URL:
<https://savannah.gnu.org/bugs/?61748>
Summary: [grohtml] infinite loop
Project: GNU troff
Submitted by: gbranden
Submitted on: Thu 30 Dec 2021 09:32:35 PM UTC
Category: Device grohtml
Severity: 4 - Important
Item Group: Crash/Not responding
Status: In Progress
Privacy: Public
Assigned to: gbranden
Open/Closed: Open
Discussion Lock: Any
Planned Release: None
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Details:
The following commit exposed an infinite loop in post-grohtml.
commit c71b4ef4aa46f9264751df37ffac4fdf796c45eb
Author: G. Branden Robinson <[email protected]>
Date: Tue Jul 27 00:10:49 2021 +1000
[grohtml]: Fix Savannah #60971.
* src/preproc/html/pre-html.cpp (makeFileName): Consistently put a dash
at the end of `macroset_template` whether the image file name stem is
user-supplied or the default. Stop adding the dash before the image
number in `image_template` instead. This makes the image file name
format reliable whether the image needs to be subdivided (eqn) or not
(tbl).
Fixes <https://savannah.gnu.org/bugs/?60971>.
However, as the eventual root-cause analysis established, this was not
the fault of the above change. What the above change (to the
pre-grohtml _preprocessor_, mind you) did seem to do was cause a
reorganization of storage later such that a read from uninitialized
memory led to a highly undesirable default point size.
Because this sort of thing can be system-dependent, I can't promise that
this is a reproducer for everyone, but it was for me.
Input:
.EQ
gsize 12
delim $$
.EN
.pp
.pp
The faster clocks are $ PN $
You _do_ need the gsize eqn directive, you _do_ need to use delimiters,
you _do_ need the extra paragraph tag, and you _do_ need the inline
eqn input. (This is an extremely reduced version of our source tree's
grnexmpl.me, which is how I noticed the problem in the first place.)
Reproduce with:
./build/test-groff -b -ww -Thtml -eg -me EXPERIMENTS/gurn.me
As I said, I can't promise that others will be able to reproduce this,
but it was highly reliable on my x86-64 Debian bullseye system.
Here's the fix, if you don't believe me.
$ git diff
diff --git a/src/devices/grohtml/post-html.cpp
b/src/devices/grohtml/post-html.cpp
index a1018e19a..5be5e9979 100644
--- a/src/devices/grohtml/post-html.cpp
+++ b/src/devices/grohtml/post-html.cpp
@@ -324,7 +324,7 @@ struct style {
};
style::style()
- : f(NULL)
+ : f(NULL), point_size(-1)
{
}
I leave as an exercise for the reader the determination of why the value
-1 is meaningful.
I had thought that argument-less constructors that don't initialize all
the fields of their objects were considered bad C++ style. (?)
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