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Re: [RFA/RFC] Add dump and load command to process record and replay


Hui Zhu wrote:

+static void
+cmd_record_fd_cleanups (void *recfdp)
+{
+  int recfd = *(int *) recfdp;
+  close (recfd);
+}

Here's a suggested comment to start documenting the file format:


/* Record log save-file format
   Version 1

     Header:
       4 bytes: magic number RECORD_FILE_MAGIC.
         NOTE: be sure to change whenever this file format changes!

     Records:
      record_end:
       1 byte:  record type (record_end)
      record_reg:
       1 byte:  record type (record_reg)
       8 bytes: register id
      16 bytes: register value
      record_mem:
       1 byte:  record type (record_mem)
       8 bytes: memory address
       8 bytes: memory length
       n bytes: memory value (n == memory length)

   Version 2 (proposed)
   [...] */

Below I'll suggest some possible debugging printfs.
Feel free to modify them to your own liking.

+static inline void
+record_read_dump (char *recfilename, int fildes, void *buf, size_t nbyte)
+{
+  if (read (fildes, buf, nbyte) != nbyte)
+    error (_("Failed to read dump of execution records in '%s'."),
+           recfilename);
+}
+
+static inline void
+record_write_dump (char *recfilename, int fildes, const void *buf,
+                   size_t nbyte)
+{
+  if (write (fildes, buf, nbyte) != nbyte)
+    error (_("Failed to write dump of execution records to '%s'."),
+           recfilename);
+}
+
+/* Dump the execution log to a file.  */
+
+static void
+cmd_record_dump (char *args, int from_tty)
+{
+  char *recfilename, recfilename_buffer[40];
+  int recfd;
+  struct record_entry *cur_record_list;
+  uint32_t magic;
+  struct regcache *regcache;
+  struct gdbarch *gdbarch;
+  struct cleanup *old_cleanups;
+  struct cleanup *set_cleanups;
+
+  if (current_target.to_stratum != record_stratum)
+    error (_("Process record is not started.\n"));
+
+  if (args && *args)
+    recfilename = args;
+  else
+    {
+      /* Default corefile name is "gdb_record.PID".  */
+      sprintf (recfilename_buffer, "gdb_record.%d", PIDGET (inferior_ptid));
+      recfilename = recfilename_buffer;
+    }
+
+  /* Open the dump file.  */
  if (record_debug)
    fprintf_unfiltered (gdb_stdlog,
                        _("Saving recording to file '%s'\n"),
                        recfilename);

+  recfd = open (recfilename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
+                S_IRUSR | S_IWUSR);
+  if (recfd < 0)
+    error (_("Failed to open '%s' for dump execution records: %s"),
+           recfilename, strerror (errno));
+  old_cleanups = make_cleanup (cmd_record_fd_cleanups, &recfd);
+
+  /* Save the current record entry to "cur_record_list".  */
+  cur_record_list = record_list;
+
+  /* Get the values of regcache and gdbarch.  */
+  regcache = get_current_regcache ();
+  gdbarch = get_regcache_arch (regcache);
+
+  /* Disable the GDB operation record.  */
+  set_cleanups = record_gdb_operation_disable_set ();
+
+  /* Write the magic code.  */
+  magic = RECORD_FILE_MAGIC;
    if (record_debug)
      fprintf_unfiltered (gdb_stdlog, _("\
  Writing 4-byte magic cookie RECORD_FILE_MAGIC (0x%08x)\n"),
                          magic);

+  record_write_dump (recfilename, recfd, &magic, 4);
+
+  /* Reverse execute to the begin of record list.  */
+  while (1)
+    {
+      /* Check for beginning and end of log.  */
+      if (record_list == &record_first)
+        break;
+
+      record_exec_entry (regcache, gdbarch, record_list);
+
+      if (record_list->prev)
+        record_list = record_list->prev;
+    }
+
+  /* Dump the entries to recfd and forward execute to the end of
+     record list.  */
+  while (1)
+    {
+      /* Dump entry.  */
+      if (record_list != &record_first)
+        {
+          uint8_t tmpu8;
+          uint64_t tmpu64;
+
+          tmpu8 = record_list->type;
+          record_write_dump (recfilename, recfd, &tmpu8, 1);
+
+          switch (record_list->type)
+            {
+            case record_reg: /* reg */
+              tmpu64 = record_list->u.reg.num;
+              if (BYTE_ORDER == LITTLE_ENDIAN)
+                tmpu64 = bswap_64 (tmpu64);
            if (record_debug)
              fprintf_unfiltered (gdb_stdlog, _("\
  Writing register %d val 0x%016llx (1 plus 8 plus %d bytes)\n"),
                                  p->u.reg.num,
                                  *(ULONGEST *) p->u.reg.val,
                                  MAX_REGISTER_SIZE);

+              record_write_dump (recfilename, recfd, &tmpu64, 8);
+
+              record_write_dump (recfilename, recfd, record_list->u.reg.val,
+                                 MAX_REGISTER_SIZE);
+              break;
+            case record_mem: /* mem */
+              if (!record_list->u.mem.mem_entry_not_accessible)
+                {
+                  tmpu64 = record_list->u.mem.addr;
+                  if (BYTE_ORDER == LITTLE_ENDIAN)
+                    tmpu64 = bswap_64 (tmpu64);
            if (record_debug)
              fprintf_unfiltered (gdb_stdlog, _("\
  Writing memory 0x%08x (1 plus 8 plus 8 bytes plus %d bytes)\n"),
                                  (unsigned int) p->u.mem.addr,
                                  p->u.mem.len);

+                  record_write_dump (recfilename, recfd, &tmpu64, 8);
+
+                  tmpu64 = record_list->u.mem.len;
+                  if (BYTE_ORDER == LITTLE_ENDIAN)
+                    tmpu64 = bswap_64 (tmpu64);
+                  record_write_dump (recfilename, recfd, &tmpu64, 8);
+
+                  record_write_dump (recfilename, recfd,
+                                     record_list->u.mem.val,
+                                     record_list->u.mem.len);
+                }
+              break;
          case record_end:
              /* FIXME: record the contents of record_end rec.  */
              if (record_debug)
                fprintf_unfiltered (gdb_stdlog, _("\
  Writing record_end (1 byte)\n"));
            break;

+            }
+        }
+
+      /* Execute entry.  */
+      record_exec_entry (regcache, gdbarch, record_list);
+
+      if (record_list->next)
+        record_list = record_list->next;
+      else
+        break;
+    }
+
+  /* Reverse execute to cur_record_list.  */
+  while (1)
+    {
+      /* Check for beginning and end of log.  */
+      if (record_list == cur_record_list)
+        break;
+
+      record_exec_entry (regcache, gdbarch, record_list);
+
+      if (record_list->prev)
+        record_list = record_list->prev;
+    }
+
+  do_cleanups (set_cleanups);
+  do_cleanups (old_cleanups);
+
+  /* Succeeded.  */
+  fprintf_filtered (gdb_stdout, _("Saved dump of execution "
+                                  "records to `%s'.\n"),
+                    recfilename);
+}
+
+/* Load the execution log from a file.  */
+
+static void
+cmd_record_load (char *args, int from_tty)
+{
+  int recfd;
+  uint32_t magic;
+  struct cleanup *old_cleanups;
+  struct cleanup *old_cleanups2;
+  struct record_entry *rec;
+  int insn_number = 0;
+
+  if (current_target.to_stratum != record_stratum)
+    {
+      cmd_record_start (NULL, from_tty);
+      printf_unfiltered (_("Auto start process record.\n"));
+    }
+
+  if (!args || (args && !*args))
+    error (_("Argument for filename required.\n"));
+
  /* Open the load file.  */
  if (record_debug)
    fprintf_unfiltered (gdb_stdlog,
                        _("Restoring recording from file '%s'\n"), args);

+  /* Open the load file.  */
+  recfd = open (args, O_RDONLY | O_BINARY);
+  if (recfd < 0)
+    error (_("Failed to open '%s' for loading execution records: %s"),
+           args, strerror (errno));
+  old_cleanups = make_cleanup (cmd_record_fd_cleanups, &recfd);
+
+  /* Check the magic code.  */
+  record_read_dump (args, recfd, &magic, 4);
+  if (magic != RECORD_FILE_MAGIC)
+    error (_("'%s' is not a valid dump of execution records."), args);
+
+  /* Load the entries in recfd to the record_arch_list_head and
+     record_arch_list_tail.  */
+  record_arch_list_head = NULL;
+  record_arch_list_tail = NULL;
+  old_cleanups2 = make_cleanup (record_arch_list_cleanups, 0);
+
+  while (1)
+    {
+      int ret;
+      uint8_t tmpu8;
+      uint64_t tmpu64;
+
+      ret = read (recfd, &tmpu8, 1);
+      if (ret < 0)
+        error (_("Failed to read dump of execution records in '%s'."), args);
+      if (ret == 0)
+        break;
+
+      switch (tmpu8)
+        {
+        case record_reg: /* reg */
+          rec = (struct record_entry *) xmalloc (sizeof (struct record_entry));
+          rec->u.reg.val = (gdb_byte *) xmalloc (MAX_REGISTER_SIZE);
+          rec->prev = NULL;
+          rec->next = NULL;
+          rec->type = record_reg;
+          /* Get num.  */
+          record_read_dump (args, recfd, &tmpu64, 8);
+          if (BYTE_ORDER == LITTLE_ENDIAN)
+            tmpu64 = bswap_64 (tmpu64);
+          rec->u.reg.num = tmpu64;
+          /* Get val.  */
+          record_read_dump (args, recfd, rec->u.reg.val, MAX_REGISTER_SIZE);
               if (record_debug)
                 fprintf_unfiltered (gdb_stdlog, _("\
  Reading register %d val 0x%016llx (1 plus 8 plus %d bytes)\n"),
                                     rec->u.reg.num,
                                     *(ULONGEST *) rec->u.reg.val,
                                     MAX_REGISTER_SIZE);

+          record_arch_list_add (rec);
+          break;
+        case record_mem: /* mem */
+          rec = (struct record_entry *) xmalloc (sizeof (struct record_entry));
+          rec->prev = NULL;
+          rec->next = NULL;
+          rec->type = record_mem;
+          /* Get addr.  */
+          record_read_dump (args, recfd, &tmpu64, 8);
+          if (BYTE_ORDER == LITTLE_ENDIAN)
+            tmpu64 = bswap_64 (tmpu64);
+          rec->u.mem.addr = tmpu64;
+          /* Get len.  */
+          record_read_dump (args, recfd, &tmpu64, 8);
+          if (BYTE_ORDER == LITTLE_ENDIAN)
+            tmpu64 = bswap_64 (tmpu64);
+          rec->u.mem.len = tmpu64;
+          rec->u.mem.mem_entry_not_accessible = 0;
+          rec->u.mem.val = (gdb_byte *) xmalloc (rec->u.mem.len);
+          /* Get val.  */
+          record_read_dump (args, recfd, rec->u.mem.val, rec->u.mem.len);
               if (record_debug)
                 fprintf_unfiltered (gdb_stdlog, _("\
  Reading memory 0x%08x (1 plus 8 plus %d bytes)\n"),
                                     (unsigned int) rec->u.mem.addr,
                                     rec->u.mem.len);

+          record_arch_list_add (rec);
+          break;
+
+        case record_end: /* end */
+          rec = (struct record_entry *) xmalloc (sizeof (struct record_entry));
+          rec->prev = NULL;
+          rec->next = NULL;
+          rec->type = record_end;
               if (record_debug)
                 fprintf_unfiltered (gdb_stdlog, _("\
  Reading record_end (one byte)\n"));

+          record_arch_list_add (rec);
+          insn_number ++;
+          break;
+
+        default:
+          error (_("Format of '%s' is not right."), args);
+          break;
+        }
+    }
+
+  discard_cleanups (old_cleanups2);
+
+  /* Add record_arch_list_head to the end of record list.  */
+  for (rec = record_list; rec->next; rec = rec->next);
+  rec->next = record_arch_list_head;
+  record_arch_list_head->prev = rec;
+
+  /* Update record_insn_num and record_insn_max_num.  */
+  record_insn_num += insn_number;
+  if (record_insn_num > record_insn_max_num)
+    {
+      record_insn_max_num = record_insn_num;
+      warning (_("Auto increase record/replay buffer limit to %d."),
+               record_insn_max_num);
+    }
+
+  do_cleanups (old_cleanups);
+
+  /* Succeeded.  */
+  fprintf_filtered (gdb_stdout, "Loaded recfile %s.\n", args);
+}
+


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