Renaming of ctf (the trace format) files

1 files changed, 1730 insertions, 0 deletions

diff --git a/gdb/tracectf.c b/gdb/tracectf.c
new file mode 100644
index 0000000..758dd56
--- /dev/null
+++ b/gdb/tracectf.c
@@ -0,0 +1,1730 @@
+/* CTF format support.
+
+   Copyright (C) 2012-2019 Free Software Foundation, Inc.
+   Contributed by Hui Zhu <hui_zhu@mentor.com>
+   Contributed by Yao Qi <yao@codesourcery.com>
+
+   This file is part of GDB.
+
+   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/>.  */
+
+#include "defs.h"
+#include "tracectf.h"
+#include "tracepoint.h"
+#include "regcache.h"
+#include <sys/stat.h>
+#include "exec.h"
+#include "completer.h"
+#include "inferior.h"
+#include "gdbthread.h"
+#include "tracefile.h"
+#include <ctype.h>
+#include <algorithm>
+#include "gdbsupport/filestuff.h"
+#include "gdbarch.h"
+
+/* The CTF target.  */
+
+static const target_info ctf_target_info = {
+  "ctf",
+  N_("CTF file"),
+  N_("(Use a CTF directory as a target.\n\
+Specify the filename of the CTF directory.")
+};
+
+class ctf_target final : public tracefile_target
+{
+public:
+  const target_info &info () const override
+  { return ctf_target_info; }
+
+  void close () override;
+  void fetch_registers (struct regcache *, int) override;
+  enum target_xfer_status xfer_partial (enum target_object object,
+						const char *annex,
+						gdb_byte *readbuf,
+						const gdb_byte *writebuf,
+						ULONGEST offset, ULONGEST len,
+						ULONGEST *xfered_len) override;
+  void files_info () override;
+  int trace_find (enum trace_find_type type, int num,
+			  CORE_ADDR addr1, CORE_ADDR addr2, int *tpp) override;
+  bool get_trace_state_variable_value (int tsv, LONGEST *val) override;
+  traceframe_info_up traceframe_info () override;
+};
+
+/* GDB saves trace buffers and other information (such as trace
+   status) got from the remote target into Common Trace Format (CTF).
+   The following types of information are expected to save in CTF:
+
+   1. The length (in bytes) of register cache.  Event "register" will
+   be defined in metadata, which includes the length.
+
+   2. Trace status.  Event "status" is defined in metadata, which
+   includes all aspects of trace status.
+
+   3. Uploaded trace variables.  Event "tsv_def" is defined in
+   metadata, which is about all aspects of a uploaded trace variable.
+   Uploaded tracepoints.   Event "tp_def" is defined in meta, which
+   is about all aspects of an uploaded tracepoint.  Note that the
+   "sequence" (a CTF type, which is a dynamically-sized array.) is
+   used for "actions" "step_actions" and "cmd_strings".
+
+   4. Trace frames.  Each trace frame is composed by several blocks
+   of different types ('R', 'M', 'V').  One trace frame is saved in
+   one CTF packet and the blocks of this frame are saved as events.
+   4.1: The trace frame related information (such as the number of
+   tracepoint associated with this frame) is saved in the packet
+   context.
+   4.2: The block 'M', 'R' and 'V' are saved in event "memory",
+   "register" and "tsv" respectively.
+   4.3: When iterating over events, babeltrace can't tell iterator
+   goes to a new packet, so we need a marker or anchor to tell GDB
+   that iterator goes into a new packet or frame.  We define event
+   "frame".  */
+
+#define CTF_MAGIC		0xC1FC1FC1
+#define CTF_SAVE_MAJOR		1
+#define CTF_SAVE_MINOR		8
+
+#define CTF_METADATA_NAME	"metadata"
+#define CTF_DATASTREAM_NAME	"datastream"
+
+/* Reserved event id.  */
+
+#define CTF_EVENT_ID_REGISTER 0
+#define CTF_EVENT_ID_TSV 1
+#define CTF_EVENT_ID_MEMORY 2
+#define CTF_EVENT_ID_FRAME 3
+#define CTF_EVENT_ID_STATUS 4
+#define CTF_EVENT_ID_TSV_DEF 5
+#define CTF_EVENT_ID_TP_DEF 6
+
+#define CTF_PID (2)
+
+/* The state kept while writing the CTF datastream file.  */
+
+struct trace_write_handler
+{
+  /* File descriptor of metadata.  */
+  FILE *metadata_fd;
+  /* File descriptor of traceframes.  */
+  FILE *datastream_fd;
+
+  /* This is the content size of the current packet.  */
+  size_t content_size;
+
+  /* This is the start offset of current packet.  */
+  long packet_start;
+};
+
+/* Write metadata in FORMAT.  */
+
+static void
+ctf_save_write_metadata (struct trace_write_handler *handler,
+			 const char *format, ...)
+  ATTRIBUTE_PRINTF (2, 3);
+
+static void
+ctf_save_write_metadata (struct trace_write_handler *handler,
+			 const char *format, ...)
+{
+  va_list args;
+
+  va_start (args, format);
+  if (vfprintf (handler->metadata_fd, format, args) < 0)
+    error (_("Unable to write metadata file (%s)"),
+	     safe_strerror (errno));
+  va_end (args);
+}
+
+/* Write BUF of length SIZE to datastream file represented by
+   HANDLER.  */
+
+static int
+ctf_save_write (struct trace_write_handler *handler,
+		const gdb_byte *buf, size_t size)
+{
+  if (fwrite (buf, size, 1, handler->datastream_fd) != 1)
+    error (_("Unable to write file for saving trace data (%s)"),
+	   safe_strerror (errno));
+
+  handler->content_size += size;
+
+  return 0;
+}
+
+/* Write a unsigned 32-bit integer to datastream file represented by
+   HANDLER.  */
+
+#define ctf_save_write_uint32(HANDLER, U32) \
+  ctf_save_write (HANDLER, (gdb_byte *) &U32, 4)
+
+/* Write a signed 32-bit integer to datastream file represented by
+   HANDLER.  */
+
+#define ctf_save_write_int32(HANDLER, INT32) \
+  ctf_save_write ((HANDLER), (gdb_byte *) &(INT32), 4)
+
+/* Set datastream file position.  Update HANDLER->content_size
+   if WHENCE is SEEK_CUR.  */
+
+static int
+ctf_save_fseek (struct trace_write_handler *handler, long offset,
+		int whence)
+{
+  gdb_assert (whence != SEEK_END);
+  gdb_assert (whence != SEEK_SET
+	      || offset <= handler->content_size + handler->packet_start);
+
+  if (fseek (handler->datastream_fd, offset, whence))
+    error (_("Unable to seek file for saving trace data (%s)"),
+	   safe_strerror (errno));
+
+  if (whence == SEEK_CUR)
+    handler->content_size += offset;
+
+  return 0;
+}
+
+/* Change the datastream file position to align on ALIGN_SIZE,
+   and write BUF to datastream file.  The size of BUF is SIZE.  */
+
+static int
+ctf_save_align_write (struct trace_write_handler *handler,
+		      const gdb_byte *buf,
+		      size_t size, size_t align_size)
+{
+  long offset
+    = (align_up (handler->content_size, align_size)
+       - handler->content_size);
+
+  if (ctf_save_fseek (handler, offset, SEEK_CUR))
+    return -1;
+
+  if (ctf_save_write (handler, buf, size))
+    return -1;
+
+  return 0;
+}
+
+/* Write events to next new packet.  */
+
+static void
+ctf_save_next_packet (struct trace_write_handler *handler)
+{
+  handler->packet_start += (handler->content_size + 4);
+  ctf_save_fseek (handler, handler->packet_start, SEEK_SET);
+  handler->content_size = 0;
+}
+
+/* Write the CTF metadata header.  */
+
+static void
+ctf_save_metadata_header (struct trace_write_handler *handler)
+{
+  ctf_save_write_metadata (handler, "/* CTF %d.%d */\n",
+			   CTF_SAVE_MAJOR, CTF_SAVE_MINOR);
+  ctf_save_write_metadata (handler,
+			   "typealias integer { size = 8; align = 8; "
+			   "signed = false; encoding = ascii;}"
+			   " := ascii;\n");
+  ctf_save_write_metadata (handler,
+			   "typealias integer { size = 8; align = 8; "
+			   "signed = false; }"
+			   " := uint8_t;\n");
+  ctf_save_write_metadata (handler,
+			   "typealias integer { size = 16; align = 16;"
+			   "signed = false; } := uint16_t;\n");
+  ctf_save_write_metadata (handler,
+			   "typealias integer { size = 32; align = 32;"
+			   "signed = false; } := uint32_t;\n");
+  ctf_save_write_metadata (handler,
+			   "typealias integer { size = 64; align = 64;"
+			   "signed = false; base = hex;}"
+			   " := uint64_t;\n");
+  ctf_save_write_metadata (handler,
+			   "typealias integer { size = 32; align = 32;"
+			   "signed = true; } := int32_t;\n");
+  ctf_save_write_metadata (handler,
+			   "typealias integer { size = 64; align = 64;"
+			   "signed = true; } := int64_t;\n");
+  ctf_save_write_metadata (handler,
+			   "typealias string { encoding = ascii;"
+			   " } := chars;\n");
+  ctf_save_write_metadata (handler, "\n");
+
+  /* Get the byte order of the host and write CTF data in this byte
+     order.  */
+#if WORDS_BIGENDIAN
+#define HOST_ENDIANNESS "be"
+#else
+#define HOST_ENDIANNESS "le"
+#endif
+
+  ctf_save_write_metadata (handler,
+			   "\ntrace {\n"
+			   "	major = %u;\n"
+			   "	minor = %u;\n"
+			   "	byte_order = %s;\n"
+			   "	packet.header := struct {\n"
+			   "		uint32_t magic;\n"
+			   "	};\n"
+			   "};\n"
+			   "\n"
+			   "stream {\n"
+			   "	packet.context := struct {\n"
+			   "		uint32_t content_size;\n"
+			   "		uint32_t packet_size;\n"
+			   "		uint16_t tpnum;\n"
+			   "	};\n"
+			   "	event.header := struct {\n"
+			   "		uint32_t id;\n"
+			   "	};\n"
+			   "};\n",
+			   CTF_SAVE_MAJOR, CTF_SAVE_MINOR,
+			   HOST_ENDIANNESS);
+  ctf_save_write_metadata (handler, "\n");
+}
+
+/* CTF trace writer.  */
+
+struct ctf_trace_file_writer
+{
+  struct trace_file_writer base;
+
+  /* States related to writing CTF trace file.  */
+  struct trace_write_handler tcs;
+};
+
+/* This is the implementation of trace_file_write_ops method
+   dtor.  */
+
+static void
+ctf_dtor (struct trace_file_writer *self)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+
+  if (writer->tcs.metadata_fd != NULL)
+    fclose (writer->tcs.metadata_fd);
+
+  if (writer->tcs.datastream_fd != NULL)
+    fclose (writer->tcs.datastream_fd);
+
+}
+
+/* This is the implementation of trace_file_write_ops method
+   target_save.  */
+
+static int
+ctf_target_save (struct trace_file_writer *self,
+		 const char *dirname)
+{
+  /* Don't support save trace file to CTF format in the target.  */
+  return 0;
+}
+
+/* This is the implementation of trace_file_write_ops method
+   start.  It creates the directory DIRNAME, metadata and datastream
+   in the directory.  */
+
+static void
+ctf_start (struct trace_file_writer *self, const char *dirname)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+  mode_t hmode = S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH;
+
+  /* Create DIRNAME.  */
+  if (mkdir (dirname, hmode) && errno != EEXIST)
+    error (_("Unable to open directory '%s' for saving trace data (%s)"),
+	   dirname, safe_strerror (errno));
+
+  memset (&writer->tcs, '\0', sizeof (writer->tcs));
+
+  std::string file_name = string_printf ("%s/%s", dirname, CTF_METADATA_NAME);
+
+  writer->tcs.metadata_fd
+    = gdb_fopen_cloexec (file_name.c_str (), "w").release ();
+  if (writer->tcs.metadata_fd == NULL)
+    error (_("Unable to open file '%s' for saving trace data (%s)"),
+	   file_name.c_str (), safe_strerror (errno));
+
+  ctf_save_metadata_header (&writer->tcs);
+
+  file_name = string_printf ("%s/%s", dirname, CTF_DATASTREAM_NAME);
+  writer->tcs.datastream_fd
+    = gdb_fopen_cloexec (file_name.c_str (), "w").release ();
+  if (writer->tcs.datastream_fd == NULL)
+    error (_("Unable to open file '%s' for saving trace data (%s)"),
+	   file_name.c_str (), safe_strerror (errno));
+}
+
+/* This is the implementation of trace_file_write_ops method
+   write_header.  Write the types of events on trace variable and
+   frame.  */
+
+static void
+ctf_write_header (struct trace_file_writer *self)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+
+
+  ctf_save_write_metadata (&writer->tcs, "\n");
+  ctf_save_write_metadata (&writer->tcs,
+			   "event {\n\tname = \"memory\";\n\tid = %u;\n"
+			   "\tfields := struct { \n"
+			   "\t\tuint64_t address;\n"
+			   "\t\tuint16_t length;\n"
+			   "\t\tuint8_t contents[length];\n"
+			   "\t};\n"
+			   "};\n", CTF_EVENT_ID_MEMORY);
+
+  ctf_save_write_metadata (&writer->tcs, "\n");
+  ctf_save_write_metadata (&writer->tcs,
+			   "event {\n\tname = \"tsv\";\n\tid = %u;\n"
+			   "\tfields := struct { \n"
+			   "\t\tuint64_t val;\n"
+			   "\t\tuint32_t num;\n"
+			   "\t};\n"
+			   "};\n", CTF_EVENT_ID_TSV);
+
+  ctf_save_write_metadata (&writer->tcs, "\n");
+  ctf_save_write_metadata (&writer->tcs,
+			   "event {\n\tname = \"frame\";\n\tid = %u;\n"
+			   "\tfields := struct { \n"
+			   "\t};\n"
+			   "};\n", CTF_EVENT_ID_FRAME);
+
+  ctf_save_write_metadata (&writer->tcs, "\n");
+  ctf_save_write_metadata (&writer->tcs,
+			  "event {\n\tname = \"tsv_def\";\n"
+			  "\tid = %u;\n\tfields := struct { \n"
+			  "\t\tint64_t initial_value;\n"
+			  "\t\tint32_t number;\n"
+			  "\t\tint32_t builtin;\n"
+			  "\t\tchars name;\n"
+			  "\t};\n"
+			  "};\n", CTF_EVENT_ID_TSV_DEF);
+
+  ctf_save_write_metadata (&writer->tcs, "\n");
+  ctf_save_write_metadata (&writer->tcs,
+			   "event {\n\tname = \"tp_def\";\n"
+			   "\tid = %u;\n\tfields := struct { \n"
+			   "\t\tuint64_t addr;\n"
+			   "\t\tuint64_t traceframe_usage;\n"
+			   "\t\tint32_t number;\n"
+			   "\t\tint32_t enabled;\n"
+			   "\t\tint32_t step;\n"
+			   "\t\tint32_t pass;\n"
+			   "\t\tint32_t hit_count;\n"
+			   "\t\tint32_t type;\n"
+			   "\t\tchars cond;\n"
+
+			  "\t\tuint32_t action_num;\n"
+			  "\t\tchars actions[action_num];\n"
+
+			  "\t\tuint32_t step_action_num;\n"
+			  "\t\tchars step_actions[step_action_num];\n"
+
+			  "\t\tchars at_string;\n"
+			  "\t\tchars cond_string;\n"
+
+			  "\t\tuint32_t cmd_num;\n"
+			  "\t\tchars cmd_strings[cmd_num];\n"
+			  "\t};\n"
+			  "};\n", CTF_EVENT_ID_TP_DEF);
+
+  gdb_assert (writer->tcs.content_size == 0);
+  gdb_assert (writer->tcs.packet_start == 0);
+
+  /* Create a new packet to contain this event.  */
+  self->ops->frame_ops->start (self, 0);
+}
+
+/* This is the implementation of trace_file_write_ops method
+   write_regblock_type.  Write the type of register event in
+   metadata.  */
+
+static void
+ctf_write_regblock_type (struct trace_file_writer *self, int size)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+
+  ctf_save_write_metadata (&writer->tcs, "\n");
+
+  ctf_save_write_metadata (&writer->tcs,
+			   "event {\n\tname = \"register\";\n\tid = %u;\n"
+			   "\tfields := struct { \n"
+			   "\t\tascii contents[%d];\n"
+			   "\t};\n"
+			   "};\n",
+			   CTF_EVENT_ID_REGISTER, size);
+}
+
+/* This is the implementation of trace_file_write_ops method
+   write_status.  */
+
+static void
+ctf_write_status (struct trace_file_writer *self,
+		  struct trace_status *ts)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+  uint32_t id;
+
+  ctf_save_write_metadata (&writer->tcs, "\n");
+  ctf_save_write_metadata (&writer->tcs,
+			   "event {\n\tname = \"status\";\n\tid = %u;\n"
+			   "\tfields := struct { \n"
+			   "\t\tint32_t stop_reason;\n"
+			   "\t\tint32_t stopping_tracepoint;\n"
+			   "\t\tint32_t traceframe_count;\n"
+			   "\t\tint32_t traceframes_created;\n"
+			   "\t\tint32_t buffer_free;\n"
+			   "\t\tint32_t buffer_size;\n"
+			   "\t\tint32_t disconnected_tracing;\n"
+			   "\t\tint32_t circular_buffer;\n"
+			   "\t};\n"
+			   "};\n",
+			   CTF_EVENT_ID_STATUS);
+
+  id = CTF_EVENT_ID_STATUS;
+  /* Event Id.  */
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &id, 4, 4);
+
+  ctf_save_write_int32 (&writer->tcs, ts->stop_reason);
+  ctf_save_write_int32 (&writer->tcs, ts->stopping_tracepoint);
+  ctf_save_write_int32 (&writer->tcs, ts->traceframe_count);
+  ctf_save_write_int32 (&writer->tcs, ts->traceframes_created);
+  ctf_save_write_int32 (&writer->tcs, ts->buffer_free);
+  ctf_save_write_int32 (&writer->tcs, ts->buffer_size);
+  ctf_save_write_int32 (&writer->tcs, ts->disconnected_tracing);
+  ctf_save_write_int32 (&writer->tcs, ts->circular_buffer);
+}
+
+/* This is the implementation of trace_file_write_ops method
+   write_uploaded_tsv.  */
+
+static void
+ctf_write_uploaded_tsv (struct trace_file_writer *self,
+			struct uploaded_tsv *tsv)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+  int32_t int32;
+  int64_t int64;
+  const gdb_byte zero = 0;
+
+  /* Event Id.  */
+  int32 = CTF_EVENT_ID_TSV_DEF;
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &int32, 4, 4);
+
+  /* initial_value */
+  int64 = tsv->initial_value;
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &int64, 8, 8);
+
+  /* number */
+  ctf_save_write_int32 (&writer->tcs, tsv->number);
+
+  /* builtin */
+  ctf_save_write_int32 (&writer->tcs, tsv->builtin);
+
+  /* name */
+  if (tsv->name != NULL)
+    ctf_save_write (&writer->tcs, (gdb_byte *) tsv->name,
+		    strlen (tsv->name));
+  ctf_save_write (&writer->tcs, &zero, 1);
+}
+
+/* This is the implementation of trace_file_write_ops method
+   write_uploaded_tp.  */
+
+static void
+ctf_write_uploaded_tp (struct trace_file_writer *self,
+		       struct uploaded_tp *tp)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+  int32_t int32;
+  int64_t int64;
+  uint32_t u32;
+  const gdb_byte zero = 0;
+
+  /* Event Id.  */
+  int32 = CTF_EVENT_ID_TP_DEF;
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &int32, 4, 4);
+
+  /* address */
+  int64 = tp->addr;
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &int64, 8, 8);
+
+  /* traceframe_usage */
+  int64 = tp->traceframe_usage;
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &int64, 8, 8);
+
+  /* number */
+  ctf_save_write_int32 (&writer->tcs, tp->number);
+
+  /* enabled */
+  ctf_save_write_int32 (&writer->tcs, tp->enabled);
+
+  /* step */
+  ctf_save_write_int32 (&writer->tcs, tp->step);
+
+  /* pass */
+  ctf_save_write_int32 (&writer->tcs, tp->pass);
+
+  /* hit_count */
+  ctf_save_write_int32 (&writer->tcs, tp->hit_count);
+
+  /* type */
+  ctf_save_write_int32 (&writer->tcs, tp->type);
+
+  /* condition  */
+  if (tp->cond != NULL)
+    ctf_save_write (&writer->tcs, (gdb_byte *) tp->cond.get (),
+		    strlen (tp->cond.get ()));
+  ctf_save_write (&writer->tcs, &zero, 1);
+
+  /* actions */
+  u32 = tp->actions.size ();
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &u32, 4, 4);
+  for (const auto &act : tp->actions)
+    ctf_save_write (&writer->tcs, (gdb_byte *) act.get (),
+		    strlen (act.get ()) + 1);
+
+  /* step_actions */
+  u32 = tp->step_actions.size ();
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &u32, 4, 4);
+  for (const auto &act : tp->step_actions)
+    ctf_save_write (&writer->tcs, (gdb_byte *) act.get (),
+		    strlen (act.get ()) + 1);
+
+  /* at_string */
+  if (tp->at_string != NULL)
+    ctf_save_write (&writer->tcs, (gdb_byte *) tp->at_string.get (),
+		    strlen (tp->at_string.get ()));
+  ctf_save_write (&writer->tcs, &zero, 1);
+
+  /* cond_string */
+  if (tp->cond_string != NULL)
+    ctf_save_write (&writer->tcs, (gdb_byte *) tp->cond_string.get (),
+		    strlen (tp->cond_string.get ()));
+  ctf_save_write (&writer->tcs, &zero, 1);
+
+  /* cmd_strings */
+  u32 = tp->cmd_strings.size ();
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &u32, 4, 4);
+  for (const auto &act : tp->cmd_strings)
+    ctf_save_write (&writer->tcs, (gdb_byte *) act.get (),
+		    strlen (act.get ()) + 1);
+
+}
+
+/* This is the implementation of trace_file_write_ops method
+   write_tdesc.  */
+
+static void
+ctf_write_tdesc (struct trace_file_writer *self)
+{
+  /* Nothing so far. */
+}
+
+/* This is the implementation of trace_file_write_ops method
+   write_definition_end.  */
+
+static void
+ctf_write_definition_end (struct trace_file_writer *self)
+{
+  self->ops->frame_ops->end (self);
+}
+
+/* This is the implementation of trace_file_write_ops method
+   end.  */
+
+static void
+ctf_end (struct trace_file_writer *self)
+{
+  struct ctf_trace_file_writer *writer = (struct ctf_trace_file_writer *) self;
+
+  gdb_assert (writer->tcs.content_size == 0);
+}
+
+/* This is the implementation of trace_frame_write_ops method
+   start.  */
+
+static void
+ctf_write_frame_start (struct trace_file_writer *self, uint16_t tpnum)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+  uint32_t id = CTF_EVENT_ID_FRAME;
+  uint32_t u32;
+
+  /* Step 1: Write packet context.  */
+  /* magic.  */
+  u32 = CTF_MAGIC;
+  ctf_save_write_uint32 (&writer->tcs, u32);
+  /* content_size and packet_size..  We still don't know the value,
+     write it later.  */
+  ctf_save_fseek (&writer->tcs, 4, SEEK_CUR);
+  ctf_save_fseek (&writer->tcs, 4, SEEK_CUR);
+  /* Tracepoint number.  */
+  ctf_save_write (&writer->tcs, (gdb_byte *) &tpnum, 2);
+
+  /* Step 2: Write event "frame".  */
+  /* Event Id.  */
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &id, 4, 4);
+}
+
+/* This is the implementation of trace_frame_write_ops method
+   write_r_block.  */
+
+static void
+ctf_write_frame_r_block (struct trace_file_writer *self,
+			 gdb_byte *buf, int32_t size)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+  uint32_t id = CTF_EVENT_ID_REGISTER;
+
+  /* Event Id.  */
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &id, 4, 4);
+
+  /* array contents.  */
+  ctf_save_align_write (&writer->tcs, buf, size, 1);
+}
+
+/* This is the implementation of trace_frame_write_ops method
+   write_m_block_header.  */
+
+static void
+ctf_write_frame_m_block_header (struct trace_file_writer *self,
+				uint64_t addr, uint16_t length)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+  uint32_t event_id = CTF_EVENT_ID_MEMORY;
+
+  /* Event Id.  */
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &event_id, 4, 4);
+
+  /* Address.  */
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &addr, 8, 8);
+
+  /* Length.  */
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &length, 2, 2);
+}
+
+/* This is the implementation of trace_frame_write_ops method
+   write_m_block_memory.  */
+
+static void
+ctf_write_frame_m_block_memory (struct trace_file_writer *self,
+				gdb_byte *buf, uint16_t length)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+
+  /* Contents.  */
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) buf, length, 1);
+}
+
+/* This is the implementation of trace_frame_write_ops method
+   write_v_block.  */
+
+static void
+ctf_write_frame_v_block (struct trace_file_writer *self,
+			 int32_t num, uint64_t val)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+  uint32_t id = CTF_EVENT_ID_TSV;
+
+  /* Event Id.  */
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &id, 4, 4);
+
+  /* val.  */
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &val, 8, 8);
+  /* num.  */
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &num, 4, 4);
+}
+
+/* This is the implementation of trace_frame_write_ops method
+   end.  */
+
+static void
+ctf_write_frame_end (struct trace_file_writer *self)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+  uint32_t u32;
+  uint32_t t;
+
+  /* Write the content size to packet header.  */
+  ctf_save_fseek (&writer->tcs, writer->tcs.packet_start + 4,
+		  SEEK_SET);
+  u32 = writer->tcs.content_size * TARGET_CHAR_BIT;
+
+  t = writer->tcs.content_size;
+  ctf_save_write_uint32 (&writer->tcs, u32);
+
+  /* Write the packet size.  */
+  u32 += 4 * TARGET_CHAR_BIT;
+  ctf_save_write_uint32 (&writer->tcs, u32);
+
+  writer->tcs.content_size = t;
+
+  /* Write zero at the end of the packet.  */
+  ctf_save_fseek (&writer->tcs, writer->tcs.packet_start + t,
+		  SEEK_SET);
+  u32 = 0;
+  ctf_save_write_uint32 (&writer->tcs, u32);
+  writer->tcs.content_size = t;
+
+  ctf_save_next_packet (&writer->tcs);
+}
+
+/* Operations to write various types of trace frames into CTF
+   format.  */
+
+static const struct trace_frame_write_ops ctf_write_frame_ops =
+{
+  ctf_write_frame_start,
+  ctf_write_frame_r_block,
+  ctf_write_frame_m_block_header,
+  ctf_write_frame_m_block_memory,
+  ctf_write_frame_v_block,
+  ctf_write_frame_end,
+};
+
+/* Operations to write trace buffers into CTF format.  */
+
+static const struct trace_file_write_ops ctf_write_ops =
+{
+  ctf_dtor,
+  ctf_target_save,
+  ctf_start,
+  ctf_write_header,
+  ctf_write_regblock_type,
+  ctf_write_status,
+  ctf_write_uploaded_tsv,
+  ctf_write_uploaded_tp,
+  ctf_write_tdesc,
+  ctf_write_definition_end,
+  NULL,
+  &ctf_write_frame_ops,
+  ctf_end,
+};
+
+/* Return a trace writer for CTF format.  */
+
+struct trace_file_writer *
+ctf_trace_file_writer_new (void)
+{
+  struct ctf_trace_file_writer *writer = XNEW (struct ctf_trace_file_writer);
+
+  writer->base.ops = &ctf_write_ops;
+
+  return (struct trace_file_writer *) writer;
+}
+
+#if HAVE_LIBBABELTRACE
+/* Use libbabeltrace to read CTF data.  The libbabeltrace provides
+   iterator to iterate over each event in CTF data and APIs to get
+   details of event and packet, so it is very convenient to use
+   libbabeltrace to access events in CTF.  */
+
+#include <babeltrace/babeltrace.h>
+#include <babeltrace/ctf/events.h>
+#include <babeltrace/ctf/iterator.h>
+
+/* The struct pointer for current CTF directory.  */
+static int handle_id = -1;
+static struct bt_context *ctx = NULL;
+static struct bt_ctf_iter *ctf_iter = NULL;
+/* The position of the first packet containing trace frame.  */
+static struct bt_iter_pos *start_pos;
+
+/* The name of CTF directory.  */
+static char *trace_dirname;
+
+static ctf_target ctf_ops;
+
+/* Destroy ctf iterator and context.  */
+
+static void
+ctf_destroy (void)
+{
+  if (ctf_iter != NULL)
+    {
+      bt_ctf_iter_destroy (ctf_iter);
+      ctf_iter = NULL;
+    }
+  if (ctx != NULL)
+    {
+      bt_context_put (ctx);
+      ctx = NULL;
+    }
+}
+
+/* Open CTF trace data in DIRNAME.  */
+
+static void
+ctf_open_dir (const char *dirname)
+{
+  struct bt_iter_pos begin_pos;
+  unsigned int count, i;
+  struct bt_ctf_event_decl * const *list;
+
+  ctx = bt_context_create ();
+  if (ctx == NULL)
+    error (_("Unable to create bt_context"));
+  handle_id = bt_context_add_trace (ctx, dirname, "ctf", NULL, NULL, NULL);
+  if (handle_id < 0)
+    {
+      ctf_destroy ();
+      error (_("Unable to use libbabeltrace on directory \"%s\""),
+	     dirname);
+    }
+
+  begin_pos.type = BT_SEEK_BEGIN;
+  ctf_iter = bt_ctf_iter_create (ctx, &begin_pos, NULL);
+  if (ctf_iter == NULL)
+    {
+      ctf_destroy ();
+      error (_("Unable to create bt_iterator"));
+    }
+
+  /* Look for the declaration of register block.  Get the length of
+     array "contents" to set trace_regblock_size.  */
+
+  bt_ctf_get_event_decl_list (handle_id, ctx, &list, &count);
+  for (i = 0; i < count; i++)
+    if (strcmp ("register", bt_ctf_get_decl_event_name (list[i])) == 0)
+      {
+	const struct bt_ctf_field_decl * const *field_list;
+	const struct bt_declaration *decl;
+
+	bt_ctf_get_decl_fields (list[i], BT_EVENT_FIELDS, &field_list,
+				&count);
+
+	gdb_assert (count == 1);
+	gdb_assert (0 == strcmp ("contents",
+				 bt_ctf_get_decl_field_name (field_list[0])));
+	decl = bt_ctf_get_decl_from_field_decl (field_list[0]);
+	trace_regblock_size = bt_ctf_get_array_len (decl);
+
+	break;
+      }
+}
+
+#define SET_INT32_FIELD(EVENT, SCOPE, VAR, FIELD)			\
+  (VAR)->FIELD = (int) bt_ctf_get_int64 (bt_ctf_get_field ((EVENT),	\
+							   (SCOPE),	\
+							   #FIELD))
+
+#define SET_ENUM_FIELD(EVENT, SCOPE, VAR, TYPE, FIELD)			\
+  (VAR)->FIELD = (TYPE) bt_ctf_get_int64 (bt_ctf_get_field ((EVENT),	\
+							    (SCOPE),	\
+							    #FIELD))
+
+
+/* EVENT is the "status" event and TS is filled in.  */
+
+static void
+ctf_read_status (struct bt_ctf_event *event, struct trace_status *ts)
+{
+  const struct bt_definition *scope
+    = bt_ctf_get_top_level_scope (event, BT_EVENT_FIELDS);
+
+  SET_ENUM_FIELD (event, scope, ts, enum trace_stop_reason, stop_reason);
+  SET_INT32_FIELD (event, scope, ts, stopping_tracepoint);
+  SET_INT32_FIELD (event, scope, ts, traceframe_count);
+  SET_INT32_FIELD (event, scope, ts, traceframes_created);
+  SET_INT32_FIELD (event, scope, ts, buffer_free);
+  SET_INT32_FIELD (event, scope, ts, buffer_size);
+  SET_INT32_FIELD (event, scope, ts, disconnected_tracing);
+  SET_INT32_FIELD (event, scope, ts, circular_buffer);
+
+  bt_iter_next (bt_ctf_get_iter (ctf_iter));
+}
+
+/* Read the events "tsv_def" one by one, extract its contents and fill
+   in the list UPLOADED_TSVS.  */
+
+static void
+ctf_read_tsv (struct uploaded_tsv **uploaded_tsvs)
+{
+  gdb_assert (ctf_iter != NULL);
+
+  while (1)
+    {
+      struct bt_ctf_event *event;
+      const struct bt_definition *scope;
+      const struct bt_definition *def;
+      uint32_t event_id;
+      struct uploaded_tsv *utsv = NULL;
+
+      event = bt_ctf_iter_read_event (ctf_iter);
+      scope = bt_ctf_get_top_level_scope (event,
+					  BT_STREAM_EVENT_HEADER);
+      event_id = bt_ctf_get_uint64 (bt_ctf_get_field (event, scope,
+						      "id"));
+      if (event_id != CTF_EVENT_ID_TSV_DEF)
+	break;
+
+      scope = bt_ctf_get_top_level_scope (event,
+					  BT_EVENT_FIELDS);
+
+      def = bt_ctf_get_field (event, scope, "number");
+      utsv = get_uploaded_tsv ((int32_t) bt_ctf_get_int64 (def),
+			       uploaded_tsvs);
+
+      def = bt_ctf_get_field (event, scope, "builtin");
+      utsv->builtin = (int32_t) bt_ctf_get_int64 (def);
+      def = bt_ctf_get_field (event, scope, "initial_value");
+      utsv->initial_value = bt_ctf_get_int64 (def);
+
+      def = bt_ctf_get_field (event, scope, "name");
+      utsv->name =  xstrdup (bt_ctf_get_string (def));
+
+      if (bt_iter_next (bt_ctf_get_iter (ctf_iter)) < 0)
+	break;
+    }
+
+}
+
+/* Read the value of element whose index is NUM from CTF and write it
+   to the corresponding VAR->ARRAY. */
+
+#define SET_ARRAY_FIELD(EVENT, SCOPE, VAR, NUM, ARRAY)	\
+  do							\
+    {							\
+      uint32_t lu32, i;						\
+      const struct bt_definition *def;				\
+								\
+      lu32 = (uint32_t) bt_ctf_get_uint64 (bt_ctf_get_field ((EVENT),	\
+							     (SCOPE),	\
+							     #NUM));	\
+      def = bt_ctf_get_field ((EVENT), (SCOPE), #ARRAY);		\
+      for (i = 0; i < lu32; i++)					\
+	{								\
+	  const struct bt_definition *element				\
+	    = bt_ctf_get_index ((EVENT), def, i);			\
+									\
+	  (VAR)->ARRAY.emplace_back					\
+	    (xstrdup (bt_ctf_get_string (element)));			\
+	}								\
+    }									\
+  while (0)
+
+/* Read a string from CTF and set VAR->FIELD. If the length of string
+   is zero, set VAR->FIELD to NULL.  */
+
+#define SET_STRING_FIELD(EVENT, SCOPE, VAR, FIELD)			\
+  do									\
+    {									\
+      const char *p = bt_ctf_get_string (bt_ctf_get_field ((EVENT),	\
+							   (SCOPE),	\
+							   #FIELD));	\
+									\
+      if (strlen (p) > 0)						\
+	(VAR)->FIELD.reset (xstrdup (p));				\
+      else								\
+	(VAR)->FIELD = NULL;						\
+    }									\
+  while (0)
+
+/* Read the events "tp_def" one by one, extract its contents and fill
+   in the list UPLOADED_TPS.  */
+
+static void
+ctf_read_tp (struct uploaded_tp **uploaded_tps)
+{
+  gdb_assert (ctf_iter != NULL);
+
+  while (1)
+    {
+      struct bt_ctf_event *event;
+      const struct bt_definition *scope;
+      uint32_t u32;
+      int32_t int32;
+      uint64_t u64;
+      struct uploaded_tp *utp = NULL;
+
+      event = bt_ctf_iter_read_event (ctf_iter);
+      scope = bt_ctf_get_top_level_scope (event,
+					  BT_STREAM_EVENT_HEADER);
+      u32 = bt_ctf_get_uint64 (bt_ctf_get_field (event, scope,
+						 "id"));
+      if (u32 != CTF_EVENT_ID_TP_DEF)
+	break;
+
+      scope = bt_ctf_get_top_level_scope (event,
+					  BT_EVENT_FIELDS);
+      int32 = (int32_t) bt_ctf_get_int64 (bt_ctf_get_field (event,
+							    scope,
+							    "number"));
+      u64 = bt_ctf_get_uint64 (bt_ctf_get_field (event, scope,
+						 "addr"));
+      utp = get_uploaded_tp (int32, u64,  uploaded_tps);
+
+      SET_INT32_FIELD (event, scope, utp, enabled);
+      SET_INT32_FIELD (event, scope, utp, step);
+      SET_INT32_FIELD (event, scope, utp, pass);
+      SET_INT32_FIELD (event, scope, utp, hit_count);
+      SET_ENUM_FIELD (event, scope, utp, enum bptype, type);
+
+      /* Read 'cmd_strings'.  */
+      SET_ARRAY_FIELD (event, scope, utp, cmd_num, cmd_strings);
+      /* Read 'actions'.  */
+      SET_ARRAY_FIELD (event, scope, utp, action_num, actions);
+      /* Read 'step_actions'.  */
+      SET_ARRAY_FIELD (event, scope, utp, step_action_num,
+		       step_actions);
+
+      SET_STRING_FIELD(event, scope, utp, at_string);
+      SET_STRING_FIELD(event, scope, utp, cond_string);
+
+      if (bt_iter_next (bt_ctf_get_iter (ctf_iter)) < 0)
+	break;
+    }
+}
+
+/* This is the implementation of target_ops method to_open.  Open CTF
+   trace data, read trace status, trace state variables and tracepoint
+   definitions from the first packet.  Set the start position at the
+   second packet which contains events on trace blocks.  */
+
+static void
+ctf_target_open (const char *dirname, int from_tty)
+{
+  struct bt_ctf_event *event;
+  uint32_t event_id;
+  const struct bt_definition *scope;
+  struct uploaded_tsv *uploaded_tsvs = NULL;
+  struct uploaded_tp *uploaded_tps = NULL;
+
+  if (!dirname)
+    error (_("No CTF directory specified."));
+
+  ctf_open_dir (dirname);
+
+  target_preopen (from_tty);
+
+  /* Skip the first packet which about the trace status.  The first
+     event is "frame".  */
+  event = bt_ctf_iter_read_event (ctf_iter);
+  scope = bt_ctf_get_top_level_scope (event, BT_STREAM_EVENT_HEADER);
+  event_id = bt_ctf_get_uint64 (bt_ctf_get_field (event, scope, "id"));
+  if (event_id != CTF_EVENT_ID_FRAME)
+    error (_("Wrong event id of the first event"));
+  /* The second event is "status".  */
+  bt_iter_next (bt_ctf_get_iter (ctf_iter));
+  event = bt_ctf_iter_read_event (ctf_iter);
+  scope = bt_ctf_get_top_level_scope (event, BT_STREAM_EVENT_HEADER);
+  event_id = bt_ctf_get_uint64 (bt_ctf_get_field (event, scope, "id"));
+  if (event_id != CTF_EVENT_ID_STATUS)
+    error (_("Wrong event id of the second event"));
+  ctf_read_status (event, current_trace_status ());
+
+  ctf_read_tsv (&uploaded_tsvs);
+
+  ctf_read_tp (&uploaded_tps);
+
+  event = bt_ctf_iter_read_event (ctf_iter);
+  /* EVENT can be NULL if we've already gone to the end of stream of
+     events.  */
+  if (event != NULL)
+    {
+      scope = bt_ctf_get_top_level_scope (event,
+					  BT_STREAM_EVENT_HEADER);
+      event_id = bt_ctf_get_uint64 (bt_ctf_get_field (event,
+						      scope, "id"));
+      if (event_id != CTF_EVENT_ID_FRAME)
+	error (_("Wrong event id of the first event of the second packet"));
+    }
+
+  start_pos = bt_iter_get_pos (bt_ctf_get_iter (ctf_iter));
+  gdb_assert (start_pos->type == BT_SEEK_RESTORE);
+
+  trace_dirname = xstrdup (dirname);
+  push_target (&ctf_ops);
+
+  inferior_appeared (current_inferior (), CTF_PID);
+  inferior_ptid = ptid_t (CTF_PID);
+  add_thread_silent (inferior_ptid);
+
+  merge_uploaded_trace_state_variables (&uploaded_tsvs);
+  merge_uploaded_tracepoints (&uploaded_tps);
+
+  post_create_inferior (&ctf_ops, from_tty);
+}
+
+/* This is the implementation of target_ops method to_close.  Destroy
+   CTF iterator and context.  */
+
+void
+ctf_target::close ()
+{
+  ctf_destroy ();
+  xfree (trace_dirname);
+  trace_dirname = NULL;
+
+  inferior_ptid = null_ptid;	/* Avoid confusion from thread stuff.  */
+  exit_inferior_silent (current_inferior ());
+
+  trace_reset_local_state ();
+}
+
+/* This is the implementation of target_ops method to_files_info.
+   Print the directory name of CTF trace data.  */
+
+void
+ctf_target::files_info ()
+{
+  printf_filtered ("\t`%s'\n", trace_dirname);
+}
+
+/* This is the implementation of target_ops method to_fetch_registers.
+   Iterate over events whose name is "register" in current frame,
+   extract contents from events, and set REGCACHE with the contents.
+   If no matched events are found, mark registers unavailable.  */
+
+void
+ctf_target::fetch_registers (struct regcache *regcache, int regno)
+{
+  struct gdbarch *gdbarch = regcache->arch ();
+  struct bt_ctf_event *event = NULL;
+  struct bt_iter_pos *pos;
+
+  /* An uninitialized reg size says we're not going to be
+     successful at getting register blocks.  */
+  if (trace_regblock_size == 0)
+    return;
+
+  gdb_assert (ctf_iter != NULL);
+  /* Save the current position.  */
+  pos = bt_iter_get_pos (bt_ctf_get_iter (ctf_iter));
+  gdb_assert (pos->type == BT_SEEK_RESTORE);
+
+  while (1)
+    {
+      const char *name;
+      struct bt_ctf_event *event1;
+
+      event1 = bt_ctf_iter_read_event (ctf_iter);
+
+      name = bt_ctf_event_name (event1);
+
+      if (name == NULL || strcmp (name, "frame") == 0)
+	break;
+      else if (strcmp (name, "register") == 0)
+	{
+	  event = event1;
+	  break;
+	}
+
+      if (bt_iter_next (bt_ctf_get_iter (ctf_iter)) < 0)
+	break;
+    }
+
+  /* Restore the position.  */
+  bt_iter_set_pos (bt_ctf_get_iter (ctf_iter), pos);
+
+  if (event != NULL)
+    {
+      int offset, regsize, regn;
+      const struct bt_definition *scope
+	= bt_ctf_get_top_level_scope (event,
+				      BT_EVENT_FIELDS);
+      const struct bt_definition *array
+	= bt_ctf_get_field (event, scope, "contents");
+      gdb_byte *regs = (gdb_byte *) bt_ctf_get_char_array (array);
+
+      /* Assume the block is laid out in GDB register number order,
+	 each register with the size that it has in GDB.  */
+      offset = 0;
+      for (regn = 0; regn < gdbarch_num_regs (gdbarch); regn++)
+	{
+	  regsize = register_size (gdbarch, regn);
+	  /* Make sure we stay within block bounds.  */
+	  if (offset + regsize >= trace_regblock_size)
+	    break;
+	  if (regcache->get_register_status (regn) == REG_UNKNOWN)
+	    {
+	      if (regno == regn)
+		{
+		  regcache->raw_supply (regno, regs + offset);
+		  break;
+		}
+	      else if (regno == -1)
+		{
+		  regcache->raw_supply (regn, regs + offset);
+		}
+	    }
+	  offset += regsize;
+	}
+    }
+  else
+    tracefile_fetch_registers (regcache, regno);
+}
+
+/* This is the implementation of target_ops method to_xfer_partial.
+   Iterate over events whose name is "memory" in
+   current frame, extract the address and length from events.  If
+   OFFSET is within the range, read the contents from events to
+   READBUF.  */
+
+enum target_xfer_status
+ctf_target::xfer_partial (enum target_object object,
+			  const char *annex, gdb_byte *readbuf,
+			  const gdb_byte *writebuf, ULONGEST offset,
+			  ULONGEST len, ULONGEST *xfered_len)
+{
+  /* We're only doing regular memory for now.  */
+  if (object != TARGET_OBJECT_MEMORY)
+    return TARGET_XFER_E_IO;
+
+  if (readbuf == NULL)
+    error (_("ctf_xfer_partial: trace file is read-only"));
+
+  if (get_traceframe_number () != -1)
+    {
+      struct bt_iter_pos *pos;
+      enum target_xfer_status res;
+      /* Records the lowest available address of all blocks that
+	 intersects the requested range.  */
+      ULONGEST low_addr_available = 0;
+
+      gdb_assert (ctf_iter != NULL);
+      /* Save the current position.  */
+      pos = bt_iter_get_pos (bt_ctf_get_iter (ctf_iter));
+      gdb_assert (pos->type == BT_SEEK_RESTORE);
+
+      /* Iterate through the traceframe's blocks, looking for
+	 memory.  */
+      while (1)
+	{
+	  ULONGEST amt;
+	  uint64_t maddr;
+	  uint16_t mlen;
+	  const struct bt_definition *scope;
+	  const struct bt_definition *def;
+	  struct bt_ctf_event *event
+	    = bt_ctf_iter_read_event (ctf_iter);
+	  const char *name = bt_ctf_event_name (event);
+
+	  if (name == NULL || strcmp (name, "frame") == 0)
+	    break;
+	  else if (strcmp (name, "memory") != 0)
+	    {
+	      if (bt_iter_next (bt_ctf_get_iter (ctf_iter)) < 0)
+		break;
+
+	      continue;
+	    }
+
+	  scope = bt_ctf_get_top_level_scope (event,
+					      BT_EVENT_FIELDS);
+
+	  def = bt_ctf_get_field (event, scope, "address");
+	  maddr = bt_ctf_get_uint64 (def);
+	  def = bt_ctf_get_field (event, scope, "length");
+	  mlen = (uint16_t) bt_ctf_get_uint64 (def);
+
+	  /* If the block includes the first part of the desired
+	     range, return as much it has; GDB will re-request the
+	     remainder, which might be in a different block of this
+	     trace frame.  */
+	  if (maddr <= offset && offset < (maddr + mlen))
+	    {
+	      const struct bt_definition *array
+		= bt_ctf_get_field (event, scope, "contents");
+	      gdb_byte *contents;
+	      int k;
+
+	      contents = (gdb_byte *) xmalloc (mlen);
+
+	      for (k = 0; k < mlen; k++)
+		{
+		  const struct bt_definition *element
+		    = bt_ctf_get_index (event, array, k);
+
+		  contents[k] = (gdb_byte) bt_ctf_get_uint64 (element);
+		}
+
+	      amt = (maddr + mlen) - offset;
+	      if (amt > len)
+		amt = len;
+
+	      memcpy (readbuf, &contents[offset - maddr], amt);
+
+	      xfree (contents);
+
+	      /* Restore the position.  */
+	      bt_iter_set_pos (bt_ctf_get_iter (ctf_iter), pos);
+
+	      if (amt == 0)
+		return TARGET_XFER_EOF;
+	      else
+		{
+		  *xfered_len = amt;
+		  return TARGET_XFER_OK;
+		}
+	    }
+
+	  if (offset < maddr && maddr < (offset + len))
+	    if (low_addr_available == 0 || low_addr_available > maddr)
+	      low_addr_available = maddr;
+
+	  if (bt_iter_next (bt_ctf_get_iter (ctf_iter)) < 0)
+	    break;
+	}
+
+      /* Restore the position.  */
+      bt_iter_set_pos (bt_ctf_get_iter (ctf_iter), pos);
+
+      /* Requested memory is unavailable in the context of traceframes,
+	 and this address falls within a read-only section, fallback
+	 to reading from executable, up to LOW_ADDR_AVAILABLE  */
+      if (offset < low_addr_available)
+	len = std::min (len, low_addr_available - offset);
+      res = exec_read_partial_read_only (readbuf, offset, len, xfered_len);
+
+      if (res == TARGET_XFER_OK)
+	return TARGET_XFER_OK;
+      else
+	{
+	  /* No use trying further, we know some memory starting
+	     at MEMADDR isn't available.  */
+	  *xfered_len = len;
+	  return TARGET_XFER_UNAVAILABLE;
+	}
+    }
+  else
+    {
+      /* Fallback to reading from read-only sections.  */
+      return section_table_read_available_memory (readbuf, offset, len, xfered_len);
+    }
+}
+
+/* This is the implementation of target_ops method
+   to_get_trace_state_variable_value.
+   Iterate over events whose name is "tsv" in current frame.  When the
+   trace variable is found, set the value of it to *VAL and return
+   true, otherwise return false.  */
+
+bool
+ctf_target::get_trace_state_variable_value (int tsvnum, LONGEST *val)
+{
+  struct bt_iter_pos *pos;
+  bool found = false;
+
+  gdb_assert (ctf_iter != NULL);
+  /* Save the current position.  */
+  pos = bt_iter_get_pos (bt_ctf_get_iter (ctf_iter));
+  gdb_assert (pos->type == BT_SEEK_RESTORE);
+
+  /* Iterate through the traceframe's blocks, looking for 'V'
+     block.  */
+  while (1)
+    {
+      struct bt_ctf_event *event
+	= bt_ctf_iter_read_event (ctf_iter);
+      const char *name = bt_ctf_event_name (event);
+
+      if (name == NULL || strcmp (name, "frame") == 0)
+	break;
+      else if (strcmp (name, "tsv") == 0)
+	{
+	  const struct bt_definition *scope;
+	  const struct bt_definition *def;
+
+	  scope = bt_ctf_get_top_level_scope (event,
+					      BT_EVENT_FIELDS);
+
+	  def = bt_ctf_get_field (event, scope, "num");
+	  if (tsvnum == (int32_t) bt_ctf_get_uint64 (def))
+	    {
+	      def = bt_ctf_get_field (event, scope, "val");
+	      *val = bt_ctf_get_uint64 (def);
+
+	      found = true;
+	    }
+	}
+
+      if (bt_iter_next (bt_ctf_get_iter (ctf_iter)) < 0)
+	break;
+    }
+
+  /* Restore the position.  */
+  bt_iter_set_pos (bt_ctf_get_iter (ctf_iter), pos);
+
+  return found;
+}
+
+/* Return the tracepoint number in "frame" event.  */
+
+static int
+ctf_get_tpnum_from_frame_event (struct bt_ctf_event *event)
+{
+  /* The packet context of events has a field "tpnum".  */
+  const struct bt_definition *scope
+    = bt_ctf_get_top_level_scope (event, BT_STREAM_PACKET_CONTEXT);
+  uint64_t tpnum
+    = bt_ctf_get_uint64 (bt_ctf_get_field (event, scope, "tpnum"));
+
+  return (int) tpnum;
+}
+
+/* Return the address at which the current frame was collected.  */
+
+static CORE_ADDR
+ctf_get_traceframe_address (void)
+{
+  struct bt_ctf_event *event = NULL;
+  struct bt_iter_pos *pos;
+  CORE_ADDR addr = 0;
+
+  gdb_assert (ctf_iter != NULL);
+  pos  = bt_iter_get_pos (bt_ctf_get_iter (ctf_iter));
+  gdb_assert (pos->type == BT_SEEK_RESTORE);
+
+  while (1)
+    {
+      const char *name;
+      struct bt_ctf_event *event1;
+
+      event1 = bt_ctf_iter_read_event (ctf_iter);
+
+      name = bt_ctf_event_name (event1);
+
+      if (name == NULL)
+	break;
+      else if (strcmp (name, "frame") == 0)
+	{
+	  event = event1;
+	  break;
+	}
+
+      if (bt_iter_next (bt_ctf_get_iter (ctf_iter)) < 0)
+	break;
+    }
+
+  if (event != NULL)
+    {
+      int tpnum = ctf_get_tpnum_from_frame_event (event);
+      struct tracepoint *tp
+	= get_tracepoint_by_number_on_target (tpnum);
+
+      if (tp && tp->loc)
+	addr = tp->loc->address;
+    }
+
+  /* Restore the position.  */
+  bt_iter_set_pos (bt_ctf_get_iter (ctf_iter), pos);
+
+  return addr;
+}
+
+/* This is the implementation of target_ops method to_trace_find.
+   Iterate the events whose name is "frame", extract the tracepoint
+   number in it.  Return traceframe number when matched.  */
+
+int
+ctf_target::trace_find (enum trace_find_type type, int num,
+			CORE_ADDR addr1, CORE_ADDR addr2, int *tpp)
+{
+  int tfnum = 0;
+  int found = 0;
+
+  if (num == -1)
+    {
+      if (tpp != NULL)
+	*tpp = -1;
+      return -1;
+    }
+
+  gdb_assert (ctf_iter != NULL);
+  /* Set iterator back to the start.  */
+  bt_iter_set_pos (bt_ctf_get_iter (ctf_iter), start_pos);
+
+  while (1)
+    {
+      struct bt_ctf_event *event;
+      const char *name;
+
+      event = bt_ctf_iter_read_event (ctf_iter);
+
+      name = bt_ctf_event_name (event);
+
+      if (event == NULL || name == NULL)
+	break;
+
+      if (strcmp (name, "frame") == 0)
+	{
+	  CORE_ADDR tfaddr;
+
+	  if (type == tfind_number)
+	    {
+	      /* Looking for a specific trace frame.  */
+	      if (tfnum == num)
+		found = 1;
+	    }
+	  else
+	    {
+	      /* Start from the _next_ trace frame.  */
+	      if (tfnum > get_traceframe_number ())
+		{
+		  switch (type)
+		    {
+		    case tfind_tp:
+		      {
+			struct tracepoint *tp = get_tracepoint (num);
+
+			if (tp != NULL
+			    && (tp->number_on_target
+				== ctf_get_tpnum_from_frame_event (event)))
+			  found = 1;
+			break;
+		      }
+		    case tfind_pc:
+		      tfaddr = ctf_get_traceframe_address ();
+		      if (tfaddr == addr1)
+			found = 1;
+		      break;
+		    case tfind_range:
+		      tfaddr = ctf_get_traceframe_address ();
+		      if (addr1 <= tfaddr && tfaddr <= addr2)
+			found = 1;
+		      break;
+		    case tfind_outside:
+		      tfaddr = ctf_get_traceframe_address ();
+		      if (!(addr1 <= tfaddr && tfaddr <= addr2))
+			found = 1;
+		      break;
+		    default:
+		      internal_error (__FILE__, __LINE__, _("unknown tfind type"));
+		    }
+		}
+	    }
+	  if (found)
+	    {
+	      if (tpp != NULL)
+		*tpp = ctf_get_tpnum_from_frame_event (event);
+
+	      /* Skip the event "frame".  */
+	      bt_iter_next (bt_ctf_get_iter (ctf_iter));
+
+	      return tfnum;
+	    }
+	  tfnum++;
+	}
+
+      if (bt_iter_next (bt_ctf_get_iter (ctf_iter)) < 0)
+	break;
+    }
+
+  return -1;
+}
+
+/* This is the implementation of target_ops method to_traceframe_info.
+   Iterate the events whose name is "memory", in current
+   frame, extract memory range information, and return them in
+   traceframe_info.  */
+
+traceframe_info_up
+ctf_target::traceframe_info ()
+{
+  traceframe_info_up info (new struct traceframe_info);
+  const char *name;
+  struct bt_iter_pos *pos;
+
+  gdb_assert (ctf_iter != NULL);
+  /* Save the current position.  */
+  pos = bt_iter_get_pos (bt_ctf_get_iter (ctf_iter));
+  gdb_assert (pos->type == BT_SEEK_RESTORE);
+
+  do
+    {
+      struct bt_ctf_event *event
+	= bt_ctf_iter_read_event (ctf_iter);
+
+      name = bt_ctf_event_name (event);
+
+      if (name == NULL || strcmp (name, "register") == 0
+	  || strcmp (name, "frame") == 0)
+	;
+      else if (strcmp (name, "memory") == 0)
+	{
+	  const struct bt_definition *scope
+	    = bt_ctf_get_top_level_scope (event,
+					  BT_EVENT_FIELDS);
+	  const struct bt_definition *def;
+
+	  def = bt_ctf_get_field (event, scope, "address");
+	  CORE_ADDR start = bt_ctf_get_uint64 (def);
+
+	  def = bt_ctf_get_field (event, scope, "length");
+	  int length = (uint16_t) bt_ctf_get_uint64 (def);
+
+	  info->memory.emplace_back (start, length);
+	}
+      else if (strcmp (name, "tsv") == 0)
+	{
+	  int vnum;
+	  const struct bt_definition *scope
+	    = bt_ctf_get_top_level_scope (event,
+					  BT_EVENT_FIELDS);
+	  const struct bt_definition *def;
+
+	  def = bt_ctf_get_field (event, scope, "num");
+	  vnum = (int) bt_ctf_get_uint64 (def);
+	  info->tvars.push_back (vnum);
+	}
+      else
+	{
+	  warning (_("Unhandled trace block type (%s) "
+		     "while building trace frame info."),
+		   name);
+	}
+
+      if (bt_iter_next (bt_ctf_get_iter (ctf_iter)) < 0)
+	break;
+    }
+  while (name != NULL && strcmp (name, "frame") != 0);
+
+  /* Restore the position.  */
+  bt_iter_set_pos (bt_ctf_get_iter (ctf_iter), pos);
+
+  return info;
+}
+
+#endif
+
+/* module initialization */
+
+void
+_initialize_ctf (void)
+{
+#if HAVE_LIBBABELTRACE
+  add_target (ctf_target_info, ctf_target_open, filename_completer);
+#endif
+}