[beta] std: Synchronize access to global env during exec
#55978
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…nt in Command::exec" This reverts commit 36fe3b6.
This commit, after reverting rust-lang#55359, applies a different fix for rust-lang#46775 while also fixing rust-lang#55775. The basic idea was to go back to pre-rust-lang#55359 libstd, and then fix rust-lang#46775 in a way that doesn't expose rust-lang#55775. The issue described in rust-lang#46775 boils down to two problems: * First, the global environment is reset during `exec` but, but if the `exec` call fails then the global environment was a dangling pointer into free'd memory as the block of memory was deallocated when `Command` is dropped. This is fixed in this commit by installing a `Drop` stack object which ensures that the `environ` pointer is preserved on a failing `exec`. * Second, the global environment was accessed in an unsynchronized fashion during `exec`. This was fixed by ensuring that the Rust-specific environment lock is acquired for these system-level operations. Thanks to Alex Gaynor for pioneering the solution here! Closes rust-lang#55775 Co-authored-by: Alex Gaynor <alex.gaynor@gmail.com>
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Nov 15, 2018
[beta] std: Synchronize access to global env during `exec` This is a beta backport of #55939
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☀️ Test successful - status-appveyor, status-travis |
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This is a beta backport of #55939