Re: [Qemu-devel] [PATCH 1/2] qemu-error: Introduce get_errno_name()

[Markus Armbruster]

Luiz Capitulino <address@hidden> writes:

> We need to expose errno in QMP, for three reasons:
>
>   1. Some error handling functions print errno codes to the user,
>      while it's debatable whether this is good or not from a user
>      perspective, sometimes it's the best we can do because it's
>      what system calls and libraries return
>
>   2. Some events (eg. BLOCK_IO_ERROR) will be made even more
>      complete with errno information
>
>   3. It's very good for debugging
>
> So, we need a way to expose those codes in QMP. We can't just use
> the codes themselfs because they may vary between systems.
>
> The best solution I can think of is to return the string
> representation of the name. For example, EIO becomes "EIO".
>
> This is what get_errno_name() does.
>
> Signed-off-by: Luiz Capitulino <address@hidden>
> ---
>  qemu-error.c |   85 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  qemu-error.h |    1 +
>  2 files changed, 86 insertions(+), 0 deletions(-)
>
> diff --git a/qemu-error.c b/qemu-error.c
> index 5a35e7c..7035417 100644
> --- a/qemu-error.c
> +++ b/qemu-error.c
> @@ -207,3 +207,88 @@ void error_report(const char *fmt, ...)
>      va_end(ap);
>      error_printf("\n");
>  }
> +
> +/*
> + * Probably only useful for QMP
> + */
> +const char *get_errno_name(int err)
> +{
> +    switch (abs(err)) {
> +    case EPERM:
> +        return "EPERM";
> +    case ENOENT:
> +        return "ENOENT";
[...]
> +    case EDOM:
> +        return "EDOM";
> +    case ERANGE:
> +        return "ERANGE";
> +    case ENOMEDIUM:
> +        return "ENOMEDIUM";
> +    case ENOTSUP:
> +        return "ENOTSUP";
> +    default:
> +        return "unknown";

How did you choose the codes to implement?  POSIX has many more...

> +    }
> +
> +    abort();
> +}
> diff --git a/qemu-error.h b/qemu-error.h
> index a45609f..c5e39b5 100644
> --- a/qemu-error.h
> +++ b/qemu-error.h
> @@ -38,4 +38,5 @@ void error_print_loc(void);
>  void error_set_progname(const char *argv0);
>  void error_report(const char *fmt, ...) __attribute__ ((format(printf, 1, 
> 2)));
>  
> +const char *get_errno_name(int err);
>  #endif