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merged 2 commits into from
May 23, 2025

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@joboet joboet commented Mar 24, 2025

CStringArray contained both CStrings and their pointers. Unfortunately, since CString uses Box, moving the CStrings into the Vec can (under stacked borrows) invalidate the pointer to the string, meaning the resulting Vec<*const c_char> was, from an opsem perspective, unusable. This PR removes removes the Vec<CString> from CStringArray, instead recreating the CString/CStr from the pointers when necessary. Also,CStringArray is now used for the process args as well, the old implementation was suffering from the same kind of bug.

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r? @Noratrieb

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@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Mar 24, 2025
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looks like we got boxed again 💀. but the fixed implementation is nicer anyways, so that's cool.
but can you add a SAFETY comment to the new unsafe blocks? it does all looks fine to me.

@rustbot rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 6, 2025
@joboet joboet added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 21, 2025
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bors commented May 21, 2025

☔ The latest upstream changes (presumably #141331) made this pull request unmergeable. Please resolve the merge conflicts.

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r=me after fixing conflicts

joboet added 2 commits May 23, 2025 17:09
`CStringArray` contained both `CString`s and their pointers. Unfortunately, since `CString` uses `Box`, moving the `CString`s into the `Vec` can (under stacked borrows) invalidate the pointer to the string, meaning the resulting `Vec<*const c_char>` was, from an opsem perspective, unusable. This PR removes removes the `Vec<CString>` from `CStringArray`, instead recreating the `CString`/`CStr` from the pointers when necessary. Also,`CStringArray` is now used for the process args as well, the old implementation was suffering from the same kind of bug.
@joboet joboet force-pushed the process_noalias branch from 1b103f1 to 89a90d6 Compare May 23, 2025 15:30
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joboet commented May 23, 2025

@bors r=@Noratrieb

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bors commented May 23, 2025

📌 Commit 89a90d6 has been approved by Noratrieb

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 23, 2025
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request May 23, 2025
std: fix aliasing bug in UNIX process implementation

`CStringArray` contained both `CString`s and their pointers. Unfortunately, since `CString` uses `Box`, moving the `CString`s into the `Vec` can (under stacked borrows) invalidate the pointer to the string, meaning the resulting `Vec<*const c_char>` was, from an opsem perspective, unusable. This PR removes removes the `Vec<CString>` from `CStringArray`, instead recreating the `CString`/`CStr` from the pointers when necessary. Also,`CStringArray` is now used for the process args as well, the old implementation was suffering from the same kind of bug.
bors added a commit that referenced this pull request May 23, 2025
Rollup of 7 pull requests

Successful merges:

 - #138896 (std: fix aliasing bug in UNIX process implementation)
 - #140832 (aarch64-linux: Default to FramePointer::NonLeaf)
 - #141065 (Updated std doctests for wasm)
 - #141369 (Simplify `format_integer_with_underscore_sep`)
 - #141374 (make shared_helpers exe function work for both cygwin and non-cygwin hosts)
 - #141398 (chore: fix typos in comment)
 - #141457 (Update mdbook to 0.4.50)

Failed merges:

 - #141405 (GetUserProfileDirectoryW is now documented to always store the size)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit c66c8e6 into rust-lang:master May 23, 2025
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@rustbot rustbot added this to the 1.89.0 milestone May 23, 2025
rust-timer added a commit that referenced this pull request May 23, 2025
Rollup merge of #138896 - joboet:process_noalias, r=Noratrieb

std: fix aliasing bug in UNIX process implementation

`CStringArray` contained both `CString`s and their pointers. Unfortunately, since `CString` uses `Box`, moving the `CString`s into the `Vec` can (under stacked borrows) invalidate the pointer to the string, meaning the resulting `Vec<*const c_char>` was, from an opsem perspective, unusable. This PR removes removes the `Vec<CString>` from `CStringArray`, instead recreating the `CString`/`CStr` from the pointers when necessary. Also,`CStringArray` is now used for the process args as well, the old implementation was suffering from the same kind of bug.
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