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`{}` with `bstr::BStr` writes U+FFFD for each byte that is not UTF-8. Two
commands formatted a path that way into data that another program reads, so
a path with such a byte came out as the path of another file:
- `bun pm bin` printed it.
- `Bun.cron()` built the crontab entry, and on macOS the LaunchAgents
directory and the plist path from `$HOME`.
Each site now joins the bytes.
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Status: fix is in this PR (#46504). Reproduction on main 9634520 and on 1.4.3-canary 367d939, Linux x64: mkdir "$(printf 'proj-\377')" && cd "$(printf 'proj-\377')" && echo '{"name":"p"}' > package.json
bun pm bin | od -An -c
# .../proj-\357\277\275/node_modules/.bin (the directory is proj-\377)
mkdir -p stub proj "$(printf 'bin-\377')" && ln "$(command -v bun)" "$(printf 'bin-\377')/bun"
printf '#!/bin/sh\n[ "$1" = -l ] && exit 1\ncat "$1" > /tmp/installed.txt\n' > stub/crontab && chmod +x stub/crontab
echo 'export default { scheduled() {} };' > proj/job.ts
(cd proj && PATH="$PWD/../stub:$PATH" "../$(printf 'bin-\377')/bun" -e 'await Bun.cron("./job.ts", "30 2 * * 1", "t")')
od -An -c /tmp/installed.txt
# 30 2 * * 1 '.../bin-\357\277\275/bun' run --cron-title=t ... (the executable is in bin-\377)CI on 20f1cce (build 132808): 179 of 181 jobs passed, and no job failed. The new tests passed on Linux and on darwin aarch64. The 2 darwin x64 test jobs have no agent yet. |
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Updated 4:49 PM PT - Oct 25th, 2026
✅ @robobun, your commit 20f1cce1ca34b799b81fef7285534299306bcb51 passed in 🧪 To try this PR locally: bunx bun-pr 46504That installs a local version of the PR into your bun-46504 --bun |
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No actionable comments were generated in the recent review.
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| Layer / File(s) | Summary |
|---|---|
Cron path handling src/runtime/api/cron.rs, test/js/bun/cron/cron.test.ts |
Crontab entries and macOS LaunchAgents paths are built from bytes. Tests cover non-UTF-8 executable, script, and home paths, including macOS registration and removal cases. |
Package manager path output src/runtime/cli/package_manager_command.rs, test/cli/install/bun-pm.test.ts |
bun pm bin writes the resolved path as bytes followed by a newline. Linux tests check project and global paths containing a non-UTF-8 byte. |
Suggested reviewers: jarred-sumner
Priority:
Merge Risk: 
20f1c
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The reported risk of these tests stopping a user’s job has been addressed. No actionable merge-blocking issue is established; the macOS tests still need their planned Darwin CI run.
Pre-merge checks: 
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Check name Status Explanation Title check The title clearly and concisely summarizes the main change: preserving path bytes in bun pm binandBun.cron.Linked Issues check Check skipped because no linked issues were found for this pull request. Out of Scope Changes check Check skipped because no linked issues were found for this pull request. Description check The description provides complete problem, fix, scope, limitations, and verification details. It does not use the template headings exactly, but it clearly covers both required topics: what the PR doe… Full details: Description check
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Explanation
The description provides complete problem, fix, scope, limitations, and verification details. It does not use the template headings exactly, but it clearly covers both required topics: what the PR does and how the changes were verified.
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Actionable comments posted: 1
- 🪄 Fix comments: Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @test/js/bun/cron/cron.test.ts:
- Line 765: Update the cron tests that call launchctl bootout so the removal
test uses a unique job title, and remove the first test’s bootout cleanup
because registration fails before a job is created. Locate the affected tests by
the `title` declaration and preserve their existing assertions.
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ℹ️ Review info
⚙️ Run configuration
- Source mode: Auto
- Repository: oven-sh/bun
- Branch: robobun/ebc35243/pm-bin-cron-path-bytes
- File: .coderabbit.yaml
- Commit: 549aee6
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📒 Files selected for processing: 4
src/runtime/api/cron.rssrc/runtime/cli/package_manager_command.rstest/cli/install/bun-pm.test.tstest/js/bun/cron/cron.test.ts
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Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.
Additional findings (outside the current diff — GitHub can't attach inline comments there):
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src/runtime/api/cron.rs— A Linux user whose bun executable path contains a newline gets a crontab thatcrontabrejects, or a split entry, from Bun.cron().abs_pathis checked for',%,\nand\rat src/runtime/api/cron.rs:809-825, butbun_exeat src/runtime/api/cron.rs:833 is only checked for'and%. The new concat at cron.rs:485-501 copies every byte ofself.bun_exeinto the entry, so a line break ends the cron line inside the single quotes. Fix: validatebun_exewith the same four-byte check asabs_path, in one shared helper used by both sites, and reject with the same "Path must not contain line breaks" error.Why this was flagged
The trigger is a bun binary installed under a directory whose name contains
\nor\r, which Linux allows, arriving through Bun.cron() on Linux. cron_register at src/runtime/api/cron.rs:827-838 takes bun_core::self_exe_path and rejects only'and%via index_of_any, while abs_path at src/runtime/api/cron.rs:820-824 also rejects line breaks. prepare_install_crontab at src/runtime/api/cron.rs:485-501 now copies the raw exe bytes into the entry, so the line30 2 * * 1 '/opt/bu\nn/bun' run ...is two crontab lines;crontab <file>either refuses the file (Bun.cron() rejects with the generic install error) or, for\r, installs a command that cannot exec. The dismissal said base behaved identically; the base did pass newlines through bstr::BStr as well, so the exposure is pre-existing, but this PR is the one that makes the exe bytes verbatim and touches both validation and the entry builder, and the two sibling checks disagree. Remedy: apply the abs_path byte validation to bun_exe through one shared function.Verification: pre-existing. On Linux, the bun executable path contains a
\nbyte and the user calls Bun.cron(). src/runtime/api/cron.rs:833 only doesindex_of_any(bun_exe.as_bytes(), b"'%"), so a line break inbun_exepasses and cron.rs:485-501 places it verbatim, socrontab <tmpfile>rejects the file. The base at 7a74841 has the identical two-byte check, so the base fails by the same route.
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Replies to the review of 549aee6:
main 179664e is merged in. |
Problem
bun pm binandBun.cron()write U+FFFD (EF BF BD) for each path byte that is not UTF-8. Inproj-\xFF,bun pm binprintsproj-\xEF\xBF\xBD/node_modules/.bin, so"$(bun pm bin)/tool"exits 127./home/jos\xE9/.bun/bin,Bun.cron()resolves and the installed crontab line exits 127.{}withbstr::BStrinto a byte sink (src/runtime/cli/package_manager_command.rs:346,src/runtime/api/cron.rs:485). 1.3.14 copied the bytes. No user reported it (fuzzing, Linux only).Fix
bun pm binwrites the path withOutput::print_bytes. The crontab entry is oneconcat().plist_pathjoins$HOMEand the plist name as bytes.test/cli/install/bun-pm.test.ts,test/js/bun/cron/cron.test.ts(4 Linux tests fail on main, 2 macOS tests pass in CI). Self-reviewed: 11 concerns raised, 10 addressed (Notes).Background
bstr::BStrlets{}take&[u8]. ItsDisplayreplaces invalid bytes: right for a message, wrong for a path.Bun.cron(path, schedule, title)registers an OS job: a crontab line on Linux, a launchd plist on macOS.core::fmt(its writers take&str) and aBStr::newlint (it sees neither statement).bun completions: completions: build the bunx link and .zshrc paths from raw bytes #46423.Downsides
bun pm bincan now print invalid UTF-8, as 1.3.x did.Bun.cron()with such a$HOMEnow fails atmkdir. Before, it registered the job from another directory.Notes
Provenance and reach. Found by automated fuzzing of paths that are not UTF-8. No issue exists, and no user reported it in 1.4.0 to 1.4.3. It needs a byte that is not UTF-8 in the project, home or install path (a Latin-1, Shift-JIS or GBK name), which Linux accepts. macOS refuses such file names, and Windows names are UTF-16.
"$(bun pm bin)",bun pm bin -gunder such a home, and a cron job whosebunis under such a path.error: Module not found). A JavaScript bin there, and a cron job whose script is there, do not run. For that script the crontab entry is again the text that 1.3.14 wrote, and no more.Repro (Linux x64, release builds of main 9634520 and of 1.4.3-canary 367d939).
Bun.cron(), with a stand-incrontabfirst onPATHso that the crontab of the user is not touched:The statements.
package_manager_command.rs:346,bun pm binandbun pm bin -gprettyln!("{}", BStr)Output::print_bytes, the same buffered writercron.rs:484-498, crontab entry (Linux)write!with fourBStrinto a scratchVec, then a copyconcat()of 13 byte partscron.rs:567-572, macOS LaunchAgents directorywrite!("{}/Library/LaunchAgents", BStr(home))[home, b"/Library/LaunchAgents"].concat()cron.rs:580-584and:1174-1178, macOS plist pathalloc_print_ztemplateplist_path(home, title)The title is
[A-Za-z0-9_-]and the schedule is normalized digits, so only the executable, the script and$HOMEcan hold such a byte. The two "Out of memory" arms on the plist path are gone: a write to aVeccannot fail.macOS (read from the code, not run here).
$HOMEis not validated, and it stays the source of the LaunchAgents path, as in 1.3.14 and the docs. APFS refuses a name that is not UTF-8, so only a$HOMEthat the environment overrides can hold such a byte. WithHOME=/x/home-\xFF, main creates/x/home-\xEF\xBF\xBD/Library/LaunchAgents, writes the plist there and bootstraps it, andBun.cron.remove()unlinks the plist of that other directory. Now the real path is used:Bun.cron()rejects withFailed to create ~/Library/LaunchAgents directory, andBun.cron.remove()unlinks nothing. The two macOS tests assert that. They gate onisMacOSonly, because neither needs a login session. A darwin aarch64 lane ran both tests green (builds 130877 and 132808).Not changed.
bun completions(bunx link,.zshrcline): completions: build the bunx link and .zshrc paths from raw bytes #46423.bun pm pack --quietwith--destinationor--filename: inproj-\xFFit printsproj-\xEF\xBF\xBD/dist/p-1.0.0.tgz. That line has printed throughbun_fmt::EscapeControlCharssince install: fix regressions and older bugs found after the package manager consolidation #45307, and that escaping writes U+FFFD for a byte that is not UTF-8 (fmt.rs:3605). 1.3.14 wrote the bytes with no escaping. A byte-exact path there needs a decision about the escaping (for example raw bytes in 0x80 to 0x9F), so it is a separate change.src/runtime/cli/run_command.rs:1102-1110: the cron runner writes the script path into JavaScript source with{}. This is not a site to convert: JavaScript source is text, and bun cannot load a module at such a path.cron.rs:611-640) and the Windows task XML. They are declared UTF-8 and cannot carry such a byte.alloc_print_zcallers that format only the title and the uid, and the marker offilter_crontab(title only).bun pm lsheader lines and the other messages: text for a person.PackageInstall.rs:2499-2514andrun_command.rs:3514-3523(a$TMPDIRpath): the same shape in other files, read but not reproduced here.Measurements (release builds of main 9634520 and of this diff on it, Linux x64).
.text: 81,932,069 -> 81,932,069 bytes,.rodataand.dataequal (size -A).PackageManagerCommand::exec12,709 -> 12,649 bytes. Crontab install (CronRegisterJob::advance_state, which inlines it) 2,317 -> 2,394 bytes (nm -S).bun pm binprint, 37-byte path: 627 -> 146 instructions, 0 -> 0 allocator calls (gdbstepifrom the return ofjoin_absto the call ofOutput::flush, 3 of 3 identical).Bun.croncrontab entry: 6 -> 3 allocator calls with no crontab, 5 -> 2 with a 10-line crontab. Instructions: 3,246 -> 773 and 3,139 -> 668 (gdb, statement window, 2 of 2 identical).bun pm bin | catwrite(1) 1 -> 1.Bun.crontemp-file write 1 -> 1 (qemu-x86_64 -strace).rust:check-all: 12 of 12 targets pass.bun bd test. The 2 macOS tests ran green on the darwin aarch64 lane of builds 130877 and 132808 (the file: 90 pass, 31 skip, 0 fail, the count with both tests run). The darwin x64 test jobs had no agent in either build. The tests did not run locally.reserve. The compiler unrolled it:.text+1,024 bytes (advance_state2,317 -> 3,215) for 1 allocator call.concat()costs 0 bytes.perf,strace,valgrindandbloatyare not installed here.Tests.
test/cli/install/bun-pm.test.ts(Linux): the project'snode_modules/.bin, and the global bin directory.test/js/bun/cron/cron.test.ts(Linux, stand-incrontab): the entry text for an executable and a script under\xFFdirectories, and a run of the installed command the way cron starts it (sh -cin$HOME) for a homejos\xE9with bun in$HOME/.bun/bin. On main that run exits 127.test/js/bun/cron/cron.test.ts(macOS): the two$HOMEtests above. Each has a launchd label of its own.no crontab for userlike crontab(1), because Serialize Bun.cron crontab edits, fail closed on crontab -l errors, filter only bun entries #41651 reads that text.Self-review. 11 concerns raised, 10 addressed. Not adopted: a split into one PR for
pm binand one forBun.cron. It is one defect with one idiom and 37 added source lines. The split stays the fallback if the cron half stalls. The review preferred to drop the macOS hunks unless a darwin lane runs their tests green. A darwin aarch64 lane did (builds 130877 and 132808), so they stay.Related.
bunxpaths, the same idiom.run --filter,build --outfile, CSS module hash, shellwhich. Its body leaves these commands to separate fixes. The branchrobobun/6c79bcdb/pm-bin-path-byteshas the samepm binstatement and no PR.bun completions.prepare_install_crontabandfilter_crontab, and adds its owncrontabstand-in tocron.test.ts.--cwd='{cwd}'to the same crontab statement throughbstr::BStr. After this PR the cwd belongs in the byte parts.$HOMEwith{}.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/cron/cron.test.ts, test/cli/install/bun-pm.test.ts