Re: [Mingw-users] [GDB] fixed problem [WAS:[GDB] v6.0 and program's I/O]

[Manu <ma...@wa...>]

I wrote:

> I've noticed a different behavior between MinGW's GDB 5.2.1
> and GDB 6.0 when running a console program.

Yes indeed:

Manu@TBIRD1000 /c/Dev/Visual-MinGW/Projects/Samples/Console/Hello
$ gdb50201 -q hello
(gdb) show new-console
Creation of new console when creating child process is on.
                                                                               ^^^^^^ GDB5.2.1
(gdb) q

Manu@TBIRD1000 /c/Dev/Visual-MinGW/Projects/Samples/Console/Hello
$ gdb -q hello
(gdb) show new-console
Creation of new console when creating child process is off.
                                                                                 ^^^^^^ GDB 6.0
(gdb) q

Thanks to Al Stevens:
http://sources.redhat.com/ml/gdb-patches/2002-09/msg00445.html

Manu.


> The 5.2.1 creates a console window, the program's output goes to
> that console, which seems correct.
> The 6.0 doesn't show a console, worse, the program's output doesn't
> show up at the right time, but just before the program exits.
>
> 0/ Sample program:
> --------------------
> /********************************************************
> * A simple Hello World.
> *
> * The stdio header declares standard input/output routines like printf.
> * The main() procedure is the program entry point.
> *
> ********************************************************/
> #include <stdio.h>
>
> int main(){
>  /* Writes a string in the DOS box. */
>  printf("Hello world !");
>  return 0; /* Program termination. */
> }
>
>
> 1/ Sample session with gdb 5.2.1:
> ----------------------------------
> Manu@TBIRD1000 /c/Dev/Visual-MinGW/Projects/Samples/Console/Hello
> $ gdb50201 -nw -q -f "C:\Dev\Visual-MinGW\Projects\Samples\Console\Hello\hello.
> exe"
> (gdb) b main.c:11
> Breakpoint 1 at 0x4012fc: file main.c, line 11.
> (gdb) run
> Starting program: C:\Dev\Visual-MinGW\Projects\Samples\Console\Hello\hello.exe
>
> Breakpoint 1, main () at main.c:12
> C:/Dev/Visual-MinGW/Projects/Samples/Console/Hello/main.c:12:349:beg:0x4012fc
>
> (gdb) info terminal
> Inferior's terminal status (currently saved by GDB):
> File descriptor flags = O_RDONLY
> ^^^^^^ GDB has saved a terminal info.
>
> (gdb) s
> ^^^^^^ The "Hello world!" outputs in the console window, which is correct.
>
> C:/Dev/Visual-MinGW/Projects/Samples/Console/Hello/main.c:13:376:beg:0x40130c
> (gdb) s
> C:/Dev/Visual-MinGW/Projects/Samples/Console/Hello/main.c:14:415:beg:0x401311
> (gdb) s
> 0x0040122d in __mingw_CRTStartup ()
> (gdb) s
> Single stepping until exit from function __mingw_CRTStartup,
> which has no line number information.
>
> Program exited normally.
> (gdb) q
>
>
> 2/ Sample session with gdb 6.0:
> ----------------------------------
> Manu@TBIRD1000 /c/Dev/Visual-MinGW/Projects/Samples/Console/Hello
> $ gdb -nw -q -f "C:\Dev\Visual-MinGW\Projects\Samples\Console\Hello\hello.exe"
> (gdb) b main.c:11
> Breakpoint 1 at 0x4012fc: file main.c, line 11.
> (gdb) run
> Starting program: C:\Dev\Visual-MinGW\Projects\Samples\Console\Hello\hello.exe
>
> Breakpoint 1, main () at main.c:12
> C:/Dev/Visual-MinGW/Projects/Samples/Console/Hello/main.c:12:349:beg:0x4012fc
>
> (gdb) info terminal
> This GDB does not control a terminal.
> ^^^^^^ well, well well.
>
> (gdb) s
> ^^^^^^ nothing outputs after the printf() at line 12.
>
> C:/Dev/Visual-MinGW/Projects/Samples/Console/Hello/main.c:13:376:beg:0x40130c
> (gdb) s
> C:/Dev/Visual-MinGW/Projects/Samples/Console/Hello/main.c:14:415:beg:0x401311
> (gdb) s
> 0x0040122d in __mingw_CRTStartup ()
> (gdb) s
> Single stepping until exit from function __mingw_CRTStartup,
> which has no line number information.
>
> Hello world !
> ^^^^^^ Thanks, but a bit too late!!!
>
> Program exited normally.
> (gdb) q
>
>
> The same behavior is observed within MSYS and Visual-MinGW.
> (redirected GDB I/O)
>
> Any information about the way GDB is supposed to process
> programs' I/O is greatly welcome.
> Thanks.
>
> Manu.
>
>
>
>
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