Improve genfile exec mode

This commit introduces interprocess communication between genfile and
subsidiary command in exec mode. Instead of using sleep as part of
the checkpoint action chain (as GNU tar did so far), genfile now inserts
--checkpoint-action=wait=SIGUSR1 into the command line and sends the
process the SIGUSR1 after having finished with the checkpoint. This
eliminates the race condition and speeds up the tests based on exec
mode.

The "wait" action is introduced in GNU tar 1.30.90.

* doc/genfile.texi: Document changes.
* tests/genfile.c (checkpoint_granularity): New variable.
(parse_opt): Optional argument to --run specifies granularity.
(CHECKPOINT_TEXT): Customize for genfile.
(exec_command): Take command as arguments. Insert the --checkpoint
and --checkpoint-action options after the command name. Use checkpoint
action wait=SIGUSR1 for synchronization. Send SIGUSR1 after processing
checkpoint.

1 files changed, 34 insertions, 41 deletions

diff --git a/tests/genfile.c b/tests/genfile.c
index 66c54df..dc822c7 100644
--- a/tests/genfile.c
+++ b/tests/genfile.c
@@ -1,11 +1,9 @@
-/* Generate a file containing some preset patterns.
-   Print statistics for existing files.
+/* Multi-purpose tool for tar and cpio testsuite.
 
-   Copyright (C) 1995, 1996, 1997, 2001, 2003, 2004, 2005, 2006, 2007,
-   2008, 2009 Free Software Foundation, Inc.
+   Copyright (C) 1995-1997, 2001-2018 Free Software Foundation, Inc.
 
    François Pinard <pinard@iro.umontreal.ca>, 1995.
-   Sergey Poznyakoff <gray@mirddin.farlep.net>, 2004, 2005, 2006, 2007, 2008.
+   Sergey Poznyakoff <gray@gnu.org>, 2004-2018.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -18,8 +16,7 @@
    General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software Foundation,
-   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 #include <system.h>
@@ -96,10 +93,8 @@ size_t block_size = 512;
 /* Block buffer for sparse file */
 char *buffer;
 
-/* Number of arguments and argument vector for mode == mode_exec */
-int exec_argc;
-char **exec_argv;
-char *checkpoint_option;
+/* Checkpoint granularity for mode == mode_exec */
+char *checkpoint_granularity;
 
 /* Time for --touch option */
 struct timespec touch_time;
@@ -165,8 +160,8 @@ static struct argp_option options[] = {
   {NULL, 0, NULL, 0,
    N_("Synchronous execution options:"), GRP},
 
-  {"run", 'r', N_("OPTION"), OPTION_ARG_OPTIONAL,
-   N_("Execute ARGS. Useful with --checkpoint and one of --cut, --append, --touch, --unlink"),
+  {"run", 'r', N_("N"), OPTION_ARG_OPTIONAL,
+   N_("Execute ARGS. Trigger checkpoints every Nth record (default 1). Useful with --checkpoint and one of --cut, --append, --touch, --unlink"),
    GRP+1 },
   {"checkpoint", OPT_CHECKPOINT, N_("NUMBER"), 0,
    N_("Perform given action (see below) upon reaching checkpoint NUMBER"),
@@ -351,11 +346,7 @@ parse_opt (int key, char *arg, struct argp_state *state)
 
     case 'r':
       mode = mode_exec;
-      if (arg)
-	{
-	  argcv_get (arg, "", NULL, &exec_argc, &exec_argv);
-	  checkpoint_option = "--checkpoint";
-	}
+      checkpoint_granularity = arg ? arg : "1";
       break;
 
     case 'T':
@@ -822,10 +813,10 @@ process_checkpoint (size_t n)
     }
 }
 
-#define CHECKPOINT_TEXT "Write checkpoint"
+#define CHECKPOINT_TEXT "genfile checkpoint"
 
 void
-exec_command (void)
+exec_command (int argc, char **argv)
 {
   int status;
   pid_t pid;
@@ -833,20 +824,28 @@ exec_command (void)
   char *p;
   FILE *fp;
   char buf[128];
-
+  int xargc;
+  char **xargv;
+  int i;
+  char checkpoint_option[80];
+  
   /* Insert --checkpoint option.
-     FIXME: This assumes that exec_argv does not use traditional tar options
+     FIXME: This assumes that argv does not use traditional tar options
      (without dash).
-     FIXME: There is no way to set checkpoint argument (granularity).
   */
-  if (checkpoint_option)
-    {
-      exec_argc++;
-      exec_argv = xrealloc (exec_argv, (exec_argc + 1) * sizeof (*exec_argv));
-      memmove (exec_argv+2, exec_argv+1,
-	       (exec_argc - 1) * sizeof (*exec_argv));
-      exec_argv[1] = checkpoint_option;
-    }
+  xargc = argc + 5;
+  xargv = xcalloc (xargc + 1, sizeof (xargv[0]));
+  xargv[0] = argv[0];
+  snprintf (checkpoint_option, sizeof (checkpoint_option),
+	    "--checkpoint=%s", checkpoint_granularity);
+  xargv[1] = checkpoint_option;
+  xargv[2] = "--checkpoint-action";
+  xargv[3] = "echo=" CHECKPOINT_TEXT " %u";
+  xargv[4] = "--checkpoint-action";
+  xargv[5] = "wait=SIGUSR1";
+
+  for (i = 1; i <= argc; i++)
+    xargv[i + 5] = argv[i];
 
 #ifdef SIGCHLD
   /* System V fork+wait does not work if SIGCHLD is ignored.  */
@@ -872,8 +871,8 @@ exec_command (void)
       /* Make sure POSIX locale is used */
       setenv ("LC_ALL", "POSIX", 1);
 
-      execvp (exec_argv[0], exec_argv);
-      error (EXIT_FAILURE, errno, "execvp %s", exec_argv[0]);
+      execvp (xargv[0], xargv);
+      error (EXIT_FAILURE, errno, "execvp %s", xargv[0]);
     }
 
   /* Master */
@@ -900,6 +899,7 @@ exec_command (void)
 	      if (!(*end && !isspace ((unsigned char) *end)))
 		{
 		  process_checkpoint (n);
+		  kill (pid, SIGUSR1);
 		  continue;
 		}
 	    }
@@ -985,14 +985,7 @@ main (int argc, char **argv)
       break;
 
     case mode_exec:
-      if (!checkpoint_option)
-	{
-	  exec_argc = argc;
-	  exec_argv = argv;
-	}
-      else if (argc)
-	error (EXIT_FAILURE, 0, _("too many arguments"));
-      exec_command ();
+      exec_command (argc, argv);
       break;
 
     default: