Fix: tail fails under pseudo with "couldn't allocate absolute path" by naoNao89 · Pull Request #9305 · uutils/coreutils

naoNao89 · 2025-11-16T13:59:09Z

tail calls .canonicalize() on stdin pipes → triggers realpath() → pseudo fails with "couldn't allocate absolute path"

Fix: Check file type first. Skip canonicalization for pipes, only canonicalize regular files.

Verified: Tested with pseudo in Ubuntu container

podman run --rm -v $(pwd):/src:Z -w /src ubuntu:24.04 /bin/bash -c '
  apt update -qq && apt install -y -qq curl pseudo build-essential > /dev/null &&
  curl --proto "=https" --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable &&
  . $HOME/.cargo/env &&
  cargo build --release -p uu_tail &&
  echo "/usr/bin/arch
/bin/busybox.nosuid 50" > /tmp/test-data.txt &&
  echo "=== Test WITHOUT pseudo ===" &&
  grep "50\$" /tmp/test-data.txt | ./target/release/tail -n 1 &&
  echo "=== Test WITH pseudo (issue #9292) ===" &&
  mkdir -p /tmp/pseudo && export PSEUDO_PREFIX=/tmp/pseudo &&
  pseudo sh -c "grep \"50\\\$\" /tmp/test-data.txt | ./target/release/tail -n 1" &&
  echo "✓ Fix verified: No '\''couldn'\''t allocate absolute path'\'' errors!"
'

=== Test WITHOUT pseudo ===
/bin/busybox.nosuid 50
✓ Pass

=== Test WITH pseudo (issue #9292) ===
/bin/busybox.nosuid 50
✓ Fix verified: No 'couldn't allocate absolute path' errors!

codspeed-hq · 2025-11-16T14:43:26Z

Merging this PR will not alter performance

✅ 319 untouched benchmarks
⏩ 46 skipped benchmarks¹

_{Comparing naoNao89:fix/issue-9292-tail-pseudo-canonicalize (d904e16) with main (21fda8c)}

46 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

github-actions · 2025-11-16T15:02:08Z

GNU testsuite comparison:

Skipping an intermittent issue tests/tail/overlay-headers (passes in this run but fails in the 'main' branch)

anastygnome · 2025-11-18T19:18:09Z

+    // On non-macOS systems, use is_stdin_directory() which works correctly
+    #[cfg(not(target_os = "macos"))]
+    {
+        if uucore::fs::is_stdin_directory(&stdin()) {


Why can't we simply fix the uucore function?

@naoNao89 ping, have you seen this comment?

What is "sr"?

@naoNao89 are you an AI?

We clarified offline that "sr" means "sorry", and "@@" is a dizzy face smiley meaning overwhelmed / confused.

@@ -> icon 😵 or 😵‍💫

if I were an AI, i would write comments in an expert tone, akin to a research paper or technical doc :v

github-actions · 2026-02-19T09:17:24Z

GNU testsuite comparison:

Skipping an intermittent issue tests/tail/follow-name (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/date/date-locale-hour is no longer failing!
Congrats! The gnu test tests/misc/io-errors is no longer failing!
Note: The gnu test tests/expand/bounded-memory is now being skipped but was previously passing.
Note: The gnu test tests/rm/many-dir-entries-vs-OOM is now being skipped but was previously passing.
Note: The gnu test tests/tail/tail-n0f is now being skipped but was previously passing.

github-actions · 2026-02-19T09:41:59Z

GNU testsuite comparison:

Skipping an intermittent issue tests/tail/symlink (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/date/date-locale-hour is no longer failing!
Congrats! The gnu test tests/misc/io-errors is no longer failing!

github-actions · 2026-02-19T11:31:05Z

GNU testsuite comparison:

GNU test failed: tests/cut/bounded-memory. tests/cut/bounded-memory is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/date/date-locale-hour. tests/date/date-locale-hour is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/misc/io-errors. tests/misc/io-errors is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/tail/symlink (fails in this run but passes in the 'main' branch)
Note: The gnu test tests/seq/seq-epipe is now being skipped but was previously passing.

github-actions · 2026-04-11T20:50:37Z

GNU testsuite comparison:

Skip an intermittent issue tests/tty/tty-eof (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/date/date-locale-hour (passes in this run but fails in the 'main' branch)

Ecordonnier · 2026-04-11T21:28:15Z

Can you please check the CI issue?

github-actions · 2026-05-25T10:26:08Z

GNU testsuite comparison:

GNU test failed: tests/tail/follow-stdin. tests/tail/follow-stdin is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/cut/bounded-memory (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tail/pipe-f (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/date/date-locale-hour (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tail/tail-n0f (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/rm/many-dir-entries-vs-OOM is now being skipped but was previously passing.
Congrats! The gnu test tests/printf/printf-surprise is now passing!

Avoid canonicalizing stdin when it's a pipe to prevent realpath() errors under pseudo (Yocto/OpenEmbedded). Changes: 1. In Input::resolve() (paths.rs): Check file type before canonicalizing. Only canonicalize regular files, skip pipes/fifos/dirs. 2. In tail_stdin() (tail.rs): Add early directory check for stdin. On non-macOS systems, detect directory stdin before path resolution to provide correct error message matching test expectations. This fixes the issue where tail commands like 'grep pattern file | tail' fail under pseudo with 'couldn't allocate absolute path' errors. Fixes uutils#9292

The macOS-specific workaround in tail_stdin() was unnecessary because fstat() on stdin's file descriptor correctly detects directories on all Unix platforms, including macOS. The real macOS issue was with canonicalize() on /dev/stdin paths, not with fstat(). Remove the duplicate platform-specific blocks and use a single call to uucore::fs::is_stdin_directory() which works on all platforms. Also consolidate the macOS-specific test into the cross-platform test_stdin_redirect_dir test, producing the correct error message on all platforms. See: rust-lang/rust#95239

… stub

naoNao89 force-pushed the fix/issue-9292-tail-pseudo-canonicalize branch 3 times, most recently from 2dda7a0 to 486df67 Compare November 16, 2025 14:42

anastygnome reviewed Nov 18, 2025

View reviewed changes

ChrisDryden mentioned this pull request Dec 19, 2025

GNU coreutils 9.9: Detailed Test report 12/19 #9729

Closed

Ecordonnier self-assigned this Feb 7, 2026

naoNao89 force-pushed the fix/issue-9292-tail-pseudo-canonicalize branch from a875910 to 6fb203c Compare February 19, 2026 09:06

naoNao89 force-pushed the fix/issue-9292-tail-pseudo-canonicalize branch from 6fb203c to 72737e7 Compare February 19, 2026 09:33

naoNao89 force-pushed the fix/issue-9292-tail-pseudo-canonicalize branch from 72737e7 to 98c7793 Compare February 19, 2026 11:23

naoNao89 force-pushed the fix/issue-9292-tail-pseudo-canonicalize branch from bb9ced1 to f54dcc6 Compare May 25, 2026 06:08

naoNao89 added 5 commits May 25, 2026 17:45

fix(tail): fix method names after rebase onto latest main

539d9f4

fix(tail): fix clippy lint and formatting after rebase

67de8d8

fix(tail): remove libc::signal call to fix WASI build after rebase

fc8d77d

naoNao89 force-pushed the fix/issue-9292-tail-pseudo-canonicalize branch from ba8ec45 to fc8d77d Compare May 25, 2026 10:45

fix(tail): gate test on non-WASI, remove unused use_polling from WASI…

fa0affc

… stub

naoNao89 force-pushed the fix/issue-9292-tail-pseudo-canonicalize branch from 0854eca to fa0affc Compare May 25, 2026 11:07

fix(tail): stabilize debug follow tests for CI

090c811

naoNao89 force-pushed the fix/issue-9292-tail-pseudo-canonicalize branch from 221d29c to 090c811 Compare May 25, 2026 16:13

naoNao89 added 2 commits May 26, 2026 08:09

fix(tail): stabilize fifo handling in CI

1d27d85

fix(tail): stabilize stdin and fifo follow

d904e16

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Merging this PR will not alter performance

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