[PATCH][TEST-CASE][DOC] Implementation of pipe to pass GDB's command output to the shell.

[Abhijit Halder <abhijit dot k dot halder at gmail dot com>]

Hi,

I am creating this new thread as the earlier threads went very long.
This patch contains code change, test-cases and documentation as well.
Please review this.

Thanks,
Abhijit Halder

diff -rup src/gdb/ChangeLog dst/gdb/ChangeLog
--- src/gdb/ChangeLog	2011-08-14 07:27:51.502233004 +0530
+++ dst/gdb/ChangeLog	2011-08-24 22:16:45.326146038 +0530
@@ -1,3 +1,13 @@
+2011-08-29  Abhijit Halder  <abhijit.k.halder@gmail.com>
+
+	Implementation of pipe to make I/O communication
+	between gdb and shell.
+
+	* NEWS: Add news item for the new command "pipe".
+	* pipe.c: New file.
+	* Makefile.in (SFILES): Add pipe.c.
+	(COMMON_OBS): Add pipe.o.
+
 2011-08-12  Doug Evans  <dje@google.com>
 
 	* NEWS: Mention new "type" attribute of python gdb.Symbol objects.
diff -rup src/gdb/doc/ChangeLog dst/gdb/doc/ChangeLog
--- src/gdb/doc/ChangeLog	2011-08-14 07:27:53.158233001 +0530
+++ dst/gdb/doc/ChangeLog	2011-08-24 22:37:01.722146068 +0530
@@ -1,3 +1,7 @@
+2011-08-29  Abhijit Halder  <abhijit.k.halder@gmail.com>
+
+	* gdb.texinfo (pipe command): New node.
+
 2011-08-12  Doug Evans  <dje@google.com>
 
 	* gdb.texinfo (Symbols In Python): Document symbol.type.
diff -rup src/gdb/doc/gdb.texinfo dst/gdb/doc/gdb.texinfo
--- src/gdb/doc/gdb.texinfo	2011-08-14 07:27:53.242233001 +0530
+++ dst/gdb/doc/gdb.texinfo	2011-08-25 00:02:42.166145990 +0530
@@ -156,6 +156,7 @@ software in general.  We will miss him.
 * GDB/MI::                      @value{GDBN}'s Machine Interface.
 * Annotations::                 @value{GDBN}'s annotation interface.
 * JIT Interface::               Using the JIT debugging interface.
+* Output Redirection::          Redirecting @value{GDBN}'s command output to shell
 
 * GDB Bugs::                    Reporting bugs in @value{GDBN}
 
@@ -30958,6 +30959,24 @@ Set @code{action_flag} to @code{JIT_UNRE
 If the JIT frees or recompiles code without unregistering it, then @value{GDBN}
 and the JIT will leak the memory used for the associated symbol files.
 
+@node Output Redirection
+@chapter Redirecting @value{GDBN}'s Command Output to the Shell
+
+@value{GDBN}'s command output can be redirected to the shell using @code{pipe}
+command for further processing.  This enables inline processing of the output of
+a particular @value{GDBN} command without explicitly invoking the @code{shell}
+command.  Further, there is no need to store the output of the @value{GDBN}
+command in any file to pass it to the shell.  Even if the environment variable
+@code{SHELL} is set, the default shell (@file{/bin/sh} on Unix systems,
+@file{COMMAND.COM} on MS-DOS, etc.) is used.  The @code{pipe} command expects
+in its argument a delimiter string (without having any whitespace), followed by
+a @value{GDBN} command, followed by the same delimiter string and finally a
+shell command.  The delimiter should not contain any leading `-'.
+
+@smallexample
+(@value{GDBP}) @b{pipe | thread apply all bt | cat >./analyze_threads.log} 
+@end smallexample
+
 @node GDB Bugs
 @chapter Reporting Bugs in @value{GDBN}
 @cindex bugs in @value{GDBN}
diff -rup src/gdb/Makefile.in dst/gdb/Makefile.in
--- src/gdb/Makefile.in	2011-07-27 23:55:26.000000000 +0530
+++ dst/gdb/Makefile.in	2011-08-14 07:31:15.802233004 +0530
@@ -713,7 +713,7 @@ SFILES = ada-exp.y ada-lang.c ada-typepr
 	objc-exp.y objc-lang.c \
 	objfiles.c osabi.c observer.c osdata.c \
 	opencl-lang.c \
-	p-exp.y p-lang.c p-typeprint.c p-valprint.c parse.c printcmd.c \
+	p-exp.y p-lang.c p-typeprint.c p-valprint.c parse.c pipe.c printcmd.c \
 	proc-service.list progspace.c \
 	prologue-value.c psymtab.c \
 	regcache.c reggroups.c remote.c remote-fileio.c reverse.c \
@@ -870,7 +870,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $
 	mi-common.o \
 	event-loop.o event-top.o inf-loop.o completer.o \
 	gdbarch.o arch-utils.o gdbtypes.o osabi.o copying.o \
-	memattr.o mem-break.o target.o parse.o language.o buildsym.o \
+	memattr.o mem-break.o target.o parse.o pipe.o language.o buildsym.o \
 	findcmd.o \
 	std-regs.o \
 	signals.o \
diff -rup src/gdb/NEWS dst/gdb/NEWS
--- src/gdb/NEWS	2011-08-14 07:27:51.582233000 +0530
+++ dst/gdb/NEWS	2011-08-14 07:50:38.562234498 +0530
@@ -64,6 +64,9 @@
 
 * New commands "info macros", and "info definitions" have been added.
 
+* New command "pipe" has been added to make GDB command output available to the
+  shell for processing. 
+
 * Changed commands
 
 watch EXPRESSION mask MASK_VALUE
diff -rup src/gdb/pipe.c dst/gdb/pipe.c
--- src/gdb/pipe.c	2011-07-29 15:15:26.078048517 +0530
+++ dst/gdb/pipe.c	2011-08-23 22:38:53.320364947 +0530
@@ -0,0 +1,227 @@
+/* Everything about pipe, for GDB.
+
+   Copyright (C) 2011 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+#include <ctype.h>
+#include "gdb_string.h"
+#include "ui-file.h"
+#include "ui-out.h"
+#include "cli/cli-utils.h"
+#include "gdbcmd.h"
+#include "libiberty.h"
+#include "exceptions.h"
+
+#if defined(__MINGW32__)
+# define SHELL "cmd.exe"
+# define OPTION_TO_SHELL "/c"
+#else
+# define SHELL "/bin/sh"
+# define OPTION_TO_SHELL "-c"
+#endif
+
+/* Structure to encapsulate all entities associated with pipe.  */
+
+struct pipe_obj
+{
+  /* The delimiter to separate out gdb-command and shell-command.  This can be
+     any arbitrary string without containing any whitespace.  There should not
+     be any leading '-' in the delimiter.  */
+  char *dlim;
+
+  /* The gdb-command.  */
+  char *gdb_cmd;
+
+  /* The shell-command.  */
+  char *shell_cmd;
+
+  /* The gdb-side stream pointer to the pipe.  */
+  FILE *handle;
+
+  /* The pex object used to create pipeline between gdb and shell.  */
+  struct pex_obj *pex;
+};
+
+/* Destruct pipe object referenced by ARG.  */
+
+static void
+destruct_pipe (void *arg)
+{
+  struct pipe_obj *pipe = (struct pipe_obj *) arg;
+
+  if (pipe->handle != NULL)
+    fclose (pipe->handle);
+
+  if (pipe->pex != NULL)
+    {
+      int status;
+
+      /* Wait till the process on the other side of the pipe completes its
+	 job before closing its file descriptors.  */
+      pex_get_status (pipe->pex, 1, &status);
+
+      if (!WIFEXITED (status))
+	warning (_("Execution of shell-command `%s' may not be completed"),
+		 pipe->shell_cmd);
+
+      pex_free (pipe->pex);
+    }
+
+  xfree (pipe->dlim);
+  xfree (pipe);
+}
+
+/* Construct a pipe object by parsing argument ARG to the pipe command.  */
+
+static struct pipe_obj *
+construct_pipe (const char *arg)
+{
+  char *p, *t;
+  struct pipe_obj *pipe = NULL;
+  struct cleanup *cleanup;
+
+  if (arg == NULL)
+    error (_("No argument is specified"));
+
+  pipe = XCNEW (struct pipe_obj);
+  cleanup = make_cleanup (destruct_pipe, pipe);
+
+  p = xstrdup (arg);
+  pipe->dlim = p;
+
+  if (*pipe->dlim == '-')
+    error (_("Delimiter pattern should not start with '-'"));
+
+  t = skip_to_space (p);
+  p = skip_spaces (t);
+
+  if (*p == '\0')
+    error (_("No gdb-command is specified"));
+
+  *t = '\0';
+  pipe->gdb_cmd = p;
+
+  for (;;)
+    {
+      t = skip_to_space (p);
+
+      if (*t == '\0')
+	error (_("No shell-command is specified"));
+
+      /* Check whether the token separated by whitespace matches with
+	 delimiter.  */ 
+      if (memcmp (p, pipe->dlim, (t - p)) == 0
+	  && pipe->dlim[t - p] == '\0')
+	{
+	  *p = '\0';
+	  pipe->shell_cmd = skip_spaces (t);
+	  break;
+	}
+
+       p = skip_spaces (t);
+    }
+
+  discard_cleanups (cleanup);
+  return pipe;
+}
+
+/* Run execute_command for PIPE and FROM_TTY.  Write output to the pipe, do not
+   display it to the screen.  */
+
+static void
+execute_command_to_pipe (struct pipe_obj *pipe, int from_tty)
+{
+  char *argv[4];
+  struct cleanup *cleanup;
+  struct ui_file *fp;
+  int status;
+  const char *errmsg;
+  volatile struct gdb_exception exception;
+
+  argv[0] = SHELL;
+  argv[1] = OPTION_TO_SHELL;
+  argv[2] = pipe->shell_cmd;
+  argv[3] = NULL;
+
+  pipe->pex = pex_init (PEX_USE_PIPES, argv[0], NULL);
+  pipe->handle = pex_input_pipe (pipe->pex, 0);
+
+  if (pipe->handle == NULL)
+    error (_("Failed to create pipe"));
+
+  errmsg = pex_run (pipe->pex, PEX_LAST, argv[0], argv, NULL, NULL, &status);
+
+  if (errmsg != NULL)
+    error (_("Failed to execute shell-command `%s' on pipe: %s %s"),
+	   pipe->shell_cmd, errmsg, safe_strerror (status));
+
+  /* GDB_STDOUT should be better already restored during these
+     restoration callbacks.  */
+  cleanup = set_batch_flag_and_make_cleanup_restore_page_info ();
+  fp = stdio_fileopen (pipe->handle);
+  make_cleanup_ui_file_delete (fp);
+  make_cleanup_restore_ui_file (&gdb_stdout);
+  make_cleanup_restore_ui_file (&gdb_stderr);
+  make_cleanup_restore_ui_file (&gdb_stdlog);
+  make_cleanup_restore_ui_file (&gdb_stdtarg);
+  make_cleanup_restore_ui_file (&gdb_stdtargerr);
+
+  if (ui_out_redirect (current_uiout, fp) < 0)
+    warning (_("Current output protocol does not support redirection"));
+  else 
+    make_cleanup_ui_out_redirect_pop (current_uiout);
+
+  gdb_stdout = fp;
+  gdb_stderr = fp;
+  gdb_stdlog = fp;
+  gdb_stdtarg = fp;
+  gdb_stdtargerr = fp;
+
+  TRY_CATCH (exception, RETURN_MASK_ERROR)
+    {
+      execute_command (pipe->gdb_cmd, from_tty);
+    }
+
+  if (exception.reason < 0)
+    exception_print (gdb_stderr, exception);
+
+  do_cleanups (cleanup);
+}
+
+/* Execute the pipe command with argument ARG and FROM_TTY.  */
+
+static void
+pipe_command (char *arg, int from_tty)
+{
+  struct pipe_obj *pipe = construct_pipe (arg);
+  struct cleanup *cleanup = make_cleanup (destruct_pipe, pipe);
+
+  execute_command_to_pipe (pipe, from_tty);
+  do_cleanups (cleanup);
+}
+
+/* Module initialization.  */
+
+void
+_initialize_pipe (void)
+{
+  add_cmd ("pipe", no_class, pipe_command, _("\
+Create pipe to pass gdb-command output to the shell for processing.\n\
+Arguments are a delimiter, followed by a gdb-command, then the same delimiter \
+again and finally a shell-command.  The delimiter can be any string \
+containing no whitespace and should not have any leading '-'."),
+	   &cmdlist);
+}
diff -rup src/gdb/testsuite/ChangeLog dst/gdb/testsuite/ChangeLog
--- src/gdb/testsuite/ChangeLog	2011-08-14 07:27:53.706232999 +0530
+++ dst/gdb/testsuite/ChangeLog	2011-08-24 22:25:47.670145996 +0530
@@ -1,3 +1,7 @@
+2011-08-29  Abhijit Halder  <abhijit.k.halder@gmail.com>
+
+	* gdb.base/pipe.exp: New file.
+
 2011-08-12  Doug Evans  <dje@google.com>
 
 	* gdb.python/py-symbol.exp: Add test for symbol.type.
diff -rup src/gdb/testsuite/gdb.base/pipe.exp dst/gdb/testsuite/gdb.base/pipe.exp
--- src/gdb/testsuite/gdb.base/pipe.exp	2011-08-16 22:37:45.969351119 +0530
+++ dst/gdb/testsuite/gdb.base/pipe.exp	2011-08-23 21:51:20.408367391 +0530
@@ -0,0 +1,52 @@
+# Copyright 2011 Free Software Foundation, Inc.
+
+# 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
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#
+# test gdb pipe commands
+#
+
+set test "pipe"
+set tempfile ${objdir}/${subdir}/${test}.x
+
+gdb_exit
+gdb_start
+
+gdb_test "pipe" "No argument is specified"
+gdb_test "pipe |" "No gdb-command is specified"
+gdb_test "pipe -x" "Delimiter pattern should not start with '-'"
+gdb_test "pipe | print 'x'" "No shell-command is specified"
+gdb_test "pipe | print 'x' |< cat" "No shell-command is specified"
+gdb_test "pipe |< print 'x' | cat" "No shell-command is specified"
+gdb_test "pipe | print 'x' >| cat" "No shell-command is specified"
+gdb_test "pipe >| print 'x' | cat" "No shell-command is specified"
+gdb_test "pipe | print 'x' | cat" " = 120 'x'"
+gdb_test "pipe | print 'x' | cat | cat" " = 120 'x'"
+
+file delete $tempfile
+gdb_test_no_output "pipe | p 'x' | cat >$tempfile"
+if ![file exists $tempfile] then {
+    perror "$tempfile does not exist."
+    return 0
+} else {
+    set fp [open $tempfile r]
+    set fdata [read $fp]
+    close $fp
+    regsub -all {\$[0-9]+} $fdata {} pattern
+    if ![string match $pattern " = 120 'x'\n"] then {
+        fail $test
+    } else {
+        pass $test
+    }
+}