event-top.c revision 1.9
1/* Top level stuff for GDB, the GNU debugger. 2 3 Copyright (C) 1999-2020 Free Software Foundation, Inc. 4 5 Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions. 6 7 This file is part of GDB. 8 9 This program is free software; you can redistribute it and/or modify 10 it under the terms of the GNU General Public License as published by 11 the Free Software Foundation; either version 3 of the License, or 12 (at your option) any later version. 13 14 This program is distributed in the hope that it will be useful, 15 but WITHOUT ANY WARRANTY; without even the implied warranty of 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 GNU General Public License for more details. 18 19 You should have received a copy of the GNU General Public License 20 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 21 22#include "defs.h" 23#include "top.h" 24#include "inferior.h" 25#include "infrun.h" 26#include "target.h" 27#include "terminal.h" 28#include "gdbsupport/event-loop.h" 29#include "event-top.h" 30#include "interps.h" 31#include <signal.h> 32#include "cli/cli-script.h" /* for reset_command_nest_depth */ 33#include "main.h" 34#include "gdbthread.h" 35#include "observable.h" 36#include "continuations.h" 37#include "gdbcmd.h" /* for dont_repeat() */ 38#include "annotate.h" 39#include "maint.h" 40#include "gdbsupport/buffer.h" 41#include "ser-event.h" 42#include "gdbsupport/gdb_select.h" 43#include "gdbsupport/gdb-sigmask.h" 44#include "async-event.h" 45 46/* readline include files. */ 47#include "readline/readline.h" 48#include "readline/history.h" 49 50/* readline defines this. */ 51#undef savestring 52 53static std::string top_level_prompt (); 54 55/* Signal handlers. */ 56#ifdef SIGQUIT 57static void handle_sigquit (int sig); 58#endif 59#ifdef SIGHUP 60static void handle_sighup (int sig); 61#endif 62static void handle_sigfpe (int sig); 63 64/* Functions to be invoked by the event loop in response to 65 signals. */ 66#if defined (SIGQUIT) || defined (SIGHUP) 67static void async_do_nothing (gdb_client_data); 68#endif 69#ifdef SIGHUP 70static void async_disconnect (gdb_client_data); 71#endif 72static void async_float_handler (gdb_client_data); 73#ifdef SIGTSTP 74static void async_sigtstp_handler (gdb_client_data); 75#endif 76static void async_sigterm_handler (gdb_client_data arg); 77 78/* Instead of invoking (and waiting for) readline to read the command 79 line and pass it back for processing, we use readline's alternate 80 interface, via callback functions, so that the event loop can react 81 to other event sources while we wait for input. */ 82 83/* Important variables for the event loop. */ 84 85/* This is used to determine if GDB is using the readline library or 86 its own simplified form of readline. It is used by the asynchronous 87 form of the set editing command. 88 ezannoni: as of 1999-04-29 I expect that this 89 variable will not be used after gdb is changed to use the event 90 loop as default engine, and event-top.c is merged into top.c. */ 91bool set_editing_cmd_var; 92 93/* This is used to display the notification of the completion of an 94 asynchronous execution command. */ 95bool exec_done_display_p = false; 96 97/* Used by the stdin event handler to compensate for missed stdin events. 98 Setting this to a non-zero value inside an stdin callback makes the callback 99 run again. */ 100int call_stdin_event_handler_again_p; 101 102/* Signal handling variables. */ 103/* Each of these is a pointer to a function that the event loop will 104 invoke if the corresponding signal has received. The real signal 105 handlers mark these functions as ready to be executed and the event 106 loop, in a later iteration, calls them. See the function 107 invoke_async_signal_handler. */ 108static struct async_signal_handler *sigint_token; 109#ifdef SIGHUP 110static struct async_signal_handler *sighup_token; 111#endif 112#ifdef SIGQUIT 113static struct async_signal_handler *sigquit_token; 114#endif 115static struct async_signal_handler *sigfpe_token; 116#ifdef SIGTSTP 117static struct async_signal_handler *sigtstp_token; 118#endif 119static struct async_signal_handler *async_sigterm_token; 120 121/* This hook is called by gdb_rl_callback_read_char_wrapper after each 122 character is processed. */ 123void (*after_char_processing_hook) (void); 124 125 126/* Wrapper function for calling into the readline library. This takes 127 care of a couple things: 128 129 - The event loop expects the callback function to have a parameter, 130 while readline expects none. 131 132 - Propagation of GDB exceptions/errors thrown from INPUT_HANDLER 133 across readline requires special handling. 134 135 On the exceptions issue: 136 137 DWARF-based unwinding cannot cross code built without -fexceptions. 138 Any exception that tries to propagate through such code will fail 139 and the result is a call to std::terminate. While some ABIs, such 140 as x86-64, require all code to be built with exception tables, 141 others don't. 142 143 This is a problem when GDB calls some non-EH-aware C library code, 144 that calls into GDB again through a callback, and that GDB callback 145 code throws a C++ exception. Turns out this is exactly what 146 happens with GDB's readline callback. 147 148 In such cases, we must catch and save any C++ exception that might 149 be thrown from the GDB callback before returning to the 150 non-EH-aware code. When the non-EH-aware function itself returns 151 back to GDB, we then rethrow the original C++ exception. 152 153 In the readline case however, the right thing to do is to longjmp 154 out of the callback, rather than do a normal return -- there's no 155 way for the callback to return to readline an indication that an 156 error happened, so a normal return would have rl_callback_read_char 157 potentially continue processing further input, redisplay the 158 prompt, etc. Instead of raw setjmp/longjmp however, we use our 159 sjlj-based TRY/CATCH mechanism, which knows to handle multiple 160 levels of active setjmp/longjmp frames, needed in order to handle 161 the readline callback recursing, as happens with e.g., secondary 162 prompts / queries, through gdb_readline_wrapper. This must be 163 noexcept in order to avoid problems with mixing sjlj and 164 (sjlj-based) C++ exceptions. */ 165 166static struct gdb_exception 167gdb_rl_callback_read_char_wrapper_noexcept () noexcept 168{ 169 struct gdb_exception gdb_expt; 170 171 /* C++ exceptions can't normally be thrown across readline (unless 172 it is built with -fexceptions, but it won't by default on many 173 ABIs). So we instead wrap the readline call with a sjlj-based 174 TRY/CATCH, and rethrow the GDB exception once back in GDB. */ 175 TRY_SJLJ 176 { 177 rl_callback_read_char (); 178 if (after_char_processing_hook) 179 (*after_char_processing_hook) (); 180 } 181 CATCH_SJLJ (ex, RETURN_MASK_ALL) 182 { 183 gdb_expt = std::move (ex); 184 } 185 END_CATCH_SJLJ 186 187 return gdb_expt; 188} 189 190static void 191gdb_rl_callback_read_char_wrapper (gdb_client_data client_data) 192{ 193 struct gdb_exception gdb_expt 194 = gdb_rl_callback_read_char_wrapper_noexcept (); 195 196 /* Rethrow using the normal EH mechanism. */ 197 if (gdb_expt.reason < 0) 198 throw_exception (std::move (gdb_expt)); 199} 200 201/* GDB's readline callback handler. Calls the current INPUT_HANDLER, 202 and propagates GDB exceptions/errors thrown from INPUT_HANDLER back 203 across readline. See gdb_rl_callback_read_char_wrapper. This must 204 be noexcept in order to avoid problems with mixing sjlj and 205 (sjlj-based) C++ exceptions. */ 206 207static void 208gdb_rl_callback_handler (char *rl) noexcept 209{ 210 /* This is static to avoid undefined behavior when calling longjmp 211 -- gdb_exception has a destructor with side effects. */ 212 static struct gdb_exception gdb_rl_expt; 213 struct ui *ui = current_ui; 214 215 try 216 { 217 /* Ensure the exception is reset on each call. */ 218 gdb_rl_expt = {}; 219 ui->input_handler (gdb::unique_xmalloc_ptr<char> (rl)); 220 } 221 catch (gdb_exception &ex) 222 { 223 gdb_rl_expt = std::move (ex); 224 } 225 226 /* If we caught a GDB exception, longjmp out of the readline 227 callback. There's no other way for the callback to signal to 228 readline that an error happened. A normal return would have 229 readline potentially continue processing further input, redisplay 230 the prompt, etc. (This is what GDB historically did when it was 231 a C program.) Note that since we're long jumping, local variable 232 dtors are NOT run automatically. */ 233 if (gdb_rl_expt.reason < 0) 234 throw_exception_sjlj (gdb_rl_expt); 235} 236 237/* Change the function to be invoked every time there is a character 238 ready on stdin. This is used when the user sets the editing off, 239 therefore bypassing readline, and letting gdb handle the input 240 itself, via gdb_readline_no_editing_callback. Also it is used in 241 the opposite case in which the user sets editing on again, by 242 restoring readline handling of the input. 243 244 NOTE: this operates on input_fd, not instream. If we are reading 245 commands from a file, instream will point to the file. However, we 246 always read commands from a file with editing off. This means that 247 the 'set editing on/off' will have effect only on the interactive 248 session. */ 249 250void 251change_line_handler (int editing) 252{ 253 struct ui *ui = current_ui; 254 255 /* We can only have one instance of readline, so we only allow 256 editing on the main UI. */ 257 if (ui != main_ui) 258 return; 259 260 /* Don't try enabling editing if the interpreter doesn't support it 261 (e.g., MI). */ 262 if (!interp_supports_command_editing (top_level_interpreter ()) 263 || !interp_supports_command_editing (command_interp ())) 264 return; 265 266 if (editing) 267 { 268 gdb_assert (ui == main_ui); 269 270 /* Turn on editing by using readline. */ 271 ui->call_readline = gdb_rl_callback_read_char_wrapper; 272 } 273 else 274 { 275 /* Turn off editing by using gdb_readline_no_editing_callback. */ 276 if (ui->command_editing) 277 gdb_rl_callback_handler_remove (); 278 ui->call_readline = gdb_readline_no_editing_callback; 279 } 280 ui->command_editing = editing; 281} 282 283/* The functions below are wrappers for rl_callback_handler_remove and 284 rl_callback_handler_install that keep track of whether the callback 285 handler is installed in readline. This is necessary because after 286 handling a target event of a background execution command, we may 287 need to reinstall the callback handler if it was removed due to a 288 secondary prompt. See gdb_readline_wrapper_line. We don't 289 unconditionally install the handler for every target event because 290 that also clears the line buffer, thus installing it while the user 291 is typing would lose input. */ 292 293/* Whether we've registered a callback handler with readline. */ 294static int callback_handler_installed; 295 296/* See event-top.h, and above. */ 297 298void 299gdb_rl_callback_handler_remove (void) 300{ 301 gdb_assert (current_ui == main_ui); 302 303 rl_callback_handler_remove (); 304 callback_handler_installed = 0; 305} 306 307/* See event-top.h, and above. Note this wrapper doesn't have an 308 actual callback parameter because we always install 309 INPUT_HANDLER. */ 310 311void 312gdb_rl_callback_handler_install (const char *prompt) 313{ 314 gdb_assert (current_ui == main_ui); 315 316 /* Calling rl_callback_handler_install resets readline's input 317 buffer. Calling this when we were already processing input 318 therefore loses input. */ 319 gdb_assert (!callback_handler_installed); 320 321 rl_callback_handler_install (prompt, gdb_rl_callback_handler); 322 callback_handler_installed = 1; 323} 324 325/* See event-top.h, and above. */ 326 327void 328gdb_rl_callback_handler_reinstall (void) 329{ 330 gdb_assert (current_ui == main_ui); 331 332 if (!callback_handler_installed) 333 { 334 /* Passing NULL as prompt argument tells readline to not display 335 a prompt. */ 336 gdb_rl_callback_handler_install (NULL); 337 } 338} 339 340/* Displays the prompt. If the argument NEW_PROMPT is NULL, the 341 prompt that is displayed is the current top level prompt. 342 Otherwise, it displays whatever NEW_PROMPT is as a local/secondary 343 prompt. 344 345 This is used after each gdb command has completed, and in the 346 following cases: 347 348 1. When the user enters a command line which is ended by '\' 349 indicating that the command will continue on the next line. In 350 that case the prompt that is displayed is the empty string. 351 352 2. When the user is entering 'commands' for a breakpoint, or 353 actions for a tracepoint. In this case the prompt will be '>' 354 355 3. On prompting for pagination. */ 356 357void 358display_gdb_prompt (const char *new_prompt) 359{ 360 std::string actual_gdb_prompt; 361 362 annotate_display_prompt (); 363 364 /* Reset the nesting depth used when trace-commands is set. */ 365 reset_command_nest_depth (); 366 367 /* Do not call the python hook on an explicit prompt change as 368 passed to this function, as this forms a secondary/local prompt, 369 IE, displayed but not set. */ 370 if (! new_prompt) 371 { 372 struct ui *ui = current_ui; 373 374 if (ui->prompt_state == PROMPTED) 375 internal_error (__FILE__, __LINE__, _("double prompt")); 376 else if (ui->prompt_state == PROMPT_BLOCKED) 377 { 378 /* This is to trick readline into not trying to display the 379 prompt. Even though we display the prompt using this 380 function, readline still tries to do its own display if 381 we don't call rl_callback_handler_install and 382 rl_callback_handler_remove (which readline detects 383 because a global variable is not set). If readline did 384 that, it could mess up gdb signal handlers for SIGINT. 385 Readline assumes that between calls to rl_set_signals and 386 rl_clear_signals gdb doesn't do anything with the signal 387 handlers. Well, that's not the case, because when the 388 target executes we change the SIGINT signal handler. If 389 we allowed readline to display the prompt, the signal 390 handler change would happen exactly between the calls to 391 the above two functions. Calling 392 rl_callback_handler_remove(), does the job. */ 393 394 if (current_ui->command_editing) 395 gdb_rl_callback_handler_remove (); 396 return; 397 } 398 else if (ui->prompt_state == PROMPT_NEEDED) 399 { 400 /* Display the top level prompt. */ 401 actual_gdb_prompt = top_level_prompt (); 402 ui->prompt_state = PROMPTED; 403 } 404 } 405 else 406 actual_gdb_prompt = new_prompt; 407 408 if (current_ui->command_editing) 409 { 410 gdb_rl_callback_handler_remove (); 411 gdb_rl_callback_handler_install (actual_gdb_prompt.c_str ()); 412 } 413 /* new_prompt at this point can be the top of the stack or the one 414 passed in. It can't be NULL. */ 415 else 416 { 417 /* Don't use a _filtered function here. It causes the assumed 418 character position to be off, since the newline we read from 419 the user is not accounted for. */ 420 fprintf_unfiltered (gdb_stdout, "%s", actual_gdb_prompt.c_str ()); 421 gdb_flush (gdb_stdout); 422 } 423} 424 425/* Return the top level prompt, as specified by "set prompt", possibly 426 overridden by the python gdb.prompt_hook hook, and then composed 427 with the prompt prefix and suffix (annotations). */ 428 429static std::string 430top_level_prompt (void) 431{ 432 char *prompt; 433 434 /* Give observers a chance of changing the prompt. E.g., the python 435 `gdb.prompt_hook' is installed as an observer. */ 436 gdb::observers::before_prompt.notify (get_prompt ()); 437 438 prompt = get_prompt (); 439 440 if (annotation_level >= 2) 441 { 442 /* Prefix needs to have new line at end. */ 443 const char prefix[] = "\n\032\032pre-prompt\n"; 444 445 /* Suffix needs to have a new line at end and \032 \032 at 446 beginning. */ 447 const char suffix[] = "\n\032\032prompt\n"; 448 449 return std::string (prefix) + prompt + suffix; 450 } 451 452 return prompt; 453} 454 455/* See top.h. */ 456 457struct ui *main_ui; 458struct ui *current_ui; 459struct ui *ui_list; 460 461/* Get a pointer to the current UI's line buffer. This is used to 462 construct a whole line of input from partial input. */ 463 464static struct buffer * 465get_command_line_buffer (void) 466{ 467 return ¤t_ui->line_buffer; 468} 469 470/* When there is an event ready on the stdin file descriptor, instead 471 of calling readline directly throught the callback function, or 472 instead of calling gdb_readline_no_editing_callback, give gdb a 473 chance to detect errors and do something. */ 474 475void 476stdin_event_handler (int error, gdb_client_data client_data) 477{ 478 struct ui *ui = (struct ui *) client_data; 479 480 if (error) 481 { 482 /* Switch to the main UI, so diagnostics always go there. */ 483 current_ui = main_ui; 484 485 delete_file_handler (ui->input_fd); 486 if (main_ui == ui) 487 { 488 /* If stdin died, we may as well kill gdb. */ 489 printf_unfiltered (_("error detected on stdin\n")); 490 quit_command ((char *) 0, 0); 491 } 492 else 493 { 494 /* Simply delete the UI. */ 495 delete ui; 496 } 497 } 498 else 499 { 500 /* Switch to the UI whose input descriptor woke up the event 501 loop. */ 502 current_ui = ui; 503 504 /* This makes sure a ^C immediately followed by further input is 505 always processed in that order. E.g,. with input like 506 "^Cprint 1\n", the SIGINT handler runs, marks the async 507 signal handler, and then select/poll may return with stdin 508 ready, instead of -1/EINTR. The 509 gdb.base/double-prompt-target-event-error.exp test exercises 510 this. */ 511 QUIT; 512 513 do 514 { 515 call_stdin_event_handler_again_p = 0; 516 ui->call_readline (client_data); 517 } 518 while (call_stdin_event_handler_again_p != 0); 519 } 520} 521 522/* See top.h. */ 523 524void 525ui_register_input_event_handler (struct ui *ui) 526{ 527 add_file_handler (ui->input_fd, stdin_event_handler, ui); 528} 529 530/* See top.h. */ 531 532void 533ui_unregister_input_event_handler (struct ui *ui) 534{ 535 delete_file_handler (ui->input_fd); 536} 537 538/* Re-enable stdin after the end of an execution command in 539 synchronous mode, or after an error from the target, and we aborted 540 the exec operation. */ 541 542void 543async_enable_stdin (void) 544{ 545 struct ui *ui = current_ui; 546 547 if (ui->prompt_state == PROMPT_BLOCKED) 548 { 549 target_terminal::ours (); 550 ui_register_input_event_handler (ui); 551 ui->prompt_state = PROMPT_NEEDED; 552 } 553} 554 555/* Disable reads from stdin (the console) marking the command as 556 synchronous. */ 557 558void 559async_disable_stdin (void) 560{ 561 struct ui *ui = current_ui; 562 563 ui->prompt_state = PROMPT_BLOCKED; 564 delete_file_handler (ui->input_fd); 565} 566 567 568/* Handle a gdb command line. This function is called when 569 handle_line_of_input has concatenated one or more input lines into 570 a whole command. */ 571 572void 573command_handler (const char *command) 574{ 575 struct ui *ui = current_ui; 576 const char *c; 577 578 if (ui->instream == ui->stdin_stream) 579 reinitialize_more_filter (); 580 581 scoped_command_stats stat_reporter (true); 582 583 /* Do not execute commented lines. */ 584 for (c = command; *c == ' ' || *c == '\t'; c++) 585 ; 586 if (c[0] != '#') 587 { 588 execute_command (command, ui->instream == ui->stdin_stream); 589 590 /* Do any commands attached to breakpoint we stopped at. */ 591 bpstat_do_actions (); 592 } 593} 594 595/* Append RL, an input line returned by readline or one of its 596 emulations, to CMD_LINE_BUFFER. Returns the command line if we 597 have a whole command line ready to be processed by the command 598 interpreter or NULL if the command line isn't complete yet (input 599 line ends in a backslash). */ 600 601static char * 602command_line_append_input_line (struct buffer *cmd_line_buffer, const char *rl) 603{ 604 char *cmd; 605 size_t len; 606 607 len = strlen (rl); 608 609 if (len > 0 && rl[len - 1] == '\\') 610 { 611 /* Don't copy the backslash and wait for more. */ 612 buffer_grow (cmd_line_buffer, rl, len - 1); 613 cmd = NULL; 614 } 615 else 616 { 617 /* Copy whole line including terminating null, and we're 618 done. */ 619 buffer_grow (cmd_line_buffer, rl, len + 1); 620 cmd = cmd_line_buffer->buffer; 621 } 622 623 return cmd; 624} 625 626/* Handle a line of input coming from readline. 627 628 If the read line ends with a continuation character (backslash), 629 save the partial input in CMD_LINE_BUFFER (except the backslash), 630 and return NULL. Otherwise, save the partial input and return a 631 pointer to CMD_LINE_BUFFER's buffer (null terminated), indicating a 632 whole command line is ready to be executed. 633 634 Returns EOF on end of file. 635 636 If REPEAT, handle command repetitions: 637 638 - If the input command line is NOT empty, the command returned is 639 saved using save_command_line () so that it can be repeated later. 640 641 - OTOH, if the input command line IS empty, return the saved 642 command instead of the empty input line. 643*/ 644 645char * 646handle_line_of_input (struct buffer *cmd_line_buffer, 647 const char *rl, int repeat, 648 const char *annotation_suffix) 649{ 650 struct ui *ui = current_ui; 651 int from_tty = ui->instream == ui->stdin_stream; 652 char *p1; 653 char *cmd; 654 655 if (rl == NULL) 656 return (char *) EOF; 657 658 cmd = command_line_append_input_line (cmd_line_buffer, rl); 659 if (cmd == NULL) 660 return NULL; 661 662 /* We have a complete command line now. Prepare for the next 663 command, but leave ownership of memory to the buffer . */ 664 cmd_line_buffer->used_size = 0; 665 666 if (from_tty && annotation_level > 1) 667 { 668 printf_unfiltered (("\n\032\032post-")); 669 puts_unfiltered (annotation_suffix); 670 printf_unfiltered (("\n")); 671 } 672 673#define SERVER_COMMAND_PREFIX "server " 674 server_command = startswith (cmd, SERVER_COMMAND_PREFIX); 675 if (server_command) 676 { 677 /* Note that we don't call `save_command_line'. Between this 678 and the check in dont_repeat, this insures that repeating 679 will still do the right thing. */ 680 return cmd + strlen (SERVER_COMMAND_PREFIX); 681 } 682 683 /* Do history expansion if that is wished. */ 684 if (history_expansion_p && from_tty && input_interactive_p (current_ui)) 685 { 686 char *cmd_expansion; 687 int expanded; 688 689 expanded = history_expand (cmd, &cmd_expansion); 690 gdb::unique_xmalloc_ptr<char> history_value (cmd_expansion); 691 if (expanded) 692 { 693 size_t len; 694 695 /* Print the changes. */ 696 printf_unfiltered ("%s\n", history_value.get ()); 697 698 /* If there was an error, call this function again. */ 699 if (expanded < 0) 700 return cmd; 701 702 /* history_expand returns an allocated string. Just replace 703 our buffer with it. */ 704 len = strlen (history_value.get ()); 705 xfree (buffer_finish (cmd_line_buffer)); 706 cmd_line_buffer->buffer = history_value.get (); 707 cmd_line_buffer->buffer_size = len + 1; 708 cmd = history_value.release (); 709 } 710 } 711 712 /* If we just got an empty line, and that is supposed to repeat the 713 previous command, return the previously saved command. */ 714 for (p1 = cmd; *p1 == ' ' || *p1 == '\t'; p1++) 715 ; 716 if (repeat && *p1 == '\0') 717 return get_saved_command_line (); 718 719 /* Add command to history if appropriate. Note: lines consisting 720 solely of comments are also added to the command history. This 721 is useful when you type a command, and then realize you don't 722 want to execute it quite yet. You can comment out the command 723 and then later fetch it from the value history and remove the 724 '#'. The kill ring is probably better, but some people are in 725 the habit of commenting things out. */ 726 if (*cmd != '\0' && from_tty && input_interactive_p (current_ui)) 727 gdb_add_history (cmd); 728 729 /* Save into global buffer if appropriate. */ 730 if (repeat) 731 { 732 save_command_line (cmd); 733 return get_saved_command_line (); 734 } 735 else 736 return cmd; 737} 738 739/* Handle a complete line of input. This is called by the callback 740 mechanism within the readline library. Deal with incomplete 741 commands as well, by saving the partial input in a global 742 buffer. 743 744 NOTE: This is the asynchronous version of the command_line_input 745 function. */ 746 747void 748command_line_handler (gdb::unique_xmalloc_ptr<char> &&rl) 749{ 750 struct buffer *line_buffer = get_command_line_buffer (); 751 struct ui *ui = current_ui; 752 char *cmd; 753 754 cmd = handle_line_of_input (line_buffer, rl.get (), 1, "prompt"); 755 if (cmd == (char *) EOF) 756 { 757 /* stdin closed. The connection with the terminal is gone. 758 This happens at the end of a testsuite run, after Expect has 759 hung up but GDB is still alive. In such a case, we just quit 760 gdb killing the inferior program too. */ 761 printf_unfiltered ("quit\n"); 762 execute_command ("quit", 1); 763 } 764 else if (cmd == NULL) 765 { 766 /* We don't have a full line yet. Print an empty prompt. */ 767 display_gdb_prompt (""); 768 } 769 else 770 { 771 ui->prompt_state = PROMPT_NEEDED; 772 773 command_handler (cmd); 774 775 if (ui->prompt_state != PROMPTED) 776 display_gdb_prompt (0); 777 } 778} 779 780/* Does reading of input from terminal w/o the editing features 781 provided by the readline library. Calls the line input handler 782 once we have a whole input line. */ 783 784void 785gdb_readline_no_editing_callback (gdb_client_data client_data) 786{ 787 int c; 788 char *result; 789 struct buffer line_buffer; 790 static int done_once = 0; 791 struct ui *ui = current_ui; 792 793 buffer_init (&line_buffer); 794 795 /* Unbuffer the input stream, so that, later on, the calls to fgetc 796 fetch only one char at the time from the stream. The fgetc's will 797 get up to the first newline, but there may be more chars in the 798 stream after '\n'. If we buffer the input and fgetc drains the 799 stream, getting stuff beyond the newline as well, a select, done 800 afterwards will not trigger. */ 801 if (!done_once && !ISATTY (ui->instream)) 802 { 803 setbuf (ui->instream, NULL); 804 done_once = 1; 805 } 806 807 /* We still need the while loop here, even though it would seem 808 obvious to invoke gdb_readline_no_editing_callback at every 809 character entered. If not using the readline library, the 810 terminal is in cooked mode, which sends the characters all at 811 once. Poll will notice that the input fd has changed state only 812 after enter is pressed. At this point we still need to fetch all 813 the chars entered. */ 814 815 while (1) 816 { 817 /* Read from stdin if we are executing a user defined command. 818 This is the right thing for prompt_for_continue, at least. */ 819 c = fgetc (ui->instream != NULL ? ui->instream : ui->stdin_stream); 820 821 if (c == EOF) 822 { 823 if (line_buffer.used_size > 0) 824 { 825 /* The last line does not end with a newline. Return it, and 826 if we are called again fgetc will still return EOF and 827 we'll return NULL then. */ 828 break; 829 } 830 xfree (buffer_finish (&line_buffer)); 831 ui->input_handler (NULL); 832 return; 833 } 834 835 if (c == '\n') 836 { 837 if (line_buffer.used_size > 0 838 && line_buffer.buffer[line_buffer.used_size - 1] == '\r') 839 line_buffer.used_size--; 840 break; 841 } 842 843 buffer_grow_char (&line_buffer, c); 844 } 845 846 buffer_grow_char (&line_buffer, '\0'); 847 result = buffer_finish (&line_buffer); 848 ui->input_handler (gdb::unique_xmalloc_ptr<char> (result)); 849} 850 851 852/* See event-top.h. */ 853 854thread_local void (*thread_local_segv_handler) (int); 855 856static void handle_sigsegv (int sig); 857 858/* Install the SIGSEGV handler. */ 859static void 860install_handle_sigsegv () 861{ 862#if defined (HAVE_SIGACTION) 863 struct sigaction sa; 864 sa.sa_handler = handle_sigsegv; 865 sigemptyset (&sa.sa_mask); 866#ifdef HAVE_SIGALTSTACK 867 sa.sa_flags = SA_ONSTACK; 868#else 869 sa.sa_flags = 0; 870#endif 871 sigaction (SIGSEGV, &sa, nullptr); 872#else 873 signal (SIGSEGV, handle_sigsegv); 874#endif 875} 876 877/* Handler for SIGSEGV. */ 878 879static void 880handle_sigsegv (int sig) 881{ 882 install_handle_sigsegv (); 883 884 if (thread_local_segv_handler == nullptr) 885 abort (); /* ARI: abort */ 886 thread_local_segv_handler (sig); 887} 888 889 890 891/* The serial event associated with the QUIT flag. set_quit_flag sets 892 this, and check_quit_flag clears it. Used by interruptible_select 893 to be able to do interruptible I/O with no race with the SIGINT 894 handler. */ 895static struct serial_event *quit_serial_event; 896 897/* Initialization of signal handlers and tokens. There is a function 898 handle_sig* for each of the signals GDB cares about. Specifically: 899 SIGINT, SIGFPE, SIGQUIT, SIGTSTP, SIGHUP, SIGWINCH. These 900 functions are the actual signal handlers associated to the signals 901 via calls to signal(). The only job for these functions is to 902 enqueue the appropriate event/procedure with the event loop. Such 903 procedures are the old signal handlers. The event loop will take 904 care of invoking the queued procedures to perform the usual tasks 905 associated with the reception of the signal. */ 906/* NOTE: 1999-04-30 This is the asynchronous version of init_signals. 907 init_signals will become obsolete as we move to have to event loop 908 as the default for gdb. */ 909void 910async_init_signals (void) 911{ 912 initialize_async_signal_handlers (); 913 914 quit_serial_event = make_serial_event (); 915 916 signal (SIGINT, handle_sigint); 917 sigint_token = 918 create_async_signal_handler (async_request_quit, NULL); 919 signal (SIGTERM, handle_sigterm); 920 async_sigterm_token 921 = create_async_signal_handler (async_sigterm_handler, NULL); 922 923 /* If SIGTRAP was set to SIG_IGN, then the SIG_IGN will get passed 924 to the inferior and breakpoints will be ignored. */ 925#ifdef SIGTRAP 926 signal (SIGTRAP, SIG_DFL); 927#endif 928 929#ifdef SIGQUIT 930 /* If we initialize SIGQUIT to SIG_IGN, then the SIG_IGN will get 931 passed to the inferior, which we don't want. It would be 932 possible to do a "signal (SIGQUIT, SIG_DFL)" after we fork, but 933 on BSD4.3 systems using vfork, that can affect the 934 GDB process as well as the inferior (the signal handling tables 935 might be in memory, shared between the two). Since we establish 936 a handler for SIGQUIT, when we call exec it will set the signal 937 to SIG_DFL for us. */ 938 signal (SIGQUIT, handle_sigquit); 939 sigquit_token = 940 create_async_signal_handler (async_do_nothing, NULL); 941#endif 942#ifdef SIGHUP 943 if (signal (SIGHUP, handle_sighup) != SIG_IGN) 944 sighup_token = 945 create_async_signal_handler (async_disconnect, NULL); 946 else 947 sighup_token = 948 create_async_signal_handler (async_do_nothing, NULL); 949#endif 950 signal (SIGFPE, handle_sigfpe); 951 sigfpe_token = 952 create_async_signal_handler (async_float_handler, NULL); 953 954#ifdef SIGTSTP 955 sigtstp_token = 956 create_async_signal_handler (async_sigtstp_handler, NULL); 957#endif 958 959 install_handle_sigsegv (); 960} 961 962/* See defs.h. */ 963 964void 965quit_serial_event_set (void) 966{ 967 serial_event_set (quit_serial_event); 968} 969 970/* See defs.h. */ 971 972void 973quit_serial_event_clear (void) 974{ 975 serial_event_clear (quit_serial_event); 976} 977 978/* Return the selectable file descriptor of the serial event 979 associated with the quit flag. */ 980 981static int 982quit_serial_event_fd (void) 983{ 984 return serial_event_fd (quit_serial_event); 985} 986 987/* See defs.h. */ 988 989void 990default_quit_handler (void) 991{ 992 if (check_quit_flag ()) 993 { 994 if (target_terminal::is_ours ()) 995 quit (); 996 else 997 target_pass_ctrlc (); 998 } 999} 1000 1001/* See defs.h. */ 1002quit_handler_ftype *quit_handler = default_quit_handler; 1003 1004/* Handle a SIGINT. */ 1005 1006void 1007handle_sigint (int sig) 1008{ 1009 signal (sig, handle_sigint); 1010 1011 /* We could be running in a loop reading in symfiles or something so 1012 it may be quite a while before we get back to the event loop. So 1013 set quit_flag to 1 here. Then if QUIT is called before we get to 1014 the event loop, we will unwind as expected. */ 1015 set_quit_flag (); 1016 1017 /* In case nothing calls QUIT before the event loop is reached, the 1018 event loop handles it. */ 1019 mark_async_signal_handler (sigint_token); 1020} 1021 1022/* See gdb_select.h. */ 1023 1024int 1025interruptible_select (int n, 1026 fd_set *readfds, fd_set *writefds, fd_set *exceptfds, 1027 struct timeval *timeout) 1028{ 1029 fd_set my_readfds; 1030 int fd; 1031 int res; 1032 1033 if (readfds == NULL) 1034 { 1035 readfds = &my_readfds; 1036 FD_ZERO (&my_readfds); 1037 } 1038 1039 fd = quit_serial_event_fd (); 1040 FD_SET (fd, readfds); 1041 if (n <= fd) 1042 n = fd + 1; 1043 1044 do 1045 { 1046 res = gdb_select (n, readfds, writefds, exceptfds, timeout); 1047 } 1048 while (res == -1 && errno == EINTR); 1049 1050 if (res == 1 && FD_ISSET (fd, readfds)) 1051 { 1052 errno = EINTR; 1053 return -1; 1054 } 1055 return res; 1056} 1057 1058/* Handle GDB exit upon receiving SIGTERM if target_can_async_p (). */ 1059 1060static void 1061async_sigterm_handler (gdb_client_data arg) 1062{ 1063 quit_force (NULL, 0); 1064} 1065 1066/* See defs.h. */ 1067volatile int sync_quit_force_run; 1068 1069/* Quit GDB if SIGTERM is received. 1070 GDB would quit anyway, but this way it will clean up properly. */ 1071void 1072handle_sigterm (int sig) 1073{ 1074 signal (sig, handle_sigterm); 1075 1076 sync_quit_force_run = 1; 1077 set_quit_flag (); 1078 1079 mark_async_signal_handler (async_sigterm_token); 1080} 1081 1082/* Do the quit. All the checks have been done by the caller. */ 1083void 1084async_request_quit (gdb_client_data arg) 1085{ 1086 /* If the quit_flag has gotten reset back to 0 by the time we get 1087 back here, that means that an exception was thrown to unwind the 1088 current command before we got back to the event loop. So there 1089 is no reason to call quit again here. */ 1090 QUIT; 1091} 1092 1093#ifdef SIGQUIT 1094/* Tell the event loop what to do if SIGQUIT is received. 1095 See event-signal.c. */ 1096static void 1097handle_sigquit (int sig) 1098{ 1099 mark_async_signal_handler (sigquit_token); 1100 signal (sig, handle_sigquit); 1101} 1102#endif 1103 1104#if defined (SIGQUIT) || defined (SIGHUP) 1105/* Called by the event loop in response to a SIGQUIT or an 1106 ignored SIGHUP. */ 1107static void 1108async_do_nothing (gdb_client_data arg) 1109{ 1110 /* Empty function body. */ 1111} 1112#endif 1113 1114#ifdef SIGHUP 1115/* Tell the event loop what to do if SIGHUP is received. 1116 See event-signal.c. */ 1117static void 1118handle_sighup (int sig) 1119{ 1120 mark_async_signal_handler (sighup_token); 1121 signal (sig, handle_sighup); 1122} 1123 1124/* Called by the event loop to process a SIGHUP. */ 1125static void 1126async_disconnect (gdb_client_data arg) 1127{ 1128 1129 try 1130 { 1131 quit_cover (); 1132 } 1133 1134 catch (const gdb_exception &exception) 1135 { 1136 fputs_filtered ("Could not kill the program being debugged", 1137 gdb_stderr); 1138 exception_print (gdb_stderr, exception); 1139 } 1140 1141 for (inferior *inf : all_inferiors ()) 1142 { 1143 switch_to_inferior_no_thread (inf); 1144 try 1145 { 1146 pop_all_targets (); 1147 } 1148 catch (const gdb_exception &exception) 1149 { 1150 } 1151 } 1152 1153 signal (SIGHUP, SIG_DFL); /*FIXME: ??????????? */ 1154 raise (SIGHUP); 1155} 1156#endif 1157 1158#ifdef SIGTSTP 1159void 1160handle_sigtstp (int sig) 1161{ 1162 mark_async_signal_handler (sigtstp_token); 1163 signal (sig, handle_sigtstp); 1164} 1165 1166static void 1167async_sigtstp_handler (gdb_client_data arg) 1168{ 1169 char *prompt = get_prompt (); 1170 1171 signal (SIGTSTP, SIG_DFL); 1172#if HAVE_SIGPROCMASK 1173 { 1174 sigset_t zero; 1175 1176 sigemptyset (&zero); 1177 gdb_sigmask (SIG_SETMASK, &zero, 0); 1178 } 1179#elif HAVE_SIGSETMASK 1180 sigsetmask (0); 1181#endif 1182 raise (SIGTSTP); 1183 signal (SIGTSTP, handle_sigtstp); 1184 printf_unfiltered ("%s", prompt); 1185 gdb_flush (gdb_stdout); 1186 1187 /* Forget about any previous command -- null line now will do 1188 nothing. */ 1189 dont_repeat (); 1190} 1191#endif /* SIGTSTP */ 1192 1193/* Tell the event loop what to do if SIGFPE is received. 1194 See event-signal.c. */ 1195static void 1196handle_sigfpe (int sig) 1197{ 1198 mark_async_signal_handler (sigfpe_token); 1199 signal (sig, handle_sigfpe); 1200} 1201 1202/* Event loop will call this function to process a SIGFPE. */ 1203static void 1204async_float_handler (gdb_client_data arg) 1205{ 1206 /* This message is based on ANSI C, section 4.7. Note that integer 1207 divide by zero causes this, so "float" is a misnomer. */ 1208 error (_("Erroneous arithmetic operation.")); 1209} 1210 1211 1212/* Set things up for readline to be invoked via the alternate 1213 interface, i.e. via a callback function 1214 (gdb_rl_callback_read_char), and hook up instream to the event 1215 loop. */ 1216 1217void 1218gdb_setup_readline (int editing) 1219{ 1220 struct ui *ui = current_ui; 1221 1222 /* This function is a noop for the sync case. The assumption is 1223 that the sync setup is ALL done in gdb_init, and we would only 1224 mess it up here. The sync stuff should really go away over 1225 time. */ 1226 if (!batch_silent) 1227 gdb_stdout = new stdio_file (ui->outstream); 1228 gdb_stderr = new stderr_file (ui->errstream); 1229 gdb_stdlog = gdb_stderr; /* for moment */ 1230 gdb_stdtarg = gdb_stderr; /* for moment */ 1231 gdb_stdtargerr = gdb_stderr; /* for moment */ 1232 1233 /* If the input stream is connected to a terminal, turn on editing. 1234 However, that is only allowed on the main UI, as we can only have 1235 one instance of readline. */ 1236 if (ISATTY (ui->instream) && editing && ui == main_ui) 1237 { 1238 /* Tell gdb that we will be using the readline library. This 1239 could be overwritten by a command in .gdbinit like 'set 1240 editing on' or 'off'. */ 1241 ui->command_editing = 1; 1242 1243 /* When a character is detected on instream by select or poll, 1244 readline will be invoked via this callback function. */ 1245 ui->call_readline = gdb_rl_callback_read_char_wrapper; 1246 1247 /* Tell readline to use the same input stream that gdb uses. */ 1248 rl_instream = ui->instream; 1249 } 1250 else 1251 { 1252 ui->command_editing = 0; 1253 ui->call_readline = gdb_readline_no_editing_callback; 1254 } 1255 1256 /* Now create the event source for this UI's input file descriptor. 1257 Another source is going to be the target program (inferior), but 1258 that must be registered only when it actually exists (I.e. after 1259 we say 'run' or after we connect to a remote target. */ 1260 ui_register_input_event_handler (ui); 1261} 1262 1263/* Disable command input through the standard CLI channels. Used in 1264 the suspend proc for interpreters that use the standard gdb readline 1265 interface, like the cli & the mi. */ 1266 1267void 1268gdb_disable_readline (void) 1269{ 1270 struct ui *ui = current_ui; 1271 1272 /* FIXME - It is too heavyweight to delete and remake these every 1273 time you run an interpreter that needs readline. It is probably 1274 better to have the interpreters cache these, which in turn means 1275 that this needs to be moved into interpreter specific code. */ 1276 1277#if 0 1278 ui_file_delete (gdb_stdout); 1279 ui_file_delete (gdb_stderr); 1280 gdb_stdlog = NULL; 1281 gdb_stdtarg = NULL; 1282 gdb_stdtargerr = NULL; 1283#endif 1284 1285 if (ui->command_editing) 1286 gdb_rl_callback_handler_remove (); 1287 delete_file_handler (ui->input_fd); 1288} 1289