[PATCH v3 1/7] Add a new $_inferior convenience variable

Pedro Alves
2016-01-06T13:03:46Z

Like $_thread, but holds the current inferior number.

gdb/ChangeLog:
2016-01-06 Pedro Alves <palves@redhat.com>

* NEWS: Mention $_inferior.
* inferior.c (inferior_id_make_value): New.
(inferior_funcs): New.
(_initialize_inferior): Create $_inferior variable.

gdb/testsuite/ChangeLog:
2016-01-06 Pedro Alves <palves@redhat.com>

* gdb.base/default.exp: Expect $_inferior as well.
* gdb.multi/base.exp: Test $_inferior.

gdb/doc/ChangeLog:
2016-01-06 Pedro Alves <palves@redhat.com>

* gdb.texinfo (Inferiors and Programs): Document the $_inferior
convenience variable.
(Convenience Vars): Likewise.
---
gdb/NEWS | 3 +++
gdb/doc/gdb.texinfo | 10 ++++++++++
gdb/inferior.c | 21 +++++++++++++++++++++
gdb/testsuite/gdb.base/default.exp | 1 +
gdb/testsuite/gdb.multi/base.exp | 4 ++++
5 files changed, 39 insertions(+)

diff --git a/gdb/NEWS b/gdb/NEWS
index 484d98d..31c870d 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,9 @@

*** Changes since GDB 7.10

+* The new convenience variable $_inferior holds the number of the
+ current inferior.
+
* Record btrace now supports non-stop mode.

* Support for tracepoints on aarch64-linux was added in GDBserver.
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 0778383..f01b703 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -2658,6 +2658,12 @@ Make inferior number @var{infno} the current inferior. The argument
in the first field of the @samp{info inferiors} display.
@end table

+@vindex $_inferior@r{, convenience variable}
+The debugger convenience variable @samp{$_inferior} contains the
+number of the current inferior. You may find this useful in writing
+breakpoint conditional expressions, command scripts, and so forth.
+@xref{Convenience Vars,, Convenience Variables}, for general
+information on convenience variables.

You can get multiple executables into a debugging session via the
@code{add-inferior} and @w{@code{clone-inferior}} commands. On some
@@ -10382,6 +10388,10 @@ gdbserver that supports the @code{qGetTIBAddr} request.
@xref{General Query Packets}.
This variable contains the address of the thread information block.

+@item $_inferior
+The number of the current inferior. @xref{Inferiors and
+Programs, ,Debugging Multiple Inferiors and Programs}.
+
@end table

@node Convenience Funs
diff --git a/gdb/inferior.c b/gdb/inferior.c
index e71104d..8f9ac33 100644
--- a/gdb/inferior.c
+++ b/gdb/inferior.c
@@ -1008,6 +1008,26 @@ show_print_inferior_events (struct ui_file *file, int from_tty,
fprintf_filtered (file, _("Printing of inferior events is %s.\n"), value);
}

+/* Return a new value for the selected inferior's id. */
+
+static struct value *
+inferior_id_make_value (struct gdbarch *gdbarch, struct internalvar *var,
+ void *ignore)
+{
+ struct inferior *inf = current_inferior ();
+
+ return value_from_longest (builtin_type (gdbarch)->builtin_int, inf->num);
+}
+
+/* Implementation of `$_inferior' variable. */
+
+static const struct internalvar_funcs inferior_funcs =
+{
+ inferior_id_make_value,
+ NULL,
+ NULL
+};
+
\f

void
@@ -1071,4 +1091,5 @@ Show printing of inferior events (e.g., inferior start and exit)."), NULL,
show_print_inferior_events,
&setprintlist, &showprintlist);

+ create_internalvar_type_lazy ("_inferior", &inferior_funcs, NULL);
}
diff --git a/gdb/testsuite/gdb.base/default.exp b/gdb/testsuite/gdb.base/default.exp
index 90bf27d..fec2cde 100644
--- a/gdb/testsuite/gdb.base/default.exp
+++ b/gdb/testsuite/gdb.base/default.exp
@@ -587,6 +587,7 @@ set show_conv_list \
{$_sdata = void} \
{$_siginfo = void} \
{$_thread = 0} \
+ {$_inferior = 1} \
{$_exception = <error: No frame selected>} \
{$_probe_argc = <error: No frame selected>} \
{$_probe_arg0 = <error: No frame selected>} \
diff --git a/gdb/testsuite/gdb.multi/base.exp b/gdb/testsuite/gdb.multi/base.exp
index 6f0bc63..1aa907d 100644
--- a/gdb/testsuite/gdb.multi/base.exp
+++ b/gdb/testsuite/gdb.multi/base.exp
@@ -44,12 +44,16 @@ if { [build_executable ${testfile}.exp ${exec3} "${srcfile3}" {debug}] == -1 } {

clean_restart ${exec1}

+gdb_test {print $_inferior} " = 1"
+
# Add an empty inferior, switch to it, and load a main executable into
# it.
gdb_test "add-inferior" "Added inferior 2.*" "add empty inferior 2"
gdb_test "inferior 2" "Switching to inferior 2.*" "switch to inferior 2"
gdb_test "file ${binfile2}" ".*" "load ${exec2} file in inferior 2"

+gdb_test {print $_inferior} " = 2" "print \$_inferior after switching"
+
# Add a new inferior and load a main executable into it in one
# command.
gdb_test "add-inferior -exec ${binfile3}" \
--
1.9.3