrument_class->augment = sysprof_tracefd_consumer_augment;
+}
+
+static void
+sysprof_tracefd_consumer_init (SysprofTracefdConsumer *self)
+{
+  self->trace_fd = -1;
+}
+
+/**
+ * sysprof_tracefd_consumer_new:
+ * @trace_fd: a file-descriptor to read from
+ *
+ * This function will take ownership of @trace_fd, If you need to keep a
+ * copy of your FD then it is suggested you use `dup()` to copy the file
+ * descriptor.
+ *
+ * Returns: (transfer full): a #SysprofInstrument
+ */
+SysprofInstrument *
+sysprof_tracefd_consumer_new (int trace_fd)
+{
+  SysprofTracefdConsumer *self;
+
+  g_return_val_if_fail (trace_fd >= -1, NULL);
+
+  self = g_object_new (SYSPROF_TYPE_TRACEFD_CONSUMER, NULL);
+  self->trace_fd = trace_fd;
+
+  return SYSPROF_INSTRUMENT (self);
+}