3.1.1 Do not leak file descriptors #35
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lhchavez
commented
Jul 14, 2024
The `openpty` function was created on a simpler time, when `O_CLOEXEC` was not even a thing. Leaking file descriptors was _fine_. But we don't live in that world anymore. This change now marks both ends of the PTY as close-on-exec, so that the file descriptors are not leaked. Importantly, since we rely on both copies (the one in ruspty and the one in the child) being closed to consider the stream done, _if_ we manage to leak the FD to another shell, there will be an unexpected third copy, so the stream will unnecessarily hang for a second (good that we added a failsafe cap on execution time)!
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jackyzha0
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Jul 14, 2024
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The
openptyfunction was created on a simpler time, whenO_CLOEXECwas not even a thing. Leaking file descriptors was fine. But we don't live in that world anymore.This change now marks both ends of the PTY as close-on-exec, so that the file descriptors are not leaked. Importantly, since we rely on both copies (the one in ruspty and the one in the child) being closed to consider the stream done, if we manage to leak the FD to another shell, there will be an unexpected third copy, so the stream will unnecessarily hang for a second (good that we added a failsafe cap on execution time)!