[Bug-gnulib] Re: requirements of 'error' module

[Simon Josefsson]

Bruno Haible <address@hidden> writes:

> Simon Josefsson wrote:
>> error: assumes the application add a symbol 'program_name'.  This is
>> difficult to do properly if my application is a library with its own
>> namespace.
>
> How should an error message from the library look like to the end user?
>
>     "libgsasl: invalid signature"
> or
>     "mutt: invalid signature"
> ?

For libgsasl, I don't want it to ever output anything on
stdout/stderr.  The error module was added because Nettle (the
low-level crypto library) used alloca, and I copied alloca from
gnulib.  I don't want to support my own alloca.c, so I rewrote Nettle
to use a fixed size buffer instead and call assert if it is too small
(it already use assert for similar errors, and only two functions was
involved, so I deemed it acceptable).

Here's what I proposed in an earlier message:

#if __GNUC__
  #define program_name program_invocation_name
#else
  char *program_name = "unknown";
#endif
#define SET_PROGRAM_NAME(name) program_name = strdup (name)

I think this should be appended with:

#define SET_PROGRAM_NAME_IF_UNSET(name) if (strcmp (program_name, "unknown") == 
0) program_name = strdup (name)

Then libraries can call

SET_PROGRAM_NAME_IF_UNSET("libgsasl")

to make error message look nicer, but applications that also use the
error package can call SET_PROGRAM_NAME("mutt") to override it.

What do you think?