[RFAv3,4/6] Implement | (pipe) command.
Commit Message
The pipe command allows to run a GDB command, and pipe its output
to a shell command:
(gdb) help pipe
Send the output of a gdb command to a shell command.
Usage: pipe [COMMAND] | SHELL_COMMAND
Usage: | [COMMAND] | SHELL_COMMAND
Usage: pipe -dX COMMAND X SHELL_COMMAND
Usage: | -dX COMMAND X SHELL_COMMAND
Executes COMMAND and sends its output to SHELL_COMMAND.
If COMMAND contains a | character, the option -dX indicates
to use the character X to separate COMMAND from SHELL_COMMAND.
With no COMMAND, repeat the last executed command
and send its output to SHELL_COMMAND.
(gdb)
For example:
(gdb) pipe print some_data_structure | grep -B3 -A3 something
The pipe character is defined as an alias for pipe command, so that
the above can be typed as:
(gdb) | print some_data_structure | grep -B3 -A3 something
If no GDB COMMAND is given, then the previous command is relaunched,
and its output is sent to the given SHELL_COMMAND.
This also defines convenience vars $_shell_exitcode and $_shell_exitsignal
to record the exit code and exit signal of the last shell command
launched by GDB e.g. by "shell", "pipe", ...
gdb/ChangeLog
2019-05-04 Philippe Waroquiers <philippe.waroquiers@skynet.be>
* cli/cli-cmds.c (pipe_command): New function.
(_initialize_cli_cmds): Call add_com for pipe_command.
Define | as an alias for pipe.
(exit_status_set_internal_vars): New function.
(shell_escape): Call exit_status_set_internal_vars.
cli/cli-decode.c (find_command_name_length): Recognize | as
a single character command.
---
gdb/cli/cli-cmds.c | 105 +++++++++++++++++++++++++++++++++++++++++++
gdb/cli/cli-decode.c | 4 +-
2 files changed, 107 insertions(+), 2 deletions(-)
Comments
On 5/4/19 5:17 PM, Philippe Waroquiers wrote:
> The pipe command allows to run a GDB command, and pipe its output
> to a shell command:
> (gdb) help pipe
> Send the output of a gdb command to a shell command.
> Usage: pipe [COMMAND] | SHELL_COMMAND
> Usage: | [COMMAND] | SHELL_COMMAND
> Usage: pipe -dX COMMAND X SHELL_COMMAND
> Usage: | -dX COMMAND X SHELL_COMMAND
> Executes COMMAND and sends its output to SHELL_COMMAND.
> If COMMAND contains a | character, the option -dX indicates
> to use the character X to separate COMMAND from SHELL_COMMAND.
> With no COMMAND, repeat the last executed command
> and send its output to SHELL_COMMAND.
> (gdb)
This help output is stale now. The current output is:
(gdb) help pipe
Send the output of a gdb command to a shell command.
Usage: | [COMMAND] | SHELL_COMMAND
Usage: | -d SEP COMMAND SEP SHELL_COMMAND
Usage: pipe [COMMAND] | SHELL_COMMAND
Usage: pipe -d SEP COMMAND SEP SHELL_COMMAND
Executes COMMAND and sends its output to SHELL_COMMAND.
If COMMAND contains a | character, the option -d SEP indicates
to use the string SEP to separate COMMAND from SHELL_COMMAND.
With no COMMAND, repeat the last executed command
and send its output to SHELL_COMMAND.
(gdb)
I think the "If COMMAND contains a | character," could be
improved with a bit of copy/editing. Something like this:
(gdb) help pipe
Send the output of a gdb command to a shell command.
Usage: | [COMMAND] | SHELL_COMMAND
Usage: | -d SEP COMMAND SEP SHELL_COMMAND
Usage: pipe [COMMAND] | SHELL_COMMAND
Usage: pipe -d SEP COMMAND SEP SHELL_COMMAND
Executes COMMAND and sends its output to SHELL_COMMAND.
The -d option indicates to use the string SEP to separate COMMAND
from SHELL_COMMAND, in alternative to |. This is useful in
case COMMAND contains a | character.
With no COMMAND, repeat the last executed command
and send its output to SHELL_COMMAND.
(Or see the suggestion in my reply to the manual patch).
Also, is there a reason you picked "-d" for the option
letter? Maybe you were thinking of "delimiter"? In
that case, maybe consider describing it with
"-d DEL" or "-d DELIM" instead of "-d SEP", but better
mnemonics. Just a suggestion.
> For example:
> (gdb) pipe print some_data_structure | grep -B3 -A3 something
>
> The pipe character is defined as an alias for pipe command, so that
> the above can be typed as:
> (gdb) | print some_data_structure | grep -B3 -A3 something
>
> If no GDB COMMAND is given, then the previous command is relaunched,
> and its output is sent to the given SHELL_COMMAND.
>
> This also defines convenience vars $_shell_exitcode and $_shell_exitsignal
> to record the exit code and exit signal of the last shell command
> launched by GDB e.g. by "shell", "pipe", ...
>
> gdb/ChangeLog
> 2019-05-04 Philippe Waroquiers <philippe.waroquiers@skynet.be>
>
> * cli/cli-cmds.c (pipe_command): New function.
> (_initialize_cli_cmds): Call add_com for pipe_command.
> Define | as an alias for pipe.
> (exit_status_set_internal_vars): New function.
> (shell_escape): Call exit_status_set_internal_vars.
> cli/cli-decode.c (find_command_name_length): Recognize | as
> a single character command.
> ---
> gdb/cli/cli-cmds.c | 105 +++++++++++++++++++++++++++++++++++++++++++
> gdb/cli/cli-decode.c | 4 +-
> 2 files changed, 107 insertions(+), 2 deletions(-)
>
> diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
> index 5f3b973f06..55fb5a9a7f 100644
> --- a/gdb/cli/cli-cmds.c
> +++ b/gdb/cli/cli-cmds.c
> @@ -24,6 +24,7 @@
> #include "completer.h"
> #include "target.h" /* For baud_rate, remote_debug and remote_timeout. */
> #include "common/gdb_wait.h" /* For shell escape implementation. */
> +#include "gdbcmd.h"
> #include "gdb_regex.h" /* Used by apropos_command. */
> #include "gdb_vfork.h"
> #include "linespec.h"
> @@ -41,6 +42,7 @@
> #include "block.h"
>
> #include "ui-out.h"
> +#include "interps.h"
>
> #include "top.h"
> #include "cli/cli-decode.h"
> @@ -695,6 +697,25 @@ echo_command (const char *text, int from_tty)
> gdb_flush (gdb_stdout);
> }
>
> +/* Sets the last launched shell command convenience variables based on
> + EXIT_STATUS. */
> +
> +static void
> +exit_status_set_internal_vars (int exit_status)
> +{
> + struct internalvar *var_code = lookup_internalvar ("_shell_exitcode");
> + static internalvar *var_signal = lookup_internalvar ("_shell_exitsignal");
^^^^^^
Did you really mean static ? At least, did you mean it just for one of them?
> +
> + clear_internalvar (var_code);
> + clear_internalvar (var_signal);
> + if (WIFEXITED (exit_status))
> + set_internalvar_integer (var_code, WEXITSTATUS (exit_status));
> + else if (WIFSIGNALED (exit_status))
> + set_internalvar_integer (var_signal, WTERMSIG (exit_status));
> + else
> + warning (_("unexpected shell command exit_status %d\n"), exit_status);
That "exit_status" in the warning is leaking out the internal variable
name in a user-facing message.
> +}
> +
> static void
> shell_escape (const char *arg, int from_tty)
> {
> @@ -716,6 +737,7 @@ shell_escape (const char *arg, int from_tty)
> /* Make sure to return to the directory GDB thinks it is, in case
> the shell command we just ran changed it. */
> chdir (current_directory);
> + exit_status_set_internal_vars (rc);
> #endif
> #else /* Can fork. */
> int status, pid;
> @@ -743,6 +765,7 @@ shell_escape (const char *arg, int from_tty)
> waitpid (pid, &status, 0);
> else
> error (_("Fork failed"));
> + exit_status_set_internal_vars (status);
> #endif /* Can fork. */
> }
>
> @@ -854,6 +877,75 @@ edit_command (const char *arg, int from_tty)
> xfree (p);
> }
>
> +/* Implementation of the "pipe" command. */
> +
> +static void
> +pipe_command (const char *arg, int from_tty)
> +{
> + const char *command = arg;
> + const char *shell_command = arg;
> + std::string separator ("|");
> +
> + if (arg == NULL)
> + error (_("Missing COMMAND"));
> +
> + shell_command = skip_spaces (shell_command);
This isn't necessary.
> +
> + if (*shell_command == '-' && *(shell_command + 1) == 'd')
> + {
> + shell_command += 2; /* Skip '-d'. */
Use check_for_argument.
> + separator = extract_arg (&shell_command);
> + if (separator.empty ())
> + error (_("Missing separator SEP after -d"));
> + command = shell_command;
> + }
> +
> + shell_command = strstr (shell_command, separator.c_str ());
> +
> + if (shell_command == nullptr)
Let's be consistent with NULL vs nullptr in new code.
> + error (_("Missing separator before SHELL_COMMAND"));
BTW, I suspect the section above would look clearer if it
referred to arg instead of shell_command, and declared
command/shell_command where they're found. Like:
if (check_for_argument (arg, "-d", 2))
{
separator = extract_arg (&arg);
if (separator.empty ())
error (_("Missing separator SEP after -d"));
}
arg = skip_spaces (arg);
const char *command = arg;
const char *shell_command = strstr (arg, separator.c_str ());
if (shell_command == nullptr)
error (_("Missing separator before SHELL_COMMAND"));
> +
> + command = skip_spaces (command);
> + std::string gdb_cmd (command, shell_command - command);
> +
> + if (gdb_cmd.empty ())
> + {
> + repeat_previous ();
> + gdb_cmd = skip_spaces (get_saved_command_line ());
> + if (gdb_cmd.empty ())
> + error (_("No previous command to relaunch"));
> + }
> +
> + shell_command += separator.length (); /* Skip the separator. */
> + shell_command = skip_spaces (shell_command);
> + if (*shell_command == '\0')
> + error (_("Missing SHELL_COMMAND"));
> +
> + FILE *to_shell_command = popen (shell_command, "w");
> +
> + if (to_shell_command == nullptr)
> + error (_("Error launching \"%s\""), shell_command);
> +
> + try
> + {
> + stdio_file pipe_file (to_shell_command);
stdio_file's destructor calls fclose unless you tell it otherwise:
/* Create a ui_file from a previously opened FILE. CLOSE_P
indicates whether the underlying file should be closed when the
stdio_file is destroyed. */
explicit stdio_file (FILE *file, bool close_p = false);
> +
> + execute_command_to_ui_file (&pipe_file, gdb_cmd.c_str (), from_tty);
So here this is calling fclose before leaving the scope. But popen
FILE's should be closed with pclose, only. I don't know why it isn't
causing problems, may be the glibc's fclose does nothing in this case.
We shouldn't rely on that.
> + }
> + catch (const gdb_exception_error &ex)
This should catch all kinds of exceptions, not just errors. E.g.,
Ctrl-C results in gdb_exception_quit, which this doesn't catch.
Write, literally:
catch (...)
to be clear that we want to catch everything.
> + {
> + pclose (to_shell_command);
> + throw;
> + }
> +
> + int exit_status = pclose (to_shell_command);
> +
> + if (exit_status < 0)
> + error (_("shell command \"%s\" errno %s"), shell_command,
> + safe_strerror (errno));
Spurious double space in the error message. Note you say "errno",
but this isn't printing the errno (the error number). I'd
suggest printing in perror_with_name style:
error (_("shell command \"%s\" failed: %s"), shell_command,
safe_strerror (errno));
Thanks,
Pedro Alves
On 5/27/19 6:48 PM, Pedro Alves wrote:
> stdio_file's destructor calls fclose unless you tell it otherwise:
>
> /* Create a ui_file from a previously opened FILE. CLOSE_P
> indicates whether the underlying file should be closed when the
> stdio_file is destroyed. */
> explicit stdio_file (FILE *file, bool close_p = false);
>
>> +
>> + execute_command_to_ui_file (&pipe_file, gdb_cmd.c_str (), from_tty);
> So here this is calling fclose before leaving the scope. But popen
> FILE's should be closed with pclose, only. I don't know why it isn't
> causing problems, may be the glibc's fclose does nothing in this case.
> We shouldn't rely on that.
>
Ahahaha. The argument defaults to false, not true. Silly me.
Thanks,
Pedro Alves
@@ -24,6 +24,7 @@
#include "completer.h"
#include "target.h" /* For baud_rate, remote_debug and remote_timeout. */
#include "common/gdb_wait.h" /* For shell escape implementation. */
+#include "gdbcmd.h"
#include "gdb_regex.h" /* Used by apropos_command. */
#include "gdb_vfork.h"
#include "linespec.h"
@@ -41,6 +42,7 @@
#include "block.h"
#include "ui-out.h"
+#include "interps.h"
#include "top.h"
#include "cli/cli-decode.h"
@@ -695,6 +697,25 @@ echo_command (const char *text, int from_tty)
gdb_flush (gdb_stdout);
}
+/* Sets the last launched shell command convenience variables based on
+ EXIT_STATUS. */
+
+static void
+exit_status_set_internal_vars (int exit_status)
+{
+ struct internalvar *var_code = lookup_internalvar ("_shell_exitcode");
+ static internalvar *var_signal = lookup_internalvar ("_shell_exitsignal");
+
+ clear_internalvar (var_code);
+ clear_internalvar (var_signal);
+ if (WIFEXITED (exit_status))
+ set_internalvar_integer (var_code, WEXITSTATUS (exit_status));
+ else if (WIFSIGNALED (exit_status))
+ set_internalvar_integer (var_signal, WTERMSIG (exit_status));
+ else
+ warning (_("unexpected shell command exit_status %d\n"), exit_status);
+}
+
static void
shell_escape (const char *arg, int from_tty)
{
@@ -716,6 +737,7 @@ shell_escape (const char *arg, int from_tty)
/* Make sure to return to the directory GDB thinks it is, in case
the shell command we just ran changed it. */
chdir (current_directory);
+ exit_status_set_internal_vars (rc);
#endif
#else /* Can fork. */
int status, pid;
@@ -743,6 +765,7 @@ shell_escape (const char *arg, int from_tty)
waitpid (pid, &status, 0);
else
error (_("Fork failed"));
+ exit_status_set_internal_vars (status);
#endif /* Can fork. */
}
@@ -854,6 +877,75 @@ edit_command (const char *arg, int from_tty)
xfree (p);
}
+/* Implementation of the "pipe" command. */
+
+static void
+pipe_command (const char *arg, int from_tty)
+{
+ const char *command = arg;
+ const char *shell_command = arg;
+ std::string separator ("|");
+
+ if (arg == NULL)
+ error (_("Missing COMMAND"));
+
+ shell_command = skip_spaces (shell_command);
+
+ if (*shell_command == '-' && *(shell_command + 1) == 'd')
+ {
+ shell_command += 2; /* Skip '-d'. */
+ separator = extract_arg (&shell_command);
+ if (separator.empty ())
+ error (_("Missing separator SEP after -d"));
+ command = shell_command;
+ }
+
+ shell_command = strstr (shell_command, separator.c_str ());
+
+ if (shell_command == nullptr)
+ error (_("Missing separator before SHELL_COMMAND"));
+
+ command = skip_spaces (command);
+ std::string gdb_cmd (command, shell_command - command);
+
+ if (gdb_cmd.empty ())
+ {
+ repeat_previous ();
+ gdb_cmd = skip_spaces (get_saved_command_line ());
+ if (gdb_cmd.empty ())
+ error (_("No previous command to relaunch"));
+ }
+
+ shell_command += separator.length (); /* Skip the separator. */
+ shell_command = skip_spaces (shell_command);
+ if (*shell_command == '\0')
+ error (_("Missing SHELL_COMMAND"));
+
+ FILE *to_shell_command = popen (shell_command, "w");
+
+ if (to_shell_command == nullptr)
+ error (_("Error launching \"%s\""), shell_command);
+
+ try
+ {
+ stdio_file pipe_file (to_shell_command);
+
+ execute_command_to_ui_file (&pipe_file, gdb_cmd.c_str (), from_tty);
+ }
+ catch (const gdb_exception_error &ex)
+ {
+ pclose (to_shell_command);
+ throw;
+ }
+
+ int exit_status = pclose (to_shell_command);
+
+ if (exit_status < 0)
+ error (_("shell command \"%s\" errno %s"), shell_command,
+ safe_strerror (errno));
+ exit_status_set_internal_vars (exit_status);
+}
+
static void
list_command (const char *arg, int from_tty)
{
@@ -1845,6 +1937,19 @@ Uses EDITOR environment variable contents as editor (or ex as default)."));
c->completer = location_completer;
+ c = add_com ("pipe", class_support, pipe_command, _("\
+Send the output of a gdb command to a shell command.\n\
+Usage: | [COMMAND] | SHELL_COMMAND\n\
+Usage: | -d SEP COMMAND SEP SHELL_COMMAND\n\
+Usage: pipe [COMMAND] | SHELL_COMMAND\n\
+Usage: pipe -d SEP COMMAND SEP SHELL_COMMAND\n\
+Executes COMMAND and sends its output to SHELL_COMMAND.\n\
+If COMMAND contains a | character, the option -d SEP indicates\n\
+to use the string SEP to separate COMMAND from SHELL_COMMAND.\n\
+With no COMMAND, repeat the last executed command\n\
+and send its output to SHELL_COMMAND."));
+ add_com_alias ("|", "pipe", class_support, 0);
+
add_com ("list", class_files, list_command, _("\
List specified function or line.\n\
With no argument, lists ten more lines after or around previous listing.\n\
@@ -1311,9 +1311,9 @@ find_command_name_length (const char *text)
Note that this is larger than the character set allowed when
creating user-defined commands. */
- /* Recognize '!' as a single character command so that, e.g., "!ls"
+ /* Recognize the single character commands so that, e.g., "!ls"
works as expected. */
- if (*p == '!')
+ if (*p == '!' || *p == '|')
return 1;
while (isalnum (*p) || *p == '-' || *p == '_'