Date: Wed, 22 Dec 2004 13:20:03 -0500 From: Garance A Drosihn <drosih@rpi.edu> To: Peter Edwards <peadar.edwards@gmail.com>, "Greg 'groggy' Lehey" <grog@freebsd.org>, FreeBSD Architecture Mailing List <arch@freebsd.org> Subject: Re: Header files with enums instead of defines? Message-ID: <p0620078abdef6999e4ee@[128.113.24.47]> In-Reply-To: <34cb7c8404122205002bd7de18@mail.gmail.com> References: <20041222010143.GS53357@wantadilla.lemis.com> <20041222090855.GO79646@cirb503493.alcatel.com.au> <20041222103844.GI801@straylight.m.ringlet.net> <34cb7c8404122205002bd7de18@mail.gmail.com>
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At 1:00 PM +0000 12/22/04, Peter Edwards wrote:
>As an alternative to Peter Jeremy's suggestion of using a GDB
>macro, you could, of course, define a type as:
>
>typedef enum {
> err_EPERM = EPERM,
> err_ENOENT = ENOENT,
> /* .... */
>} errno_t
>
>Then within gdb:
>
>Breakpoint 1, main (argc=1, argv=0xbfbfe55c) at e.c:21
>21 int rc = write(-1, "X", 1);
>(gdb) n
>22 pause();
>(gdb) p (errno_t)errno
>$1 = err_EBADF
>(gdb)
Ooo, that's a nice trick.
>(Note if you actually try this, you need to define at least one
>object of the errno_t type in your program to generate the type
>in the executable output.)
This note made me think of another possible trick:
(gdb) printf "== '%s'\n", strerror(errno)
== 'No such file or directory'
I recommend the extra baggage in the print statement. Initially I
happened to test this by trying:
(gdb) printf "%s\n", strerror(4)
Interrupted system call
And I kept thinking that *gdb* was telling me the 'printf' call was
getting interrupted. For a few minutes, I thought I had stumbled
across some serious bug!
I expect this only works if your program references strerror(),
but I haven't tried it in other situations.
--
Garance Alistair Drosehn = gad@gilead.netel.rpi.edu
Senior Systems Programmer or gad@freebsd.org
Rensselaer Polytechnic Institute or drosih@rpi.edu
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