[FFmpeg-devel] [PATCH] Implement av_strerror()

[Måns Rullgård]

Stefano Sabatini <stefano.sabatini-lala at poste.it> writes:

> On date Sunday 2010-03-14 14:16:17 +0100, Michael Niedermayer encoded:
>> On Sun, Mar 14, 2010 at 01:03:58PM +0100, Stefano Sabatini wrote:
> [...]
>> > +int av_strerror(int errnum, char *errbuf, size_t errbuf_size)
>> > +{
>> > +    int ret = 0;
>> > +
>> > +    switch (errnum) {
>> > +#define HANDLE_ERROR(ERR, ERRSTR) case AVERROR_##ERR: av_strlcpy(errbuf, ERRSTR, errbuf_size); break
>> > +
>> > +#if LIBAVUTIL_VERSION_MAJOR < 51
>> > +    HANDLE_ERROR(IO            , "I/O error");
>> > +    HANDLE_ERROR(NOENT         , "No such file or directory");
>> > +    HANDLE_ERROR(NOMEM         , "Not enough memory");
>> > +#endif
>> > +    HANDLE_ERROR(EOF           , "End of file");
>> > +    HANDLE_ERROR(INVALIDDATA   , "Invalid data found");
>> > +    HANDLE_ERROR(NOFMT         , "Unknown format");
>> > +    HANDLE_ERROR(NOTSUPP       , "Operation not supported");
>> > +    HANDLE_ERROR(NUMEXPECTED   , "Number syntax expected in filename");
>> > +    HANDLE_ERROR(PATCHWELCOME  , "Not yet implemented in FFmpeg, patches welcome");
>> 
>> case X: s= "kjfdkfjhfkjh"; break;
>> ...
>> 
>> av_strlcpy(s)
>
> Updated, I have a small preference for keeping the macro but I'll
> remove that if you don't like it.
>
> Regards.
> -- 
> FFmpeg = Furious and Free Monstrous Peaceless Extended Gigant
>
> From 462a236c4d244f426e35eb3f0dda34ce4356ce32 Mon Sep 17 00:00:00 2001
> From: Stefano Sabatini <stefano.sabatini-lala at poste.it>
> Date: Sun, 14 Mar 2010 01:06:46 +0100
> Subject: [PATCH 7/8] Implement av_strerror().
>
> ---
>  libavutil/Makefile |    1 +
>  libavutil/avutil.h |    2 +-
>  libavutil/error.c  |   55 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  libavutil/error.h  |   11 ++++++++++
>  4 files changed, 68 insertions(+), 1 deletions(-)
>  create mode 100644 libavutil/error.c
>
> [...]
>
> +int av_strerror(int errnum, char *errbuf, size_t errbuf_size)
> +{
> +    int ret = 0;
> +    const char *errstr = NULL;
> +
> +    switch (errnum) {
> +#define HANDLE_ERROR(ERR, ERRSTR) case AVERROR_##ERR: errstr = ERRSTR; break
> +
> +#if LIBAVUTIL_VERSION_MAJOR < 51
> +        HANDLE_ERROR(IO           , "I/O error");
> +        HANDLE_ERROR(NOENT        , "No such file or directory");
> +        HANDLE_ERROR(NOMEM        , "Not enough memory");
> +#endif
> +        HANDLE_ERROR(EOF          , "End of file");
> +        HANDLE_ERROR(INVALIDDATA  , "Invalid data found");
> +        HANDLE_ERROR(NOFMT        , "Unknown format");
> +        HANDLE_ERROR(NOTSUPP      , "Operation not supported");
> +        HANDLE_ERROR(NUMEXPECTED  , "Number syntax expected in filename");
> +        HANDLE_ERROR(PATCHWELCOME , "Not yet implemented in FFmpeg, patches welcome");
> +    }

Please drop the macro.  It only obfuscates.

> +    if (errstr) {
> +        av_strlcatf(errbuf, errbuf_size, errstr);

av_strlcpy()

> +    } else {
> +#if _POSIX_C_SOURCE >= 200112L
> +        ret = strerror_r(AVUNERROR(errnum), errbuf, errbuf_size);
> +#else
> +        av_strlcatf(errbuf, errbuf_size, "Error number %d", errnum);
> +#endif

This is wrong for two reasons:

1.  We define _POSIX_C_SOURCE to 200112.
2.  strerror_r() is optional.

The correct solution is to check_func it in configure.

-- 
M?ns Rullg?rd
mans at mansr.com