[PATCH v3 3/4] gdb/cli: add '.' as an argument for 'list' command

Bruno Larsen via Gdb-patches
2023-06-21T10:46:59Z

Currently, after the user has used the list command once, there is no
way to ask GDB to print the location where the inferior is stopped.
This commit adds a way to do that using '.' as a new argument for the
'list' command. If the inferior isn't running, the command throws an
error. The test gdb.base/list.exp was updated to test this new argument.

Because this necessitated having the inferior running and the test was
(seemingly unnecessarily) using printf in a non-essential way and it
would make the resulting log harder to read for no benefit, it was
replaced by a differen t statement.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>
---
gdb/NEWS | 4 ++++
gdb/cli/cli-cmds.c | 26 ++++++++++++++++++++--
gdb/doc/gdb.texinfo | 5 +++++
gdb/testsuite/gdb.base/list.exp | 38 +++++++++++++++++++++++++++++++++
gdb/testsuite/gdb.base/list1.c | 2 +-
5 files changed, 72 insertions(+), 3 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 348e73dd15f..d3779c1e953 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -85,6 +85,10 @@
this purpose is the last solitary line printed, if there was one,
else the lines around the main function.

+* The 'list' command now accepts '.' as an argument, which tells GDB to
+ print the location where the inferior is stopped. If the inferior hasn't
+ started yet, the command will error out.
+
* New commands

maintenance print record-instruction [ N ]
diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
index 5973aebfad3..a966142eaea 100644
--- a/gdb/cli/cli-cmds.c
+++ b/gdb/cli/cli-cmds.c
@@ -1232,14 +1232,14 @@ list_command (const char *arg, int from_tty)
const char *p;

/* Pull in the current default source line if necessary. */
- if (arg == NULL || ((arg[0] == '+' || arg[0] == '-') && arg[1] == '\0'))
+ if (arg == NULL || ((arg[0] == '+' || arg[0] == '-' || arg[0] == '.') && arg[1] == '\0'))
{
set_default_source_symtab_and_line ();
symtab_and_line cursal = get_current_source_symtab_and_line ();

/* If this is the first "list" since we've set the current
source line, center the listing around that line. */
- if (get_first_line_listed () == 0)
+ if (get_first_line_listed () == 0 && (arg == nullptr || arg[0] != '.'))
{
list_around_line (arg, cursal);
}
@@ -1293,6 +1293,27 @@ list_command (const char *arg, int from_tty)
print_source_lines (cursal.symtab, range, 0);
}

+ /* "l *" lists the default location again. */
+ else if (arg[0] == '.')
+ {
+ try
+ {
+ /* Find the current line by getting the PC of the currently
+ selected frame, and finding the line associated to it. */
+ frame_info_ptr frame = get_selected_frame (nullptr);
+ CORE_ADDR curr_pc = get_frame_pc (frame);
+ cursal = find_pc_line (curr_pc, 0);
+ }
+ catch (const gdb_exception &e)
+ {
+ /* If there was an exception above, it means the inferior
+ is not running, so reset the current source location to
+ the default. */
+ error (_("Inferior is not running. No current location."));
+ }
+ list_around_line (arg, cursal);
+ }
+
return;
}

@@ -2800,6 +2821,7 @@ and send its output to SHELL_COMMAND."));
= 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\
+\"list .\" lists ten lines arond where the inferior is stopped.\n\
\"list -\" lists the ten lines before a previous ten-line listing.\n\
One argument specifies a line, and ten lines are listed around that line.\n\
Two arguments with comma between specify starting and ending lines to list.\n\
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 55010f69a1c..e4e374d138c 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -9151,8 +9151,13 @@ it prints the lines around the function @code{main}.

@item list -
Print lines just before the lines last printed.
+
+@item list .
+Print the lines surrounding the location that is where the inferior
+is stopped.
@end table

+
@cindex @code{list}, how many lines to display
By default, @value{GDBN} prints ten source lines with any of these forms of
the @code{list} command. You can change this using @code{set listsize}:
diff --git a/gdb/testsuite/gdb.base/list.exp b/gdb/testsuite/gdb.base/list.exp
index 35e099ebaff..f853a9b814d 100644
--- a/gdb/testsuite/gdb.base/list.exp
+++ b/gdb/testsuite/gdb.base/list.exp
@@ -400,6 +400,41 @@ proc test_list_invalid_args {} {
"second use of \"list +INVALID\""
}

+proc test_list_current_location {} {
+ global binfile
+ # If the first "list" command that GDB runs is "list ." GDB may be
+ # unable to recognize that the inferior isn't running, so we should
+ # reload the inferior to test that condition.
+ clean_restart
+ gdb_file_cmd ${binfile}
+
+ # Ensure that we are printing 10 lines
+ if {![set_listsize 10]} {
+ return
+ }
+
+ # First guarantee that GDB correctly identifies that the inferior
+ # isn't running.
+ gdb_test "list ." "Inferior is not running. No current location." \
+ "list . with inferior not running"
+
+ if {![runto_main]} {
+ warning "couldn't start inferior"
+ return
+ }
+
+ # Walk forward some lines
+ gdb_test "until 15" ".*15.*foo.*"
+
+ # Test that the correct location is printed and that
+ # using just "list" will print the following lines.
+ gdb_test "list ." ".*" "list current line after starting"
+ gdb_test "list" ".*" "confirm we are printing the following lines"
+
+ # Test that list . will reset to current location
+ gdb_test "list ." ".*" "list around current line again"
+}
+
clean_restart
gdb_file_cmd ${binfile}

@@ -519,4 +554,7 @@ test_list "list -" 10 2 "7-8" "5-6"
# the current line.
test_list "list -" 10 1 "7" "6"

+# Test printing the location where the inferior is stopped.
+test_list_current_location
+
remote_exec build "rm -f list0.h"
diff --git a/gdb/testsuite/gdb.base/list1.c b/gdb/testsuite/gdb.base/list1.c
index d694495c3fb..9297f958f46 100644
--- a/gdb/testsuite/gdb.base/list1.c
+++ b/gdb/testsuite/gdb.base/list1.c
@@ -7,7 +7,7 @@ void bar (int x)
-
- */
{
- printf ("%d\n", x);
+ x++;

long_line ();
}
--
2.40.1