comm: fix appending doubles to events

[mathstuf]

Only the length of the added string needs to be added to the length of
the string.

Introduced in 1a99091.

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@keis

[keis]

Actually I think it's supposed to be assigning the len and not adding to it. Reading up on the functions again it looks like g_string_set_size modifies len which I think I was trying to adjust for but I clearly messed that up 😓

[mathstuf]

The old code (before it became a function) just added the strlen, but either fix should work.

[keis]

I think that was buggy but it would only trigger when resizing the string. heh, really wish I would have put some comment in about that because I really can't remember now.

[mathstuf]

Looking at g_string_set_size, it doesn't look to be the function we really want to be using here. Maybe just using g_string_append with a stack array is best here rather than trying to be too clever.

[keis]

agreed. it's a bit of a hack to begin with. +1 on using a buffer on the stack.

[mathstuf]

Updated to use the buffer on the stack.

[keis]

LGTM!