shell: report the operand as written in cat, touch and mkdir errors - #39189
shell: report the operand as written in cat, touch and mkdir errors#39189robobun wants to merge 1 commit into
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Status: reproduced on linux-x64 and windows-x64 with the system bun. CI: the two previous builds had every Linux, Alpine, ASAN and Windows shard green and only the darwin-aarch64 test shards canceled before running, same as the builds on main at the time; the build for 91a0fa0 is the current one. |
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WalkthroughThe shell now preserves caller-provided paths in Windows file-open errors. Tests cover missing relative, nested, absolute, and interpolated ChangesShell path error reporting
Suggested reviewers: 🚥 Pre-merge checks | ✅ 4✅ Passed checks (4 passed)
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Inline comments:
In `@src/runtime/shell/interpreter.rs`:
- Around line 2244-2251: Update the Windows path-resolution error handling in
shell_openat/get_fd_path so failures from shell_get_path retain the
caller-provided path instead of being cleared by with_fd; retag the error before
propagating it, while preserving existing system-call error behavior.
In `@test/js/bun/shell/bunshell.test.ts`:
- Line 553: Update the redirected-file read in the test around
results["err.txt"] to use an absolute path, while preserving the relative 2>
err.txt operand in the child script so the test still verifies relative
redirection behavior.
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Fix all unresolved CodeRabbit comments on this PR:
- Push a commit to this branch (recommended)
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src/runtime/shell/interpreter.rstest/js/bun/shell/bunshell.test.ts
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LGTM — one-line fix bringing the Windows file-open branch of shell_openat in line with its three siblings, which already re-tag the error with the caller's operand.
What was reviewed:
- Confirmed the POSIX branch, both Windows
O_DIRECTORYbranches, andshell_statatalready use the identical.map_err(|e| e.with_path(path.as_bytes()))pattern — this was the lone outlier. - Checked
bun_sys::Error::with_path: preserveserrnoandsyscall, replaces onlypath; the..Default::default()reset offd/destmatches what every sibling branch already does. - Test follows harness conventions (
tempDir, spreadbunEnv, concurrent pipe drain, exact-message assertions across relative/subdir/POSIX-absolute/host-absolute/redirected variants) and the PR documents fail-before on windows-x64.
Extended reasoning...
Overview
The PR changes one line in src/runtime/shell/interpreter.rs: the Windows non-O_DIRECTORY branch of shell_openat now chains .map_err(|e| e.with_path(path.as_bytes())) onto bun_sys::open(p, ...), so the returned error names the operand as the caller wrote it rather than the cwd-resolved absolute path. The doc comment is updated to state this contract. A new test in test/js/bun/shell/bunshell.test.ts spawns bun with BUN_ENABLE_EXPERIMENTAL_SHELL_BUILTINS=1 and asserts the exact cat: <operand>: No such file or directory message across five operand shapes.
Security risks
None. This changes only which path string is copied into a shell builtin's error message; no auth, no untrusted-input parsing, no memory ownership changes.
Level of scrutiny
Low. The code change is mechanical: it applies the exact .map_err pattern already used by the POSIX branch (line 2300), both Windows O_DIRECTORY branches (lines 2274, 2289), and shell_statat (line 2236). I read bun_sys::Error::with_path — it copies errno and syscall and replaces path, defaulting fd/from_libuv/dest; this is identical to what the sibling branches already accept, so no behavior beyond the displayed path can differ from them.
Other factors
The test is well-constructed per REVIEW.md: uses tempDir from harness, spreads bunEnv, drains stdout/stderr/exited concurrently, asserts stderr and the parsed result object before exitCode, covers the variant matrix (relative, subdir-relative, POSIX-absolute, host-absolute, and stderr redirected to a file), and asserts exact strings rather than toContain. The /bunshell-missing-operand.txt operand is a filesystem-root probe, but the name is unique enough not to collide on CI runners. The PR description shows the test failing on windows-x64 with the parent-commit canary and passing with the debug build, satisfying the fail-before requirement (the changed code is #[cfg(windows)], so Linux passes both ways by construction). No outstanding reviewer comments; no prior claude[bot] reviews on this PR.
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Updated 8:41 PM PT - Aug 15th, 2026
✅ @robobun, your commit 91a0fa0d62c73678cb0038cba9b3067b2434c862 passed in 🧪 To try this PR locally: bunx bun-pr 39189That installs a local version of the PR into your bun-39189 --bun |
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LGTM — one-line Windows fix that brings the file-open branch of shell_openat in line with its three siblings.
What was reviewed:
- Confirmed the new
.map_err(|e| e.with_path(path.as_bytes()))matches the POSIX branch and both WindowsO_DIRECTORYbranches at interpreter.rs:2271/2286/2297, and thatwith_pathpreserves errno + syscall tag. - Test follows harness conventions (tempDir, spread bunEnv, concurrent pipe drain, combined
.toEqual, exitCode asserted last, err.txt read via absolute path). - Checked the
shell_get_path(...)?early-return concern raised in review — sibling branches propagate it identically, and the doc comment was narrowed accordingly.
Extended reasoning...
Overview
This PR fixes a Windows-only cosmetic bug in Bun shell's builtin cat: when opening a missing file, the error message printed the resolved absolute path (C:\Users\...\missing.txt) instead of the operand as the user typed it (missing.txt). The functional change is a single .map_err(|e| e.with_path(path.as_bytes())) added to the Windows non-O_DIRECTORY branch of shell_openat in src/runtime/shell/interpreter.rs. The other change is a one-line doc-comment update. A new test in test/js/bun/shell/bunshell.test.ts covers relative, subdirectory, POSIX-absolute, host-absolute, and 2> redirect operands.
Security risks
None. The change only substitutes which path string is attached to an already-produced bun_sys::Error on the failure path; with_path copies errno and syscall tag verbatim and boxes the caller's path bytes. No new syscalls, no changed control flow on success, no user input reaching new code.
Level of scrutiny
Low. The changed line is inside #[cfg(windows)], and the exact same expression already appears on the three sibling branches (interpreter.rs:2271, 2286, 2297) — this is bringing the one outlier into line rather than introducing a new pattern. The only user-visible effect is the path shown in an error message.
Other factors
- The PR description documents fail-before on windows-x64 with the system bun and pass-after with the debug build; on Linux the changed branch is not compiled and the test passes both ways (expected — POSIX was already correct).
- The test is well-constructed: placed in the existing shell test file, uses
tempDir/bunEnv/bunExe(), drains stdout/stderr/exited concurrently, asserts a combined object with.toEqual, and readserr.txtback via an absolute path (addressing the earlier review comment). - All CodeRabbit and comment-cop feedback threads are resolved; the doc-comment was pared down to one line in 5a25007 in response.
robobun
changed the title
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LGTM — one-line re-tag on the Windows file branch of shell_openat to match its three siblings, plus the same operand-as-written fix in touch/mkdir's error paths.
What was reviewed:
- Confirmed the new
.map_err(|e| e.with_path(path.as_bytes()))is byte-identical to the POSIX and bothO_DIRECTORYbranches inshell_openat. - Checked
mkdir::operand()correctly strips the in-place NUL only for the absolute case, and touch'sthis.filepathis never mutated so no strip is needed there. - Test covers cat/touch/mkdir × relative/subdir/POSIX-absolute/host-absolute and the fd-backed
2>path; drains pipes concurrently, readserr-*.txtby absolute path, asserts exit code last.
Extended reasoning...
Overview
Five files touched. The core fix is one line in src/runtime/shell/interpreter.rs: the Windows non-directory branch of shell_openat now re-tags open errors with the caller's operand via .map_err(|e| e.with_path(path.as_bytes())), matching the POSIX branch and both Windows O_DIRECTORY branches (lines 2271, 2286, 2297) byte-for-byte. touch.rs and mkdir.rs get the analogous fix — their thread-pool tasks now tag errors with the operand as written (&this.filepath / this.operand()) instead of the resolved absolute path. Builtin.rs gains a one-line doc comment. A new test in bunshell.test.ts exercises cat/touch/mkdir across four operand shapes plus the 2> redirect path.
Security risks
None. This changes only which path string appears in a user-facing error message; errno and syscall tag are preserved by with_path. No parsing of untrusted input, no auth/crypto/permissions.
Level of scrutiny
Low. The interpreter.rs change is a one-line pattern match against three existing siblings in the same function. The touch/mkdir changes are error-message-only (success paths untouched). The mkdir operand() helper's NUL-strip is correct: filepath starts as arg_bytes(i).to_vec() (no NUL), and run_from_thread_pool pushes a NUL in place only for absolute operands; strip_suffix handles both. Touch never mutates this.filepath (it joins into a separate stack buffer), so no strip is needed there.
Other factors
The PR description includes fail-before output on windows-x64 against the canary at the branch parent, and passing runs on both Windows and Linux with the debug build. All CodeRabbit and comment-cop threads are resolved (absolute-path read for err.txt, doc comment trimmed to one line). The test follows harness conventions: tempDir, bunEnv spread, concurrent pipe drain via Promise.all, stderr asserted before exitCode, hermetic (no network). No prior claude review on this PR.
The builtin cat (on Windows), touch and mkdir (everywhere) resolve the operand against the cwd before the syscall and tagged the error with that resolved path, so "mkdir nodir/a" printed "mkdir: /tmp/x/nodir/a: No such file or directory" while ls, rm, mv and the coreutils name the operand as the user wrote it. shell_openat's Windows file branch now re-tags the open error with the caller's path like its sibling branches; touch and mkdir tag the operand they were given instead of the joined path (mkdir strips the NUL its absolute branch appends in place). The contract is noted on Builtin::task_error_to_string, the one printer of err.path. The new test runs cat, touch and mkdir (including mkdir -p and a touch whose utimes() fails outright) against relative, nested, rooted and absolute operands plus a 2> redirect each, and the cat completion test now pins the exact message it previously had to accept either form of.
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LGTM — small, targeted alignment of three shell builtins' error messages with what ls/rm/mv and coreutils already do.
What was reviewed:
with_pathcopies the slice into aBox, sothis.operand()/&this.filepathborrows end before thethis.err =assignment; no borrowck or lifetime concern.- mkdir's
operand()correctly strips the in-place NUL that the absolute branch appends; touch'sthis.filepathcomes fromarg_bytes().to_vec()and never carries a NUL. - The interpreter.rs change mirrors the existing
shell_statatand both WindowsO_DIRECTORYbranches line-for-line. - Test covers both mkdir code paths (plain and
-p), both touch error sites (utimes and the open fallback), both output paths (captured and2>redirect), and relative/subdir/rooted/absolute operands; fail-before verified on linux-x64 and windows-x64.
Extended reasoning...
Overview
Five files touched: three per-builtin one-to-two-line swaps (filepath.as_bytes() → the operand as written) in touch.rs and mkdir.rs, one .map_err(|e| e.with_path(path.as_bytes())) on the Windows file-open branch of shell_openat in interpreter.rs, one doc line on task_error_to_string in Builtin.rs stating the contract, and an ~80-line table-driven test in bunshell.test.ts plus a 4-line tightening of an existing regex assertion to an exact string.
Security risks
None. This only changes which path string is copied into a bun_sys::Error for display. The operand was already user-controlled and already printed by ls/rm/mv; this aligns three more builtins with that same behavior. No auth, crypto, permission, or parsing changes.
Level of scrutiny
Low-to-moderate. Error-message formatting in shell builtins, no control-flow or memory-ownership changes. with_path clones its argument into a Box<[u8]> (checked src/sys/Error.rs:220), so the new call sites introduce no lifetime hazards. The mkdir operand() helper is two lines of strip_suffix handling the one case where run_from_thread_pool mutates filepath in place. The interpreter.rs change makes the Windows non-directory branch match its three sibling branches exactly.
Other factors
The test is thorough and follows harness conventions: tempDir, spread bunEnv, concurrent pipe drain, stderr asserted before exitCode, absolute-path file reads for the redirect check, BUN_ENABLE_EXPERIMENTAL_SHELL_BUILTINS=1 so the builtin cat runs on every platform. The PR description shows fail-before output on both linux-x64 (6 rows) and windows-x64 (11 rows) with the system bun, and 565/577 passing on the debug build. CI build 98779 passed all 177 jobs that ran (darwin cancellations were fleet-wide, not this PR). All CodeRabbit and comment-cop feedback has been addressed and resolved; no outstanding human reviewer comments. The PR explicitly scopes out the sibling cp defect to avoid conflicting with in-flight #38162, and notes the merge interactions with #38379/#39147/#39198.
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Problem
/tmp/x:mkdir nodir/aprintsmkdir: /tmp/x/nodir/a: No such file or directory(every platform, mkdir is always a builtin)touch nodir/fprintstouch: /tmp/x/nodir/f: No such file or directory(every platform, touch is always a builtin)cat missing.txtprintscat: C:\...\x\missing.txt: No such file or directory(Windows only, where cat is a builtin by default; on POSIX both system cat and the builtin printcat: missing.txt: ...)ls: missing: No such file or directory), so this is one message family with three stragglers.shell_openat(src/runtime/shell/interpreter.rs), Windows file branch: it resolves the operand against the cwd withshell_get_pathand returns thebun_sys::openerror unchanged, soerr.pathis the resolved path. The POSIX branch, both WindowsO_DIRECTORYbranches andshell_statatalready re-tag with the caller's path. The builtin cat is the only caller of that branch that printserr.path.ShellTouchTask::run_from_thread_pool(src/runtime/shell/builtin/touch.rs): the localfilepathis the operand joined onto the cwd and both error sites tag with it; the operand isthis.filepath.ShellMkdirTask::run_from_thread_pool(src/runtime/shell/builtin/mkdir.rs): same shadowing at both error sites (-pand plain). Its absolute branch additionally NUL-terminatesthis.filepathin place.Builtin::task_error_to_string(src/runtime/shell/Builtin.rs) prints<builtin>: <err.path>: <message>, so whatever path is tagged is what the user sees.Fix
shell_openat's Windows file branch re-tags the error withpathlike its sibling branches (.map_err(|e| e.with_path(path.as_bytes()))).&this.filepathat both sites; mkdir tagsself.operand()at both sites, a two-line helper returningfilepathminus the NUL its absolute branch may have appended.task_error_to_stringstates the contract:err.pathis printed as the operand, so a builtin that resolves an operand tags the error with it as written.with_pathkeeps errno and syscall tag and replaces only the path, so only the operand part of the message changes. Already-absolute operands come out unchanged (cat and mkdir passed them through verbatim before; touch printed them normalized).mkdir -pkeeps naming the whole operand when an intermediate component is what failed, as it did before; only resolved vs as-written changes.ShellCpTask::is_dirin cp.rs, on by default only on Windows) has the same defect with a different layout (cp: No such file or directory: /tmp/x/missing.txt). shell(cp): report ENAMETOOLONG instead of panicking on operands longer than the path buffers #38162 is rewriting exactly that code, so cp is left for a follow-up on top of it (noted there).mkdir -vandcp -vprint the created/copied paths resolved. That is output rather than an error message and cp's form is pinned by existing tests, so it stays as is.--verbose) already accepts either form of the EEXIST line and needs nothing. shell(cat): keep going after an operand it cannot open or read (stacked on #35337) #39198 can tighten its relaxedcat: ... missing.txtregex the same way this PR tightens shell(cat): map Step to a Yield in one place #39147's. The one code line in interpreter.rs merges cleanly into Remove get_fd_path: derive paths from cwd and what was opened, not from fds #38365 (checked withgit merge-tree).builtins name a failing operand as written: one child process withBUN_ENABLE_EXPERIMENTAL_SHELL_BUILTINS=1(so cat is the builtin on every platform) runs cat, touch and mkdir against a relative operand, one with a subdirectory component, a rooted one (/bunshell-missing-operand/...) and an absolute one, plustouch afile/file.txt(utimes() itself fails, the second touch site) andmkdir -p afile/child(the-psite), and each builtin's first row again with2> err-<builtin>.txt; every row asserts the exact<builtin>: <operand>: <message>line. That reaches all five changed tag sites.builtin cat finishes from its reader and writer completions(from shell(cat): map Step to a Yield in one place #39147): thecat: ... missing.txtmatcher that had to accept the absolute path is now the exact string.USE_SYSTEM_BUN=1(main): the table test fails on its 8 touch/mkdir rows (including both new ones); the cat test passes, as expected on POSIXUSE_SYSTEM_BUN=1(canary built from main): the table test fails on 13 rows and the cat test on 2; output belowbun bd testof both tests at 91a0fa0: pass; bunshell.test.ts + commands/ on the previous revision: 565 pass, 3 unrelated failures (ls permission-denied tests, which fail the same way on main because the container runs as root, and one ls test that hit its 5 s budget in the parallel run and passes alone)bun bd test test/js/bun/shell/bunshell.test.ts test/js/bun/shell/commands/at 91a0fa0: 580 pass, 0 failBackground
cat,ls,mkdir, ...) are implemented in-process under src/runtime/shell/builtin/.catandcpare builtins by default only on Windows (posix_disabledin Builtin.rs); elsewhere they are spawned unlessBUN_ENABLE_EXPERIMENTAL_SHELL_BUILTINS=1is set. touch and mkdir are builtins everywhere.shell_openat(dir, path, ...)is the shell's openat: the shell holds its cwd as an fd and opens operands relative to it. POSIX usesopenat(2); libuv has no openat on Windows, soshell_get_pathfirst turns the operand into an absolute path and a plainopenis used. touch and mkdir do not go through it: they run on a worker thread and join the operand onto the cwd string themselves.bun_sys::Erroris the syscall error: errno, syscall tag and an optionalpath.Error::with_pathcopies errno and tag and replaces the path.Builtin::task_error_to_stringturns it into the<builtin>: <path>: <message>line, mapping errno through the coreutils message table.Fail-before on windows-x64 (system bun, canary built from main)
(the
err-<builtin>.txtrows repeat the first-row lines and are omitted above)Fail-before on linux-x64 (system bun, main)
Earlier shapes of this PR
The first revision fixed only the
shell_openatline (cat on Windows) with a cat-only test, which could only fail on Windows. Review turned up touch and mkdir doing the same thing on every platform, and #38379 about to assert the joined-path form for them, so the PR was widened to the three builtins and the contract line moved fromshell_openat's doc comment (which conflicted with #38365) to the printer. A second review pass pointed out that the table only reached two of the four touch/mkdir sites, which added thetouch afile/file.txtandmkdir -p afile/childrows; the branch was then rebased onto main so that #39147's merged test could be tightened here.no test proof · iteration 0 · Platform-specific test(s) that do not run on this machine. Deferring to CI, which covers all platforms: test/js/bun/shell/bunshell.test.ts