Re: [PATCH] Check return value of bfd_init

[Simon Marchi <simon.marchi@ericsson.com>]

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On 2018-10-25 11:03 a.m., Tom Tromey wrote:
> Alan recently added a way for BFD library users to check whether they
> were in fact loading a compatible version of BFD:
> 
> https://sourceware.org/ml/binutils/2018-10/msg00198.html
> 
> It seemed reasonable to me that gdb should do this check as well, in
> case someone is dynamically linking against BFD.  Tested by rebuilding
> and then starting the resulting gdb.
> 
> gdb/ChangeLog
> 2018-10-25  Tom Tromey  <tom@tromey.com>
> 
> 	* main.c (captured_main_1): Check return value of bfd_init.
> ---
>  gdb/ChangeLog | 4 ++++
>  gdb/main.c    | 3 ++-
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index 61dc039d4fe..a90c2978185 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,7 @@
> +2018-10-25  Tom Tromey  <tom@tromey.com>
> +
> +	* main.c (captured_main_1): Check return value of bfd_init.
> +
>  2018-10-25  Andrew Burgess  <andrew.burgess@embecosm.com>
>  
>  	* python/py-function.c (convert_values_to_python): Return
> diff --git a/gdb/main.c b/gdb/main.c
> index 8709357e924..96def3080eb 100644
> --- a/gdb/main.c
> +++ b/gdb/main.c
> @@ -506,7 +506,8 @@ captured_main_1 (struct captured_main_args *context)
>    textdomain (PACKAGE);
>  #endif
>  
> -  bfd_init ();
> +  if (bfd_init () != BFD_INIT_MAGIC)
> +    error (_("fatal error: libbfd ABI mismatch"));
>    notice_open_fds ();
>  
>    saved_command_line = (char *) xstrdup ("");
> 

It doesn't work to call error that early.  Try to reverse the condition and start
gdb, you'll get:

$ ./gdb
ASAN:SIGSEGV
=================================================================
==12947==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000090 (pc 0x0000013a7a2f bp 0x7ffcbd048510 sp 0x7ffcbd048460 T0)
    #0 0x13a7a2e in gdb_main(captured_main_args*) /home/emaisin/src/binutils-gdb/gdb/main.c:1194
    #1 0xb27098 in main /home/emaisin/src/binutils-gdb/gdb/gdb.c:32
    #2 0x7ff24431482f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
    #3 0xb26ef8 in _start (/home/emaisin/build/binutils-gdb/gdb/gdb+0xb26ef8)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /home/emaisin/src/binutils-gdb/gdb/main.c:1194 gdb_main(captured_main_args*)
==12947==ABORTING


So fprintf to stderr and exit instead?

Simon
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