This commit fixes a "-gdb-set logging redirect on" crash by not
handling "logging redirect on" on the fly.

Previous discussion here:
 https://sourceware.org/ml/gdb-patches/2017-01/msg00467.html

Code for handling "logging redirect on" on the fly was added here:
 https://sourceware.org/ml/gdb-patches/2010-08/msg00202.html

Meanwhile, MI gained support for logging, but flipping redirect "on"
on the fly was not considered.  The result is that this sequence of
commands crashes GDB:

 -gdb-set logging on
 -gdb-set logging redirect on

 Program received signal SIGSEGV, Segmentation fault.
 0x00000000008dd7bc in gdb_flush (file=0x2a097f0) at /home/pedro/gdb/mygit/cxx-convertion/src/gdb/ui-file.c:95
 194       file->to_flush (file);
 (top-gdb) bt
 #0  0x00000000008dd7bc in gdb_flush(ui_file*) (file=0x2a097f0) at /home/pedro/gdb/mygit/cxx-convertion/src/gdb/ui-file.c:95
 #1  0x00000000007b5f34 in gdb_wait_for_event(int) (block=0) at /home/pedro/gdb/mygit/cxx-convertion/src/gdb/event-loop.c:752
 #2  0x00000000007b52b6 in gdb_do_one_event() () at /home/pedro/gdb/mygit/cxx-convertion/src/gdb/event-loop.c:322
 #3  0x00000000007b5362 in start_event_loop() () at /home/pedro/gdb/mygit/cxx-convertion/src/gdb/event-loop.c:371
 #4  0x000000000082704a in captured_command_loop(void*) (data=0x0) at /home/pedro/gdb/mygit/cxx-convertion/src/gdb/main.c:325
 #5  0x00000000007b8d7c in catch_errors(int (*)(void*), void*, char*, return_mask) (func=0x827008 <captured_command_loop(void*)>, func_args=0x0, errstring=0x11dee51 "", mask=RETURN_MASK_ALL) at /home/pedro/gdb/mygit/cxx-convertion/src/gdb/exceptions.c:236
 #6  0x000000000082839b in captured_main(void*) (data=0x7fffffffd820) at /home/pedro/gdb/mygit/cxx-convertion/src/gdb/main.c:1148
 During symbol reading, cannot get low and high bounds for subprogram DIE at 24065.
 #7  0x00000000008283c4 in gdb_main(captured_main_args*) (args=0x7fffffffd820) at /home/pedro/gdb/mygit/cxx-convertion/src/gdb/main.c:1158
 #8  0x0000000000412d4d in main(int, char**) (argc=4, argv=0x7fffffffd928) at /home/pedro/gdb/mygit/cxx-convertion/src/gdb/gdb.c:32

The handling of redirect on the fly is not really a use case we need
to handle, IMO.  Its inconsistent (other "set logging foo" commands
aren't handled on the fly), and complicates the code significantly.
Instead of complicating it further for MI, go back to the original
idea of warning, only:

  https://sourceware.org/ml/gdb-patches/2010-08/msg00083.html

New test included.

gdb/ChangeLog:
2017-02-02  Pedro Alves  <palves@redhat.com>

	* cli/cli-logging.c (maybe_warn_already_logging): New factored out
	from ...
	(set_logging_overwrite): ... here.
	(logging_no_redirect_file): Delete.
	(set_logging_redirect): Don't handle redirection on the fly.
	Instead warn that "logging off" / "logging on" is necessary.
	(pop_output_files): Delete references to logging_no_redirect_file.
	(show_logging_command): Always speak in terms of what will happen
	once logging is reenabled.

gdb/testsuite/ChangeLog:
2017-02-02  Pedro Alves  <palves@redhat.com>

	* gdb.mi/mi-logging.exp: Add "redirect while already logging"
	tests.

gdb/ChangeLog:
2017-02-02  Pedro Alves  <palves@redhat.com>

	* disasm.h (gdb_pretty_print_disassembler): Tweak intro comment.

gdb_pretty_print_insn allocates and destroys a couple local buffers
each time it is called, which can be many times when disassembling a
region of memory.  Avoid that overhead by adding a new class that
holds the buffers and making gdb_pretty_print_insn a method of that
class, so that the buffers can be reused across calls.

gdb/ChangeLog:
2017-02-02  Pedro Alves  <palves@redhat.com>

	* disasm.c (gdb_pretty_print_insn): Rename to ...
	(gdb_pretty_print_disassembler::pretty_print_insn): ... this.
	Remove gdbarch parameter.  Adapt to clear the object's buffers
	instead of allocating new buffers, and to print using the object's
	gdb_disassembler instead of calling gdb_print_insn.
	(dump_insns): Use gdb_pretty_print_disassembler.
	* disasm.h (gdb_pretty_print_insn): Delete declaration.
	(gdb_pretty_print_disassembler): New class.
	* record-btrace.c (btrace_insn_history): Use
	gdb_pretty_print_disassembler.

This patch starts from the desire to eliminate
make_cleanup_ui_file_delete, but then goes beyond.  It makes ui_file &
friends a real C++ class hierarchy, and switches temporary
ui_file-like objects to stack-based allocation.

- mem_fileopen -> string_file

mem_fileopen is replaced with a new string_file class that is treated
as a value class created on the stack.  This alone eliminates most
make_cleanup_ui_file_delete calls, and, simplifies code a whole lot
(diffstat shows around 1k loc dropped.)

string_file's internal buffer is a std::string, thus the "string" in
the name.  This simplifies the implementation much, compared to
mem_fileopen, which managed growing its internal buffer manually.

- ui_file_as_string, ui_file_strdup, ui_file_obsavestring all gone

The new string_file class has a string() method that provides direct
writable access to the internal std::string buffer.  This replaced
ui_file_as_string, which forced a copy of the same data the stream had
inside.  With direct access via a writable reference, we can instead
move the string out of the string_stream, avoiding deep string
copying.

Related, ui_file_xstrdup calls are replaced with xstrdup'ping the
stream's string, and ui_file_obsavestring is replaced by
obstack_copy0.

With all those out of the way, getting rid of the weird ui_file_put
mechanism was possible.

- New ui_file::printf, ui_file::puts, etc. methods

These simplify / clarify client code.  I considered splitting
client-code changes, like these, e.g.:

  -  stb = mem_fileopen ();
  -  fprintf_unfiltered (stb, "%s%s%s",
  -		      _("The valid values are:\n"),
  -		      regdesc,
  -		      _("The default is \"std\"."));
  +  string_file stb;
  +  stb.printf ("%s%s%s",
  +	      _("The valid values are:\n"),
  +	      regdesc,
  +	      _("The default is \"std\"."));

In two steps, with the first step leaving fprintf_unfiltered (etc.)
calls in place, and only afterwards do a pass to change all those to
call stb.printf etc..  I didn't do that split, because (when I tried),
it turned out to be pointless make-work: the first pass would have to
touch the fprintf_unfiltered line anyway, to replace "stb" with
"&stb".

- gdb_fopen replaced with stack-based objects

This avoids the need for cleanups or unique_ptr's.  I.e., this:

      struct ui_file *file = gdb_fopen (filename, "w");
      if (filename == NULL)
 	perror_with_name (filename);
      cleanups = make_cleanup_ui_file_delete (file);
      // use file.
      do_cleanups (cleanups);

is replaced with this:

      stdio_file file;
      if (!file.open (filename, "w"))
 	perror_with_name (filename);
      // use file.

- odd contorsions in null_file_write / null_file_fputs around when to
  call to_fputs / to_write eliminated.

- Global null_stream object

A few places that were allocating a ui_file in order to print to
"nowhere" are adjusted to instead refer to a new 'null_stream' global
stream.

- TUI's tui_sfileopen eliminated.  TUI's ui_file much simplified

The TUI's ui_file was serving a dual purpose.  It supported being used
as string buffer, and supported being backed by a stdio FILE.  The
string buffer part is gone, replaced by using of string_file.  The
'FILE *' support is now much simplified, by making the TUI's ui_file
inherit from stdio_file.

gdb/ChangeLog:
2017-02-02  Pedro Alves  <palves@redhat.com>

	* ada-lang.c (type_as_string): Use string_file.
	* ada-valprint.c (ada_print_floating): Use string_file.
	* ada-varobj.c (ada_varobj_scalar_image)
	(ada_varobj_get_value_image): Use string_file.
	* aix-thread.c (aix_thread_extra_thread_info): Use string_file.
	* arm-tdep.c (_initialize_arm_tdep): Use string_printf.
	* breakpoint.c (update_inserted_breakpoint_locations)
	(insert_breakpoint_locations, reattach_breakpoints)
	(print_breakpoint_location, print_one_detail_ranged_breakpoint)
	(print_it_watchpoint): Use string_file.
	(save_breakpoints): Use stdio_file.
	* c-exp.y (oper): Use string_file.
	* cli/cli-logging.c (set_logging_redirect): Use ui_file_up and
	tee_file.
	(pop_output_files): Use delete.
	(handle_redirections): Use stdio_file and tee_file.
	* cli/cli-setshow.c (do_show_command): Use string_file.
	* compile/compile-c-support.c (c_compute_program): Use
	string_file.
	* compile/compile-c-symbols.c (generate_vla_size): Take a
	'string_file &' instead of a 'ui_file *'.
	(generate_c_for_for_one_variable): Take a 'string_file &' instead
	of a 'ui_file *'.  Use string_file.
	(generate_c_for_variable_locations): Take a 'string_file &'
	instead of a 'ui_file *'.
	* compile/compile-internal.h (generate_c_for_for_one_variable):
	Take a 'string_file &' instead of a 'ui_file *'.
	* compile/compile-loc2c.c (push, pushf, unary, binary)
	(print_label, pushf_register_address, pushf_register)
	(do_compile_dwarf_expr_to_c): Take a 'string_file &' instead of a
	'ui_file *'.  Adjust.
	* compile/compile.c (compile_to_object): Use string_file.
	* compile/compile.h (compile_dwarf_expr_to_c)
	(compile_dwarf_bounds_to_c): Take a 'string_file &' instead of a
	'ui_file *'.
	* cp-support.c (inspect_type): Use string_file and obstack_copy0.
	(replace_typedefs_qualified_name): Use string_file and
	obstack_copy0.
	* disasm.c (gdb_pretty_print_insn): Use string_file.
	(gdb_disassembly): Adjust reference the null_stream global.
	(do_ui_file_delete): Delete.
	(gdb_insn_length): Use null_stream.
	* dummy-frame.c (maintenance_print_dummy_frames): Use stdio_file.
	* dwarf2loc.c (dwarf2_compile_property_to_c)
	(locexpr_generate_c_location, loclist_generate_c_location): Take a
	'string_file &' instead of a 'ui_file *'.
	* dwarf2loc.h (dwarf2_compile_property_to_c): Likewise.
	* dwarf2read.c (do_ui_file_peek_last): Delete.
	(dwarf2_compute_name): Use string_file.
	* event-top.c (gdb_setup_readline): Use stdio_file.
	* gdbarch.sh (verify_gdbarch): Use string_file.
	* gdbtypes.c (safe_parse_type): Use null_stream.
	* guile/scm-breakpoint.c (gdbscm_breakpoint_commands): Use
	string_file.
	* guile/scm-disasm.c (gdbscm_print_insn_from_port): Take a
	'string_file *' instead of a 'ui_file *'.
	(gdbscm_arch_disassemble): Use string_file.
	* guile/scm-frame.c (frscm_print_frame_smob): Use string_file.
	* guile/scm-ports.c (class ioscm_file_port): Now a class that
	inherits from ui_file.
	(ioscm_file_port_delete, ioscm_file_port_rewind)
	(ioscm_file_port_put): Delete.
	(ioscm_file_port_write): Rename to ...
	(ioscm_file_port::write): ... this.  Remove file_port_magic
	checks.
	(ioscm_file_port_new): Delete.
	(ioscm_with_output_to_port_worker): Use ioscm_file_port and
	ui_file_up.
	* guile/scm-type.c (tyscm_type_name): Use string_file.
	* guile/scm-value.c (vlscm_print_value_smob, gdbscm_value_print):
	Use string_file.
	* infcmd.c (print_return_value_1): Use string_file.
	* infrun.c (print_target_wait_results): Use string_file.
	* language.c (add_language): Use string_file.
	* location.c (explicit_to_string_internal): Use string_file.
	* main.c (captured_main_1): Use null_file.
	* maint.c (maintenance_print_architecture): Use stdio_file.
	* mi/mi-cmd-stack.c (list_arg_or_local): Use string_file.
	* mi/mi-common.h (struct mi_interp) <out, err, log, targ,
	event_channel>: Change type to mi_console_file pointer.
	* mi/mi-console.c (mi_console_file_fputs, mi_console_file_flush)
	(mi_console_file_delete): Delete.
	(struct mi_console_file): Delete.
	(mi_console_file_magic): Delete.
	(mi_console_file_new): Delete.
	(mi_console_file::mi_console_file): New.
	(mi_console_file_delete): Delete.
	(mi_console_file_fputs): Delete.
	(mi_console_file::write): New.
	(mi_console_raw_packet): Delete.
	(mi_console_file::flush): New.
	(mi_console_file_flush): Delete.
	(mi_console_set_raw): Rename to ...
	(mi_console_file::set_raw): ... this.
	* mi/mi-console.h (class mi_console_file): New class.
	(mi_console_file_new, mi_console_set_raw): Delete.
	* mi/mi-interp.c (mi_interpreter_init): Use mi_console_file.
	(mi_set_logging): Use delete and tee_file.  Adjust.
	* mi/mi-main.c (output_register): Use string_file.
	(mi_cmd_data_evaluate_expression): Use string_file.
	(mi_cmd_data_read_memory): Use string_file.
	(mi_cmd_execute, print_variable_or_computed): Use string_file.
	* mi/mi-out.c (mi_ui_out::main_stream): New.
	(mi_ui_out::rewind): Use main_stream and
	string_file.
	(mi_ui_out::put): Use main_stream and string_file.
	(mi_ui_out::mi_ui_out): Remove 'stream' parameter.
	Allocate a 'string_file' instead.
	(mi_out_new): Don't allocate a mem_fileopen stream here.
	* mi/mi-out.h (mi_ui_out::mi_ui_out): Remove 'stream' parameter.
	(mi_ui_out::main_stream): Declare method.
	* printcmd.c (eval_command): Use string_file.
	* psymtab.c (maintenance_print_psymbols): Use stdio_file.
	* python/py-arch.c (archpy_disassemble): Use string_file.
	* python/py-breakpoint.c (bppy_get_commands): Use string_file.
	* python/py-frame.c (frapy_str): Use string_file.
	* python/py-framefilter.c (py_print_type, py_print_single_arg):
	Use string_file.
	* python/py-type.c (typy_str): Use string_file.
	* python/py-unwind.c (unwind_infopy_str): Use string_file.
	* python/py-value.c (valpy_str): Use string_file.
	* record-btrace.c (btrace_insn_history): Use string_file.
	* regcache.c (regcache_print): Use stdio_file.
	* reggroups.c (maintenance_print_reggroups): Use stdio_file.
	* remote.c (escape_buffer): Use string_file.
	* rust-lang.c (rust_get_disr_info): Use string_file.
	* serial.c (serial_open_ops_1): Use stdio_file.
	(do_serial_close): Use delete.
	* stack.c (print_frame_arg): Use string_file.
	(print_frame_args): Remove local mem_fileopen stream, not used.
	(print_frame): Use string_file.
	* symmisc.c (maintenance_print_symbols): Use stdio_file.
	* symtab.h (struct symbol_computed_ops) <generate_c_location>:
	Take a 'string_file *' instead of a 'ui_file *'.
	* top.c (new_ui): Use stdio_file and stderr_file.
	(free_ui): Use delete.
	(execute_command_to_string): Use string_file.
	(quit_confirm): Use string_file.
	* tracepoint.c (collection_list::append_exp): Use string_file.
	* tui/tui-disasm.c (tui_disassemble): Use string_file.
	* tui/tui-file.c: Don't include "ui-file.h".
	(enum streamtype, struct tui_stream): Delete.
	(tui_file_new, tui_file_delete, tui_fileopen, tui_sfileopen)
	(tui_file_isatty, tui_file_rewind, tui_file_put): Delete.
	(tui_file::tui_file): New method.
	(tui_file_fputs): Delete.
	(tui_file_get_strbuf): Delete.
	(tui_file::puts): New method.
	(tui_file_adjust_strbuf): Delete.
	(tui_file_flush): Delete.
	(tui_file::flush): New method.
	* tui/tui-file.h: Tweak intro comment.
	Include ui-file.h.
	(tui_fileopen, tui_sfileopen, tui_file_get_strbuf)
	(tui_file_adjust_strbuf): Delete declarations.
	(class tui_file): New class.
	* tui/tui-io.c (tui_initialize_io): Use tui_file.
	* tui/tui-regs.c (tui_restore_gdbout): Use delete.
	(tui_register_format): Use string_stream.
	* tui/tui-stack.c (tui_make_status_line): Use string_file.
	(tui_get_function_from_frame): Use string_file.
	* typeprint.c (type_to_string): Use string_file.
	* ui-file.c (struct ui_file, ui_file_magic, ui_file_new): Delete.
	(null_stream): New global.
	(ui_file_delete): Delete.
	(ui_file::ui_file): New.
	(null_file_isatty): Delete.
	(ui_file::~ui_file): New.
	(null_file_rewind): Delete.
	(ui_file::printf): New.
	(null_file_put): Delete.
	(null_file_flush): Delete.
	(ui_file::putstr): New.
	(null_file_write): Delete.
	(ui_file::putstrn): New.
	(null_file_read): Delete.
	(ui_file::putc): New.
	(null_file_fputs): Delete.
	(null_file_write_async_safe): Delete.
	(ui_file::vprintf): New.
	(null_file_delete): Delete.
	(null_file::write): New.
	(null_file_fseek): Delete.
	(null_file::puts): New.
	(ui_file_data): Delete.
	(null_file::write_async_safe): New.
	(gdb_flush, ui_file_isatty): Adjust.
	(ui_file_put, ui_file_rewind): Delete.
	(ui_file_write): Adjust.
	(ui_file_write_for_put): Delete.
	(ui_file_write_async_safe, ui_file_read): Adjust.
	(ui_file_fseek): Delete.
	(fputs_unfiltered): Adjust.
	(set_ui_file_flush, set_ui_file_isatty, set_ui_file_rewind)
	(set_ui_file_put, set_ui_file_write, set_ui_file_write_async_safe)
	(set_ui_file_read, set_ui_file_fputs, set_ui_file_fseek)
	(set_ui_file_data): Delete.
	(string_file::~string_file, string_file::write)
	(struct accumulated_ui_file, do_ui_file_xstrdup, ui_file_xstrdup)
	(do_ui_file_as_string, ui_file_as_string): Delete.
	(do_ui_file_obsavestring, ui_file_obsavestring): Delete.
	(struct mem_file): Delete.
	(mem_file_new): Delete.
	(stdio_file::stdio_file): New.
	(mem_file_delete): Delete.
	(stdio_file::stdio_file): New.
	(mem_fileopen): Delete.
	(stdio_file::~stdio_file): New.
	(mem_file_rewind): Delete.
	(stdio_file::set_stream): New.
	(mem_file_put): Delete.
	(stdio_file::open): New.
	(mem_file_write): Delete.
	(stdio_file_magic, struct stdio_file): Delete.
	(stdio_file_new, stdio_file_delete, stdio_file_flush): Delete.
	(stdio_file::flush): New.
	(stdio_file_read): Rename to ...
	(stdio_file::read): ... this.  Adjust.
	(stdio_file_write): Rename to ...
	(stdio_file::write): ... this.  Adjust.
	(stdio_file_write_async_safe): Rename to ...
	(stdio_file::write_async_safe) ... this.  Adjust.
	(stdio_file_fputs): Rename to ...
	(stdio_file::puts) ... this.  Adjust.
	(stdio_file_isatty): Delete.
	(stdio_file_fseek): Delete.
	(stdio_file::isatty): New.
	(stderr_file_write): Rename to ...
	(stderr_file::write) ... this.  Adjust.
	(stderr_file_fputs): Rename to ...
	(stderr_file::puts) ... this.  Adjust.
	(stderr_fileopen, stdio_fileopen, gdb_fopen): Delete.
	(stderr_file::stderr_file): New.
	(tee_file_magic): Delete.
	(struct tee_file): Delete.
	(tee_file::tee_file): New.
	(tee_file_new): Delete.
	(tee_file::~tee_file): New.
	(tee_file_delete): Delete.
	(tee_file_flush): Rename to ...
	(tee_file::flush): ... this.  Adjust.
	(tee_file_write): Rename to ...
	(tee_file::write): ... this.  Adjust.
	(tee_file::write_async_safe): New.
	(tee_file_fputs): Rename to ...
	(tee_file::puts): ... this.  Adjust.
	(tee_file_isatty): Rename to ...
	(tee_file::isatty): ... this.  Adjust.
	* ui-file.h (struct obstack, struct ui_file): Don't
	forward-declare.
	(ui_file_new, ui_file_flush_ftype, set_ui_file_flush)
	(ui_file_write_ftype)
	(set_ui_file_write, ui_file_fputs_ftype, set_ui_file_fputs)
	(ui_file_write_async_safe_ftype, set_ui_file_write_async_safe)
	(ui_file_read_ftype, set_ui_file_read, ui_file_isatty_ftype)
	(set_ui_file_isatty, ui_file_rewind_ftype, set_ui_file_rewind)
	(ui_file_put_method_ftype, ui_file_put_ftype, set_ui_file_put)
	(ui_file_delete_ftype, set_ui_file_data, ui_file_fseek_ftype)
	(set_ui_file_fseek): Delete.
	(ui_file_data, ui_file_delete, ui_file_rewind)
	(struct ui_file): New.
	(ui_file_up): New.
	(class null_file): New.
	(null_stream): Declare.
	(ui_file_write_for_put, ui_file_put): Delete.
	(ui_file_xstrdup, ui_file_as_string, ui_file_obsavestring):
	Delete.
	(ui_file_fseek, mem_fileopen, stdio_fileopen, stderr_fileopen)
	(gdb_fopen, tee_file_new): Delete.
	(struct string_file): New.
	(struct stdio_file): New.
	(stdio_file_up): New.
	(struct stderr_file): New.
	(class tee_file): New.
	* ui-out.c (ui_out::field_stream): Take a 'string_file &' instead
	of a 'ui_file *'.  Adjust.
	* ui-out.h (class ui_out) <field_stream>: Likewise.
	* utils.c (do_ui_file_delete, make_cleanup_ui_file_delete)
	(null_stream): Delete.
	(error_stream): Take a 'string_file &' instead of a 'ui_file *'.
	Adjust.
	* utils.h (struct ui_file): Delete forward declaration..
	(make_cleanup_ui_file_delete, null_stream): Delete declarations.
	(error_stream): Take a 'string_file &' instead of a
	'ui_file *'.
	* varobj.c (varobj_value_get_print_value): Use string_file.
	* xtensa-tdep.c (xtensa_verify_config): Use string_file.
	* gdbarch.c: Regenerate.

ui_file_rewind is a ui_file method that only really works with mem
buffer files, and is a nop on other ui_file types.  It'd be desirable
to eliminate it from the base ui_file interface, and move it to the
"mem_fileopen" subclass of ui_file instead.  A following patch does
just that.

Unfortunately, there are a couple references to ui_file_rewind inside
gdb_disassembler::pretty_print_insn that were made harder to eliminate
with the recent addition of the gdb_disassembler wrapper.

Before the gdb_disassembler wrapper was added, in commit
e47ad6c0 ("Refactor disassembly code"), gdb_pretty_print_insn
used to be passed a ui_file pointer as argument, and it was simple to
adjust that pointer be a "mem_fileopen" ui_file pointer instead, since
there's only one gdb_pretty_print_insn caller.

That commit made gdb_pretty_print_insn be a method of
gdb_disassembler, and removed the method's ui_file parameter at the
same time, replaced by referencing the gdb_disassembler's stream
instead.  The trouble is that a gdb_disassembler can be instantiated
with a pointer any kind of ui_file.  Casting the gdb_disassembler's
stream to a mem_fileopen ui_file inside
gdb_disassembler::pretty_print_insn in order to call the reset method
would be gross hack.

The fix here is to:

 - make gdb_disassembler::pretty_print_insn a be free function again
   instead of a method of gdb_disassembler.  I.e., bring back
   gdb_pretty_print_insn.

 - but, don't add back the ui_file * parameter.  Instead, move the
   mem_fileopen allocation inside.  That is a better interface, given
   that the ui_file is only ever used as temporary scratch buffer as
   an implementation detail of gdb_pretty_print_insn.  The function's
   real "where to send output" parameter is the ui_out pointer.  (A
   following patch will add back buffer reuse across invocations
   differently).

 - don't add back a disassemble_info pointer either.  That used to be
   necessary for this bit:

	  err = m_di.read_memory_func (pc, &data, 1, &m_di);
	  if (err != 0)
	    m_di.memory_error_func (err, pc, &m_di);

   ... but AFAIK, it's not really necessary.  We can replace those
   three lines with a call to read_code.  This seems to fix a
   regression even, because before commit d8b49cf0 ("Don't throw
   exception in dis_asm_memory_error"), that memory_error_func call
   would throw an error/exception, but now it only records the error
   in the gdb_disassembler's m_err_memaddr field.  (read_code throws
   on error.)

With all these, gdb_pretty_print_insn is completely layered on top of
gdb_disassembler only using the latter's public API.

gdb/ChangeLog:
2017-02-02  Pedro Alves  <palves@redhat.com>

	* disasm.c (gdb_disassembler::pretty_print_insn): Rename to...
	(gdb_pretty_print_insn): ... this.  Now a free function.  Add back
	a 'gdbarch' parameter.  Allocate a mem_fileopen stream here.
	Adjust to call gdb_print_insn instead of
	gdb_disassembler::print_insn.
	(dump_insns, do_mixed_source_and_assembly_deprecated)
	(do_mixed_source_and_assembly, do_assembly_only): Add back a
	'gdbarch' parameter.  Remove gdb_disassembler parameter.
	(gdb_disassembly): Don't allocate a gdb_disassembler here.
	* disasm.h (gdb_disassembler::pretty_print_insn): Delete
	declaration.
	(gdb_pretty_print_insn): Re-add declaration.
	* record-btrace.c (btrace_insn_history): Don't allocate a
	gdb_disassembler here.  Adjust to call gdb_pretty_print_insn.

ld/
	* testsuite/lib/ld-lib.exp (check_libdl_available): New function.
	* testsuite/ld-elf/shared.exp (run_tests): Split tests which require
	dlopen support into "dlopen_run_tests".  These tests include dl1*main
	and dl6*main.
	(dlopen_run_tests): New and only run it when check_libdl_available
	returns true.  XFAIL on *-*-netbsdelf*.

The file_string parameter was added in 8f0eea0e (sorry, no title back
then) and has never actually been used.

gdb/ChangeLog:

	* disasm.h (gdb_disassembly): Remove file_string parameter.
	* disasm.c (gdb_disassembly): Likewise.
	* cli/cli-cmds.c (print_disassembly): Adapt.
	* mi/mi-cmd-disas.c (mi_cmd_disassemble): Likewise.
	* stack.c (do_gdb_disassembly): Likewise.

Fix commit 171191ba ("Add support for STT_IFUNC"),
<https://sourceware.org/ml/binutils/2008-12/msg00052.html>, commit
e04d7088 ("PR ld/14088: Always display addend as signed hex
number"), <https://sourceware.org/ml/binutils/2012-05/msg00123.html> and
commit 343dbc36 ("Print addend as signed in objdump"),
<https://sourceware.org/ml/binutils/2012-05/msg00163.html> regressions:

FAIL: VxWorks executable test 1 (dynamic)
FAIL: ld-mips-elf/vxworks-forced-local-1

seen with `mips-vxworks' and `mipsel-vxworks' targets and adjust dump
patterns according to changes made to the presentation of relocation
addends in `readelf -r' and `objdump -r' output.

	ld/
	* testsuite/ld-mips-elf/vxworks-forced-local-1.d: Correct the
	presentation of relocation addends.
	* testsuite/ld-mips-elf/vxworks1-lib.rd: Likewise.
	* testsuite/ld-mips-elf/vxworks1.dd: Likewise.
	* testsuite/ld-mips-elf/vxworks1.rd: Likewise.

Correct a commit ec9ab52c ("gas: consistently emit diagnostics for
non-zero data emission to .bss/.struct"),
<https://sourceware.org/ml/binutils/2015-12/msg00073.html> regression:

.../ld/testsuite/ld-mips-elf/tls-multi-got-1-1.s: Assembler messages:
.../ld/testsuite/ld-mips-elf/tls-multi-got-1-1.s:39: Error: attempt to store non-zero value in section `.tbss'
ERROR: -EB -march=mips1 -32 -KPIC .../ld/testsuite/ld-mips-elf/tls-multi-got-1-1.s: assembly failed
UNRESOLVED: Shared library with multiple GOTs and TLS

in MIPS target testing and move `tlsvar_ld' to `.tdata' section, in line
with the remaining local dynamic definitions introduced with the set of
tests added with commit f4e584bd ("TLS support for MIPS"),
<https://sourceware.org/ml/binutils/2005-02/msg00607.html>.

	ld/
	* testsuite/ld-mips-elf/tls-multi-got-1-1.s: Place `tlsvar_ld'
	in `.tdata' section.
	* testsuite/ld-mips-elf/tls-multi-got-1.got: Adjust accordingly.
	* testsuite/ld-mips-elf/tls-multi-got-1.r: Likewise.

When a variable's location is expressed as DW_OP_implicit_value, but the
given value is longer than needed, which bytes should be used?  GDB's
current logic was introduced with a patch from 2011 and uses the "least
significant" bytes:

  https://sourceware.org/ml/gdb-patches/2011-08/msg00123.html

Now consider a sub-value from such a location at a given offset, accessed
through DW_OP_implicit_pointer.  Which bytes should be used for that?  The
patch above *always* uses the last bytes on big-endian targets, ignoring
the offset.

E.g., given the code snippet

  const char foo[] = "Hello, world!";
  const char *a = &foo[0];
  const char *b = &foo[7];

assume that `foo' is described as DW_OP_implicit_value and `a' and `b'
each as DW_OP_implicit_pointer into that value.  Then with current GDB
`*a' and `*b' yield the same result -- the string's zero terminator.

This patch basically reverts the portion of the patch above that deals
with DW_OP_implicit_value.  This fixes the offset handling and also goes
back to dropping the last instead of the first bytes on big-endian targets
if the implicit value is longer than needed.  The latter aspect of the
change probably doesn't matter for actual programs, but simplifies the
logic.

The patch also cleans up the original code a bit and adds appropriate test
cases.

gdb/testsuite/ChangeLog:

	* gdb.dwarf2/dw2-op-stack-value.exp: Adjust expected result of
	taking a 2-byte value out of a 4-byte DWARF implicit value on
	big-endian targets.
	* gdb.dwarf2/nonvar-access.exp: Add more comments to existing
	logic.  Add test cases for DW_OP_implicit.

gdb/ChangeLog:

	* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): For
	DWARF_VALUE_LITERAL, no longer ignore the offset on big-endian
	targets.  And if the implicit value is longer than needed, extract
	the first bytes instead of the "least significant" ones.

If GDB is running when gdb_skip_xml_tests is called with
--target_board=native-extended-gdbserer.exp, it fails with:

    (gdb) FAIL: ....exp: set tdesc filename .../trivial.xml (got interactive prompt)
    monitor exit

Diagnose this in gdb_skip_xml_tests to generate a more meaningful error message:

    ERROR: tcl error sourcing ....exp.
    ERROR: GDB must not be running in gdb_skip_xml_tests.
        while executing
    [...]

testsuite/
	* lib/gdb.exp (gdb_skip_xml_tests): Error if GDB is running.

Parts of gdb.btrace/enable.exp are only valid for native debug.  The check for
skip_gdbserver_tests is done while GDB is running, though, which causes it to
fail with --target_board=native-extended-gdbserver.  Exit GDB before that check.

testsuite/
	* gdb.btrace/enable.exp: Call gdb_exit before skip_gdbserver_tests.

With --target_board=native-extended-gdbserver non-stop tests are failing with

    UNTESTED: gdb.btrace/non-stop.exp: failed to run to main

Fix that by adding '-ex "set non-stop on"' to GDBFLAGS before restarting.

testsuite/
	* gdb.btrace/non-stop.exp: Add '-ex "set non-stop on"' to GDBFLAGS.

We may silently skip gdb.btrace tests if

  - the target does not support record-btrace
  - the target does not support TSX
  - the target does not support gdbserver
  - we fail to compile the test
  - we fail to run to main

Add unsupported/untested messages for each of those.

testsuite/
	* gdb.btrace/buffer-size.exp: Add unsupported/untested message if
	the test is skipped.
	* gdb.btrace/data.exp: Likewise.
	* gdb.btrace/delta.exp: Likewise.
	* gdb.btrace/dlopen.exp: Likewise.
	* gdb.btrace/enable-running.exp: Likewise.
	* gdb.btrace/enable.exp: Likewise.
	* gdb.btrace/exception.exp: Likewise.
	* gdb.btrace/function_call_history.exp: Likewise.
	* gdb.btrace/gcore.exp: Likewise.
	* gdb.btrace/instruction_history.exp: Likewise.
	* gdb.btrace/multi-thread-step.exp: Likewise.
	* gdb.btrace/nohist.exp: Likewise.
	* gdb.btrace/non-stop.exp: Likewise.
	* gdb.btrace/reconnect.exp: Likewise.
	* gdb.btrace/record_goto-step.exp: Likewise.
	* gdb.btrace/record_goto.exp: Likewise.
	* gdb.btrace/rn-dl-bind.exp: Likewise.
	* gdb.btrace/segv.exp: Likewise.
	* gdb.btrace/step.exp: Likewise.
	* gdb.btrace/stepi.exp: Likewise.
	* gdb.btrace/tailcall-only.exp: Likewise.
	* gdb.btrace/tailcall.exp: Likewise.
	* gdb.btrace/tsx.exp: Likewise.
	* gdb.btrace/unknown_functions.exp: Likewise.
	* gdb.btrace/vdso.exp: Likewise.

When recording is started for a running thread, GDB was able to start tracing
but then failed to read registers to insert the initial entry for the current
PC.  We don't really need that initial entry if we don't know where exactly we
started recording.  Skip that step to allow recording to be started while
threads are running.

If we do run into errors, we need to undo the tracing enable to not leak this
thread.  The operation did not complete so our caller won't clean up this
thread.

For the BTRACE_FORMAT_PT btrace format, we don't need that initial entry since
it will be recorded in the trace.  We can omit the call to btrace_add_pc.

gdb/
	* btrace.c (btrace_enable): Do not call btrace_add_pc for
	BTRACE_FORMAT_PT or if can_access_registers_ptid returns false.
	(btrace_fetch): Assert can_access_registers_ptid.
	* record-btrace.c (require_btrace_thread, record_btrace_info): Call
	validate_registers_access.

testsuite/
	* gdb.btrace/enable-running.c: New.
	* gdb.btrace/enable-running.exp: New.

Add a function can_access_registers_ptid that behaves like
validate_registers_access but returns a boolean value instead of throwing an
exception.

gdb/
	* gdbthread.h (can_access_registers_ptid): New.
	* thread.c (can_access_registers_ptid): New.

ld/
	* testsuite/ld-unique/unique.exp (Could not link a dynamic executable):
	Append $board_cflags to link commands.

ld/

2017-01-31  Senthil Kumar Selvaraj <senthilkumar.selvaraj@microchip.com>

	* testsuite/ld-scripts/print-memory-usage-1.l: Relax
	check for digit in second decimal place.

gold/
	PR gold/21090
	* x86_64.cc (Target_x86_64::can_convert_mov_to_lea): Add check
	for predefined symbol.
	(Target_x86_64::Relocate::relocate): Fix formatting.

	ld/
	PR ld/20828
	* testsuite/ld-elf/shared.exp: Correct PR ld/20828 test
	indentation.

gdb/ChangeLog:
2017-02-01  Pedro Alves  <palves@redhat.com>

	* i386-tdep.c (i386_fast_tracepoint_valid_at): Use gdb_insn_length.

gdb/ChangeLog:
2017-01-31  Pedro Alves  <palves@redhat.com>

	* mi/mi-interp.c (mi_breakpoint_created, mi_breakpoint_modified):
	Fix typos.

gdb/ChangeLog:
2017-01-31  Pedro Alves  <palves@redhat.com>

	* stack.c (print_frame_args): Remove local mem_fileopen stream,
	not used.

Whoops, this function returns a std::string.

gdb/ChangeLog:
2017-01-31  Pedro Alves  <palves@redhat.com>

	* varobj.c (varobj_value_get_print_value): Remove xstrdup call.

A following patch will want to do

   string_file str_file;

   scoped_restore save_stdout
    = make_scoped_restore (&gdb_stdout, &str_file);

where gdb_stdout is a ui_file *, and string_file is a type that
inherits from ui_file, but that doesn't compile today:

  src/gdb/top.c: In function ‘std::__cxx11::string execute_command_to_string(char*, int)’:
  src/gdb/top.c:710:50: error: no matching function for call to ‘make_scoped_restore(ui_file**, string_file*)’
       = make_scoped_restore (&gdb_stdout, &str_file);
						    ^
  [...]
  In file included from src/gdb/utils.h:25:0,
		   from src/gdb/defs.h:732,
		   from src/gdb/top.c:20:
  src/gdb/common/scoped_restore.h:94:24: note: candidate: template<class T> scoped_restore_tmpl<T> make_scoped_restore(T*, T)
   scoped_restore_tmpl<T> make_scoped_restore (T *var, T value)
			  ^
  src/gdb/common/scoped_restore.h:94:24: note:   template argument deduction/substitution failed:
  src/gdb/top.c:710:50: note:   deduced conflicting types for parameter ‘T’ (‘ui_file*’ and ‘string_file*’)
       = make_scoped_restore (&gdb_stdout, &str_file);
						    ^

This commit makes code such as the above possible.

gdb/ChangeLog:
2017-01-31  Pedro Alves  <palves@redhat.com>

	* common/scoped_restore.h
	(scoped_restore_tmpl::scoped_restore_tmpl): Template on T2, and
	change the value's parameter type to T2.
	(make_scoped_restore): Likewise.

ld	* ldmain.c (add_archive_element): Eliminate string buffer.
	* ldlang.c (lang_print_asneeded): Likewise.

Complement commit 9d862524 ("MIPS: Verify the ISA mode and alignment
of branch and jump targets") and add GAS and LD options to control the
checks for invalid branches between ISA modes introduced there, to help
with some handwritten code lacking `.insn' annotation for labels used as
branch targets and code produced by older versions of GCC which suffers
from the issue with branches to code that has been optimized away,
addressed with GCC commit 242424 ("MIPS/GCC: Mark trailing labels with
`.insn'"), <https://gcc.gnu.org/ml/gcc-patches/2016-11/msg01061.html>.

	bfd/
	* elfxx-mips.h (_bfd_mips_elf_insn32): Rename prototype to...
	(_bfd_mips_elf_linker_flags): ... this.  Add another parameter.
	* elfxx-mips.c (mips_elf_link_hash_table): Add
	`ignore_branch_isa' member.
	(mips_elf_perform_relocation): Do not treat an ISA mode mismatch
	in branch relocation calculation as an error if
	`ignore_branch_isa' has been set.
	(_bfd_mips_elf_insn32): Rename to...
	(_bfd_mips_elf_linker_flags): ... this.  Rename the `on'
	parameter to `insn32' and add an `ignore_branch_isa' parameter.
	Handle the new parameter.

	gas/
	* config/tc-mips.c (mips_ignore_branch_isa): New variable.
	(options): Add OPTION_IGNORE_BRANCH_ISA and
	OPTION_NO_IGNORE_BRANCH_ISA enum values.
	(md_longopts): Add "mignore-branch-isa" and
	"mno-ignore-branch-isa" options.
	(md_parse_option): Handle OPTION_IGNORE_BRANCH_ISA and
	OPTION_NO_IGNORE_BRANCH_ISA.
	(fix_bad_cross_mode_branch_p): Return FALSE if
	`mips_ignore_branch_isa' has been set.
	(md_show_usage): Add `-mignore-branch-isa' and
	`-mno-ignore-branch-isa'.

	* doc/as.texinfo (Target MIPS options): Add
	`-mignore-branch-isa' and `-mno-ignore-branch-isa' options.
	(-mignore-branch-isa, -mno-ignore-branch-isa): New options.
	* doc/c-mips.texi (MIPS Options): Add `-mignore-branch-isa' and
	`-mno-ignore-branch-isa' options.

	* testsuite/gas/mips/branch-local-ignore-2.d: New test.
	* testsuite/gas/mips/branch-local-ignore-3.d: New test.
	* testsuite/gas/mips/branch-local-ignore-n32-2.d: New test.
	* testsuite/gas/mips/branch-local-ignore-n32-3.d: New test.
	* testsuite/gas/mips/branch-local-ignore-n64-2.d: New test.
	* testsuite/gas/mips/branch-local-ignore-n64-3.d: New test.
	* testsuite/gas/mips/mips.exp: Run the new tests.

	ld/
	* emultempl/mipself.em (ignore_branch_isa): New variable.
	(mips_create_output_section_statements): Rename
	`_bfd_mips_elf_insn32' called to `_bfd_mips_elf_linker_flags',
	add `ignore_branch_isa' argument.
	(PARSE_AND_LIST_PROLOGUE): Add OPTION_IGNORE_BRANCH_ISA and
	OPTION_NO_IGNORE_BRANCH_ISA enum values.
	(PARSE_AND_LIST_LONGOPTS): Add "ignore-branch-isa" and
	"no-ignore-branch-isa" options.
	(PARSE_AND_LIST_OPTIONS): Add `--ignore-branch-isa' and
	`--no-ignore-branch-isa'.
	(PARSE_AND_LIST_ARGS_CASES): Handle OPTION_IGNORE_BRANCH_ISA and
	OPTION_NO_IGNORE_BRANCH_ISA.

	* ld.texinfo (Options specific to MIPS targets): Add
	`--ignore-branch-isa' and `--no-ignore-branch-isa' options.
	(ld and the MIPS family): Likewise.

	* testsuite/ld-mips-elf/bal-jalx-pic-ignore.d: New test.
	* testsuite/ld-mips-elf/bal-jalx-pic-ignore-n32.d: New test.
	* testsuite/ld-mips-elf/bal-jalx-pic-ignore-n64.d: New test.
	* testsuite/ld-mips-elf/unaligned-branch-ignore-2.d: New test.
	* testsuite/ld-mips-elf/unaligned-branch-ignore-r6-1: New test.
	* testsuite/ld-mips-elf/unaligned-branch-ignore-mips16: New
	test.
	* testsuite/ld-mips-elf/unaligned-branch-ignore-micromips: New
	test.
	* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.

	gas/
	* testsuite/gas/mips/branch-local-2.d: New test.
	* testsuite/gas/mips/branch-local-3.d: New test.
	* testsuite/gas/mips/branch-local-n32-2.d: New test.
	* testsuite/gas/mips/branch-local-n32-3.d: New test.
	* testsuite/gas/mips/branch-local-n64-2.d: New test.
	* testsuite/gas/mips/branch-local-n64-3.d: New test.
	* testsuite/gas/mips/mips.exp: Fold corresponding list tests
	into the new tests.

Gah!  Though this time I blame autocompletion.

	Fix long-standing buglet and fallout from now-default initfini-array.
	* emulparams/criself.sh (USER_LABEL_PREFIX): Define.
	(OTHER_READONLY_SECTIONS, ENTRY): Delete now-redunant defines.

	* emulparams/criself.sh (USER_LABEL_PREFIX): Define.
	(OTHER_READONLY_SECTIONS, ENTRY): Delete now-redunant defines.

ld/
	* testsuite/ld-elf/elf.exp ("pr20995-2", "Build pr20995-2.so"): XFAIL on
	arm*-*-eabi*.

Some technical discussions about the reason of this XFAIL are available at

  https://sourceware.org/ml/binutils/2017-01/msg00441.html

This patch allows examination of the registers FS_BASE and GS_BASE
for Linux Systems running on 64bit. Tests for simple read and write
of the new registers is also added with this patch.

2017-01-27  Walfred Tedeschi  <walfred.tedeschi@intel.com>
	    Richard Henderson  <rth@redhat.com>

gdb/ChangeLog:

	* amd64-linux-nat.c (PTRACE_ARCH_PRCTL): New define.
	(amd64_linux_fetch_inferior_registers): Add case to fetch FS_BASE
	GS_BASE for older kernels.
	(amd64_linux_store_inferior_registers): Add case to store FS_BASE
	GS_BASE for older kernels.
	* amd64-linux-tdep.c (amd64_linux_gregset_reg_offset): Add FS_BASE
	and GS_BASE to the offset table.
	(amd64_linux_register_reggroup_p): Add FS_BASE and GS_BASE to the
	system register group.
	* amd64-nat.c (amd64_native_gregset_reg_offset): Implements case
	for older kernels.
	* amd64-tdep.c (amd64_init_abi): Add segment registers for the
	amd64 ABI.
	* amd64-tdep.h (amd64_regnum): Add AMD64_FSBASE_REGNUM and
	AMD64_GSBASE_REGNUM.
	(AMD64_NUM_REGS): Set to AMD64_GSBASE_REGNUM + 1.
	* features/Makefile (amd64-linux.dat, amd64-avx-linux.dat)
	(amd64-mpx-linux.dat, amd64-avx512-linux.dat, x32-linux.dat)
	(x32-avx-linux.dat, x32-avx512-linux.dat): Add
	i386/64bit-segments.xml in those rules.
	* features/i386/64bit-segments.xml: New file.
	* features/i386/amd64-avx-mpx-linux.xml: Add 64bit-segments.xml.
	* features/i386/amd64-avx-linux.xml: Add 64bit-segments.xml.
	* features/i386/amd64-avx512-linux.xml: Add 64bit-segments.xml.
	* features/i386/amd64-mpx-linux.xml: Add 64bit-segments.xml.
	* features/i386/x32-avx512-linux.xml: Add 64bit-segments.xml.
	* features/i386/x32-avx-linux.xml: Add 64bit-segments.xml.
	* features/i386/amd64-linux.xml: Add 64bit-segments.xml.
	* features/i386/amd64-avx-linux.c: Regenerated.
	* features/i386/amd64-avx-mpx-linux.c: Regenerated.
	* features/i386/amd64-avx-mpx.c: Regenerated.
	* features/i386/amd64-avx512-linux.c: Regenerated.
	* features/i386/amd64-linux.c: Regenerated.
	* features/i386/amd64-mpx-linux.c: Regenerated.
	* features/i386/i386-avx-mpx-linux.c: Regenerated.
	* features/i386/i386-avx-mpx.c: Regenerated.
	* features/i386/x32-avx-linux.c: Regenerated.
	* features/i386/x32-avx512-linux.c: Regenerated.
	* regformats/i386/amd64-avx-linux.dat: Regenerated.
	* regformats/i386/amd64-avx-mpx-linux.dat: Regenerated.
	* regformats/i386/amd64-avx512-linux.dat: Regenerated.
	* regformats/i386/amd64-linux.dat: Regenerated.
	* regformats/i386/amd64-mpx-linux.dat: Regenerated.
	* regformats/i386/x32-avx-linux.dat: Regenerated.
	* regformats/i386/x32-avx512-linux.dat: Regenerated.
	* regformats/i386/x32-linux.dat: Regenerated.

gdb/doc/ChangeLog:

	* gdb.texinfo (i386 Features): Add system segment registers
	as feature.

gdb/gdbserver/ChangeLog:

	* linux-x86-low.c (x86_64_regmap): Add fs_base and gs_base
	to the register table.
	(x86_fill_gregset): Add support for old kernels for the
	fs_base and gs_base system registers.
	(x86_store_gregset): Likewise.
	* configure.srv (srv_i386_64bit_xmlfiles): Add 64bit-segments.xml.

gdb/testsuite/ChangeLog:

	* gdb.arch/amd64-gs_base.c: New file.
	* gdb.arch/amd64-gs_base.exp: New file.

Change-Id: I2e0eeb93058a2320d4d3b045082643cfe4aff963
Signed-off-by: Walfred Tedeschi <walfred.tedeschi@intel.com>