2003-04-21 Andrew Cagney <cagney@redhat.com>
* infcall.c: New file.
* infcall.h: New file.
* valarith.c: Include "infcall.h".
* scm-lang.c, objc-lang.cm, hppa-tdep.c, gcore.c: Ditto.
* eval.c, ada-valprint.c, ada-lang.c: Ditto.
* Makefile.in (valarith.o, scm-lang.o): Update dependencies.
(objc-lang.o, hppa-tdep.o, gcore.o): Update dependencies.
(eval.o, ada-valprint.o, ada-lang.o): Update dependencies.
(SFILES): Add "infcall.c"
(COMMON_OBS): Add "infcall.o".
(infcall.o): Specify dependencies.
* value.h (call_function_by_hand): Delete declaration.
* inferior.h (run_stack_dummy): Delete declaration.
* infcmd.c (breakpoint_auto_delete_contents): Move to "infcall.c".
(run_stack_dummy): Move to "infcall.c", merged into
call_function_by_hand.
* valops.c (call_function_by_hand): Moved to "infcall.c".
(find_function_addr, value_arg_coerce): Ditto.
(unwindonsignal_p, coerce_float_to_double): Ditto.
(_initialize_valops): Move "set/show coerce-float-to-double", and
"set/show unwindonsignal" commands to "infcall.c".
* v850-tdep.c, target.h: Update comments.
* sparc-tdep.c (sparc_fix_call_dummy): Update comments.
* sh-tdep.c (sh_init_extra_frame_info): Update comments.
(sh64_init_extra_frame_info): Update comments.
* mn10300-tdep.c: Update comments.
* mcore-tdep.c (mcore_init_extra_frame_info): Update comments.
* config/sparc/tm-sparc.h: Update comments.
* breakpoint.h: Update comments.
* avr-tdep.c (avr_init_extra_frame_info): Update comments.
* arm-tdep.c: Update comment.
2003-04-21 18:48:41 +02:00
|
|
|
/* Perform an inferior function call, for GDB, the GNU debugger.
|
|
|
|
|
|
2018-01-01 05:43:02 +01:00
|
|
|
Copyright (C) 2003-2018 Free Software Foundation, Inc.
|
2003-04-21 Andrew Cagney <cagney@redhat.com>
* infcall.c: New file.
* infcall.h: New file.
* valarith.c: Include "infcall.h".
* scm-lang.c, objc-lang.cm, hppa-tdep.c, gcore.c: Ditto.
* eval.c, ada-valprint.c, ada-lang.c: Ditto.
* Makefile.in (valarith.o, scm-lang.o): Update dependencies.
(objc-lang.o, hppa-tdep.o, gcore.o): Update dependencies.
(eval.o, ada-valprint.o, ada-lang.o): Update dependencies.
(SFILES): Add "infcall.c"
(COMMON_OBS): Add "infcall.o".
(infcall.o): Specify dependencies.
* value.h (call_function_by_hand): Delete declaration.
* inferior.h (run_stack_dummy): Delete declaration.
* infcmd.c (breakpoint_auto_delete_contents): Move to "infcall.c".
(run_stack_dummy): Move to "infcall.c", merged into
call_function_by_hand.
* valops.c (call_function_by_hand): Moved to "infcall.c".
(find_function_addr, value_arg_coerce): Ditto.
(unwindonsignal_p, coerce_float_to_double): Ditto.
(_initialize_valops): Move "set/show coerce-float-to-double", and
"set/show unwindonsignal" commands to "infcall.c".
* v850-tdep.c, target.h: Update comments.
* sparc-tdep.c (sparc_fix_call_dummy): Update comments.
* sh-tdep.c (sh_init_extra_frame_info): Update comments.
(sh64_init_extra_frame_info): Update comments.
* mn10300-tdep.c: Update comments.
* mcore-tdep.c (mcore_init_extra_frame_info): Update comments.
* config/sparc/tm-sparc.h: Update comments.
* breakpoint.h: Update comments.
* avr-tdep.c (avr_init_extra_frame_info): Update comments.
* arm-tdep.c: Update comment.
2003-04-21 18:48:41 +02:00
|
|
|
|
|
|
|
|
This file is part of GDB.
|
|
|
|
|
|
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
|
|
|
it under the terms of the GNU General Public License as published by
|
2007-08-23 20:08:50 +02:00
|
|
|
the Free Software Foundation; either version 3 of the License, or
|
2003-04-21 Andrew Cagney <cagney@redhat.com>
* infcall.c: New file.
* infcall.h: New file.
* valarith.c: Include "infcall.h".
* scm-lang.c, objc-lang.cm, hppa-tdep.c, gcore.c: Ditto.
* eval.c, ada-valprint.c, ada-lang.c: Ditto.
* Makefile.in (valarith.o, scm-lang.o): Update dependencies.
(objc-lang.o, hppa-tdep.o, gcore.o): Update dependencies.
(eval.o, ada-valprint.o, ada-lang.o): Update dependencies.
(SFILES): Add "infcall.c"
(COMMON_OBS): Add "infcall.o".
(infcall.o): Specify dependencies.
* value.h (call_function_by_hand): Delete declaration.
* inferior.h (run_stack_dummy): Delete declaration.
* infcmd.c (breakpoint_auto_delete_contents): Move to "infcall.c".
(run_stack_dummy): Move to "infcall.c", merged into
call_function_by_hand.
* valops.c (call_function_by_hand): Moved to "infcall.c".
(find_function_addr, value_arg_coerce): Ditto.
(unwindonsignal_p, coerce_float_to_double): Ditto.
(_initialize_valops): Move "set/show coerce-float-to-double", and
"set/show unwindonsignal" commands to "infcall.c".
* v850-tdep.c, target.h: Update comments.
* sparc-tdep.c (sparc_fix_call_dummy): Update comments.
* sh-tdep.c (sh_init_extra_frame_info): Update comments.
(sh64_init_extra_frame_info): Update comments.
* mn10300-tdep.c: Update comments.
* mcore-tdep.c (mcore_init_extra_frame_info): Update comments.
* config/sparc/tm-sparc.h: Update comments.
* breakpoint.h: Update comments.
* avr-tdep.c (avr_init_extra_frame_info): Update comments.
* arm-tdep.c: Update comment.
2003-04-21 18:48:41 +02:00
|
|
|
(at your option) any later version.
|
|
|
|
|
|
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
|
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
|
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
|
|
|
GNU General Public License for more details.
|
|
|
|
|
|
|
|
|
|
You should have received a copy of the GNU General Public License
|
2007-08-23 20:08:50 +02:00
|
|
|
along with this program. If not, see <http://www.gnu.org/licenses/>. */
|
2003-04-21 Andrew Cagney <cagney@redhat.com>
* infcall.c: New file.
* infcall.h: New file.
* valarith.c: Include "infcall.h".
* scm-lang.c, objc-lang.cm, hppa-tdep.c, gcore.c: Ditto.
* eval.c, ada-valprint.c, ada-lang.c: Ditto.
* Makefile.in (valarith.o, scm-lang.o): Update dependencies.
(objc-lang.o, hppa-tdep.o, gcore.o): Update dependencies.
(eval.o, ada-valprint.o, ada-lang.o): Update dependencies.
(SFILES): Add "infcall.c"
(COMMON_OBS): Add "infcall.o".
(infcall.o): Specify dependencies.
* value.h (call_function_by_hand): Delete declaration.
* inferior.h (run_stack_dummy): Delete declaration.
* infcmd.c (breakpoint_auto_delete_contents): Move to "infcall.c".
(run_stack_dummy): Move to "infcall.c", merged into
call_function_by_hand.
* valops.c (call_function_by_hand): Moved to "infcall.c".
(find_function_addr, value_arg_coerce): Ditto.
(unwindonsignal_p, coerce_float_to_double): Ditto.
(_initialize_valops): Move "set/show coerce-float-to-double", and
"set/show unwindonsignal" commands to "infcall.c".
* v850-tdep.c, target.h: Update comments.
* sparc-tdep.c (sparc_fix_call_dummy): Update comments.
* sh-tdep.c (sh_init_extra_frame_info): Update comments.
(sh64_init_extra_frame_info): Update comments.
* mn10300-tdep.c: Update comments.
* mcore-tdep.c (mcore_init_extra_frame_info): Update comments.
* config/sparc/tm-sparc.h: Update comments.
* breakpoint.h: Update comments.
* avr-tdep.c (avr_init_extra_frame_info): Update comments.
* arm-tdep.c: Update comment.
2003-04-21 18:48:41 +02:00
|
|
|
|
|
|
|
|
#ifndef INFCALL_H
|
|
|
|
|
#define INFCALL_H
|
|
|
|
|
|
2015-05-13 15:55:09 +02:00
|
|
|
#include "dummy-frame.h"
|
|
|
|
|
|
2003-04-21 Andrew Cagney <cagney@redhat.com>
* infcall.c: New file.
* infcall.h: New file.
* valarith.c: Include "infcall.h".
* scm-lang.c, objc-lang.cm, hppa-tdep.c, gcore.c: Ditto.
* eval.c, ada-valprint.c, ada-lang.c: Ditto.
* Makefile.in (valarith.o, scm-lang.o): Update dependencies.
(objc-lang.o, hppa-tdep.o, gcore.o): Update dependencies.
(eval.o, ada-valprint.o, ada-lang.o): Update dependencies.
(SFILES): Add "infcall.c"
(COMMON_OBS): Add "infcall.o".
(infcall.o): Specify dependencies.
* value.h (call_function_by_hand): Delete declaration.
* inferior.h (run_stack_dummy): Delete declaration.
* infcmd.c (breakpoint_auto_delete_contents): Move to "infcall.c".
(run_stack_dummy): Move to "infcall.c", merged into
call_function_by_hand.
* valops.c (call_function_by_hand): Moved to "infcall.c".
(find_function_addr, value_arg_coerce): Ditto.
(unwindonsignal_p, coerce_float_to_double): Ditto.
(_initialize_valops): Move "set/show coerce-float-to-double", and
"set/show unwindonsignal" commands to "infcall.c".
* v850-tdep.c, target.h: Update comments.
* sparc-tdep.c (sparc_fix_call_dummy): Update comments.
* sh-tdep.c (sh_init_extra_frame_info): Update comments.
(sh64_init_extra_frame_info): Update comments.
* mn10300-tdep.c: Update comments.
* mcore-tdep.c (mcore_init_extra_frame_info): Update comments.
* config/sparc/tm-sparc.h: Update comments.
* breakpoint.h: Update comments.
* avr-tdep.c (avr_init_extra_frame_info): Update comments.
* arm-tdep.c: Update comment.
2003-04-21 18:48:41 +02:00
|
|
|
struct value;
|
2003-04-30 03:27:53 +02:00
|
|
|
struct type;
|
|
|
|
|
|
Calling ifunc functions when target has no debug info but resolver has
After the previous patch, on Fedora 27 (glibc 2.26), if you try
calling strlen in the inferior, you now get:
(top-gdb) p strlen ("hello")
'__strlen_avx2' has unknown return type; cast the call to its declared return type
This is correct, because __strlen_avx2 is written in assembly.
We can improve on this though -- if the final ifunc resolved/target
function has no debug info, but the ifunc _resolver_ does have debug
info, we can try extracting the final function's type from the type
that the resolver returns. E.g.,:
typedef size_t (*strlen_t) (const char*);
size_t my_strlen (const char *) { /* some implementation */ }
strlen_t strlen_resolver (unsigned long hwcap) { return my_strlen; }
extern size_t strlen (const char *s);
__typeof (strlen) strlen __attribute__ ((ifunc ("strlen_resolver")));
In the strlen example above, the resolver returns strlen_t, which is a
typedef for pointer to a function that returns size_t. "strlen_t" is
the type of both the user-visible "strlen", and of the the target
function that implements it.
This patch teaches GDB to extract that type.
This is done for actual inferior function calls (in infcall.c), and
for ptype (in eval_call). By the time we get to either of these
places, we've already lost the original symbol/minsym, and only have
values and types to work with. Hence the changes to c-exp.y and
evaluate_var_msym_value, to ensure that we propagate the ifunc
minsymbol's info.
The change to make ifunc symbols have no/unknown return type exposes a
latent problem -- gdb.compile/compile-ifunc.exp calls a no-debug-info
function, but we did not warn about it. The test is fixed by this
commit too.
gdb/ChangeLog:
2018-04-26 Pedro Alves <palves@redhat.com>
* blockframe.c (find_gnu_ifunc_target_type): New function.
(find_function_type): New.
* eval.c (evaluate_var_msym_value): For GNU ifunc types, always
return a value with a memory address.
(eval_call): For calls to GNU ifunc functions, try to find the
type of the target function from the type that the resolver
returns.
* gdbtypes.c (objfile_type): Don't install a return type for ifunc
symbols.
* infcall.c (find_function_return_type): Delete.
(find_function_addr): Add 'function_type' parameter. For calls to
GNU ifunc functions, try to find the type of the target function
from the type that the resolver returns, and return it via
FUNCTION_TYPE.
(call_function_by_hand_dummy): Adjust to use the function type
returned by find_function_addr.
(find_function_addr): Add 'function_type' parameter and move
description here.
* symtab.h (find_function_type, find_gnu_ifunc_target_type): New
declarations.
gdb/testsuite/ChangeLog:
2018-04-26 Pedro Alves <palves@redhat.com>
* gdb.compile/compile-ifunc.exp: Also expect "function has unknown
return type" warnings.
2018-04-26 14:01:26 +02:00
|
|
|
/* Determine a function's address and its return type from its value.
|
|
|
|
|
If the function is a GNU ifunc, then return the address of the
|
|
|
|
|
target function, and set *FUNCTION_TYPE to the target function's
|
|
|
|
|
type, and *RETVAL_TYPE to the target function's return type.
|
|
|
|
|
Calls error() if the function is not valid for calling. */
|
|
|
|
|
|
2003-04-30 03:27:53 +02:00
|
|
|
extern CORE_ADDR find_function_addr (struct value *function,
|
Calling ifunc functions when target has no debug info but resolver has
After the previous patch, on Fedora 27 (glibc 2.26), if you try
calling strlen in the inferior, you now get:
(top-gdb) p strlen ("hello")
'__strlen_avx2' has unknown return type; cast the call to its declared return type
This is correct, because __strlen_avx2 is written in assembly.
We can improve on this though -- if the final ifunc resolved/target
function has no debug info, but the ifunc _resolver_ does have debug
info, we can try extracting the final function's type from the type
that the resolver returns. E.g.,:
typedef size_t (*strlen_t) (const char*);
size_t my_strlen (const char *) { /* some implementation */ }
strlen_t strlen_resolver (unsigned long hwcap) { return my_strlen; }
extern size_t strlen (const char *s);
__typeof (strlen) strlen __attribute__ ((ifunc ("strlen_resolver")));
In the strlen example above, the resolver returns strlen_t, which is a
typedef for pointer to a function that returns size_t. "strlen_t" is
the type of both the user-visible "strlen", and of the the target
function that implements it.
This patch teaches GDB to extract that type.
This is done for actual inferior function calls (in infcall.c), and
for ptype (in eval_call). By the time we get to either of these
places, we've already lost the original symbol/minsym, and only have
values and types to work with. Hence the changes to c-exp.y and
evaluate_var_msym_value, to ensure that we propagate the ifunc
minsymbol's info.
The change to make ifunc symbols have no/unknown return type exposes a
latent problem -- gdb.compile/compile-ifunc.exp calls a no-debug-info
function, but we did not warn about it. The test is fixed by this
commit too.
gdb/ChangeLog:
2018-04-26 Pedro Alves <palves@redhat.com>
* blockframe.c (find_gnu_ifunc_target_type): New function.
(find_function_type): New.
* eval.c (evaluate_var_msym_value): For GNU ifunc types, always
return a value with a memory address.
(eval_call): For calls to GNU ifunc functions, try to find the
type of the target function from the type that the resolver
returns.
* gdbtypes.c (objfile_type): Don't install a return type for ifunc
symbols.
* infcall.c (find_function_return_type): Delete.
(find_function_addr): Add 'function_type' parameter. For calls to
GNU ifunc functions, try to find the type of the target function
from the type that the resolver returns, and return it via
FUNCTION_TYPE.
(call_function_by_hand_dummy): Adjust to use the function type
returned by find_function_addr.
(find_function_addr): Add 'function_type' parameter and move
description here.
* symtab.h (find_function_type, find_gnu_ifunc_target_type): New
declarations.
gdb/testsuite/ChangeLog:
2018-04-26 Pedro Alves <palves@redhat.com>
* gdb.compile/compile-ifunc.exp: Also expect "function has unknown
return type" warnings.
2018-04-26 14:01:26 +02:00
|
|
|
struct type **retval_type,
|
|
|
|
|
struct type **function_type = NULL);
|
2003-04-21 Andrew Cagney <cagney@redhat.com>
* infcall.c: New file.
* infcall.h: New file.
* valarith.c: Include "infcall.h".
* scm-lang.c, objc-lang.cm, hppa-tdep.c, gcore.c: Ditto.
* eval.c, ada-valprint.c, ada-lang.c: Ditto.
* Makefile.in (valarith.o, scm-lang.o): Update dependencies.
(objc-lang.o, hppa-tdep.o, gcore.o): Update dependencies.
(eval.o, ada-valprint.o, ada-lang.o): Update dependencies.
(SFILES): Add "infcall.c"
(COMMON_OBS): Add "infcall.o".
(infcall.o): Specify dependencies.
* value.h (call_function_by_hand): Delete declaration.
* inferior.h (run_stack_dummy): Delete declaration.
* infcmd.c (breakpoint_auto_delete_contents): Move to "infcall.c".
(run_stack_dummy): Move to "infcall.c", merged into
call_function_by_hand.
* valops.c (call_function_by_hand): Moved to "infcall.c".
(find_function_addr, value_arg_coerce): Ditto.
(unwindonsignal_p, coerce_float_to_double): Ditto.
(_initialize_valops): Move "set/show coerce-float-to-double", and
"set/show unwindonsignal" commands to "infcall.c".
* v850-tdep.c, target.h: Update comments.
* sparc-tdep.c (sparc_fix_call_dummy): Update comments.
* sh-tdep.c (sh_init_extra_frame_info): Update comments.
(sh64_init_extra_frame_info): Update comments.
* mn10300-tdep.c: Update comments.
* mcore-tdep.c (mcore_init_extra_frame_info): Update comments.
* config/sparc/tm-sparc.h: Update comments.
* breakpoint.h: Update comments.
* avr-tdep.c (avr_init_extra_frame_info): Update comments.
* arm-tdep.c: Update comment.
2003-04-21 18:48:41 +02:00
|
|
|
|
|
|
|
|
/* Perform a function call in the inferior.
|
|
|
|
|
|
|
|
|
|
ARGS is a vector of values of arguments (NARGS of them). FUNCTION
|
|
|
|
|
is a value, the function to be called. Returns a value
|
|
|
|
|
representing what the function returned. May fail to return, if a
|
|
|
|
|
breakpoint or signal is hit during the execution of the function.
|
|
|
|
|
|
Stop assuming no-debug-info functions return int
The fact that GDB defaults to assuming that functions return int, when
it has no debug info for the function has been a recurring source of
user confusion. Recently this came up on the errno pretty printer
discussions. Shortly after, it came up again on IRC, with someone
wondering why does getenv() in GDB return a negative int:
(gdb) p getenv("PATH")
$1 = -6185
This question (with s/getenv/random-other-C-runtime-function) is a FAQ
on IRC.
The reason for the above is:
(gdb) p getenv
$2 = {<text variable, no debug info>} 0x7ffff7751d80 <getenv>
(gdb) ptype getenv
type = int ()
... which means that GDB truncated the 64-bit pointer that is actually
returned from getent to 32-bit, and then sign-extended it:
(gdb) p /x -6185
$6 = 0xffffe7d7
The workaround is to cast the function to the right type, like:
(gdb) p ((char *(*) (const char *)) getenv) ("PATH")
$3 = 0x7fffffffe7d7 "/usr/local/bin:/"...
IMO, we should do better than this.
I see the "assume-int" issue the same way I see printing bogus values
for optimized-out variables instead of "<optimized out>" -- I'd much
rather that the debugger tells me "I don't know" and tells me how to
fix it than showing me bogus misleading results, making me go around
tilting at windmills.
If GDB prints a signed integer when you're expecting a pointer or
aggregate, you at least have some sense that something is off, but
consider the case of the function actually returning a 64-bit integer.
For example, compile this without debug info:
unsigned long long
function ()
{
return 0x7fffffffffffffff;
}
Currently, with pristine GDB, you get:
(gdb) p function ()
$1 = -1 # incorrect
(gdb) p /x function ()
$2 = 0xffffffff # incorrect
maybe after spending a few hours debugging you suspect something is
wrong with that -1, and do:
(gdb) ptype function
type = int ()
and maybe, just maybe, you realize that the function actually returns
unsigned long long. And you try to fix it with:
(gdb) p /x (unsigned long long) function ()
$3 = 0xffffffffffffffff # incorrect
... which still produces the wrong result, because GDB simply applied
int to unsigned long long conversion. Meaning, it sign-extended the
integer that it extracted from the return of the function, to 64-bits.
and then maybe, after asking around on IRC, you realize you have to
cast the function to a pointer of the right type, and call that. It
won't be easy, but after a few missteps, you'll get to it:
..... (gdb) p /x ((unsigned long long(*) ()) function) ()
$666 = 0x7fffffffffffffff # finally! :-)
So to improve on the user experience, this patch does the following
(interrelated) things:
- makes no-debug-info functions no longer default to "int" as return
type. Instead, they're left with NULL/"<unknown return type>"
return type.
(gdb) ptype getenv
type = <unknown return type> ()
- makes calling a function with unknown return type an error.
(gdb) p getenv ("PATH")
'getenv' has unknown return type; cast the call to its declared return type
- and then to make it easier to call the function, makes it possible
to _only_ cast the return of the function to the right type,
instead of having to cast the function to a function pointer:
(gdb) p (char *) getenv ("PATH") # now Just Works
$3 = 0x7fffffffe7d7 "/usr/local/bin:/"...
(gdb) p ((char *(*) (const char *)) getenv) ("PATH") # continues working
$4 = 0x7fffffffe7d7 "/usr/local/bin:/"...
I.e., it makes GDB default the function's return type to the type
of the cast, and the function's parameters to the type of the
arguments passed down.
After this patch, here's what you'll get for the "unsigned long long"
example above:
(gdb) p function ()
'function' has unknown return type; cast the call to its declared return type
(gdb) p /x (unsigned long long) function ()
$4 = 0x7fffffffffffffff # correct!
Note that while with "print" GDB shows the name of the function that
has the problem:
(gdb) p getenv ("PATH")
'getenv' has unknown return type; cast the call to its declared return type
which can by handy in more complicated expressions, "ptype" does not:
(gdb) ptype getenv ("PATH")
function has unknown return type; cast the call to its declared return type
This will be fixed in the next patch.
gdb/ChangeLog:
2017-09-04 Pedro Alves <palves@redhat.com>
* ada-lang.c (ada_evaluate_subexp) <TYPE_CODE_FUNC>: Don't handle
TYPE_GNU_IFUNC specially here. Throw error if return type is
unknown.
* ada-typeprint.c (print_func_type): Handle functions with unknown
return type.
* c-typeprint.c (c_type_print_base): Handle functions and methods
with unknown return type.
* compile/compile-c-symbols.c (convert_symbol_bmsym)
<mst_text_gnu_ifunc>: Use nodebug_text_gnu_ifunc_symbol.
* compile/compile-c-types.c: Include "objfiles.h".
(convert_func): For functions with unknown return type, warn and
default to int.
* compile/compile-object-run.c (compile_object_run): Adjust call
to call_function_by_hand_dummy.
* elfread.c (elf_gnu_ifunc_resolve_addr): Adjust call to
call_function_by_hand.
* eval.c (evaluate_subexp_standard): Adjust calls to
call_function_by_hand. Handle functions and methods with unknown
return type. Pass expect_type to call_function_by_hand.
* f-typeprint.c (f_type_print_base): Handle functions with unknown
return type.
* gcore.c (call_target_sbrk): Adjust call to
call_function_by_hand.
* gdbtypes.c (objfile_type): Leave nodebug text symbol with NULL
return type instead of int. Make nodebug_text_gnu_ifunc_symbol be
an integer address type instead of nodebug.
* guile/scm-value.c (gdbscm_value_call): Adjust call to
call_function_by_hand.
* infcall.c (error_call_unknown_return_type): New function.
(call_function_by_hand): New "default_return_type" parameter.
Pass it down.
(call_function_by_hand_dummy): New "default_return_type"
parameter. Use it instead of defaulting to int. If there's no
default and the return type is unknown, throw an error. If
there's a default return type, and the called function has no
debug info, then assume the function is prototyped.
* infcall.h (call_function_by_hand, call_function_by_hand_dummy):
New "default_return_type" parameter.
(error_call_unknown_return_type): New declaration.
* linux-fork.c (call_lseek): Cast return type of lseek.
(inferior_call_waitpid, checkpoint_command): Adjust calls to
call_function_by_hand.
* linux-tdep.c (linux_infcall_mmap, linux_infcall_munmap): Adjust
calls to call_function_by_hand.
* m2-typeprint.c (m2_procedure): Handle functions with unknown
return type.
* objc-lang.c (lookup_objc_class, lookup_child_selector)
(value_nsstring, print_object_command): Adjust calls to
call_function_by_hand.
* p-typeprint.c (pascal_type_print_varspec_prefix): Handle
functions with unknown return type.
(pascal_type_print_func_varspec_suffix): New function.
(pascal_type_print_varspec_suffix) <TYPE_CODE_FUNC,
TYPE_CODE_METHOD>: Use it.
* python/py-value.c (valpy_call): Adjust call to
call_function_by_hand.
* rust-lang.c (rust_evaluate_funcall): Adjust call to
call_function_by_hand.
* valarith.c (value_x_binop, value_x_unop): Adjust calls to
call_function_by_hand.
* valops.c (value_allocate_space_in_inferior): Adjust call to
call_function_by_hand.
* typeprint.c (type_print_unknown_return_type): New function.
* typeprint.h (type_print_unknown_return_type): New declaration.
gdb/testsuite/ChangeLog:
2017-09-04 Pedro Alves <palves@redhat.com>
* gdb.base/break-main-file-remove-fail.exp (test_remove_bp): Cast
return type of munmap in infcall.
* gdb.base/break-probes.exp: Cast return type of foo in infcall.
* gdb.base/checkpoint.exp: Simplify using for loop. Cast return
type of ftell in infcall.
* gdb.base/dprintf-detach.exp (dprintf_detach_test): Cast return
type of getpid in infcall.
* gdb.base/infcall-exec.exp: Cast return type of execlp in
infcall.
* gdb.base/info-os.exp: Cast return type of getpid in infcall.
Bail on failure to extract the pid.
* gdb.base/nodebug.c: #include <stdint.h>.
(multf, multf_noproto, mult, mult_noproto, add8, add8_noproto):
New functions.
* gdb.base/nodebug.exp (test_call_promotion): New procedure.
Change expected output of print/whatis/ptype with functions with
no debug info. Test all supported languages. Call
test_call_promotion.
* gdb.compile/compile.exp: Adjust expected output to expect
warning.
* gdb.threads/siginfo-threads.exp: Likewise.
2017-09-04 21:21:13 +02:00
|
|
|
DFEAULT_RETURN_TYPE is used as function return type if the return
|
|
|
|
|
type is unknown. This is used when calling functions with no debug
|
|
|
|
|
info.
|
|
|
|
|
|
2011-01-09 04:08:57 +01:00
|
|
|
ARGS is modified to contain coerced values. */
|
2003-04-21 Andrew Cagney <cagney@redhat.com>
* infcall.c: New file.
* infcall.h: New file.
* valarith.c: Include "infcall.h".
* scm-lang.c, objc-lang.cm, hppa-tdep.c, gcore.c: Ditto.
* eval.c, ada-valprint.c, ada-lang.c: Ditto.
* Makefile.in (valarith.o, scm-lang.o): Update dependencies.
(objc-lang.o, hppa-tdep.o, gcore.o): Update dependencies.
(eval.o, ada-valprint.o, ada-lang.o): Update dependencies.
(SFILES): Add "infcall.c"
(COMMON_OBS): Add "infcall.o".
(infcall.o): Specify dependencies.
* value.h (call_function_by_hand): Delete declaration.
* inferior.h (run_stack_dummy): Delete declaration.
* infcmd.c (breakpoint_auto_delete_contents): Move to "infcall.c".
(run_stack_dummy): Move to "infcall.c", merged into
call_function_by_hand.
* valops.c (call_function_by_hand): Moved to "infcall.c".
(find_function_addr, value_arg_coerce): Ditto.
(unwindonsignal_p, coerce_float_to_double): Ditto.
(_initialize_valops): Move "set/show coerce-float-to-double", and
"set/show unwindonsignal" commands to "infcall.c".
* v850-tdep.c, target.h: Update comments.
* sparc-tdep.c (sparc_fix_call_dummy): Update comments.
* sh-tdep.c (sh_init_extra_frame_info): Update comments.
(sh64_init_extra_frame_info): Update comments.
* mn10300-tdep.c: Update comments.
* mcore-tdep.c (mcore_init_extra_frame_info): Update comments.
* config/sparc/tm-sparc.h: Update comments.
* breakpoint.h: Update comments.
* avr-tdep.c (avr_init_extra_frame_info): Update comments.
* arm-tdep.c: Update comment.
2003-04-21 18:48:41 +02:00
|
|
|
|
Stop assuming no-debug-info functions return int
The fact that GDB defaults to assuming that functions return int, when
it has no debug info for the function has been a recurring source of
user confusion. Recently this came up on the errno pretty printer
discussions. Shortly after, it came up again on IRC, with someone
wondering why does getenv() in GDB return a negative int:
(gdb) p getenv("PATH")
$1 = -6185
This question (with s/getenv/random-other-C-runtime-function) is a FAQ
on IRC.
The reason for the above is:
(gdb) p getenv
$2 = {<text variable, no debug info>} 0x7ffff7751d80 <getenv>
(gdb) ptype getenv
type = int ()
... which means that GDB truncated the 64-bit pointer that is actually
returned from getent to 32-bit, and then sign-extended it:
(gdb) p /x -6185
$6 = 0xffffe7d7
The workaround is to cast the function to the right type, like:
(gdb) p ((char *(*) (const char *)) getenv) ("PATH")
$3 = 0x7fffffffe7d7 "/usr/local/bin:/"...
IMO, we should do better than this.
I see the "assume-int" issue the same way I see printing bogus values
for optimized-out variables instead of "<optimized out>" -- I'd much
rather that the debugger tells me "I don't know" and tells me how to
fix it than showing me bogus misleading results, making me go around
tilting at windmills.
If GDB prints a signed integer when you're expecting a pointer or
aggregate, you at least have some sense that something is off, but
consider the case of the function actually returning a 64-bit integer.
For example, compile this without debug info:
unsigned long long
function ()
{
return 0x7fffffffffffffff;
}
Currently, with pristine GDB, you get:
(gdb) p function ()
$1 = -1 # incorrect
(gdb) p /x function ()
$2 = 0xffffffff # incorrect
maybe after spending a few hours debugging you suspect something is
wrong with that -1, and do:
(gdb) ptype function
type = int ()
and maybe, just maybe, you realize that the function actually returns
unsigned long long. And you try to fix it with:
(gdb) p /x (unsigned long long) function ()
$3 = 0xffffffffffffffff # incorrect
... which still produces the wrong result, because GDB simply applied
int to unsigned long long conversion. Meaning, it sign-extended the
integer that it extracted from the return of the function, to 64-bits.
and then maybe, after asking around on IRC, you realize you have to
cast the function to a pointer of the right type, and call that. It
won't be easy, but after a few missteps, you'll get to it:
..... (gdb) p /x ((unsigned long long(*) ()) function) ()
$666 = 0x7fffffffffffffff # finally! :-)
So to improve on the user experience, this patch does the following
(interrelated) things:
- makes no-debug-info functions no longer default to "int" as return
type. Instead, they're left with NULL/"<unknown return type>"
return type.
(gdb) ptype getenv
type = <unknown return type> ()
- makes calling a function with unknown return type an error.
(gdb) p getenv ("PATH")
'getenv' has unknown return type; cast the call to its declared return type
- and then to make it easier to call the function, makes it possible
to _only_ cast the return of the function to the right type,
instead of having to cast the function to a function pointer:
(gdb) p (char *) getenv ("PATH") # now Just Works
$3 = 0x7fffffffe7d7 "/usr/local/bin:/"...
(gdb) p ((char *(*) (const char *)) getenv) ("PATH") # continues working
$4 = 0x7fffffffe7d7 "/usr/local/bin:/"...
I.e., it makes GDB default the function's return type to the type
of the cast, and the function's parameters to the type of the
arguments passed down.
After this patch, here's what you'll get for the "unsigned long long"
example above:
(gdb) p function ()
'function' has unknown return type; cast the call to its declared return type
(gdb) p /x (unsigned long long) function ()
$4 = 0x7fffffffffffffff # correct!
Note that while with "print" GDB shows the name of the function that
has the problem:
(gdb) p getenv ("PATH")
'getenv' has unknown return type; cast the call to its declared return type
which can by handy in more complicated expressions, "ptype" does not:
(gdb) ptype getenv ("PATH")
function has unknown return type; cast the call to its declared return type
This will be fixed in the next patch.
gdb/ChangeLog:
2017-09-04 Pedro Alves <palves@redhat.com>
* ada-lang.c (ada_evaluate_subexp) <TYPE_CODE_FUNC>: Don't handle
TYPE_GNU_IFUNC specially here. Throw error if return type is
unknown.
* ada-typeprint.c (print_func_type): Handle functions with unknown
return type.
* c-typeprint.c (c_type_print_base): Handle functions and methods
with unknown return type.
* compile/compile-c-symbols.c (convert_symbol_bmsym)
<mst_text_gnu_ifunc>: Use nodebug_text_gnu_ifunc_symbol.
* compile/compile-c-types.c: Include "objfiles.h".
(convert_func): For functions with unknown return type, warn and
default to int.
* compile/compile-object-run.c (compile_object_run): Adjust call
to call_function_by_hand_dummy.
* elfread.c (elf_gnu_ifunc_resolve_addr): Adjust call to
call_function_by_hand.
* eval.c (evaluate_subexp_standard): Adjust calls to
call_function_by_hand. Handle functions and methods with unknown
return type. Pass expect_type to call_function_by_hand.
* f-typeprint.c (f_type_print_base): Handle functions with unknown
return type.
* gcore.c (call_target_sbrk): Adjust call to
call_function_by_hand.
* gdbtypes.c (objfile_type): Leave nodebug text symbol with NULL
return type instead of int. Make nodebug_text_gnu_ifunc_symbol be
an integer address type instead of nodebug.
* guile/scm-value.c (gdbscm_value_call): Adjust call to
call_function_by_hand.
* infcall.c (error_call_unknown_return_type): New function.
(call_function_by_hand): New "default_return_type" parameter.
Pass it down.
(call_function_by_hand_dummy): New "default_return_type"
parameter. Use it instead of defaulting to int. If there's no
default and the return type is unknown, throw an error. If
there's a default return type, and the called function has no
debug info, then assume the function is prototyped.
* infcall.h (call_function_by_hand, call_function_by_hand_dummy):
New "default_return_type" parameter.
(error_call_unknown_return_type): New declaration.
* linux-fork.c (call_lseek): Cast return type of lseek.
(inferior_call_waitpid, checkpoint_command): Adjust calls to
call_function_by_hand.
* linux-tdep.c (linux_infcall_mmap, linux_infcall_munmap): Adjust
calls to call_function_by_hand.
* m2-typeprint.c (m2_procedure): Handle functions with unknown
return type.
* objc-lang.c (lookup_objc_class, lookup_child_selector)
(value_nsstring, print_object_command): Adjust calls to
call_function_by_hand.
* p-typeprint.c (pascal_type_print_varspec_prefix): Handle
functions with unknown return type.
(pascal_type_print_func_varspec_suffix): New function.
(pascal_type_print_varspec_suffix) <TYPE_CODE_FUNC,
TYPE_CODE_METHOD>: Use it.
* python/py-value.c (valpy_call): Adjust call to
call_function_by_hand.
* rust-lang.c (rust_evaluate_funcall): Adjust call to
call_function_by_hand.
* valarith.c (value_x_binop, value_x_unop): Adjust calls to
call_function_by_hand.
* valops.c (value_allocate_space_in_inferior): Adjust call to
call_function_by_hand.
* typeprint.c (type_print_unknown_return_type): New function.
* typeprint.h (type_print_unknown_return_type): New declaration.
gdb/testsuite/ChangeLog:
2017-09-04 Pedro Alves <palves@redhat.com>
* gdb.base/break-main-file-remove-fail.exp (test_remove_bp): Cast
return type of munmap in infcall.
* gdb.base/break-probes.exp: Cast return type of foo in infcall.
* gdb.base/checkpoint.exp: Simplify using for loop. Cast return
type of ftell in infcall.
* gdb.base/dprintf-detach.exp (dprintf_detach_test): Cast return
type of getpid in infcall.
* gdb.base/infcall-exec.exp: Cast return type of execlp in
infcall.
* gdb.base/info-os.exp: Cast return type of getpid in infcall.
Bail on failure to extract the pid.
* gdb.base/nodebug.c: #include <stdint.h>.
(multf, multf_noproto, mult, mult_noproto, add8, add8_noproto):
New functions.
* gdb.base/nodebug.exp (test_call_promotion): New procedure.
Change expected output of print/whatis/ptype with functions with
no debug info. Test all supported languages. Call
test_call_promotion.
* gdb.compile/compile.exp: Adjust expected output to expect
warning.
* gdb.threads/siginfo-threads.exp: Likewise.
2017-09-04 21:21:13 +02:00
|
|
|
extern struct value *call_function_by_hand (struct value *function,
|
|
|
|
|
type *default_return_type,
|
|
|
|
|
int nargs,
|
2003-04-21 Andrew Cagney <cagney@redhat.com>
* infcall.c: New file.
* infcall.h: New file.
* valarith.c: Include "infcall.h".
* scm-lang.c, objc-lang.cm, hppa-tdep.c, gcore.c: Ditto.
* eval.c, ada-valprint.c, ada-lang.c: Ditto.
* Makefile.in (valarith.o, scm-lang.o): Update dependencies.
(objc-lang.o, hppa-tdep.o, gcore.o): Update dependencies.
(eval.o, ada-valprint.o, ada-lang.o): Update dependencies.
(SFILES): Add "infcall.c"
(COMMON_OBS): Add "infcall.o".
(infcall.o): Specify dependencies.
* value.h (call_function_by_hand): Delete declaration.
* inferior.h (run_stack_dummy): Delete declaration.
* infcmd.c (breakpoint_auto_delete_contents): Move to "infcall.c".
(run_stack_dummy): Move to "infcall.c", merged into
call_function_by_hand.
* valops.c (call_function_by_hand): Moved to "infcall.c".
(find_function_addr, value_arg_coerce): Ditto.
(unwindonsignal_p, coerce_float_to_double): Ditto.
(_initialize_valops): Move "set/show coerce-float-to-double", and
"set/show unwindonsignal" commands to "infcall.c".
* v850-tdep.c, target.h: Update comments.
* sparc-tdep.c (sparc_fix_call_dummy): Update comments.
* sh-tdep.c (sh_init_extra_frame_info): Update comments.
(sh64_init_extra_frame_info): Update comments.
* mn10300-tdep.c: Update comments.
* mcore-tdep.c (mcore_init_extra_frame_info): Update comments.
* config/sparc/tm-sparc.h: Update comments.
* breakpoint.h: Update comments.
* avr-tdep.c (avr_init_extra_frame_info): Update comments.
* arm-tdep.c: Update comment.
2003-04-21 18:48:41 +02:00
|
|
|
struct value **args);
|
|
|
|
|
|
2014-05-14 22:16:22 +02:00
|
|
|
/* Similar to call_function_by_hand and additional call
|
|
|
|
|
register_dummy_frame_dtor with DUMMY_DTOR and DUMMY_DTOR_DATA for the
|
|
|
|
|
created inferior call dummy frame. */
|
|
|
|
|
|
|
|
|
|
extern struct value *
|
Stop assuming no-debug-info functions return int
The fact that GDB defaults to assuming that functions return int, when
it has no debug info for the function has been a recurring source of
user confusion. Recently this came up on the errno pretty printer
discussions. Shortly after, it came up again on IRC, with someone
wondering why does getenv() in GDB return a negative int:
(gdb) p getenv("PATH")
$1 = -6185
This question (with s/getenv/random-other-C-runtime-function) is a FAQ
on IRC.
The reason for the above is:
(gdb) p getenv
$2 = {<text variable, no debug info>} 0x7ffff7751d80 <getenv>
(gdb) ptype getenv
type = int ()
... which means that GDB truncated the 64-bit pointer that is actually
returned from getent to 32-bit, and then sign-extended it:
(gdb) p /x -6185
$6 = 0xffffe7d7
The workaround is to cast the function to the right type, like:
(gdb) p ((char *(*) (const char *)) getenv) ("PATH")
$3 = 0x7fffffffe7d7 "/usr/local/bin:/"...
IMO, we should do better than this.
I see the "assume-int" issue the same way I see printing bogus values
for optimized-out variables instead of "<optimized out>" -- I'd much
rather that the debugger tells me "I don't know" and tells me how to
fix it than showing me bogus misleading results, making me go around
tilting at windmills.
If GDB prints a signed integer when you're expecting a pointer or
aggregate, you at least have some sense that something is off, but
consider the case of the function actually returning a 64-bit integer.
For example, compile this without debug info:
unsigned long long
function ()
{
return 0x7fffffffffffffff;
}
Currently, with pristine GDB, you get:
(gdb) p function ()
$1 = -1 # incorrect
(gdb) p /x function ()
$2 = 0xffffffff # incorrect
maybe after spending a few hours debugging you suspect something is
wrong with that -1, and do:
(gdb) ptype function
type = int ()
and maybe, just maybe, you realize that the function actually returns
unsigned long long. And you try to fix it with:
(gdb) p /x (unsigned long long) function ()
$3 = 0xffffffffffffffff # incorrect
... which still produces the wrong result, because GDB simply applied
int to unsigned long long conversion. Meaning, it sign-extended the
integer that it extracted from the return of the function, to 64-bits.
and then maybe, after asking around on IRC, you realize you have to
cast the function to a pointer of the right type, and call that. It
won't be easy, but after a few missteps, you'll get to it:
..... (gdb) p /x ((unsigned long long(*) ()) function) ()
$666 = 0x7fffffffffffffff # finally! :-)
So to improve on the user experience, this patch does the following
(interrelated) things:
- makes no-debug-info functions no longer default to "int" as return
type. Instead, they're left with NULL/"<unknown return type>"
return type.
(gdb) ptype getenv
type = <unknown return type> ()
- makes calling a function with unknown return type an error.
(gdb) p getenv ("PATH")
'getenv' has unknown return type; cast the call to its declared return type
- and then to make it easier to call the function, makes it possible
to _only_ cast the return of the function to the right type,
instead of having to cast the function to a function pointer:
(gdb) p (char *) getenv ("PATH") # now Just Works
$3 = 0x7fffffffe7d7 "/usr/local/bin:/"...
(gdb) p ((char *(*) (const char *)) getenv) ("PATH") # continues working
$4 = 0x7fffffffe7d7 "/usr/local/bin:/"...
I.e., it makes GDB default the function's return type to the type
of the cast, and the function's parameters to the type of the
arguments passed down.
After this patch, here's what you'll get for the "unsigned long long"
example above:
(gdb) p function ()
'function' has unknown return type; cast the call to its declared return type
(gdb) p /x (unsigned long long) function ()
$4 = 0x7fffffffffffffff # correct!
Note that while with "print" GDB shows the name of the function that
has the problem:
(gdb) p getenv ("PATH")
'getenv' has unknown return type; cast the call to its declared return type
which can by handy in more complicated expressions, "ptype" does not:
(gdb) ptype getenv ("PATH")
function has unknown return type; cast the call to its declared return type
This will be fixed in the next patch.
gdb/ChangeLog:
2017-09-04 Pedro Alves <palves@redhat.com>
* ada-lang.c (ada_evaluate_subexp) <TYPE_CODE_FUNC>: Don't handle
TYPE_GNU_IFUNC specially here. Throw error if return type is
unknown.
* ada-typeprint.c (print_func_type): Handle functions with unknown
return type.
* c-typeprint.c (c_type_print_base): Handle functions and methods
with unknown return type.
* compile/compile-c-symbols.c (convert_symbol_bmsym)
<mst_text_gnu_ifunc>: Use nodebug_text_gnu_ifunc_symbol.
* compile/compile-c-types.c: Include "objfiles.h".
(convert_func): For functions with unknown return type, warn and
default to int.
* compile/compile-object-run.c (compile_object_run): Adjust call
to call_function_by_hand_dummy.
* elfread.c (elf_gnu_ifunc_resolve_addr): Adjust call to
call_function_by_hand.
* eval.c (evaluate_subexp_standard): Adjust calls to
call_function_by_hand. Handle functions and methods with unknown
return type. Pass expect_type to call_function_by_hand.
* f-typeprint.c (f_type_print_base): Handle functions with unknown
return type.
* gcore.c (call_target_sbrk): Adjust call to
call_function_by_hand.
* gdbtypes.c (objfile_type): Leave nodebug text symbol with NULL
return type instead of int. Make nodebug_text_gnu_ifunc_symbol be
an integer address type instead of nodebug.
* guile/scm-value.c (gdbscm_value_call): Adjust call to
call_function_by_hand.
* infcall.c (error_call_unknown_return_type): New function.
(call_function_by_hand): New "default_return_type" parameter.
Pass it down.
(call_function_by_hand_dummy): New "default_return_type"
parameter. Use it instead of defaulting to int. If there's no
default and the return type is unknown, throw an error. If
there's a default return type, and the called function has no
debug info, then assume the function is prototyped.
* infcall.h (call_function_by_hand, call_function_by_hand_dummy):
New "default_return_type" parameter.
(error_call_unknown_return_type): New declaration.
* linux-fork.c (call_lseek): Cast return type of lseek.
(inferior_call_waitpid, checkpoint_command): Adjust calls to
call_function_by_hand.
* linux-tdep.c (linux_infcall_mmap, linux_infcall_munmap): Adjust
calls to call_function_by_hand.
* m2-typeprint.c (m2_procedure): Handle functions with unknown
return type.
* objc-lang.c (lookup_objc_class, lookup_child_selector)
(value_nsstring, print_object_command): Adjust calls to
call_function_by_hand.
* p-typeprint.c (pascal_type_print_varspec_prefix): Handle
functions with unknown return type.
(pascal_type_print_func_varspec_suffix): New function.
(pascal_type_print_varspec_suffix) <TYPE_CODE_FUNC,
TYPE_CODE_METHOD>: Use it.
* python/py-value.c (valpy_call): Adjust call to
call_function_by_hand.
* rust-lang.c (rust_evaluate_funcall): Adjust call to
call_function_by_hand.
* valarith.c (value_x_binop, value_x_unop): Adjust calls to
call_function_by_hand.
* valops.c (value_allocate_space_in_inferior): Adjust call to
call_function_by_hand.
* typeprint.c (type_print_unknown_return_type): New function.
* typeprint.h (type_print_unknown_return_type): New declaration.
gdb/testsuite/ChangeLog:
2017-09-04 Pedro Alves <palves@redhat.com>
* gdb.base/break-main-file-remove-fail.exp (test_remove_bp): Cast
return type of munmap in infcall.
* gdb.base/break-probes.exp: Cast return type of foo in infcall.
* gdb.base/checkpoint.exp: Simplify using for loop. Cast return
type of ftell in infcall.
* gdb.base/dprintf-detach.exp (dprintf_detach_test): Cast return
type of getpid in infcall.
* gdb.base/infcall-exec.exp: Cast return type of execlp in
infcall.
* gdb.base/info-os.exp: Cast return type of getpid in infcall.
Bail on failure to extract the pid.
* gdb.base/nodebug.c: #include <stdint.h>.
(multf, multf_noproto, mult, mult_noproto, add8, add8_noproto):
New functions.
* gdb.base/nodebug.exp (test_call_promotion): New procedure.
Change expected output of print/whatis/ptype with functions with
no debug info. Test all supported languages. Call
test_call_promotion.
* gdb.compile/compile.exp: Adjust expected output to expect
warning.
* gdb.threads/siginfo-threads.exp: Likewise.
2017-09-04 21:21:13 +02:00
|
|
|
call_function_by_hand_dummy (struct value *function,
|
|
|
|
|
type *default_return_type,
|
|
|
|
|
int nargs,
|
2014-05-14 22:16:22 +02:00
|
|
|
struct value **args,
|
2015-05-13 15:55:09 +02:00
|
|
|
dummy_frame_dtor_ftype *dummy_dtor,
|
2014-05-14 22:16:22 +02:00
|
|
|
void *dummy_dtor_data);
|
|
|
|
|
|
Stop assuming no-debug-info functions return int
The fact that GDB defaults to assuming that functions return int, when
it has no debug info for the function has been a recurring source of
user confusion. Recently this came up on the errno pretty printer
discussions. Shortly after, it came up again on IRC, with someone
wondering why does getenv() in GDB return a negative int:
(gdb) p getenv("PATH")
$1 = -6185
This question (with s/getenv/random-other-C-runtime-function) is a FAQ
on IRC.
The reason for the above is:
(gdb) p getenv
$2 = {<text variable, no debug info>} 0x7ffff7751d80 <getenv>
(gdb) ptype getenv
type = int ()
... which means that GDB truncated the 64-bit pointer that is actually
returned from getent to 32-bit, and then sign-extended it:
(gdb) p /x -6185
$6 = 0xffffe7d7
The workaround is to cast the function to the right type, like:
(gdb) p ((char *(*) (const char *)) getenv) ("PATH")
$3 = 0x7fffffffe7d7 "/usr/local/bin:/"...
IMO, we should do better than this.
I see the "assume-int" issue the same way I see printing bogus values
for optimized-out variables instead of "<optimized out>" -- I'd much
rather that the debugger tells me "I don't know" and tells me how to
fix it than showing me bogus misleading results, making me go around
tilting at windmills.
If GDB prints a signed integer when you're expecting a pointer or
aggregate, you at least have some sense that something is off, but
consider the case of the function actually returning a 64-bit integer.
For example, compile this without debug info:
unsigned long long
function ()
{
return 0x7fffffffffffffff;
}
Currently, with pristine GDB, you get:
(gdb) p function ()
$1 = -1 # incorrect
(gdb) p /x function ()
$2 = 0xffffffff # incorrect
maybe after spending a few hours debugging you suspect something is
wrong with that -1, and do:
(gdb) ptype function
type = int ()
and maybe, just maybe, you realize that the function actually returns
unsigned long long. And you try to fix it with:
(gdb) p /x (unsigned long long) function ()
$3 = 0xffffffffffffffff # incorrect
... which still produces the wrong result, because GDB simply applied
int to unsigned long long conversion. Meaning, it sign-extended the
integer that it extracted from the return of the function, to 64-bits.
and then maybe, after asking around on IRC, you realize you have to
cast the function to a pointer of the right type, and call that. It
won't be easy, but after a few missteps, you'll get to it:
..... (gdb) p /x ((unsigned long long(*) ()) function) ()
$666 = 0x7fffffffffffffff # finally! :-)
So to improve on the user experience, this patch does the following
(interrelated) things:
- makes no-debug-info functions no longer default to "int" as return
type. Instead, they're left with NULL/"<unknown return type>"
return type.
(gdb) ptype getenv
type = <unknown return type> ()
- makes calling a function with unknown return type an error.
(gdb) p getenv ("PATH")
'getenv' has unknown return type; cast the call to its declared return type
- and then to make it easier to call the function, makes it possible
to _only_ cast the return of the function to the right type,
instead of having to cast the function to a function pointer:
(gdb) p (char *) getenv ("PATH") # now Just Works
$3 = 0x7fffffffe7d7 "/usr/local/bin:/"...
(gdb) p ((char *(*) (const char *)) getenv) ("PATH") # continues working
$4 = 0x7fffffffe7d7 "/usr/local/bin:/"...
I.e., it makes GDB default the function's return type to the type
of the cast, and the function's parameters to the type of the
arguments passed down.
After this patch, here's what you'll get for the "unsigned long long"
example above:
(gdb) p function ()
'function' has unknown return type; cast the call to its declared return type
(gdb) p /x (unsigned long long) function ()
$4 = 0x7fffffffffffffff # correct!
Note that while with "print" GDB shows the name of the function that
has the problem:
(gdb) p getenv ("PATH")
'getenv' has unknown return type; cast the call to its declared return type
which can by handy in more complicated expressions, "ptype" does not:
(gdb) ptype getenv ("PATH")
function has unknown return type; cast the call to its declared return type
This will be fixed in the next patch.
gdb/ChangeLog:
2017-09-04 Pedro Alves <palves@redhat.com>
* ada-lang.c (ada_evaluate_subexp) <TYPE_CODE_FUNC>: Don't handle
TYPE_GNU_IFUNC specially here. Throw error if return type is
unknown.
* ada-typeprint.c (print_func_type): Handle functions with unknown
return type.
* c-typeprint.c (c_type_print_base): Handle functions and methods
with unknown return type.
* compile/compile-c-symbols.c (convert_symbol_bmsym)
<mst_text_gnu_ifunc>: Use nodebug_text_gnu_ifunc_symbol.
* compile/compile-c-types.c: Include "objfiles.h".
(convert_func): For functions with unknown return type, warn and
default to int.
* compile/compile-object-run.c (compile_object_run): Adjust call
to call_function_by_hand_dummy.
* elfread.c (elf_gnu_ifunc_resolve_addr): Adjust call to
call_function_by_hand.
* eval.c (evaluate_subexp_standard): Adjust calls to
call_function_by_hand. Handle functions and methods with unknown
return type. Pass expect_type to call_function_by_hand.
* f-typeprint.c (f_type_print_base): Handle functions with unknown
return type.
* gcore.c (call_target_sbrk): Adjust call to
call_function_by_hand.
* gdbtypes.c (objfile_type): Leave nodebug text symbol with NULL
return type instead of int. Make nodebug_text_gnu_ifunc_symbol be
an integer address type instead of nodebug.
* guile/scm-value.c (gdbscm_value_call): Adjust call to
call_function_by_hand.
* infcall.c (error_call_unknown_return_type): New function.
(call_function_by_hand): New "default_return_type" parameter.
Pass it down.
(call_function_by_hand_dummy): New "default_return_type"
parameter. Use it instead of defaulting to int. If there's no
default and the return type is unknown, throw an error. If
there's a default return type, and the called function has no
debug info, then assume the function is prototyped.
* infcall.h (call_function_by_hand, call_function_by_hand_dummy):
New "default_return_type" parameter.
(error_call_unknown_return_type): New declaration.
* linux-fork.c (call_lseek): Cast return type of lseek.
(inferior_call_waitpid, checkpoint_command): Adjust calls to
call_function_by_hand.
* linux-tdep.c (linux_infcall_mmap, linux_infcall_munmap): Adjust
calls to call_function_by_hand.
* m2-typeprint.c (m2_procedure): Handle functions with unknown
return type.
* objc-lang.c (lookup_objc_class, lookup_child_selector)
(value_nsstring, print_object_command): Adjust calls to
call_function_by_hand.
* p-typeprint.c (pascal_type_print_varspec_prefix): Handle
functions with unknown return type.
(pascal_type_print_func_varspec_suffix): New function.
(pascal_type_print_varspec_suffix) <TYPE_CODE_FUNC,
TYPE_CODE_METHOD>: Use it.
* python/py-value.c (valpy_call): Adjust call to
call_function_by_hand.
* rust-lang.c (rust_evaluate_funcall): Adjust call to
call_function_by_hand.
* valarith.c (value_x_binop, value_x_unop): Adjust calls to
call_function_by_hand.
* valops.c (value_allocate_space_in_inferior): Adjust call to
call_function_by_hand.
* typeprint.c (type_print_unknown_return_type): New function.
* typeprint.h (type_print_unknown_return_type): New declaration.
gdb/testsuite/ChangeLog:
2017-09-04 Pedro Alves <palves@redhat.com>
* gdb.base/break-main-file-remove-fail.exp (test_remove_bp): Cast
return type of munmap in infcall.
* gdb.base/break-probes.exp: Cast return type of foo in infcall.
* gdb.base/checkpoint.exp: Simplify using for loop. Cast return
type of ftell in infcall.
* gdb.base/dprintf-detach.exp (dprintf_detach_test): Cast return
type of getpid in infcall.
* gdb.base/infcall-exec.exp: Cast return type of execlp in
infcall.
* gdb.base/info-os.exp: Cast return type of getpid in infcall.
Bail on failure to extract the pid.
* gdb.base/nodebug.c: #include <stdint.h>.
(multf, multf_noproto, mult, mult_noproto, add8, add8_noproto):
New functions.
* gdb.base/nodebug.exp (test_call_promotion): New procedure.
Change expected output of print/whatis/ptype with functions with
no debug info. Test all supported languages. Call
test_call_promotion.
* gdb.compile/compile.exp: Adjust expected output to expect
warning.
* gdb.threads/siginfo-threads.exp: Likewise.
2017-09-04 21:21:13 +02:00
|
|
|
/* Throw an error indicating that the user tried to call a function
|
|
|
|
|
that has unknown return type. FUNC_NAME is the name of the
|
|
|
|
|
function to be included in the error message; may be NULL, in which
|
|
|
|
|
case the error message doesn't include a function name. */
|
|
|
|
|
|
|
|
|
|
extern void error_call_unknown_return_type (const char *func_name);
|
|
|
|
|
|
2003-04-21 Andrew Cagney <cagney@redhat.com>
* infcall.c: New file.
* infcall.h: New file.
* valarith.c: Include "infcall.h".
* scm-lang.c, objc-lang.cm, hppa-tdep.c, gcore.c: Ditto.
* eval.c, ada-valprint.c, ada-lang.c: Ditto.
* Makefile.in (valarith.o, scm-lang.o): Update dependencies.
(objc-lang.o, hppa-tdep.o, gcore.o): Update dependencies.
(eval.o, ada-valprint.o, ada-lang.o): Update dependencies.
(SFILES): Add "infcall.c"
(COMMON_OBS): Add "infcall.o".
(infcall.o): Specify dependencies.
* value.h (call_function_by_hand): Delete declaration.
* inferior.h (run_stack_dummy): Delete declaration.
* infcmd.c (breakpoint_auto_delete_contents): Move to "infcall.c".
(run_stack_dummy): Move to "infcall.c", merged into
call_function_by_hand.
* valops.c (call_function_by_hand): Moved to "infcall.c".
(find_function_addr, value_arg_coerce): Ditto.
(unwindonsignal_p, coerce_float_to_double): Ditto.
(_initialize_valops): Move "set/show coerce-float-to-double", and
"set/show unwindonsignal" commands to "infcall.c".
* v850-tdep.c, target.h: Update comments.
* sparc-tdep.c (sparc_fix_call_dummy): Update comments.
* sh-tdep.c (sh_init_extra_frame_info): Update comments.
(sh64_init_extra_frame_info): Update comments.
* mn10300-tdep.c: Update comments.
* mcore-tdep.c (mcore_init_extra_frame_info): Update comments.
* config/sparc/tm-sparc.h: Update comments.
* breakpoint.h: Update comments.
* avr-tdep.c (avr_init_extra_frame_info): Update comments.
* arm-tdep.c: Update comment.
2003-04-21 18:48:41 +02:00
|
|
|
#endif
|