compat/terminal.c

   1 #include "git-compat-util.h"
   2 #include "compat/terminal.h"
   3 #include "gettext.h"
   4 #include "sigchain.h"
   5 #include "strbuf.h"
   6 #include "run-command.h"
   7 #include "string-list.h"
   8 #include "hashmap.h"
   9
  10 #if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE)
  11
  12 static void restore_term_on_signal(int sig)
  13 {
  14         restore_term();
  15         /* restore_term calls sigchain_pop_common */
  16         raise(sig);
  17 }
  18
  19 #ifdef HAVE_DEV_TTY
  20
  21 #define INPUT_PATH "/dev/tty"
  22 #define OUTPUT_PATH "/dev/tty"
  23
  24 static volatile sig_atomic_t term_fd_needs_closing;
  25 static int term_fd = -1;
  26 static struct termios old_term;
  27
  28 static const char *background_resume_msg;
  29 static const char *restore_error_msg;
  30 static volatile sig_atomic_t ttou_received;
  31
  32 /* async safe error function for use by signal handlers. */
  33 static void write_err(const char *msg)
  34 {
  35         write_in_full(2, "error: ", strlen("error: "));
  36         write_in_full(2, msg, strlen(msg));
  37         write_in_full(2, "\n", 1);
  38 }
  39
  40 static void print_background_resume_msg(int signo)
  41 {
  42         int saved_errno = errno;
  43         sigset_t mask;
  44         struct sigaction old_sa;
  45         struct sigaction sa = { .sa_handler = SIG_DFL };
  46
  47         ttou_received = 1;
  48         write_err(background_resume_msg);
  49         sigaction(signo, &sa, &old_sa);
  50         raise(signo);
  51         sigemptyset(&mask);
  52         sigaddset(&mask, signo);
  53         sigprocmask(SIG_UNBLOCK, &mask, NULL);
  54         /* Stopped here */
  55         sigprocmask(SIG_BLOCK, &mask, NULL);
  56         sigaction(signo, &old_sa, NULL);
  57         errno = saved_errno;
  58 }
  59
  60 static void restore_terminal_on_suspend(int signo)
  61 {
  62         int saved_errno = errno;
  63         int res;
  64         struct termios t;
  65         sigset_t mask;
  66         struct sigaction old_sa;
  67         struct sigaction sa = { .sa_handler = SIG_DFL };
  68         int can_restore = 1;
  69
  70         if (tcgetattr(term_fd, &t) < 0)
  71                 can_restore = 0;
  72
  73         if (tcsetattr(term_fd, TCSAFLUSH, &old_term) < 0)
  74                 write_err(restore_error_msg);
  75
  76         sigaction(signo, &sa, &old_sa);
  77         raise(signo);
  78         sigemptyset(&mask);
  79         sigaddset(&mask, signo);
  80         sigprocmask(SIG_UNBLOCK, &mask, NULL);
  81         /* Stopped here */
  82         sigprocmask(SIG_BLOCK, &mask, NULL);
  83         sigaction(signo, &old_sa, NULL);
  84         if (!can_restore) {
  85                 write_err(restore_error_msg);
  86                 goto out;
  87         }
  88         /*
  89          * If we resume in the background then we receive SIGTTOU when calling
  90          * tcsetattr() below. Set up a handler to print an error message in that
  91          * case.
  92          */
  93         sigemptyset(&mask);
  94         sigaddset(&mask, SIGTTOU);
  95         sa.sa_mask = old_sa.sa_mask;
  96         sa.sa_handler = print_background_resume_msg;
  97         sa.sa_flags = SA_RESTART;
  98         sigaction(SIGTTOU, &sa, &old_sa);
  99  again:
 100         ttou_received = 0;
 101         sigprocmask(SIG_UNBLOCK, &mask, NULL);
 102         res = tcsetattr(term_fd, TCSAFLUSH, &t);
 103         sigprocmask(SIG_BLOCK, &mask, NULL);
 104         if (ttou_received)
 105                 goto again;
 106         else if (res < 0)
 107                 write_err(restore_error_msg);
 108         sigaction(SIGTTOU, &old_sa, NULL);
 109  out:
 110         errno = saved_errno;
 111 }
 112
 113 static void reset_job_signals(void)
 114 {
 115         if (restore_error_msg) {
 116                 signal(SIGTTIN, SIG_DFL);
 117                 signal(SIGTTOU, SIG_DFL);
 118                 signal(SIGTSTP, SIG_DFL);
 119                 restore_error_msg = NULL;
 120                 background_resume_msg = NULL;
 121         }
 122 }
 123
 124 static void close_term_fd(void)
 125 {
 126         if (term_fd_needs_closing)
 127                 close(term_fd);
 128         term_fd_needs_closing = 0;
 129         term_fd = -1;
 130 }
 131
 132 void restore_term(void)
 133 {
 134         if (term_fd < 0)
 135                 return;
 136
 137         tcsetattr(term_fd, TCSAFLUSH, &old_term);
 138         close_term_fd();
 139         sigchain_pop_common();
 140         reset_job_signals();
 141 }
 142
 143 int save_term(enum save_term_flags flags)
 144 {
 145         struct sigaction sa;
 146
 147         if (term_fd < 0)
 148                 term_fd = ((flags & SAVE_TERM_STDIN)
 149                            ? 0
 150                            : open("/dev/tty", O_RDWR));
 151         if (term_fd < 0)
 152                 return -1;
 153         term_fd_needs_closing = !(flags & SAVE_TERM_STDIN);
 154         if (tcgetattr(term_fd, &old_term) < 0) {
 155                 close_term_fd();
 156                 return -1;
 157         }
 158         sigchain_push_common(restore_term_on_signal);
 159         /*
 160          * If job control is disabled then the shell will have set the
 161          * disposition of SIGTSTP to SIG_IGN.
 162          */
 163         sigaction(SIGTSTP, NULL, &sa);
 164         if (sa.sa_handler == SIG_IGN)
 165                 return 0;
 166
 167         /* avoid calling gettext() from signal handler */
 168         background_resume_msg = _("cannot resume in the background, please use 'fg' to resume");
 169         restore_error_msg = _("cannot restore terminal settings");
 170         sa.sa_handler = restore_terminal_on_suspend;
 171         sa.sa_flags = SA_RESTART;
 172         sigemptyset(&sa.sa_mask);
 173         sigaddset(&sa.sa_mask, SIGTSTP);
 174         sigaddset(&sa.sa_mask, SIGTTIN);
 175         sigaddset(&sa.sa_mask, SIGTTOU);
 176         sigaction(SIGTSTP, &sa, NULL);
 177         sigaction(SIGTTIN, &sa, NULL);
 178         sigaction(SIGTTOU, &sa, NULL);
 179
 180         return 0;
 181 }
 182
 183 static int disable_bits(enum save_term_flags flags, tcflag_t bits)
 184 {
 185         struct termios t;
 186
 187         if (save_term(flags) < 0)
 188                 return -1;
 189
 190         t = old_term;
 191
 192         t.c_lflag &= ~bits;
 193         if (bits & ICANON) {
 194                 t.c_cc[VMIN] = 1;
 195                 t.c_cc[VTIME] = 0;
 196         }
 197         if (!tcsetattr(term_fd, TCSAFLUSH, &t))
 198                 return 0;
 199
 200         sigchain_pop_common();
 201         reset_job_signals();
 202         close_term_fd();
 203         return -1;
 204 }
 205
 206 static int disable_echo(enum save_term_flags flags)
 207 {
 208         return disable_bits(flags, ECHO);
 209 }
 210
 211 static int enable_non_canonical(enum save_term_flags flags)
 212 {
 213         return disable_bits(flags, ICANON | ECHO);
 214 }
 215
 216 /*
 217  * On macos it is not possible to use poll() with a terminal so use select
 218  * instead.
 219  */
 220 static int getchar_with_timeout(int timeout)
 221 {
 222         struct timeval tv, *tvp = NULL;
 223         fd_set readfds;
 224         int res;
 225
 226  again:
 227         if (timeout >= 0) {
 228                 tv.tv_sec = timeout / 1000;
 229                 tv.tv_usec = (timeout % 1000) * 1000;
 230                 tvp = &tv;
 231         }
 232
 233         FD_ZERO(&readfds);
 234         FD_SET(0, &readfds);
 235         res = select(1, &readfds, NULL, NULL, tvp);
 236         if (!res)
 237                 return EOF;
 238         if (res < 0) {
 239                 if (errno == EINTR)
 240                         goto again;
 241                 else
 242                         return EOF;
 243         }
 244         return getchar();
 245 }
 246
 247 #elif defined(GIT_WINDOWS_NATIVE)
 248
 249 #define INPUT_PATH "CONIN$"
 250 #define OUTPUT_PATH "CONOUT$"
 251 #define FORCE_TEXT "t"
 252
 253 static int use_stty = 1;
 254 static struct string_list stty_restore = STRING_LIST_INIT_DUP;
 255 static HANDLE hconin = INVALID_HANDLE_VALUE;
 256 static HANDLE hconout = INVALID_HANDLE_VALUE;
 257 static DWORD cmode_in, cmode_out;
 258
 259 void restore_term(void)
 260 {
 261         if (use_stty) {
 262                 struct child_process cp = CHILD_PROCESS_INIT;
 263
 264                 if (stty_restore.nr == 0)
 265                         return;
 266
 267                 strvec_push(&cp.args, "stty");
 268                 for (size_t i = 0; i < stty_restore.nr; i++)
 269                         strvec_push(&cp.args, stty_restore.items[i].string);
 270                 run_command(&cp);
 271                 string_list_clear(&stty_restore, 0);
 272                 return;
 273         }
 274
 275         sigchain_pop_common();
 276
 277         if (hconin == INVALID_HANDLE_VALUE)
 278                 return;
 279
 280         SetConsoleMode(hconin, cmode_in);
 281         CloseHandle(hconin);
 282         if (cmode_out) {
 283                 assert(hconout != INVALID_HANDLE_VALUE);
 284                 SetConsoleMode(hconout, cmode_out);
 285                 CloseHandle(hconout);
 286         }
 287
 288         hconin = hconout = INVALID_HANDLE_VALUE;
 289 }
 290
 291 int save_term(enum save_term_flags flags)
 292 {
 293         hconin = CreateFileA("CONIN$", GENERIC_READ | GENERIC_WRITE,
 294             FILE_SHARE_READ, NULL, OPEN_EXISTING,
 295             FILE_ATTRIBUTE_NORMAL, NULL);
 296         if (hconin == INVALID_HANDLE_VALUE)
 297                 return -1;
 298
 299         if (flags & SAVE_TERM_DUPLEX) {
 300                 hconout = CreateFileA("CONOUT$", GENERIC_READ | GENERIC_WRITE,
 301                         FILE_SHARE_WRITE, NULL, OPEN_EXISTING,
 302                         FILE_ATTRIBUTE_NORMAL, NULL);
 303                 if (hconout == INVALID_HANDLE_VALUE)
 304                         goto error;
 305
 306                 GetConsoleMode(hconout, &cmode_out);
 307         }
 308
 309         GetConsoleMode(hconin, &cmode_in);
 310         use_stty = 0;
 311         sigchain_push_common(restore_term_on_signal);
 312         return 0;
 313 error:
 314         CloseHandle(hconin);
 315         hconin = INVALID_HANDLE_VALUE;
 316         return -1;
 317 }
 318
 319 static int disable_bits(enum save_term_flags flags, DWORD bits)
 320 {
 321         if (use_stty) {
 322                 struct child_process cp = CHILD_PROCESS_INIT;
 323
 324                 strvec_push(&cp.args, "stty");
 325
 326                 if (bits & ENABLE_LINE_INPUT) {
 327                         string_list_append(&stty_restore, "icanon");
 328                         /*
 329                          * POSIX allows VMIN and VTIME to overlap with VEOF and
 330                          * VEOL - let's hope that is not the case on windows.
 331                          */
 332                         strvec_pushl(&cp.args, "-icanon", "min", "1", "time", "0", NULL);
 333                 }
 334
 335                 if (bits & ENABLE_ECHO_INPUT) {
 336                         string_list_append(&stty_restore, "echo");
 337                         strvec_push(&cp.args, "-echo");
 338                 }
 339
 340                 if (bits & ENABLE_PROCESSED_INPUT) {
 341                         string_list_append(&stty_restore, "-ignbrk");
 342                         string_list_append(&stty_restore, "intr");
 343                         string_list_append(&stty_restore, "^c");
 344                         strvec_push(&cp.args, "ignbrk");
 345                         strvec_push(&cp.args, "intr");
 346                         strvec_push(&cp.args, "");
 347                 }
 348
 349                 if (run_command(&cp) == 0)
 350                         return 0;
 351
 352                 /* `stty` could not be executed; access the Console directly */
 353                 use_stty = 0;
 354         }
 355
 356         if (save_term(flags) < 0)
 357                 return -1;
 358
 359         if (!SetConsoleMode(hconin, cmode_in & ~bits)) {
 360                 CloseHandle(hconin);
 361                 hconin = INVALID_HANDLE_VALUE;
 362                 sigchain_pop_common();
 363                 return -1;
 364         }
 365
 366         return 0;
 367 }
 368
 369 static int disable_echo(enum save_term_flags flags)
 370 {
 371         return disable_bits(flags, ENABLE_ECHO_INPUT);
 372 }
 373
 374 static int enable_non_canonical(enum save_term_flags flags)
 375 {
 376         return disable_bits(flags,
 377                             ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
 378 }
 379
 380 /*
 381  * Override `getchar()`, as the default implementation does not use
 382  * `ReadFile()`.
 383  *
 384  * This poses a problem when we want to see whether the standard
 385  * input has more characters, as the default of Git for Windows is to start the
 386  * Bash in a MinTTY, which uses a named pipe to emulate a pty, in which case
 387  * our `poll()` emulation calls `PeekNamedPipe()`, which seems to require
 388  * `ReadFile()` to be called first to work properly (it only reports 0
 389  * available bytes, otherwise).
 390  *
 391  * So let's just override `getchar()` with a version backed by `ReadFile()` and
 392  * go our merry ways from here.
 393  */
 394 static int mingw_getchar(void)
 395 {
 396         DWORD read = 0;
 397         unsigned char ch;
 398
 399         if (!ReadFile(GetStdHandle(STD_INPUT_HANDLE), &ch, 1, &read, NULL))
 400                 return EOF;
 401
 402         if (!read) {
 403                 error("Unexpected 0 read");
 404                 return EOF;
 405         }
 406
 407         return ch;
 408 }
 409 #define getchar mingw_getchar
 410
 411 static int getchar_with_timeout(int timeout)
 412 {
 413         struct pollfd pfd = { .fd = 0, .events = POLLIN };
 414
 415         if (poll(&pfd, 1, timeout) < 1)
 416                 return EOF;
 417
 418         return getchar();
 419 }
 420
 421 #endif
 422
 423 #ifndef FORCE_TEXT
 424 #define FORCE_TEXT
 425 #endif
 426
 427 char *git_terminal_prompt(const char *prompt, int echo)
 428 {
 429         static struct strbuf buf = STRBUF_INIT;
 430         int r;
 431         FILE *input_fh, *output_fh;
 432
 433         input_fh = fopen(INPUT_PATH, "r" FORCE_TEXT);
 434         if (!input_fh)
 435                 return NULL;
 436
 437         output_fh = fopen(OUTPUT_PATH, "w" FORCE_TEXT);
 438         if (!output_fh) {
 439                 fclose(input_fh);
 440                 return NULL;
 441         }
 442
 443         if (!echo && disable_echo(0)) {
 444                 fclose(input_fh);
 445                 fclose(output_fh);
 446                 return NULL;
 447         }
 448
 449         fputs(prompt, output_fh);
 450         fflush(output_fh);
 451
 452         r = strbuf_getline_lf(&buf, input_fh);
 453         if (!echo) {
 454                 putc('\n', output_fh);
 455                 fflush(output_fh);
 456         }
 457
 458         restore_term();
 459         fclose(input_fh);
 460         fclose(output_fh);
 461
 462         if (r == EOF)
 463                 return NULL;
 464         return buf.buf;
 465 }
 466
 467 /*
 468  * The `is_known_escape_sequence()` function returns 1 if the passed string
 469  * corresponds to an Escape sequence that the terminal capabilities contains.
 470  *
 471  * To avoid depending on ncurses or other platform-specific libraries, we rely
 472  * on the presence of the `infocmp` executable to do the job for us (failing
 473  * silently if the program is not available or refused to run).
 474  */
 475 struct escape_sequence_entry {
 476         struct hashmap_entry entry;
 477         char sequence[FLEX_ARRAY];
 478 };
 479
 480 static int sequence_entry_cmp(const void *hashmap_cmp_fn_data UNUSED,
 481                               const struct hashmap_entry *he1,
 482                               const struct hashmap_entry *he2,
 483                               const void *keydata)
 484 {
 485         const struct escape_sequence_entry
 486                 *e1 = container_of(he1, const struct escape_sequence_entry, entry),
 487                 *e2 = container_of(he2, const struct escape_sequence_entry, entry);
 488         return strcmp(e1->sequence, keydata ? keydata : e2->sequence);
 489 }
 490
 491 static int is_known_escape_sequence(const char *sequence)
 492 {
 493         static struct hashmap sequences;
 494         static int initialized;
 495
 496         if (!initialized) {
 497                 struct child_process cp = CHILD_PROCESS_INIT;
 498                 struct strbuf buf = STRBUF_INIT;
 499                 char *p, *eol;
 500
 501                 hashmap_init(&sequences, sequence_entry_cmp, NULL, 0);
 502
 503                 strvec_pushl(&cp.args, "infocmp", "-L", "-1", NULL);
 504                 if (pipe_command(&cp, NULL, 0, &buf, 0, NULL, 0))
 505                         strbuf_setlen(&buf, 0);
 506
 507                 for (eol = p = buf.buf; *p; p = eol + 1) {
 508                         p = strchr(p, '=');
 509                         if (!p)
 510                                 break;
 511                         p++;
 512                         eol = strchrnul(p, '\n');
 513
 514                         if (starts_with(p, "\\E")) {
 515                                 char *comma = memchr(p, ',', eol - p);
 516                                 struct escape_sequence_entry *e;
 517
 518                                 p[0] = '^';
 519                                 p[1] = '[';
 520                                 FLEX_ALLOC_MEM(e, sequence, p, comma - p);
 521                                 hashmap_entry_init(&e->entry,
 522                                                    strhash(e->sequence));
 523                                 hashmap_add(&sequences, &e->entry);
 524                         }
 525                         if (!*eol)
 526                                 break;
 527                 }
 528                 initialized = 1;
 529         }
 530
 531         return !!hashmap_get_from_hash(&sequences, strhash(sequence), sequence);
 532 }
 533
 534 int read_key_without_echo(struct strbuf *buf)
 535 {
 536         static int warning_displayed;
 537         int ch;
 538
 539         if (warning_displayed || enable_non_canonical(SAVE_TERM_STDIN) < 0) {
 540                 if (!warning_displayed) {
 541                         warning("reading single keystrokes not supported on "
 542                                 "this platform; reading line instead");
 543                         warning_displayed = 1;
 544                 }
 545
 546                 return strbuf_getline(buf, stdin);
 547         }
 548
 549         strbuf_reset(buf);
 550         ch = getchar();
 551         if (ch == EOF) {
 552                 restore_term();
 553                 return EOF;
 554         }
 555         strbuf_addch(buf, ch);
 556
 557         if (ch == '\033' /* ESC */) {
 558                 /*
 559                  * We are most likely looking at an Escape sequence. Let's try
 560                  * to read more bytes, waiting at most half a second, assuming
 561                  * that the sequence is complete if we did not receive any byte
 562                  * within that time.
 563                  *
 564                  * Start by replacing the Escape byte with ^[ */
 565                 strbuf_splice(buf, buf->len - 1, 1, "^[", 2);
 566
 567                 /*
 568                  * Query the terminal capabilities once about all the Escape
 569                  * sequences it knows about, so that we can avoid waiting for
 570                  * half a second when we know that the sequence is complete.
 571                  */
 572                 while (!is_known_escape_sequence(buf->buf)) {
 573                         ch = getchar_with_timeout(500);
 574                         if (ch == EOF)
 575                                 break;
 576                         strbuf_addch(buf, ch);
 577                 }
 578         }
 579
 580         restore_term();
 581         return 0;
 582 }
 583
 584 #else
 585
 586 int save_term(enum save_term_flags flags)
 587 {
 588         /* no duplex support available */
 589         return -!!(flags & SAVE_TERM_DUPLEX);
 590 }
 591
 592 void restore_term(void)
 593 {
 594 }
 595
 596 char *git_terminal_prompt(const char *prompt, int echo UNUSED)
 597 {
 598         return getpass(prompt);
 599 }
 600
 601 int read_key_without_echo(struct strbuf *buf)
 602 {
 603         static int warning_displayed;
 604         const char *res;
 605
 606         if (!warning_displayed) {
 607                 warning("reading single keystrokes not supported on this "
 608                         "platform; reading line instead");
 609                 warning_displayed = 1;
 610         }
 611
 612         res = getpass("");
 613         strbuf_reset(buf);
 614         if (!res)
 615                 return EOF;
 616         strbuf_addstr(buf, res);
 617         return 0;
 618 }
 619
 620 #endif