Repair a corrupt font?

Report · May 25, 2012

I have an extensive collection of fonts (60,0000+). Several hundred of them will crash my system when I open one of them in Finder (double-click the font icon). I picked one at random for some serious examination.

I looked at my sample with many font tools. My latest tool was FontDoctor (v5 and v7). FontDoctor reported "no problems found" with my font. Yet the crash persists.

Please suggest a tool that can do a thorough job of investigating and repairing my corrupt fonts.

Gary

(Mac OS 9 & X)

Report · May 25, 2012

I'm more of a Windows font techie, but maybe these questions can help

someone address your issue:

Is there any pattern to the fonts that fail?

Are they all the same format?

Are they all stored the same way or in similar locations?

Do they work in applications? All applications or only Adobe or only

non-Adobe?

What are the fonts' sources - downloads from free sites? Purchases from

name foundries (Adobe, Linotype, Hoefler, etc.)? Old CD's from

fly-by-night companies like WSI and Southern Software?

Do you have a font editor such as FontLab or Glyphs? If so, have you

tried simply opening a font in the editor and re-generating it? (This

often works for older fonts in Windows, where current Windows isn't as

fault-tolerant as previous versions)

- Herb

Report · May 25, 2012

Answers to your questions:
Is there any pattern to the fonts that fail?
None that I can see. The only thing they have in common is the type of crash. All crashes are tagged with a "divide by zero" error.
Are they all the same format?
Yes. TrueType.

Are they all stored the same way or in similar locations?
They are stored alphabetically - one folder for each letter; ie all fonts beginning with the letter "A" are in the "A" folder, etc.
Do they work in applications? All applications or only Adobe or only
non-Adobe?
These fonts crash all apps that try to display text. However, I can open them with most of my diagnostic type apps.
What are the fonts' sources - downloads from free sites? Purchases from
name foundries (Adobe, Linotype, Hoefler, etc.)? Old CD's from
fly-by-night companies like WSI and Southern Software?
My fonts come from everywhere - purchase, CD graphics collections, downloads. But I am unable to tell where a particular font came from.
Do you have a font editor such as FontLab or Glyphs? If so, have you
tried simply opening a font in the editor and re-generating it? (This
often works for older fonts in Windows, where current Windows isn't as
fault-tolerant as previous versions)
I have Fontographer. With it I am able to open my test font and display all of its characters. But when I "generate fonts" with it, the resulting font file crashes my system in the same way as the original font does.
Gary

Report · May 26, 2012

Since it doesn't appear to be corrupt try deleting your font cache in OS X.

Report · Aug 06, 2012

Well it turns out that NO tool can repair this font. So I wrote my own.

The problem turned out to be a bad 'hhea' table. The values for Ascender, Descender and LineGap were all zero.

Once I changed these values to something reasonable, the font appeared like magic and my system no longer crashes with a "Divide by Zero" error.

Gary