From 136afab8c7d8a8a91dbf38e79be4f9dc4125d552 Mon Sep 17 00:00:00 2001 From: Philippe Waroquiers Date: Tue, 23 Apr 2019 23:43:24 +0200 Subject: [PATCH] Implement show | set may-call-functions [on|off] Inferior function calls are powerful but might lead to undesired results such as crashes when calling nested functions (frequently used in particular in Ada). This implements a GDB setting to disable calling inferior functions. Note: the idea is that if/when the 'slash command' patch is pushed, that this setting can be changed e.g. by using the shortcut /c. This is version 2 of the patch. It handles all the received comments, mostly replace 'can-call' by 'may-call', and avoid using 'inferior function call' in factor of 'calling function in the program'. 2019-04-26 Philippe Waroquiers gdb/ChangeLog * NEWS: Mention the new set|show may-call-functions. * infcall.c (may_call_functions_p): New variable. (show_may_call_functions_p): New function. (call_function_by_hand_dummy): Throws an error if not may-call-functions. (_initialize_infcall): Call add_setshow_boolean_cmd for may-call-functions. gdb/testsuite/ChangeLog * gdb.base/callexit.exp: Test may-call-functions off. gdb/doc/ChangeLog * gdb.texinfo (Calling): Document the new set|show may-call-functions. --- gdb/ChangeLog | 10 ++++++++++ gdb/NEWS | 12 ++++++++++++ gdb/doc/ChangeLog | 5 +++++ gdb/doc/gdb.texinfo | 22 ++++++++++++++++++++++ gdb/infcall.c | 26 ++++++++++++++++++++++++++ gdb/testsuite/ChangeLog | 4 ++++ gdb/testsuite/gdb.base/callexit.exp | 7 +++++++ 7 files changed, 86 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index e0120e7743f..58aa736d28e 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,13 @@ +2019-04-27 Philippe Waroquiers + + * NEWS: Mention the new set|show may-call-functions. + * infcall.c (may_call_functions_p): New variable. + (show_may_call_functions_p): New function. + (call_function_by_hand_dummy): Throws an error if not + may-call-functions. + (_initialize_infcall): Call add_setshow_boolean_cmd for + may-call-functions. + 2019-04-25 Keith Seitz PR c++/24367 diff --git a/gdb/NEWS b/gdb/NEWS index 5309a8f923b..42b04e952a3 100644 --- a/gdb/NEWS +++ b/gdb/NEWS @@ -27,6 +27,18 @@ 'array_indexes', 'symbols', 'unions', 'deref_refs', 'actual_objects', 'static_members', 'max_elements', 'repeat_threshold', and 'format'. +* New commands + +set may-call-functions [on|off] +show may-call-functions + This controls whether GDB will attempt to call functions in + the program, such as with expressions in the print command. It + defaults to on. Calling functions in the program being debugged + can have undesired side effects. It is now possible to forbid + such function calls. If function calls are forbidden, GDB will throw + an error when a command (such as print expression) calls a function + in the program. + *** Changes in GDB 8.3 * GDB and GDBserver now support access to additional registers on diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog index ba152329d75..3efed670fa2 100644 --- a/gdb/doc/ChangeLog +++ b/gdb/doc/ChangeLog @@ -1,3 +1,8 @@ +2019-04-27 Philippe Waroquiers + + * gdb.texinfo (Calling): Document the new + set|show may-call-functions. + 2019-04-22 Pedro Alves * gdb.texinfo (Reverse Execution): Mention and xref process record diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index 0733e1acfd2..cf8333d86be 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -18693,6 +18693,28 @@ the default C@t{++} exception handler and the inferior terminated. Show the current setting of stack unwinding in the functions called by @value{GDBN}. +@item set may-call-functions +@kindex set may-call-functions +@cindex disabling calling functions in the program +@cindex calling functions in the program, disabling +Set permission to call functions in the program. +This controls whether @value{GDBN} will attempt to call functions in +the program, such as with expressions in the @code{print} command. It +defaults to @code{on}. + +To call a function in the program, @value{GDBN} has to temporarily +modify the state of the inferior. This has potentially undesired side +effects. Also, having @value{GDBN} call nested functions is likely to +be erroneous and may even crash the program being debugged. You can +avoid such hazards by forbidding @value{GDBN} from calling functions +in the program being debugged. If calling functions in the program +is forbidden, GDB will throw an error when a command (such as printing +an expression) starts a function call in the program. + +@item show may-call-functions +@kindex show may-call-functions +Show permission to call functions in the program. + @end table @subsection Calling functions with no debug info diff --git a/gdb/infcall.c b/gdb/infcall.c index af60fdc56b2..f99206c4582 100644 --- a/gdb/infcall.c +++ b/gdb/infcall.c @@ -55,6 +55,17 @@ asynchronous inferior function call implementation, and that in turn means restructuring the code so that it is event driven. */ +static int may_call_functions_p = 1; +static void +show_may_call_functions_p (struct ui_file *file, int from_tty, + struct cmd_list_element *c, + const char *value) +{ + fprintf_filtered (file, + _("Permission to call functions in the program is %s.\n"), + value); +} + /* How you should pass arguments to a function depends on whether it was defined in K&R style or prototype style. If you define a function using the K&R syntax that takes a `float' argument, then @@ -708,6 +719,10 @@ call_function_by_hand_dummy (struct value *function, struct gdb_exception e; char name_buf[RAW_FUNCTION_ADDRESS_SIZE]; + if (!may_call_functions_p) + error (_("Cannot call functions in the program: " + "may-call-functions is off.")); + if (!target_has_execution) noprocess (); @@ -1359,6 +1374,17 @@ When the function is done executing, GDB will silently stop."), void _initialize_infcall (void) { + add_setshow_boolean_cmd ("may-call-functions", no_class, + &may_call_functions_p, _("\ +Set permission to call functions in the program."), _("\ +Show permission to call functions in the program."), _("\ +When this permission is on, GDB may call functions in the program.\n\ +Otherwise, any sort of attempt to call a function in the program\n\ +will result in an error."), + NULL, + show_may_call_functions_p, + &setlist, &showlist); + add_setshow_boolean_cmd ("coerce-float-to-double", class_obscure, &coerce_float_to_double_p, _("\ Set coercion of floats to doubles when calling functions."), _("\ diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index 9b0725a0335..e81409387e1 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2019-04-27 Philippe Waroquiers + + * gdb.base/callexit.exp: Test may-call-functions off. + 2019-04-25 Keith Seitz PR c++/24367 diff --git a/gdb/testsuite/gdb.base/callexit.exp b/gdb/testsuite/gdb.base/callexit.exp index b6d9ae3f875..9a32d3d54a5 100644 --- a/gdb/testsuite/gdb.base/callexit.exp +++ b/gdb/testsuite/gdb.base/callexit.exp @@ -37,6 +37,13 @@ if { ![runto_main] } { return 0 } +# Verify set may-call-functions behaviour. +gdb_test_no_output "set may-call-functions off" +gdb_test "call callexit()" \ + "Cannot call functions in the program: may-call-functions is off." \ + "inferior function call refused in off state" +gdb_test_no_output "set may-call-functions on" + # Call function (causing the program to exit), and see if gdb handles # it properly. gdb_test "call callexit()" \