"--export-png=" assert-fails if given bad argument

[Arthur O'Dwyer]

Inkscape currently uses a very scary-looking "assertion failed" message to report bad command-line arguments. I expect this is considered a low-priority cosmetic feature, but it would still be nice to do some error-checking and give a friendlier message that doesn't begin with a lot of asterisks, a PID, and the word "CRITICAL" in all caps.

% inkscape "--export-png=" myfile.svg
DPI: 300
Background RRGGBBAA: ffffff00
Area 0:0:247.5:337.5 exported to 825 x 1125 pixels (300 dpi)
Bitmap saved as:
** (inkscape:7189): CRITICAL **: bool sp_png_write_rgba_striped(SPDocument*, const gchar*, long unsigned int, long unsigned int, double, double, int (*)(const guchar**, int, int, void*), void*): assertion `fp != NULL' failed

% inkscape -v
** (inkscape:7234): WARNING **: Invalid option -v

% inkscape --version
Inkscape 0.48.2 r9819 (Jul 11 2011)

[su_v (suv-lp)]

Reproduced with Inkscape 0.48.2, 0.48.3.1 and 0.48+devel r11016 on OS X 10.7.2.

[su_v (suv-lp)]

Using '--export-pdf' as bad argument instead of '--export-png' even triggers a real crash:

$ inkscape -V
Inkscape 0.48.2 r9819 (Dec 21 2011)
$ inkscape "--export-pdf=" myfile.svg
inkscape: fopen(): No such file or directoryterminate called throwing an exception
Emergency save activated!
Emergency save completed. Inkscape will close now.
If you can reproduce this crash, please file a bug at www.inkscape.org
with a detailed description of the steps leading to the crash, so we can fix it.
** Message: Error: Inkscape encountered an internal error and will close now.

Abort trap: 6
$
$ inkgcc46 -V
Inkscape 0.48+devel r11016 custom (Feb 25 2012)
$ inkgcc46 "--export-pdf=" myfile.svg
inkscape: fopen(): No such file or directory
terminate called after throwing an instance of 'Inkscape::Extension::Output::save_failed'

Emergency save activated!
Emergency save completed. Inkscape will close now.
If you can reproduce this crash, please file a bug at www.inkscape.org
with a detailed description of the steps leading to the crash, so we can fix it.
** Message: Error: Inkscape encountered an internal error and will close now.

Abort trap: 6
$

[su_v (suv-lp)]

Fixed in trunk rev >= 12972
<http://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/revision/12972>

$ inkscape "--export-png=" myfile.svg

** (inkscape:75276): WARNING **: Can't open file: myfile.svg (doesn't exist)

** (inkscape:75276): WARNING **: Can't open file: myfile.svg (doesn't exist)

** (inkscape:75276): WARNING **: Specified document myfile.svg cannot be opened (does not exist or not a valid SVG file)
$
$ inkscape "--export-png=" myfile.pdf
I/O Error: Couldn't open file 'myfile.pdf': No such file or directory.
** Message: couldn't open the PDF file.

** (inkscape:75277): WARNING **: Can't open file: myfile.pdf (doesn't exist)

** (inkscape:75277): WARNING **: Specified document myfile.pdf cannot be opened (does not exist or not a valid SVG file)
$

See also:
<http://article.gmane.org/gmane.comp.graphics.inkscape.devel/42536>

[Arthur O'Dwyer (arthur-j-odwyer)]

Sorry, but from the above output and looking at the source code touched in r12972, it doesn't *look* like anything relevant was fixed. (Feel free to re-close this bug with an appropriate summary if the bug is actually fixed, but please test it first.)

~suv, notice that in your cut-and-pasted error output, you're not triggering the assertion codepath. The error messages you're getting are because you've given *input* filenames which don't exist. The reported assertion-failure happens when the *output* file cannot be created. Create your input files first, *then* try the supplied command lines.

(BTW, it's also weird that a single missing input file gave you *three* error messages on stderr. Surely there's some UX work to be done in that area.)

[su_v (suv-lp)]

@Arthur - you are correct (my test was bogus, and the issue as reported is not fixed). Sorry for the noise!

[su_v (suv-lp)]

For the sake of completeness, here's the output of the correct test with latest build:

$ inkscape -V
Inkscape 0.48+devel r12980 (Jan 26 2014)
$ ll drawing.svg
-rw-r--r-- 1 su_v staff 1742 Dec 7 11:04 drawing.svg
$ inkscape "--export-png=" drawing.svg
Background RRGGBBAA: ffffff00
Area 0:0:744.094:1052.36 exported to 744 x 1052 pixels (90 dpi)
Bitmap saved as:

** (inkscape:41856): CRITICAL **: bool sp_png_write_rgba_striped(SPDocument*, const gchar*, long unsigned int, long unsigned int, double, double, int (*)(const guchar**, void**, int, int, void*), void*): assertion 'fp != NULL' failed
$

[Martin Owens (doctormo)]

I was super excited to have a serendipitous bug close. Alas, this requires a real fix:

So, please see r12981 where I've protected png, pdf(ps/eps), wmf and emf exports from the command line.

[Arthur O'Dwyer (arthur-j-odwyer)]

Oh my god. You guys. :P

Shall I open a new bug report for the still-broken case of

inkscape --export-pdf=. myfile.svg

or shall I just give up in despair?

Look, the assertion failure is very specific. Inkscape assert-fails if it gets into sp_png_write_rgba_striped() with fp == NULL. If you don't fix that assertion failure, then this bug hasn't been fixed yet.

[Martin Owens (doctormo)]

See r12982. Which catches the actual errors and outputs a warning.

[Arthur O'Dwyer (arthur-j-odwyer)]

Well, that patch at least seems plausible. It probably doesn't deal with ~suv's export-pdf example, but at this point it's close enough for horseshoes and/or government work. I don't mind if you want to call it closed.

[su_v (suv-lp)]

> inkscape --export-pdf=. myfile.svg

Nit-picking:

$ inkscape --export-ps=. drawing.svg
$ inkscape --export-eps=. drawing.svg

r12982 reports failure for 'pdf' even if the user attempted to export to PostScript or EPS

$ inkscape --export-emf=. drawing.svg
$ inkscape --export-wmf=. drawing.svg

Other file formats: emf/wmf export still crashes with '.' as output file name - probably better handled in a separate report. And then there are more formats pending to be added as command line option (e.g. odg - bug #201614).