stdbuf cannot use libstdbuf on the same directory if /proc is masked

$ run0 mv /usr/lib/uutils-coreutils/libstdbuf.so -t /tmp
$ cp /usr/bin/stdbuf -t /tmp
$ unshare -rm bash -c "mount -t tmpfs tmpfs /proc && /tmp/stdbuf -oL true"
stdbuf: External libstdbuf not found at configured path: /usr/lib/uutils-coreutils/libstdbuf.so

$ unshare -rm bash -c "mount -t tmpfs tmpfs /proc && /tmp/gnu-stdbuf -oL true"
# success

I believe it is because std::env::current_exe() requires /proc/self/exe:

coreutils/src/uu/stdbuf/src/stdbuf.rs

Line 189 in e939eda

if let Ok(exe_path) = std::env::current_exe() {

@Ecordonnier

@Ecordonnier

It seems GNU use argv[0]. But if we need to care about secutiry, we could use AT_EXECFN at least on Linux. I don't know what can we use for other platforms.

This is not security critical as far as I know, since stdbuf is not seteuid. I think the path discovery should be implemented the same way than in GNU coreutils.

What happens if those test steps are executed with GNU coreutils?

GNU tries to search libstdbuf based on argv[0] i.e. stdbuf success if libstdbuf.so is present at same dir with argv[0].

GNU found libstdbuf from PATH:

$ env PATH=/home/a/bin/gnu9.10 stdbuf -oL true # ok
$ mv '/home/a/bin/gnu9.10/libstdbuf.so' '/home/a/bin/gnu9.10/libstdbuf.so-'
$ env PATH=/home/a/bin/gnu9.10 stdbuf -oL true
stdbuf: failed to find `libstdbuf.so'

Since std rejected improving current_exe, I'll wait #10773 's uucore function.

I still have no idea how to do #11134 (comment) on non-Llinux.

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stdbuf cannot use libstdbuf on the same directory if /proc is masked #11134

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stdbuf cannot use libstdbuf on the same directory if /proc is masked #11134

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oech3 commented on Feb 26, 2026

oech3 commented on Feb 27, 2026

Ecordonnier commented on Feb 27, 2026

Ecordonnier commented on Feb 27, 2026

oech3 commented on Feb 27, 2026

oech3 commented on Mar 10, 2026

oech3 commented on Apr 1, 2026

oech3 commented on Apr 20, 2026

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