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forkachild / C-Simple-JSON-Parser

Extremely lightweight, easy-to-use & blazing fast JSON parsing library written in pure C
https://forkachild.github.io/C-Simple-JSON-Parser/
MIT License
45 stars 16 forks source link

json_free() guidance #22

Open milankowww opened 5 months ago

milankowww commented 5 months ago

What is the proper guideline for json_free() to prevent memory leaks? It seems to me from the recursive nature of json_free() that it is sufficient to call it for the topmost object, but still, in the README example you don't call it on any error, which leads me to believe the example contains a memory leak (of course the program exits but that's not the point).

Is it "call it on the value of the topmost unwrap but only if it was successful", or is it something else?

forkachild commented 5 months ago

Yes, your assumption is correct. It will leak memory on failure. This can be resolved in 2 ways:

  1. Calling json_free() at fallible points in each parsing step.
  2. Sizing the JSON before parsing. This will solve the following:
    1. Fail without allocating anything.
    2. Have one monolithic allocation, avoiding redundant segmentation (due to multiple allocations).
    3. Contiguous cache-friendly memory access.

I would strongly prefer solution 2. What are your thoughts on this?