[FFmpeg-devel] [PATCH] Make the ffmpeg "Overwrite ? [y/N]" question work with more than one file to overwrite

[Stefano Sabatini]

On date Friday 2009-03-13 18:32:40 -0700, Baptiste Coudurier encoded:
> On 3/13/2009 6:30 PM, Michael Niedermayer wrote:
> > On Sat, Mar 14, 2009 at 01:14:13AM +0100, Stefano Sabatini wrote:
> >> On date Wednesday 2009-03-11 01:42:10 +0100, Michael Niedermayer encoded:
> >>> On Tue, Mar 10, 2009 at 09:36:00PM +0100, Stefano Sabatini wrote:
> >>>> Hi all,
> >>>>
> >>>> I recently stepped into this:
> >>>> stefano at geppetto ~/s/ffmpeg> ffmpeg -i in123.mpeg out0.avi out1.ogg -y -map 0:2 -map 0:1
> >>>> [...]
> >>>> Input #0, mpeg, from 'in123.mpeg':
> >>>>   Duration: 00:03:40.05, start: 0.500000, bitrate: 81 kb/s
> >>>>     Stream #0.0[0x1c0]: Audio: mp2, 48000 Hz, stereo, s16, 64 kb/s
> >>>>     Stream #0.1[0x1c1]: Audio: mp2, 48000 Hz, stereo, s16, 64 kb/s
> >>>>     Stream #0.2[0x1c2]: Audio: mp2, 48000 Hz, stereo, s16, 64 kb/s
> >>>> File 'out0.avi' already exists. Overwrite ? [y/N] y   
> >>>> File 'out1.ogg' already exists. Overwrite ? [y/N]
> >>>> Not overwriting - exiting
> >>>>
> >>>> After the first question is replied, the stdin buffer still contains
> >>>> the '\n' buffered, then ffmpeg read from it with getchar(), get a
> >>>> '\n', which is different from 'Y' and abort immediately.
> >>>>
> >>>> Patch fixes it.
> >>>>
> >>>> Regards.
> >>>> -- 
> >>>> FFmpeg = Fast and Faboulous Most Picky Energized Gorilla
> >>>> Index: ffmpeg.c
> >>>> ===================================================================
> >>>> --- ffmpeg.c	(revision 17926)
> >>>> +++ ffmpeg.c	(working copy)
> >>>> @@ -3362,12 +3362,13 @@
> >>>>               filename[1] == ':' ||
> >>>>               av_strstart(filename, "file:", NULL))) {
> >>>>              if (url_exist(filename)) {
> >>>> -                int c;
> >>>> +                char c, line[256];
> >>>>  
> >>>>                  if (!using_stdin) {
> >>>>                      fprintf(stderr,"File '%s' already exists. Overwrite ? [y/N] ", filename);
> >>>>                      fflush(stderr);
> >>>> -                    c = getchar();
> >>>> +                    fgets(line, sizeof(line), stdin);
> >>>> +                    sscanf(line, "%c", &c);
> >>> what weird mess is this ?
> >>> getchar();getchar()
> >> underkill, what if the user prints more than one character?
> > 
> > if the user enters more than 2 chars to a question asking for one
> > then interpreting this as 'y' is maybe not such a good idea.

This is the behaviour of many programs which reads yes/no repyies from
stdin, in particular I refer to the coreutils.

But we can easily change this, and force the user to provide any
case-insensitive substring of "yes" for example.

> > also, from a user POV, just having to press y and no enter would be nice

That's potentially dangerous, IMO is safer to let the user *explicitely*
press enter to confirm.

> > 
> 
> Weee termcap :>
> Don't forget mingw though.

Anyway if we decide that this is a good idea, we can extend read_yes()
to support that.

Regards.
-- 
FFmpeg = Frightening & Fiendish Mastodontic Pitiful Enigmatic Gymnast
-------------- next part --------------
A non-text attachment was scrubbed...
Name: implement-read-yes.patch
Type: text/x-diff
Size: 853 bytes
Desc: not available
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20090314/ed28a5bc/attachment.patch>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ffmpeg-use-read-yes.patch
Type: text/x-diff
Size: 747 bytes
Desc: not available
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20090314/ed28a5bc/attachment-0001.patch>