Re: [PATCH] An implementation of pipe to make I/O communication between gdb and shell.

[Abhijit Halder <abhijit.k.halder@gmail.com>]

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On Wed, Aug 3, 2011 at 5:09 AM, Sergio Durigan Junior
<sergiodj@redhat.com> wrote:
> Jan Kratochvil <jan.kratochvil@redhat.com> writes:
>
>> Sure maybe "pipe" is no longer the right name and "redirect" or so matches the
>> functionality better.
>
> FWIW I think that, given the current status of the patch, `redirect' is
> better than `pipe', indeed.
>

I have made corrections suggested by Sergio Durigan Junior in his
code-review. Only the documentation section I am leaving for the time
being.

 Makefile.in |    4 -
 pipe.c      |  223 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 ui-file.c   |   14 +++
 ui-file.h   |    3
 4 files changed, 242 insertions(+), 2 deletions(-)


Thanks,
Abhijit Halder

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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	2011-07-29 16:12:32.578048797 +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/pipe.c dst/gdb/pipe.c
--- src/gdb/pipe.c	2011-07-29 15:15:26.078048517 +0530
+++ dst/gdb/pipe.c	2011-08-03 12:08:59.529850285 +0530
@@ -0,0 +1,223 @@
+/* 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 "gdbcmd.h"
+#include <ctype.h>
+#include "gdb_string.h"
+#include "ui-file.h"
+#include "cli/cli-utils.h"
+
+/* List of characters that can be used as delimiter to separate out
+   gdb-command and shell command.  */
+#define PIPE_DELIMITER "|/\\'\"`#@!$%<^>-"
+
+typedef char *iostream_mode_t;
+
+#define RD_TEXT "r"
+#define WR_TEXT "w"
+
+struct pipe_t
+{
+  /* The shell-command.  */
+  char *shell_cmd;
+
+  /* The gdb-command.  */
+  char *gdb_cmd;
+
+  /* The delimiter to separate out gdb-command and shell-command.  */
+  char dlim;
+
+  /* The mode of gdb side pipe (read or write).  */
+  iostream_mode_t mode;
+
+  /* The stream pointer of pipe.  */
+  FILE *handle;
+};
+
+/* Prototype of local function.  */
+
+static struct pipe_t *construct_pipe (char *);
+
+static void destruct_pipe (struct pipe_t *);
+
+static struct pipe_t *execute_command_to_pipe (struct pipe_t *, int);
+
+static void pipe_command (char *, int);
+
+static struct pipe_t *
+construct_pipe (char *p)
+{
+  struct pipe_t *pipe = NULL;
+  int found_mode = 0, pipe_opt_done = 0;
+  struct cleanup *old_chain;
+
+  if (p != NULL && *p != '\0')
+    {
+      pipe = xmalloc (sizeof (struct pipe_t));
+      old_chain = make_cleanup (xfree, pipe);
+
+      /* Default mode of pipe.  */
+      pipe->mode = WR_TEXT;
+
+      while (!pipe_opt_done)
+        {
+          p = skip_spaces (p);
+
+          /* If we don't get an argument started with '-' and which is not 
+             even a value associated with some option, we consider it as a 
+             potential delimiter and stop parsing for further option 
+             arguments.  */
+          if (*p != '-')
+            break;
+
+          switch (*++p)
+            {
+            case 'r':
+              if (found_mode)
+                {
+                  error (_("Invalid option"));
+                  do_cleanups (old_chain);
+                  return NULL;
+                }
+              pipe->mode = RD_TEXT;
+              found_mode = 1;
+              ++p;
+              break;
+
+            case 'w':
+              if (found_mode)
+                {
+                  error (_("Invalid option"));
+                  do_cleanups (old_chain);
+                  return NULL;
+                }
+              pipe->mode = WR_TEXT;
+              found_mode = 1;
+              ++p;
+              break;
+
+            case ' ':
+              pipe_opt_done = 1;
+              ++p;
+              break;
+
+            default:
+              error (_("Invalid option"));
+              do_cleanups (old_chain);
+              return NULL;
+            }
+        }
+
+      p = skip_spaces (p);
+      pipe->dlim = *p++;
+      p = skip_spaces (p);
+      pipe->gdb_cmd = p;
+
+      /* Validate the delimiter from a pre-defined whitelist characters.
+         This will enforce not to use special (e.g., alpha-numeric) list
+         of characters.  */
+      /* NOTE: If DLIM become null, P points to a bad string, hence 
+         before doing further processing of P we should check DLIM.  */
+      if (pipe->dlim == '\0'
+          || strchr (PIPE_DELIMITER, pipe->dlim) == NULL)
+        {
+          error (_("Invalid delimiter '%c'"), pipe->dlim);
+          do_cleanups (old_chain);
+          return NULL;
+        }
+
+      if ((p = strchr (p, pipe->dlim)) == NULL)
+        {
+          error (_("Found no shell command"));
+          do_cleanups (old_chain);
+          return NULL;
+        }
+
+      *p++ = '\0';
+      pipe->shell_cmd = p;
+
+      pipe->handle = popen (pipe->shell_cmd, pipe->mode);
+
+      if (!pipe->handle)
+        {
+          error (_("Failed to create pipe.\n%s"), strerror (errno));
+          do_cleanups (old_chain);
+          return NULL;
+        }
+    }
+
+  return pipe;
+}
+
+static void
+destruct_pipe (struct pipe_t *pipe)
+{
+  pclose (pipe->handle);
+  xfree (pipe);
+}
+
+static struct pipe_t *
+execute_command_to_pipe (struct pipe_t *pipe, int from_tty)
+{
+  FILE *fstream, *pstream;
+  struct ui_file *gdb_stdio;
+
+  if (!pipe->mode)
+    internal_error (__FILE__, __LINE__,
+                    _("execute_command_to_pipe: un-initialized pipe"));
+  else if (!strcmp (pipe->mode, RD_TEXT))
+    gdb_stdio = gdb_stdin;
+  else if (!strcmp (pipe->mode, WR_TEXT))
+    gdb_stdio = gdb_stdout;
+  else
+    internal_error (__FILE__, __LINE__,
+                    _("execute_command_to_pipe: bad pipe mode"));
+  pstream = pipe->handle;
+  fstream = gdb_modify_io (gdb_stdio, pstream);
+  execute_command (pipe->gdb_cmd, from_tty);
+  pstream = gdb_modify_io (gdb_stdio, fstream);
+  pipe->handle = pstream;
+  return pipe;
+}
+
+static void
+pipe_command (char *arg, int from_tty)
+{
+  struct pipe_t *pipe;
+
+  pipe = construct_pipe (arg);
+  if (pipe != NULL) 
+    {
+      pipe = execute_command_to_pipe (pipe, from_tty);
+      destruct_pipe (pipe);
+    }
+}
+
+void
+_initialize_pipe (void)
+{
+  add_cmd ("pipe", no_class, pipe_command, _("\
+Create pipe between gdb and shell for I/O based communication.\n\
+Arguments are option(s) to the command, then a delimiter character, \
+then the gdb-command and finally the shell-command.\n\
+If no option is given, the default behavior of pipe will be to \
+pass the gdb-command output to the shell."), 
+           &cmdlist);
+}
diff -rup src/gdb/ui-file.c dst/gdb/ui-file.c
--- src/gdb/ui-file.c	2011-05-14 11:14:36.000000000 +0530
+++ dst/gdb/ui-file.c	2011-07-29 14:32:07.838049413 +0530
@@ -619,6 +619,20 @@ stdio_fileopen (FILE *file)
   return stdio_file_new (file, 0);
 }
 
+FILE *
+gdb_modify_io (struct ui_file *file, FILE *iostream_new)
+{
+  FILE *iostream_old;
+  struct stdio_file *stdio = ui_file_data (file);
+
+  if (stdio->magic != &stdio_file_magic)
+    internal_error (__FILE__, __LINE__,
+		    _("gdb_modify_io: bad magic number"));
+  iostream_old = stdio->file;
+  stdio->file = iostream_new;
+  return iostream_old;
+}
+
 struct ui_file *
 gdb_fopen (char *name, char *mode)
 {
diff -rup src/gdb/ui-file.h dst/gdb/ui-file.h
--- src/gdb/ui-file.h	2011-05-13 22:58:20.000000000 +0530
+++ dst/gdb/ui-file.h	2011-08-02 17:17:54.130442994 +0530
@@ -126,6 +126,9 @@ extern struct ui_file *stdio_fileopen (F
 /* Open NAME returning an STDIO based UI_FILE.  */
 extern struct ui_file *gdb_fopen (char *name, char *mode);
 
+/* Modify the file I/O stream pointer of an STDIO based UI_FILE.  */
+extern FILE *gdb_modify_io (struct ui_file *file, FILE *iostream_new);
+
 /* Create a file which writes to both ONE and TWO.  CLOSE_ONE
    and CLOSE_TWO indicate whether the original files should be
    closed when the new file is closed.  */

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2011-07-29 Abhijit Halder <abhijit.k.halder@symantec.com>

	Implementation of pipe to make I/O communication 
	between gdb and shell.

	* ui-file.c (gdb_modify_io): New function.
	* ui-file.h (gdb_modify_io): Function prototype.
	* pipe.c: New file.
	* Makefile.in (SFILES): Add pipe.c.
	(COMMON_OBS): Add pipe.o.