GDB 7.6.50

gdb/ctf.c

Index: gdb/ctf.c
diff --git a/gdb/ctf.c b/gdb/ctf.c
new file mode 100644
index 0000000000000000000000000000000000000000..b886d67fa18238bbc74425b9a4332cab7f084340
--- /dev/null
+++ b/gdb/ctf.c
@@ -0,0 +1,1853 @@
+/* CTF format support.
+
+   Copyright (C) 2012-2013 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 "ctf.h"
+#include "tracepoint.h"
+#include "regcache.h"
+#include <sys/stat.h>
+#include "exec.h"
+#include "completer.h"
+
+#include <ctype.h>
+
+/* 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
+
+/* 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, ...)
+{
+  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)
+{
+  const char metadata_fmt[] =
+  "\ntrace {\n"
+  "	major = %u;\n"
+  "	minor = %u;\n"
+  "	byte_order = %s;\n"		/* be or le */
+  "	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_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, metadata_fmt,
+			   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;
+}
+
+#ifdef USE_WIN32API
+#undef mkdir
+#define mkdir(pathname, mode) mkdir (pathname)
+#endif
+
+/* 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)
+{
+  char *file_name;
+  struct cleanup *old_chain;
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+  int i;
+  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));
+
+  file_name = xstrprintf ("%s/%s", dirname, CTF_METADATA_NAME);
+  old_chain = make_cleanup (xfree, file_name);
+
+  writer->tcs.metadata_fd = fopen (file_name, "w");
+  if (writer->tcs.metadata_fd == NULL)
+    error (_("Unable to open file '%s' for saving trace data (%s)"),
+	   file_name, safe_strerror (errno));
+  do_cleanups (old_chain);
+
+  ctf_save_metadata_header (&writer->tcs);
+
+  file_name = xstrprintf ("%s/%s", dirname, CTF_DATASTREAM_NAME);
+  old_chain = make_cleanup (xfree, file_name);
+  writer->tcs.datastream_fd = fopen (file_name, "w");
+  if (writer->tcs.datastream_fd == NULL)
+    error (_("Unable to open file '%s' for saving trace data (%s)"),
+	   file_name, safe_strerror (errno));
+  do_cleanups (old_chain);
+}
+
+/* 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;
+  int32_t int32;
+
+  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;
+  unsigned int len;
+  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;
+  int a;
+  char *act;
+
+  /* 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, strlen (tp->cond));
+  ctf_save_write (&writer->tcs, &zero, 1);
+
+  /* actions */
+  u32 = VEC_length (char_ptr, tp->actions);
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &u32, 4, 4);
+  for (a = 0; VEC_iterate (char_ptr, tp->actions, a, act); ++a)
+    ctf_save_write (&writer->tcs, (gdb_byte *) act, strlen (act) + 1);
+
+  /* step_actions */
+  u32 = VEC_length (char_ptr, tp->step_actions);
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &u32, 4, 4);
+  for (a = 0; VEC_iterate (char_ptr, tp->step_actions, a, act); ++a)
+    ctf_save_write (&writer->tcs, (gdb_byte *) act, strlen (act) + 1);
+
+  /* at_string */
+  if (tp->at_string != NULL)
+    ctf_save_write (&writer->tcs, (gdb_byte *) tp->at_string,
+		    strlen (tp->at_string));
+  ctf_save_write (&writer->tcs, &zero, 1);
+
+  /* cond_string */
+  if (tp->cond_string != NULL)
+    ctf_save_write (&writer->tcs, (gdb_byte *) tp->cond_string,
+		    strlen (tp->cond_string));
+  ctf_save_write (&writer->tcs, &zero, 1);
+
+  /* cmd_strings */
+  u32 = VEC_length (char_ptr, tp->cmd_strings);
+  ctf_save_align_write (&writer->tcs, (gdb_byte *) &u32, 4, 4);
+  for (a = 0; VEC_iterate (char_ptr, tp->cmd_strings, a, act); ++a)
+    ctf_save_write (&writer->tcs, (gdb_byte *) act, strlen (act) + 1);
+
+}
+
+/* This is the implementation of trace_file_write_ops method
+   write_definition_end.  */
+
+static void
+ctf_write_definition_end (struct trace_file_writer *self)
+{
+  struct ctf_trace_file_writer *writer
+    = (struct ctf_trace_file_writer *) self;
+
+  self->ops->frame_ops->end (self);
+}
+
+/* The minimal file size of data stream.  It is required by
+   babeltrace.  */
+
+#define CTF_FILE_MIN_SIZE		4096
+
+/* 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);
+  /* The babeltrace requires or assumes that the size of datastream
+     file is greater than 4096 bytes.  If we don't generate enough
+     packets and events, create a fake packet which has zero event,
+      to use up the space.  */
+  if (writer->tcs.packet_start < CTF_FILE_MIN_SIZE)
+    {
+      uint32_t u32;
+
+      /* magic.  */
+      u32 = CTF_MAGIC;
+      ctf_save_write_uint32 (&writer->tcs, u32);
+
+      /* content_size.  */
+      u32 = 0;
+      ctf_save_write_uint32 (&writer->tcs, u32);
+
+      /* packet_size.  */
+      u32 = 12;
+      if (writer->tcs.packet_start + u32 < CTF_FILE_MIN_SIZE)
+	u32 = CTF_FILE_MIN_SIZE - writer->tcs.packet_start;
+
+      u32 *= TARGET_CHAR_BIT;
+      ctf_save_write_uint32 (&writer->tcs, u32);
+
+      /* tpnum.  */
+      u32 = 0;
+      ctf_save_write (&writer->tcs, (gdb_byte *) &u32, 2);
+
+      /* Enlarge the file to CTF_FILE_MIN_SIZE is it is still less
+	 than that.  */
+      if (CTF_FILE_MIN_SIZE
+	  > (writer->tcs.packet_start + writer->tcs.content_size))
+	{
+	  gdb_byte b = 0;
+
+	  /* Fake the content size to avoid assertion failure in
+	     ctf_save_fseek.  */
+	  writer->tcs.content_size = (CTF_FILE_MIN_SIZE
+				      - 1 - writer->tcs.packet_start);
+	  ctf_save_fseek (&writer->tcs, CTF_FILE_MIN_SIZE - 1,
+			  SEEK_SET);
+	  ctf_save_write (&writer->tcs, &b, 1);
+	}
+    }
+}
+
+/* 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_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
+    = xmalloc (sizeof (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 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 struct target_ops 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 (char *dirname)
+{
+  int ret;
+  struct bt_iter_pos begin_pos;
+  struct bt_iter_pos *pos;
+
+  ctx = bt_context_create ();
+  if (ctx == NULL)
+    error (_("Unable to create bt_context"));
+  ret = bt_context_add_trace (ctx, dirname, "ctf", NULL, NULL, NULL);
+  if (ret < 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"));
+    }
+
+  /* Iterate over events, and look for an event for register block
+     to set trace_regblock_size.  */
+
+  /* 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 *event;
+
+      event = bt_ctf_iter_read_event (ctf_iter);
+
+      name = bt_ctf_event_name (event);
+
+      if (name == NULL)
+	break;
+      else if (strcmp (name, "register") == 0)
+	{
+	  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");
+
+	  trace_regblock_size
+	    = bt_ctf_get_array_len (bt_ctf_get_decl_from_def (array));
+	}
+
+      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);
+}
+
+#define SET_INT32_FIELD(EVENT, SCOPE, VAR, FIELD)			\
+  (VAR)->FIELD = (int) 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_INT32_FIELD (event, scope, ts, 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 u32, i;						\
+      const struct bt_definition *def;				\
+								\
+      u32 = (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 < u32; i++)					\
+	{								\
+	  const struct bt_definition *element				\
+	    = bt_ctf_get_index ((EVENT), def, i);			\
+									\
+	  VEC_safe_push (char_ptr, (VAR)->ARRAY,			\
+			 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 = 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_INT32_FIELD (event, scope, utp, 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_open (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);
+
+  merge_uploaded_trace_state_variables (&uploaded_tsvs);
+  merge_uploaded_tracepoints (&uploaded_tps);
+}
+
+/* This is the implementation of target_ops method to_close.  Destroy
+   CTF iterator and context.  */
+
+static void
+ctf_close (void)
+{
+  ctf_destroy ();
+  xfree (trace_dirname);
+  trace_dirname = NULL;
+
+  trace_reset_local_state ();
+}
+
+/* This is the implementation of target_ops method to_files_info.
+   Print the directory name of CTF trace data.  */
+
+static void
+ctf_files_info (struct target_ops *t)
+{
+  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.  */
+
+static void
+ctf_fetch_registers (struct target_ops *ops,
+		     struct regcache *regcache, int regno)
+{
+  struct gdbarch *gdbarch = get_regcache_arch (regcache);
+  int offset, regn, regsize, pc_regno;
+  gdb_byte *regs = NULL;
+  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)
+    {
+      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");
+
+      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_register_status (regcache, regn) == REG_UNKNOWN)
+	    {
+	      if (regno == regn)
+		{
+		  regcache_raw_supply (regcache, regno, regs + offset);
+		  break;
+		}
+	      else if (regno == -1)
+		{
+		  regcache_raw_supply (regcache, regn, regs + offset);
+		}
+	    }
+	  offset += regsize;
+	}
+      return;
+    }
+
+  regs = alloca (trace_regblock_size);
+
+  /* We get here if no register data has been found.  Mark registers
+     as unavailable.  */
+  for (regn = 0; regn < gdbarch_num_regs (gdbarch); regn++)
+    regcache_raw_supply (regcache, regn, NULL);
+
+  /* We can often usefully guess that the PC is going to be the same
+     as the address of the tracepoint.  */
+  pc_regno = gdbarch_pc_regnum (gdbarch);
+  if (pc_regno >= 0 && (regno == -1 || regno == pc_regno))
+    {
+      struct tracepoint *tp = get_tracepoint (get_tracepoint_number ());
+
+      if (tp != NULL && tp->base.loc)
+	{
+	  /* But don't try to guess if tracepoint is multi-location...  */
+	  if (tp->base.loc->next != NULL)
+	    {
+	      warning (_("Tracepoint %d has multiple "
+			 "locations, cannot infer $pc"),
+		       tp->base.number);
+	      return;
+	    }
+	  /* ... or does while-stepping.  */
+	  if (tp->step_count > 0)
+	    {
+	      warning (_("Tracepoint %d does while-stepping, "
+			 "cannot infer $pc"),
+		       tp->base.number);
+	      return;
+	    }
+
+	  store_unsigned_integer (regs, register_size (gdbarch, pc_regno),
+				  gdbarch_byte_order (gdbarch),
+				  tp->base.loc->address);
+	  regcache_raw_supply (regcache, pc_regno, regs);
+	}
+    }
+}
+
+/* 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.  */
+
+static LONGEST
+ctf_xfer_partial (struct target_ops *ops, enum target_object object,
+		  const char *annex, gdb_byte *readbuf,
+		  const gdb_byte *writebuf, ULONGEST offset,
+		  LONGEST len)
+{
+  /* We're only doing regular memory for now.  */
+  if (object != TARGET_OBJECT_MEMORY)
+    return -1;
+
+  if (readbuf == NULL)
+    error (_("ctf_xfer_partial: trace file is read-only"));
+
+  if (get_traceframe_number () != -1)
+    {
+      struct bt_iter_pos *pos;
+      int i = 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;
+	  enum bfd_endian byte_order
+	    = gdbarch_byte_order (target_gdbarch ());
+	  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 (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");
+	      const struct bt_declaration *decl
+		= bt_ctf_get_decl_from_def (array);
+	      gdb_byte *contents;
+	      int k;
+
+	      contents = 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);
+
+	      return amt;
+	    }
+
+	  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);
+    }
+
+  /* It's unduly pedantic to refuse to look at the executable for
+     read-only pieces; so do the equivalent of readonly regions aka
+     QTro packet.  */
+  if (exec_bfd != NULL)
+    {
+      asection *s;
+      bfd_size_type size;
+      bfd_vma vma;
+
+      for (s = exec_bfd->sections; s; s = s->next)
+	{
+	  if ((s->flags & SEC_LOAD) == 0
+	      || (s->flags & SEC_READONLY) == 0)
+	    continue;
+
+	  vma = s->vma;
+	  size = bfd_get_section_size (s);
+	  if (vma <= offset && offset < (vma + size))
+	    {
+	      ULONGEST amt;
+
+	      amt = (vma + size) - offset;
+	      if (amt > len)
+		amt = len;
+
+	      amt = bfd_get_section_contents (exec_bfd, s,
+					      readbuf, offset - vma, amt);
+	      return amt;
+	    }
+	}
+    }
+
+  /* Indicate failure to find the requested memory block.  */
+  return -1;
+}
+
+/* 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.  */
+
+static int
+ctf_get_trace_state_variable_value (int tsvnum, LONGEST *val)
+{
+  struct bt_iter_pos *pos;
+  int found = 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 '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 = 1;
+	    }
+	}
+
+      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->base.loc)
+	addr = tp->base.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.  */
+
+static int
+ctf_trace_find (enum trace_find_type type, int num,
+		CORE_ADDR addr1, CORE_ADDR addr2, int *tpp)
+{
+  int ret = -1;
+  int tfnum = 0;
+  int found = 0;
+  struct bt_iter_pos pos;
+
+  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)
+    {
+      int id;
+      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_has_stack.
+   The target has a stack when GDB has already selected one trace
+   frame.  */
+
+static int
+ctf_has_stack (struct target_ops *ops)
+{
+  return get_traceframe_number () != -1;
+}
+
+/* This is the implementation of target_ops method to_has_registers.
+   The target has registers when GDB has already selected one trace
+   frame.  */
+
+static int
+ctf_has_registers (struct target_ops *ops)
+{
+  return get_traceframe_number () != -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.  */
+
+static struct traceframe_info *
+ctf_traceframe_info (void)
+{
+  struct traceframe_info *info = XCNEW (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;
+	  struct mem_range *r;
+
+	  r = VEC_safe_push (mem_range_s, info->memory, NULL);
+	  def = bt_ctf_get_field (event, scope, "address");
+	  r->start = bt_ctf_get_uint64 (def);
+
+	  def = bt_ctf_get_field (event, scope, "length");
+	  r->length = (uint16_t) bt_ctf_get_uint64 (def);
+	}
+      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_int64 (def);
+	  VEC_safe_push (int, info->tvars, 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;
+}
+
+/* This is the implementation of target_ops method to_get_trace_status.
+   The trace status for a file is that tracing can never be run.  */
+
+static int
+ctf_get_trace_status (struct trace_status *ts)
+{
+  /* Other bits of trace status were collected as part of opening the
+     trace files, so nothing to do here.  */
+
+  return -1;
+}
+
+static void
+init_ctf_ops (void)
+{
+  memset (&ctf_ops, 0, sizeof (ctf_ops));
+
+  ctf_ops.to_shortname = "ctf";
+  ctf_ops.to_longname = "CTF file";
+  ctf_ops.to_doc = "Use a CTF directory as a target.\n\
+Specify the filename of the CTF directory.";
+  ctf_ops.to_open = ctf_open;
+  ctf_ops.to_close = ctf_close;
+  ctf_ops.to_fetch_registers = ctf_fetch_registers;
+  ctf_ops.to_xfer_partial = ctf_xfer_partial;
+  ctf_ops.to_files_info = ctf_files_info;
+  ctf_ops.to_get_trace_status = ctf_get_trace_status;
+  ctf_ops.to_trace_find = ctf_trace_find;
+  ctf_ops.to_get_trace_state_variable_value
+    = ctf_get_trace_state_variable_value;
+  ctf_ops.to_stratum = process_stratum;
+  ctf_ops.to_has_stack = ctf_has_stack;
+  ctf_ops.to_has_registers = ctf_has_registers;
+  ctf_ops.to_traceframe_info = ctf_traceframe_info;
+  ctf_ops.to_magic = OPS_MAGIC;
+}
+
+#endif
+
+/* -Wmissing-prototypes */
+
+extern initialize_file_ftype _initialize_ctf;
+
+/* module initialization */
+
+void
+_initialize_ctf (void)
+{
+#if HAVE_LIBBABELTRACE
+  init_ctf_ops ();
+
+  add_target_with_completer (&ctf_ops, filename_completer);
+#endif
+}