.bak files after compressing images

Rand Brittain · 12-21-2015, 05:13 PM

Is the bug that got fixed in the most previous release the one that left tiny .bak files in books that got compressed?

If so, were the .bak files replacing images? I got the impression that they were just there alongside images since I didn't notice missing stuff. If they were replacing images in the book I probably need to check through my library more carefully.

JSWolf · 12-21-2015, 05:50 PM

I too found I got .bak files left behind in the ePub. This is a bug. I hope this is fixed in 2.47.

JSWolf · 12-21-2015, 06:38 PM

I still get .bak files in the ePub with Calibre 2.47 64-bit Windows.

eschwartz · 12-21-2015, 07:07 PM

The fix related to files being accidentally "compressed" into zero-byte files.

But I don't see any references in the source code to *.bak files, the temporary files which ARE created are deleted, and I cannot find any *.bak files appearing in my newly-polished books.

Arch Linux latest, calibre v2.47.0.r13.gc98dc66

Rand Brittain · 12-21-2015, 10:34 PM

I tried the tool on my 800-book library and got about 50 books with .bak files in them. Nothing seemed to be missing, so I just used the modify tool to delete any files that weren't in the manifest from them.

(There seemed to be a correlation between jobs that took a long time to process in the queue and files that left .bak after processing, but I can't really say with any exactitude.)

kovidgoyal · 12-21-2015, 10:44 PM

I think it only happens for for some .png files -- the tool calibre uses, optipng creates them. However, it is supposed to only create them when the -backup or -keep options are provided, which calibre does not do. So it looks like a bug in some versions of optipng. I can add a check to calibre to look for and delete these files after optipng runs. They are harmless, being zero bytes in size, (apart from causing epubcheck to complain) so you can just delete them from the epub files, or leave them in there -- it does not matter.

kovidgoyal · 12-21-2015, 11:05 PM

@Rand: Yes indeed, compressing PNG files is much slower than JPEG files (PNG compression happens by trial and error of compression parameters to zlib).

kovidgoyal · 12-21-2015, 11:11 PM

https://github.com/kovidgoyal/calibr...4963a5eba1360a

Rand Brittain · 12-22-2015, 10:36 AM

Looks like there's no meaningful harm, done, then, but it's good to know that it wasn't just me.

12-21-2015, 05:13 PM	#1
Rand Brittain Bookmaker Posts: 427 Karma: 2143650 Join Date: Sep 2010 Device: Cybook Opus	.bak files after compressing images Is the bug that got fixed in the most previous release the one that left tiny .bak files in books that got compressed? If so, were the .bak files replacing images? I got the impression that they were just there alongside images since I didn't notice missing stuff. If they were replacing images in the book I probably need to check through my library more carefully.

12-21-2015, 07:07 PM	#4
eschwartz Ex-Helpdesk Junkie Posts: 19,421 Karma: 85400180 Join Date: Nov 2012 Location: The Beaten Path, USA, Roundworld, This Side of Infinity Device: Kindle Touch fw5.3.7 (Wifi only)	The fix related to files being accidentally "compressed" into zero-byte files. But I don't see any references in the source code to .bak files, the temporary files which ARE created are deleted, and I cannot find any .bak files appearing in my newly-polished books. Arch Linux latest, calibre v2.47.0.r13.gc98dc66 Last edited by eschwartz; 12-21-2015 at 07:09 PM.

12-21-2015, 10:44 PM	#6
kovidgoyal creator of calibre Posts: 45,251 Karma: 27110894 Join Date: Oct 2006 Location: Mumbai, India Device: Various	I think it only happens for for some .png files -- the tool calibre uses, optipng creates them. However, it is supposed to only create them when the -backup or -keep options are provided, which calibre does not do. So it looks like a bug in some versions of optipng. I can add a check to calibre to look for and delete these files after optipng runs. They are harmless, being zero bytes in size, (apart from causing epubcheck to complain) so you can just delete them from the epub files, or leave them in there -- it does not matter. Last edited by kovidgoyal; 12-21-2015 at 11:06 PM.

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12-21-2015, 05:50 PM	#2
JSWolf Resident Curmudgeon Posts: 79,417 Karma: 145491800 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	I too found I got .bak files left behind in the ePub. This is a bug. I hope this is fixed in 2.47.

12-21-2015, 06:38 PM	#3
JSWolf Resident Curmudgeon Posts: 79,417 Karma: 145491800 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	I still get .bak files in the ePub with Calibre 2.47 64-bit Windows.

12-21-2015, 10:34 PM	#5
Rand Brittain Bookmaker Posts: 427 Karma: 2143650 Join Date: Sep 2010 Device: Cybook Opus	I tried the tool on my 800-book library and got about 50 books with .bak files in them. Nothing seemed to be missing, so I just used the modify tool to delete any files that weren't in the manifest from them. (There seemed to be a correlation between jobs that took a long time to process in the queue and files that left .bak after processing, but I can't really say with any exactitude.)

12-21-2015, 11:05 PM	#7
kovidgoyal creator of calibre Posts: 45,251 Karma: 27110894 Join Date: Oct 2006 Location: Mumbai, India Device: Various	@Rand: Yes indeed, compressing PNG files is much slower than JPEG files (PNG compression happens by trial and error of compression parameters to zlib).

12-21-2015, 11:11 PM	#8
kovidgoyal creator of calibre Posts: 45,251 Karma: 27110894 Join Date: Oct 2006 Location: Mumbai, India Device: Various	https://github.com/kovidgoyal/calibr...4963a5eba1360a

12-22-2015, 10:36 AM	#9
Rand Brittain Bookmaker Posts: 427 Karma: 2143650 Join Date: Sep 2010 Device: Cybook Opus	Looks like there's no meaningful harm, done, then, but it's good to know that it wasn't just me.

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