src/background.c

   1 /* {{{ Copyright */
   2
   3 /* Background support.
   4
   5    Copyright (C) 1996, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007,
   6    2011
   7    The Free Software Foundation, Inc.
   8
   9    Written by:
  10    Miguel de Icaza, 1996
  11
  12    This file is part of the Midnight Commander.
  13
  14    The Midnight Commander is free software: you can redistribute it
  15    and/or modify it under the terms of the GNU General Public License as
  16    published by the Free Software Foundation, either version 3 of the License,
  17    or (at your option) any later version.
  18
  19    The Midnight Commander is distributed in the hope that it will be useful,
  20    but WITHOUT ANY WARRANTY; without even the implied warranty of
  21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22    GNU General Public License for more details.
  23
  24    You should have received a copy of the GNU General Public License
  25    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  26  */
  27
  28 /* }}} */
  29
  30 /** \file background.c
  31  *  \brief Source: Background support
  32  */
  33
  34 #include <config.h>
  35
  36 #include <stdlib.h>
  37 #include <errno.h>
  38 #include <signal.h>
  39 #include <stdarg.h>
  40 #include <stdio.h>
  41 #include <string.h>
  42
  43 #include <sys/types.h>
  44 #include <sys/stat.h>
  45 #include <sys/wait.h>           /* waitpid() */
  46 #include <unistd.h>
  47 #include <fcntl.h>
  48
  49 #include "lib/global.h"
  50 #include "lib/tty/key.h"        /* add_select_channel(), delete_select_channel() */
  51 #include "lib/widget.h"         /* message() */
  52 #include "lib/event-types.h"
  53
  54 #include "filemanager/fileopctx.h"      /* FileOpContext */
  55
  56 #include "background.h"
  57
  58 /*** global variables ****************************************************************************/
  59
  60 #define MAXCALLARGS 4           /* Number of arguments supported */
  61
  62 /*** file scope macro definitions ****************************************************************/
  63
  64 /*** file scope type declarations ****************************************************************/
  65
  66 enum ReturnType
  67 {
  68     Return_String,
  69     Return_Integer
  70 };
  71
  72 /*** file scope variables ************************************************************************/
  73
  74 /* File descriptor for talking to our parent */
  75 static int parent_fd;
  76
  77 /* File descriptor for messages from our parent */
  78 static int from_parent_fd;
  79
  80 struct TaskList *task_list = NULL;
  81
  82 static int background_attention (int fd, void *closure);
  83
  84 /*** file scope functions ************************************************************************/
  85 /* --------------------------------------------------------------------------------------------- */
  86
  87 static void
  88 register_task_running (FileOpContext * ctx, pid_t pid, int fd, int to_child, char *info)
  89 {
  90     TaskList *new;
  91
  92     new = g_new (TaskList, 1);
  93     new->pid = pid;
  94     new->info = info;
  95     new->state = Task_Running;
  96     new->next = task_list;
  97     new->fd = fd;
  98     new->to_child_fd = to_child;
  99     task_list = new;
 100
 101     add_select_channel (fd, background_attention, ctx);
 102 }
 103
 104 /* --------------------------------------------------------------------------------------------- */
 105
 106 static int
 107 destroy_task_and_return_fd (pid_t pid)
 108 {
 109     TaskList *p = task_list;
 110     TaskList *prev = 0;
 111
 112     while (p)
 113     {
 114         if (p->pid == pid)
 115         {
 116             if (prev)
 117                 prev->next = p->next;
 118             else
 119                 task_list = p->next;
 120             g_free (p->info);
 121             g_free (p);
 122             return p->fd;
 123         }
 124         prev = p;
 125         p = p->next;
 126     }
 127
 128     /* pid not found */
 129     return -1;
 130 }
 131
 132 /* --------------------------------------------------------------------------------------------- */
 133 /* {{{ Parent handlers */
 134
 135 /* Parent/child protocol
 136  *
 137  * the child (the background) process send the following:
 138  * void *routine -- routine to be invoked in the parent
 139  * int  nargc    -- number of arguments
 140  * int  type     -- Return argument type.
 141  *
 142  * If the routine is zero, then it is a way to tell the parent
 143  * that the process is dying.
 144  *
 145  * nargc arguments in the following format:
 146  * int size of the coming block
 147  * size bytes with the block
 148  *
 149  * Now, the parent loads all those and then invokes
 150  * the routine with pointers to the information passed
 151  * (we just support pointers).
 152  *
 153  * If the return type is integer:
 154  *
 155  *     the parent then writes an int to the child with
 156  *     the return value from the routine and the values
 157  *     of any global variable that is modified in the parent
 158  *     currently: do_append and recursive_result.
 159  *
 160  * If the return type is a string:
 161  *
 162  *     the parent writes the resulting string length
 163  *     if the result string was NULL or the empty string,
 164  *     then the length is zero.
 165  *     The parent then writes the string length and frees
 166  *     the result string.
 167  */
 168 /*
 169  * Receive requests from background process and invoke the
 170  * specified routine
 171  */
 172
 173 static int
 174 background_attention (int fd, void *closure)
 175 {
 176     FileOpContext *ctx;
 177     int have_ctx;
 178     union
 179     {
 180         int (*have_ctx0) (int);
 181         int (*have_ctx1) (int, char *);
 182         int (*have_ctx2) (int, char *, char *);
 183         int (*have_ctx3) (int, char *, char *, char *);
 184         int (*have_ctx4) (int, char *, char *, char *, char *);
 185
 186         int (*non_have_ctx0) (FileOpContext *, int);
 187         int (*non_have_ctx1) (FileOpContext *, int, char *);
 188         int (*non_have_ctx2) (FileOpContext *, int, char *, char *);
 189         int (*non_have_ctx3) (FileOpContext *, int, char *, char *, char *);
 190         int (*non_have_ctx4) (FileOpContext *, int, char *, char *, char *, char *);
 191
 192         char *(*ret_str0) ();
 193         char *(*ret_str1) (char *);
 194         char *(*ret_str2) (char *, char *);
 195         char *(*ret_str3) (char *, char *, char *);
 196         char *(*ret_str4) (char *, char *, char *, char *);
 197
 198         void *pointer;
 199     } routine;
 200     /*    void *routine; */
 201     int argc, i, result, status;
 202     char *data[MAXCALLARGS];
 203     ssize_t bytes, ret;
 204     struct TaskList *p;
 205     int to_child_fd = -1;
 206     enum ReturnType type;
 207
 208     ctx = closure;
 209
 210     bytes = read (fd, &routine.pointer, sizeof (routine));
 211     if (bytes == -1 || (size_t) bytes < (sizeof (routine)))
 212     {
 213         const char *background_process_error = _("Background process error");
 214
 215         unregister_task_running (ctx->pid, fd);
 216         if (!waitpid (ctx->pid, &status, WNOHANG))
 217         {
 218             /* the process is still running, but it misbehaves - kill it */
 219             kill (ctx->pid, SIGTERM);
 220             message (D_ERROR, background_process_error, _("Unknown error in child"));
 221             return 0;
 222         }
 223
 224         /* 0 means happy end */
 225         if (WIFEXITED (status) && (WEXITSTATUS (status) == 0))
 226             return 0;
 227
 228         message (D_ERROR, background_process_error, _("Child died unexpectedly"));
 229
 230         return 0;
 231     }
 232
 233     if ((read (fd, &argc, sizeof (argc)) != sizeof (argc)) ||
 234         (read (fd, &type, sizeof (type)) != sizeof (type)) ||
 235         (read (fd, &have_ctx, sizeof (have_ctx)) != sizeof (have_ctx)))
 236     {
 237         message (D_ERROR, _("Background protocol error"), _("Reading failed"));
 238         return 0;
 239     }
 240
 241     if (argc > MAXCALLARGS)
 242     {
 243         message (D_ERROR, _("Background protocol error"),
 244                  _("Background process sent us a request for more arguments\n"
 245                    "than we can handle."));
 246     }
 247
 248     if (have_ctx)
 249     {
 250         if (read (fd, ctx, sizeof (FileOpContext)) != sizeof (FileOpContext))
 251         {
 252             message (D_ERROR, _("Background protocol error"), _("Reading failed"));
 253             return 0;
 254         }
 255     }
 256
 257     for (i = 0; i < argc; i++)
 258     {
 259         int size;
 260
 261         if (read (fd, &size, sizeof (size)) != sizeof (size))
 262         {
 263             message (D_ERROR, _("Background protocol error"), _("Reading failed"));
 264             return 0;
 265         }
 266         data[i] = g_malloc (size + 1);
 267         if (read (fd, data[i], size) != size)
 268         {
 269             message (D_ERROR, _("Background protocol error"), _("Reading failed"));
 270             return 0;
 271         }
 272         data[i][size] = 0;      /* NULL terminate the blocks (they could be strings) */
 273     }
 274
 275     /* Find child task info by descriptor */
 276     /* Find before call, because process can destroy self after */
 277     for (p = task_list; p; p = p->next)
 278     {
 279         if (p->fd == fd)
 280             break;
 281     }
 282
 283     if (p)
 284         to_child_fd = p->to_child_fd;
 285
 286     if (to_child_fd == -1)
 287         message (D_ERROR, _("Background process error"), _("Unknown error in child"));
 288
 289     /* Handle the call */
 290     if (type == Return_Integer)
 291     {
 292         if (!have_ctx)
 293             switch (argc)
 294             {
 295             case 0:
 296                 result = routine.have_ctx0 (Background);
 297                 break;
 298             case 1:
 299                 result = routine.have_ctx1 (Background, data[0]);
 300                 break;
 301             case 2:
 302                 result = routine.have_ctx2 (Background, data[0], data[1]);
 303                 break;
 304             case 3:
 305                 result = routine.have_ctx3 (Background, data[0], data[1], data[2]);
 306                 break;
 307             case 4:
 308                 result = routine.have_ctx4 (Background, data[0], data[1], data[2], data[3]);
 309                 break;
 310             }
 311         else
 312             switch (argc)
 313             {
 314             case 0:
 315                 result = routine.non_have_ctx0 (ctx, Background);
 316                 break;
 317             case 1:
 318                 result = routine.non_have_ctx1 (ctx, Background, data[0]);
 319                 break;
 320             case 2:
 321                 result = routine.non_have_ctx2 (ctx, Background, data[0], data[1]);
 322                 break;
 323             case 3:
 324                 result = routine.non_have_ctx3 (ctx, Background, data[0], data[1], data[2]);
 325                 break;
 326             case 4:
 327                 result =
 328                     routine.non_have_ctx4 (ctx, Background, data[0], data[1], data[2], data[3]);
 329                 break;
 330             }
 331
 332         /* Send the result code and the value for shared variables */
 333         ret = write (to_child_fd, &result, sizeof (int));
 334         if (have_ctx && to_child_fd != -1)
 335             ret = write (to_child_fd, ctx, sizeof (FileOpContext));
 336     }
 337     else if (type == Return_String)
 338     {
 339         int len;
 340         char *resstr = NULL;
 341
 342         /* FIXME: string routines should also use the Foreground/Background
 343          * parameter.  Currently, this is not used here
 344          */
 345         switch (argc)
 346         {
 347         case 0:
 348             resstr = routine.ret_str0 ();
 349             break;
 350         case 1:
 351             resstr = routine.ret_str1 (data[0]);
 352             break;
 353         case 2:
 354             resstr = routine.ret_str2 (data[0], data[1]);
 355             break;
 356         case 3:
 357             resstr = routine.ret_str3 (data[0], data[1], data[2]);
 358             break;
 359         case 4:
 360             resstr = routine.ret_str4 (data[0], data[1], data[2], data[3]);
 361             break;
 362         default:
 363             g_assert_not_reached ();
 364         }
 365         if (resstr)
 366         {
 367             len = strlen (resstr);
 368             ret = write (to_child_fd, &len, sizeof (len));
 369             if (len != 0)
 370                 ret = write (to_child_fd, resstr, len);
 371             g_free (resstr);
 372         }
 373         else
 374         {
 375             len = 0;
 376             ret = write (to_child_fd, &len, sizeof (len));
 377         }
 378     }
 379     for (i = 0; i < argc; i++)
 380         g_free (data[i]);
 381
 382     repaint_screen ();
 383     return 0;
 384 }
 385
 386
 387 /* --------------------------------------------------------------------------------------------- */
 388 /* }}} */
 389
 390 /* {{{ client RPC routines */
 391
 392 /* Sends the header for a call to a routine in the parent process.  If the file
 393  * operation context is not NULL, then it requests that the first parameter of
 394  * the call be a file operation context.
 395  */
 396
 397 static void
 398 parent_call_header (void *routine, int argc, enum ReturnType type, FileOpContext * ctx)
 399 {
 400     int have_ctx;
 401     ssize_t ret;
 402
 403     have_ctx = (ctx != NULL);
 404
 405     ret = write (parent_fd, &routine, sizeof (routine));
 406     ret = write (parent_fd, &argc, sizeof (int));
 407     ret = write (parent_fd, &type, sizeof (type));
 408     ret = write (parent_fd, &have_ctx, sizeof (have_ctx));
 409
 410     if (have_ctx)
 411         ret = write (parent_fd, ctx, sizeof (FileOpContext));
 412 }
 413
 414 /* --------------------------------------------------------------------------------------------- */
 415
 416 static int
 417 parent_va_call (void *routine, gpointer data, int argc, va_list ap)
 418 {
 419     int i;
 420     ssize_t ret;
 421     struct FileOpContext *ctx = (struct FileOpContext *) data;
 422
 423     parent_call_header (routine, argc, Return_Integer, ctx);
 424     for (i = 0; i < argc; i++)
 425     {
 426         int len;
 427         void *value;
 428
 429         len = va_arg (ap, int);
 430         value = va_arg (ap, void *);
 431         ret = write (parent_fd, &len, sizeof (int));
 432         ret = write (parent_fd, value, len);
 433     }
 434
 435     ret = read (from_parent_fd, &i, sizeof (int));
 436     if (ctx)
 437         ret = read (from_parent_fd, ctx, sizeof (FileOpContext));
 438
 439     return i;
 440 }
 441
 442 /* --------------------------------------------------------------------------------------------- */
 443
 444 static char *
 445 parent_va_call_string (void *routine, int argc, va_list ap)
 446 {
 447     char *str;
 448     int i;
 449
 450     parent_call_header (routine, argc, Return_String, NULL);
 451     for (i = 0; i < argc; i++)
 452     {
 453         int len;
 454         void *value;
 455
 456         len = va_arg (ap, int);
 457         value = va_arg (ap, void *);
 458         if ((write (parent_fd, &len, sizeof (int)) != sizeof (int)) ||
 459             (write (parent_fd, value, len) != len))
 460         {
 461             return NULL;
 462         }
 463     }
 464
 465     if (read (from_parent_fd, &i, sizeof (int)) != sizeof (int))
 466         return NULL;
 467     if (!i)
 468         return NULL;
 469     str = g_malloc (i + 1);
 470     if (read (from_parent_fd, str, i) != i)
 471     {
 472         g_free (str);
 473         return NULL;
 474     }
 475     str[i] = 0;
 476     return str;
 477 }
 478
 479 /* --------------------------------------------------------------------------------------------- */
 480 /*** public functions ****************************************************************************/
 481 /* --------------------------------------------------------------------------------------------- */
 482
 483 void
 484 unregister_task_running (pid_t pid, int fd)
 485 {
 486     destroy_task_and_return_fd (pid);
 487     delete_select_channel (fd);
 488 }
 489
 490 /* --------------------------------------------------------------------------------------------- */
 491
 492 void
 493 unregister_task_with_pid (pid_t pid)
 494 {
 495     int fd = destroy_task_and_return_fd (pid);
 496     if (fd != -1)
 497         delete_select_channel (fd);
 498 }
 499
 500
 501 /* --------------------------------------------------------------------------------------------- */
 502 /**
 503  * Try to make the Midnight Commander a background job
 504  *
 505  * Returns:
 506  *  1 for parent
 507  *  0 for child
 508  * -1 on failure
 509  */
 510 int
 511 do_background (struct FileOpContext *ctx, char *info)
 512 {
 513     int comm[2];                /* control connection stream */
 514     int back_comm[2];           /* back connection */
 515     pid_t pid;
 516
 517     if (pipe (comm) == -1)
 518         return -1;
 519
 520     if (pipe (back_comm) == -1)
 521         return -1;
 522
 523     pid = fork ();
 524     if (pid == -1)
 525     {
 526         int saved_errno = errno;
 527
 528         (void) close (comm[0]);
 529         (void) close (comm[1]);
 530         (void) close (back_comm[0]);
 531         (void) close (back_comm[1]);
 532         errno = saved_errno;
 533         return -1;
 534     }
 535
 536     if (pid == 0)
 537     {
 538         int nullfd;
 539
 540         parent_fd = comm[1];
 541         from_parent_fd = back_comm[0];
 542
 543         mc_global.we_are_background = TRUE;
 544         top_dlg = NULL;
 545
 546         /* Make stdin/stdout/stderr point somewhere */
 547         close (0);
 548         close (1);
 549         close (2);
 550
 551         nullfd = open ("/dev/null", O_RDWR);
 552         if (nullfd != -1)
 553         {
 554             while (dup2 (nullfd, 0) == -1 && errno == EINTR)
 555                 ;
 556             while (dup2 (nullfd, 1) == -1 && errno == EINTR)
 557                 ;
 558             while (dup2 (nullfd, 2) == -1 && errno == EINTR)
 559                 ;
 560         }
 561
 562         return 0;
 563     }
 564     else
 565     {
 566         ctx->pid = pid;
 567         register_task_running (ctx, pid, comm[0], back_comm[1], info);
 568         return 1;
 569     }
 570 }
 571
 572 /* --------------------------------------------------------------------------------------------- */
 573
 574 int
 575 parent_call (void *routine, struct FileOpContext *ctx, int argc, ...)
 576 {
 577     int ret;
 578     va_list ap;
 579
 580     va_start (ap, argc);
 581     ret = parent_va_call (routine, (gpointer) ctx, argc, ap);
 582     va_end (ap);
 583
 584     return ret;
 585 }
 586
 587 /* --------------------------------------------------------------------------------------------- */
 588
 589 char *
 590 parent_call_string (void *routine, int argc, ...)
 591 {
 592     va_list ap;
 593     char *str;
 594
 595     va_start (ap, argc);
 596     str = parent_va_call_string (routine, argc, ap);
 597     va_end (ap);
 598
 599     return str;
 600 }
 601
 602 /* --------------------------------------------------------------------------------------------- */
 603
 604 /* event callback */
 605 gboolean
 606 background_parent_call (const gchar * event_group_name, const gchar * event_name,
 607                         gpointer init_data, gpointer data)
 608 {
 609     ev_background_parent_call_t *event_data = (ev_background_parent_call_t *) data;
 610
 611     (void) event_group_name;
 612     (void) event_name;
 613     (void) init_data;
 614
 615     event_data->ret.i =
 616         parent_va_call (event_data->routine, event_data->ctx, event_data->argc, event_data->ap);
 617
 618     return TRUE;
 619 }
 620
 621 /* --------------------------------------------------------------------------------------------- */
 622
 623 /* event callback */
 624 gboolean
 625 background_parent_call_string (const gchar * event_group_name, const gchar * event_name,
 626                                gpointer init_data, gpointer data)
 627 {
 628     ev_background_parent_call_t *event_data = (ev_background_parent_call_t *) data;
 629
 630     (void) event_group_name;
 631     (void) event_name;
 632     (void) init_data;
 633
 634     event_data->ret.s =
 635         parent_va_call_string (event_data->routine, event_data->argc, event_data->ap);
 636
 637     return TRUE;
 638 }
 639
 640 /* --------------------------------------------------------------------------------------------- */