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

Philippe Waroquiers
2018-08-25T20:53:30Z

On Sat, 2018-08-25 at 21:32 +0200, Philippe Waroquiers wrote:
> 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
See also the RFA (in 'review needed status')
https://sourceware.org/ml/gdb-patches/2018-07/msg00131.html
where I (inconsistently with my comment above but still consistent with the
shell) have used single quotes for such purposes.

Like for the level versus number, we should aim at a single approach
in gdb for such things ...

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