Re: [PATCH][gdb/testsuite] Use prototype to call libc functions

[Tom de Vries <tdevries@suse.de>]

On 9/5/22 14:27, Tom de Vries via Gdb-patches wrote:
> Hi,
> 
> On openSUSE Tumbleweed (using glibc 2.36), I run into:
> ...
> (gdb) print /d (int) munmap (4198400, 4096)^M
> Invalid cast.^M
> (gdb) FAIL: gdb.base/break-main-file-remove-fail.exp: cmdline: \
>    get integer valueof "(int) munmap (4198400, 4096)"
> ...
> 
> The problem is that after starting the executable, the symbol has type
> "void (*) (void)":
> ...
> (gdb) p munmap
> $1 = {<text variable, no debug info>} 0x401030 <munmap@plt>
> (gdb) start
>    ...
> (gdb) p munmap
> $2 = {void (void)} 0x7ffff7feb9a0 <__GI_munmap>
> ...
> which causes the "Invalid cast" error.
> 
> Looking at the debug info for glibc for symbol __GI_munmap:
> ...
>   <0><189683>: Abbrev Number: 1 (DW_TAG_compile_unit)
>      <189691>   DW_AT_name        : ../sysdeps/unix/syscall-template.S
>      <189699>   DW_AT_producer    : GNU AS 2.39.0
> <1><1896ae>: Abbrev Number: 2 (DW_TAG_subprogram)
>      <1896af>   DW_AT_name        : __GI___munmap
>      <1896b3>   DW_AT_external    : 1
>      <1896b4>   DW_AT_low_pc      : 0x10cad0
>      <1896bc>   DW_AT_high_pc     : 37
> ...
> that's probably caused by this bit (or similar bits for other munmap aliases).
> 
> This is fixed in gas on trunk by commit 5578fbf672e ("GAS: Add a return type
> tag to DWARF DIEs generated for function symbols").
> 
> Work around this (for say gas 2.39) by explicitly specifying the prototype for
> munmap.
> 
> Likewise for getpid in a couple of other test-cases.
> 
> Tested on x86_64-linux.
> 
> Any comments?
> 

I've pushed this, given that it fixes gdb-rawhide-x86_64 buildbot.

Thanks,
- Tom

> [gdb/testsuite] Use prototype to call libc functions
> 
> ---
>   gdb/testsuite/gdb.base/break-main-file-remove-fail.exp | 4 +++-
>   gdb/testsuite/gdb.base/dprintf-detach.exp              | 2 +-
>   gdb/testsuite/gdb.base/info-os.exp                     | 2 +-
>   gdb/testsuite/gdb.threads/siginfo-threads.exp          | 2 +-
>   4 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/gdb/testsuite/gdb.base/break-main-file-remove-fail.exp b/gdb/testsuite/gdb.base/break-main-file-remove-fail.exp
> index 41c3114aa05..444b1d33ace 100644
> --- a/gdb/testsuite/gdb.base/break-main-file-remove-fail.exp
> +++ b/gdb/testsuite/gdb.base/break-main-file-remove-fail.exp
> @@ -87,7 +87,9 @@ proc test_remove_bp { initial_load } {
>   	# should warn the user about it.
>   	set pagesize [get_integer_valueof "pg_size" 0]
>   	set align_addr [expr $bp_addr - $bp_addr % $pagesize]
> -	set munmap [get_integer_valueof "(int) munmap ($align_addr, $pagesize)" -1]
> +	set munmap_prototype "int (*) (void *, size_t)"
> +	set munmap_expr "(($munmap_prototype) munmap) ($align_addr, $pagesize)"
> +	set munmap [get_integer_valueof $munmap_expr -1]
>   
>   	if {$munmap != 0} {
>   	    unsupported "can't munmap foo's page"
> diff --git a/gdb/testsuite/gdb.base/dprintf-detach.exp b/gdb/testsuite/gdb.base/dprintf-detach.exp
> index 692048f82a3..b6da01a2845 100644
> --- a/gdb/testsuite/gdb.base/dprintf-detach.exp
> +++ b/gdb/testsuite/gdb.base/dprintf-detach.exp
> @@ -52,7 +52,7 @@ proc dprintf_detach_test { breakpoint_always_inserted dprintf_style disconnected
>   	# Get PID of test program.
>   	set inferior_pid -1
>   	set test "get inferior process ID"
> -	gdb_test_multiple "call (int) getpid ()" $test {
> +	gdb_test_multiple "call ((int (*) (void)) getpid) ()" $test {
>   	    -re ".* = ($decimal).*$gdb_prompt $" {
>   		set inferior_pid $expect_out(1,string)
>   		pass $test
> diff --git a/gdb/testsuite/gdb.base/info-os.exp b/gdb/testsuite/gdb.base/info-os.exp
> index 7967e2e43df..d12f8750a9c 100644
> --- a/gdb/testsuite/gdb.base/info-os.exp
> +++ b/gdb/testsuite/gdb.base/info-os.exp
> @@ -39,7 +39,7 @@ if ![runto_main] then {
>   # Get PID of test program.
>   set inferior_pid ""
>   set test "get inferior process ID"
> -gdb_test_multiple "call (int) getpid()" $test {
> +gdb_test_multiple "call ((int (*) (void)) getpid) ()" $test {
>       -re ".* = ($decimal).*$gdb_prompt $" {
>   	set inferior_pid $expect_out(1,string)
>   	pass $test
> diff --git a/gdb/testsuite/gdb.threads/siginfo-threads.exp b/gdb/testsuite/gdb.threads/siginfo-threads.exp
> index f10c7fdcd25..8dd34b753a2 100644
> --- a/gdb/testsuite/gdb.threads/siginfo-threads.exp
> +++ b/gdb/testsuite/gdb.threads/siginfo-threads.exp
> @@ -41,7 +41,7 @@ gdb_breakpoint [gdb_get_line_number "break-at-exit"]
>   
>   set test "get pid"
>   set pid ""
> -gdb_test_multiple "p (int) getpid ()" $test {
> +gdb_test_multiple "p ((int (*) (void))getpid) ()" $test {
>       -re " = (\[0-9\]+)\r\n$gdb_prompt $" {
>   	set pid $expect_out(1,string)
>   	pass $test