Re: [PATCH 2/2] gdb: Allow parenthesis to group arguments to user-defined commands

Philippe Waroquiers
2018-08-25T19:32:18Z

Woudn't it be more 'usual' (and maybe simpler) to use a \ for this ?
e.g. like the shell:
ls ab\ cd
ls: cannot access 'ab cd': No such file or directory

Philippe

On Wed, 2018-08-15 at 15:39 +0100, Andrew Burgess wrote:
> When calling a user-defined command then currently, arguments are
> whitespace separated. This means that it is impossible to pass a
> single argument that contains a whitespace.
>
> The exception to the no whitespace rule is strings, a string argument,
> enclosed in double, or single quotes, can contain whitespace.
>
> However, if a user wants to reference, for example, a type name that
> contains a space, as in these examples:
>
> user_command *((unsigned long long *) some_pointer)
>
> user_command {unsigned long long}some_pointer
>
> then this will not work, as the whitespace between 'unsigned' and
> 'long', as well as the whitespace between 'long' and 'long', will mean
> GDB interprets this as many arguments.
>
> The solution proposed in this patch is to allow parenthesis to be used
> to group arguments, so the use could now write:
>
> user_command (*((unsigned long long *) some_pointer))
>
> user_command ({unsigned long long}some_pointer)
>
> And GDB will interpret these as a single argument.
>
> gdb/ChangeLog:
>
> * cli/cli-script.c (user_args::user_args): Allow parenthesis to
> group arguments.
>
> gdb/testsuite/ChangeLog:
>
> * gdb.base/commands.exp (args_with_whitespace): New proc, which is
> added to the list of procs to call.
> * gdb.base/run.c (global_var): Defined global.
>
> gdb/doc/ChangeLog:
>
> * gdb.texinfo (Define): Additional documentation about argument
> syntax.
> ---
> gdb/ChangeLog | 5 ++++
> gdb/cli/cli-script.c | 8 +++++-
> gdb/doc/ChangeLog | 5 ++++
> gdb/doc/gdb.texinfo | 54 +++++++++++++++++++++++++++++++++----
> gdb/testsuite/ChangeLog | 6 +++++
> gdb/testsuite/gdb.base/commands.exp | 36 +++++++++++++++++++++++++
> gdb/testsuite/gdb.base/run.c | 3 +++
> 7 files changed, 111 insertions(+), 6 deletions(-)
>
> diff --git a/gdb/cli/cli-script.c b/gdb/cli/cli-script.c
> index 6f31a400197..fd80ab9fbcf 100644
> --- a/gdb/cli/cli-script.c
> +++ b/gdb/cli/cli-script.c
> @@ -758,6 +758,7 @@ user_args::user_args (const char *command_line)
> int squote = 0;
> int dquote = 0;
> int bsquote = 0;
> + int pdepth = 0;
>
> /* Strip whitespace. */
> while (*p == ' ' || *p == '\t')
> @@ -769,7 +770,8 @@ user_args::user_args (const char *command_line)
> /* Get to the end of this argument. */
> while (*p)
> {
> - if (((*p == ' ' || *p == '\t')) && !squote && !dquote && !bsquote)
> + if (((*p == ' ' || *p == '\t'))
> + && !squote && !dquote && !bsquote && pdepth == 0)
> break;
> else
> {
> @@ -793,6 +795,10 @@ user_args::user_args (const char *command_line)
> squote = 1;
> else if (*p == '"')
> dquote = 1;
> + else if (*p == '(')
> + pdepth++;
> + else if (*p == ')')
> + pdepth--;
> }
> p++;
> }
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 433a2698a92..11cbef97b8f 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -25219,14 +25219,58 @@
>
> @noindent
> This defines the command @code{adder}, which prints the sum of
> -its three arguments. Note the arguments are text substitutions, so they may
> -reference variables, use complex expressions, or even perform inferior
> -functions calls.
> +its three arguments.
> +
> +The arguments to user-defined commands are text substitutions, so they
> +may reference variables, use complex expressions, or even perform
> +inferior functions calls. Each argument is separated with whitespace,
> +so in the previous example three arguments were passed. The following
> +example also passes three arguments, though the arguments are more
> +complex:
> +
> +@smallexample
> +adder 10+1 10+2 10+3
> +@end smallexample
> +
> +@noindent
> +However, if whitespace were added around the @code{+} characters, then
> +9 arguments would be passed, @code{adder} only uses the first 3 of
> +these arguments, and the others would be silently ignored:
> +
> +@smallexample
> +adder 10 + 1 10 + 2 10 + 3
> +@end smallexample
> +
> +@noindent
> +Parenthesis can be uses to group complex expressions that include
> +whitespace into a single argument, so the previous example can be
> +modified to pass just 3 arguments again, like this:
> +
> +@smallexample
> +adder (10 + 1) (10 + 2) (10 + 3)
> +@end smallexample
> +
> +@noindent
> +The parenthesis are passed through as part of the argument, so the
> +previous example causes @value{GDBN} to evaluate:
> +
> +@smallexample
> +print (10 + 1) + (10 + 2) + (10 + 3)
> +@end smallexample
> +
> +@noindent
> +Nested parenthesis are also allowed within an argument, in the
> +following example 3 arguments are still passed:
> +
> +@smallexample
> +adder (10 + 1) (10 + (1 + 1)) (10 + (1 + (1 + 1)))
> +@end smallexample
>
> @cindex argument count in user-defined commands
> @cindex how many arguments (user-defined commands)
> -In addition, @code{$argc} may be used to find out how many arguments have
> -been passed.
> +@noindent
> +Within a user-defined command @code{$argc} may be used to find out how
> +many arguments have been passed.
>
> @smallexample
> define adder
> diff --git a/gdb/testsuite/gdb.base/commands.exp b/gdb/testsuite/gdb.base/commands.exp
> index 7ce33fdefa9..42ffd6fa0af 100644
> --- a/gdb/testsuite/gdb.base/commands.exp
> +++ b/gdb/testsuite/gdb.base/commands.exp
> @@ -1125,6 +1125,41 @@ proc_with_prefix backslash_in_multi_line_command_test {} {
> gdb_test "print 1" "" "run command"
> }
>
> +proc_with_prefix args_with_whitespace {} {
> + gdb_test_multiple "define show_args" "define show_args" {
> + -re "End with" {
> + pass "define show_args"
> + }
> + }
> +
> + # This test should alternate between 0xdeadbeef and 0xfeedface two times.
> + gdb_test \
> + [multi_line_input \
> + {printf "nargs=%d:", $argc} \
> + {set $i = 0} \
> + {while $i < $argc} \
> + {printf " "} \
> + {eval "echo '$arg%d'", $i} \
> + {set $i = $i + 1} \
> + {end} \
> + {printf "\n"} \
> + {end}] \
> + "" \
> + "enter commands"
> +
> + gdb_test "show_args 1 2 3" \
> + "nargs=3: '1' '2' '3'"
> +
> + gdb_test "show_args 1 (1 + 1) (1 + (1 + 1))" \
> + "nargs=3: '1' '\\(1 \\+ 1\\)' '\\(1 \\+ \\(1 \\+ 1\\)\\)'"
> +
> + gdb_test "show_args ({unsigned long long} &global_var)" \
> + "nargs=1: '\\({unsigned long long} &global_var\\)'"
> +
> + gdb_test "show_args (*((unsigned long long *) &global_var))" \
> + "nargs=1: '\\(\\*\\(\\(unsigned long long \\*\\) &global_var\\)\\)'"
> +}
> +
> gdbvar_simple_if_test
> gdbvar_simple_while_test
> gdbvar_complex_if_while_test
> @@ -1154,5 +1189,6 @@ backslash_in_multi_line_command_test
> define_if_without_arg_test
> loop_break_test
> loop_continue_test
> +args_with_whitespace
> # This one should come last, as it redefines "backtrace".
> redefine_backtrace_test
> diff --git a/gdb/testsuite/gdb.base/run.c b/gdb/testsuite/gdb.base/run.c
> index 614b018260d..d89bad78bb4 100644
> --- a/gdb/testsuite/gdb.base/run.c
> +++ b/gdb/testsuite/gdb.base/run.c
> @@ -8,6 +8,9 @@
>
> #include "../lib/unbuffer_output.c"
>
> +/* Used by commands.exp test script. */
> +volatile unsigned long long global_var = 34;
> +
> int factorial (int);
>
> int