JuliaLang/julia

More libgit2 memory ownership issues

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#24,464 opened on Nov 3, 2017

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 (0 comments) (1 reaction) (0 assignees)Julia (48,709 stars) (5,773 forks)batch import
help wantedlibgit2

Description

https://github.com/JuliaLang/julia/blob/8cd97c5980c0a6fb0860996399f49b2679aedddd/base/libgit2/blob.jl#L21 ptr needs to be kept alive until the copy is done

msg_ptr needs to be scoped to c

The resulting signature needs to be duplicated or scoped to c

I suspect this is ok for regular uses of the iteration protocol, but it would be good to scope the ConfigEntry to the iterator that produced it.

Two bugs: a) delta_ptr needs to be scoped to the diff b) the file names inside the Delta are scoped to the diff as well (see https://github.com/libgit2/libgit2/blob/master/src/diff_generate.c#L47). Probably easiest to duplicate these rather than keep the diff around.

Same issue.

The result of the ccall is an interior pointer into the AnnotatedCommit, so we need to make sure to keep that alive until after the unsafe load

Need to keep the array alive until the hash is created (or even better let the array propagate to ccall, so ccall will do it for you).

Keep the git reference alive until the string is created

Same issue as the other getindex methods

Same issue

Object needs to be kept alive until the string result is created

Same in these four functions

The usual

The usual

oid_ptr needs to be appropriately scoped

And anything else I might have missed

Contributor guide

Tech stack
c
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
C programmingmemory management conceptsJulia C interfacelibgit2 internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
The issue identifies multiple memory ownership bugs in libgit2 bindings across several files in base/libgit2/. Each bug involves interior pointers or scoping issues where a pointer becomes invalid after the owning object is garbage collected. The fix typically requires ensuring that the pointer is scoped to the lifetime of the owning object or duplicating the data. For example, in blame.jl lines 31-39, hunk ptr points into blame, so the hunk must be used before blame goes out of scope. Similarly, in commit.jl, msg ptr needs to be scoped to c. The assignee should review each linked line, understand the relevant C API (libgit2) and Julia's garbage collection, and apply scoping or memory duplication patterns consistent with the rest of the codebase. There is no existing PR or assignee, so the issue is available for a contributor willing to do careful memory analysis.