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

Abhijit Halder
2011-08-03T07:06:06Z

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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.