Header files with enums instead of defines?

[Garance A Drosihn]

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 at gilead.netel.rpi.edu
Senior Systems Programmer           or  gad at freebsd.org
Rensselaer Polytechnic Institute    or  drosih at rpi.edu