libstd: unix process spawning: fix bug with setting stdio #30490
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r? @brson (rust_highfive has picked a reviewer for you, use r? to override) |
src/libstd/sys/unix/process.rs
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Could this use FileDesc instead of RawStdio here? (as RawStdio is just a type alias)
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Thanks! Could you be sure to also add a test for this? |
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@alexcrichton addressed all comments! I wasn't sure about the right place for such a test, but I think run-pass is a good fit. |
src/test/run-pass/issue-30490.rs
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Could this test be written without creating files? Keeping everything in-memory is generally better for isolation. I think this should basically just be able to use combinations of pipes, right?
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@alexcrichton rewrote the test to use pipes instead of files and to re-exec itself instead of calling a shell |
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@bors: r+ 751fce0974dd4f634539c37ba759d13c4f894d09 Thanks! |
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http://buildbot.rust-lang.org/builders/auto-win-gnu-64-nopt-t/builds/2525/steps/test/logs/stdio |
bors
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Dec 25, 2015
* If the requested descriptors to inherit are stdio descriptors there
are situations where they will not be set correctly
* Example: parent's stdout --> child's stderr
parent's stderr --> child's stdout
* Solution: if the requested descriptors for the child are stdio
descriptors, `dup` them before overwriting the child's stdio
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Doh! Forgot some @alexcrichton @Manishearth should be fixed now |
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⌛ Testing commit 7f7a059 with merge 6f86431... |
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💔 Test failed - auto-win-msvc-32-opt |
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@bors: retry On Mon, Jan 11, 2016 at 3:21 PM, bors notifications@github.com wrote:
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bors
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Jan 11, 2016
* If the requested descriptors to inherit are stdio descriptors there
are situations where they will not be set correctly
* Example: parent's stdout --> child's stderr
parent's stderr --> child's stdout
* Solution: if the requested descriptors for the child are stdio
descriptors, `dup` them before overwriting the child's stdio
Example of a program which exhibits the bug:
```rust
// stdio.rs
use std::io::Write;
use std::io::{stdout, stderr};
use std::process::{Command, Stdio};
use std::os::unix::io::FromRawFd;
fn main() {
stdout().write_all("parent stdout\n".as_bytes()).unwrap();
stderr().write_all("parent stderr\n".as_bytes()).unwrap();
Command::new("sh")
.arg("-c")
.arg("echo 'child stdout'; echo 'child stderr' 1>&2")
.stdin(Stdio::inherit())
.stdout(unsafe { FromRawFd::from_raw_fd(2) })
.stderr(unsafe { FromRawFd::from_raw_fd(1) })
.status()
.unwrap_or_else(|e| { panic!("failed to execute process: {}", e) });
}
```
Before:
```
$ rustc --version
rustc 1.7.0-nightly (8ad12c3 2015-12-19)
$ rustc stdio.rs && ./stdio >out 2>err
$ cat out
parent stdout
$ cat err
parent stderr
child stdout
child stderr
```
After (expected):
```
$ rustc --version
rustc 1.7.0-dev (712ecce 2015-12-19)
$ rustc stdio.rs && ./stdio >out 2>err
$ cat out
parent stdout
child stderr
$ cat err
parent stderr
child stdout
```
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I think the original report here shows an program which has undefined behaviour. The documentation for
Calling this on 0, 1 or 2 is clearly wrong. |
This was referenced Nov 9, 2021
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are situations where they will not be set correctly
parent's stderr --> child's stdout
descriptors,
dupthem before overwriting the child's stdioExample of a program which exhibits the bug:
Before:
After (expected):