install: stop aborting on link: specifiers and patch paths longer than the path buffers

[robobun]

Problem

• bun install aborts on two more package.json values that are longer than bun's fixed path buffers (4096 bytes on Linux, 1024 on macOS, 32767 * 3 + 1 on Windows). Both are pre-existing in 1.4.0; the sibling workspace: and local .tgz cases are fixed by install: fail instead of panicking when a local tarball or workspace: path does not fit the path buffer #37462 and are not touched here.
• "x": "link:<name>", src/install/resolvers/folder_resolver.rs, normalize_package_json_path, three overflows in one function:
  • the name is normalized through the 1024 byte thread-local scratch of normalize_string, so any name over 1024 bytes aborts: panic: range end index 1025 out of range for slice of length 1024
  • "/package.json" and the NUL terminator are appended to the absolute path without a length check. This one is also reachable with a file: dependency: the folder path itself is length-checked when package.json is parsed (lockfile/Package.rs), the 13 appended bytes are not, so a folder whose absolute path is within 13 bytes of the buffer size aborts: panic: range end index 4104 out of range for slice of length 4096, or panic: index out of bounds: the len is 4096 but the index is 4096 for the NUL
  • get_or_put copies the name as written into a stack PathBuffer before reading the target's package.json, so a name that only fits once normalized (x/../x/../.../foo) aborts after resolving: panic: range end index 100003 out of range for slice of length 4096
• Once the resolver accepts such a name, the hoisted installer (src/install/PackageInstaller.rs, Symlink arm of install_package_with_name_and_resolution) concatenates the global link directory and the name into folder_path_buf without a length check: panic: range end index 5063 out of range for slice of length 4096.
• "patchedDependencies": { "x@1.0.0": "patches/<long>.patch" }, src/install/patch_install.rs: calc_hash (on a thread pool worker, for every entry, whether or not x is a dependency) and apply join the path onto the project directory with join_z_buf into a PathBuffer: panic: range end index 5033 out of range for slice of length 4094.

Fix

• normalize_package_json_path returns None when the package.json path does not fit: the name is normalized with normalize_string_spill (heap when longer than the scratch), the .-prefixed branch joins with abs_buf_checked, the other branch computes the length up front, and the last byte of the buffer is reserved for the NUL. get_or_put maps None to Error::Sys(ENAMETOOLONG), which prints exactly what the OS-rejected case already prints (error: ENAMETOOLONG ... x@link:... failed to resolve, exit 1). The Searched in formatter now builds its ./-prefixed message by appending the relative path to an owned buffer (instead of writing the prefix in front of the path buffer through a pointer cast) and prints the value as written when it does not fit; its output is unchanged and bun-workspaces.test.ts now asserts it.
• The resolver's copy of the name moves to a Box<[u8]>. The copy is still needed (the slice can point into the lockfile string buffer, which reading the target's package.json grows), it just no longer has a fixed size.
• The hoisted installer checks the concatenated length and fails the package (ENAMETOOLONG: link path for package foo is too long, Failed to install 1 package, exit 1; nothing is printed under --silent), the same way the Folder arm above it fails an over-long folder path. Such a target could never be linked anyway: symlink(2) rejects targets longer than PATH_MAX.
• The patch tasks join with join_z_buf_spill, so the path is built on the heap when it does not fit and the OS rejects it. calc_hash's non-ENOENT stat failure used to add a warning saying the patch file is empty (never printed, the main thread then printed a generic "Failed to calculate hash"); it now adds an error with the errno: error: failed to read patch file: ENAMETOOLONG: /proj/patches/ppp...patch: File name too long (stat()), exit 1 as before.
• FileSystem::normalize in src/resolver/lib.rs was the only remaining wrapper around the 1024 byte scratch and has no callers left, so it is removed. The other two direct normalize_string callers outside bun_paths (run_command.rs, Windows only, and the shell's rm) have their own open PRs (cli: stop aborting on absolute script paths longer than 1024 bytes on Windows #37528, shell(rm): stop panicking on operands longer than the path scratch buffers #37521).
• Tests, each of which aborts on the unfixed build (USE_SYSTEM_BUN=1) and passes with bun bd test:
  • test/cli/install/bun-link.test.ts: a 100 kB link: name fails with ENAMETOOLONG; a 100 kB x/../ name that normalizes to a registered link resolves and then fails in the installer (and fails quietly with --silent); the same name for an unregistered package fails with the usual Package "..." is not linked (pins that a long name goes through normal resolution)
  • test/cli/install/bun-install.test.ts (POSIX): a file: dependency whose package.json path is exactly the buffer size, or longer by less than "/package.json", fails with ENAMETOOLONG; one byte below the buffer size it is still looked up on disk (Could not find package.json), which passes before and after and pins the boundary
  • test/cli/install/bun-install-patch.test.ts: a 100 kB patch path fails with the error above (the errno assertion is skipped on Windows, which may report the path as missing instead)
• Also run: the whole of bun-install-patch.test.ts, bad-workspace.test.ts and bun-workspaces.test.ts, and the file: tests of bun-install.test.ts, all green. bun-link.test.ts's "should link dependency without crashing" fails on main with a debug build independently of this change (the debug-only stack dump on install failure lands in stdout, see install: make the debug-build stack dump on package install failure opt-in #37335). cargo check -p bun_install passes for x86_64-pc-windows-msvc and aarch64-apple-darwin; clippy is clean.

Not in this PR

• --linker isolated has its own copy of the installer overflow: isolated_install/Installer.rs append_store_path appends the link name into a length-assuming path (panic: index out of bounds: the len is 4096 but the index is 4096). It is reachable today from a bun.lock with a long link: resolution and, after this PR, from a link: name that only fits once normalized. Reported separately; it sits in the area install: fail the package with ENAMETOOLONG when the isolated linker walks an entry that does not fit the path buffer #37424 is changing.
• workspace:<long path> and ./<long>.tgz: install: fail instead of panicking when a local tarball or workspace: path does not fit the path buffer #37462.

Background

• PathBuffer is a stack array of MAX_PATH_BYTES (the OS PATH_MAX) that most of the install code builds paths in. The joining helpers in bun_paths::resolve_path write into whatever buffer they are given and index out of bounds if the result does not fit; the _checked variants return None instead and the _spill variants grow a caller-provided Vec instead. normalize_string is the variant that writes into a 1024 byte thread-local buffer.
• The folder resolver (folder_resolver.rs) is shared by file: folders, workspace: packages and link: names: it builds the absolute path of the target's package.json, reads it and records the package. For link: the prefix is the global link directory (bun link registers packages there) and the recorded resolution is the name exactly as written, which is what the installers later symlink to.
• patchedDependencies are hashed on a thread pool before anything is installed (PatchTask::calc_hash), so the patch path is joined even when the patched package is not a dependency.

Probe: all shapes on the unfixed and fixed builds (Linux, offline)

unfixed (1.4.0)                                               fixed
link 300 bytes          error: ENAMETOOLONG (OS)              same
link 1025 bytes         panic ... length 1024                 error: ENAMETOOLONG
link 5000 / 100000      panic ... length 1024                 error: ENAMETOOLONG
link 100k of x/../foo   panic ... length 4096 (get_or_put)    Package "x" is not linked
  (foo registered)      panic ... length 4096 (get_or_put)    ENAMETOOLONG: link path for package foo is too long
file: pkg.json path
  = buffer - 1          Could not find package.json           same
  = buffer              panic: index out of bounds 4096       error: ENAMETOOLONG
  = buffer + 8          panic ... 4104 out of range for 4096  error: ENAMETOOLONG
patch path 300 bytes    Couldn't find patch file              same
patch path 5000 / 100k  panic ... length 4094                 error: failed to read patch file: ENAMETOOLONG: ...
workspace: not found    Searched in "./packages/x"            same

Rebase onto 1b88ad3: bun-install-patch.test.ts had gained a describe block at the end of the file on main (patchedDependencies declared by a dependency), so the new block here now follows it and the harness import merges both lists. install_package_with_name_and_resolution had turned its IS_PENDING_PACKAGE_INSTALL const generic into the is_pending_package_install parameter, so the new Symlink check passes that, like the Folder arm next to it. No other changes.

---

no test proof · iteration 1 · Platform-specific test(s) that do not run on this machine. Deferring to CI, which covers all platforms: test/cli/install/bun-install-patch.test.ts test/cli/install/bun-install.test.ts test/cli/install/bun-link.test.ts

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• test/cli/install/bun-link.test.ts

Walkthrough

Installation path handling now checks buffer capacity, supports spilled path storage, reports ENAMETOOLONG, preserves symlink path ownership, and reports patch-file stat errors. CLI tests cover oversized patch, folder, link, and workspace dependency paths.

Changes

Path Buffer Safety

Layer / File(s)	Summary
Fallible path normalization src/install/resolvers/folder_resolver.rs, src/resolver/lib.rs	Folder resolution now uses capacity-aware normalization and returns ENAMETOOLONG for oversized paths. Global symlink paths are copied into owned storage. The obsolete FileSystem::normalize method was removed.
Bounded installation and patch paths src/install/PackageInstaller.rs, src/install/patch_install.rs	Symlink installation rejects paths that exceed the fixed buffer. Patch operations use spill buffers, and non-ENOENT stat failures report the underlying error.
Path-length regression coverage test/cli/install/bun-install-patch.test.ts, test/cli/install/bun-install.test.ts, test/cli/install/bun-link.test.ts, test/cli/install/bun-workspaces.test.ts	Tests cover oversized patch, folder, and link dependency paths, plus workspace path diagnostics, platform-specific errors, silent mode, cleanup, and partial-install prevention.

Suggested reviewers: jarred-sumner

🚥 Pre-merge checks | ✅ 2 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Linked Issues check	⚠️ Warning	The PR addresses install path-buffer overflows, but directly linked issue #39 requires Node.js-compatible build output and is unrelated.	Link the PR to an install-related issue, or add changes that satisfy the coding objectives in #39.
Out of Scope Changes check	⚠️ Warning	All implementation and test changes target install path-buffer handling, not the directly linked Node.js build objectives in #39.	Relink the PR to the relevant install issue and keep #39 separate, or implement the required Node.js build changes.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: preventing aborts from oversized link specifiers and patch paths.
Description check	✅ Passed	The description clearly explains the problem, fix, scope, tests, and verification results, despite not using the template headings exactly.

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[robobun]

Status: ready for review. The diff is green; what is left red on the last CI run is not this PR's.

Reproduced on 1.4.0 and on a debug build of main (e6978042a) with an offline bun install on a package.json containing "x": "link:" + "m".repeat(5000) (panic: range end index 5000 out of range for slice of length 1024) and "patchedDependencies": { "x@1.0.0": "patches/" + "m".repeat(5000) + ".patch" } (panic: range end index 5033 out of range for slice of length 4094), plus the file: boundary and normalizing link: shapes listed in the description. All of them exit 1 with an error on this branch.

CI on the current head (477e259, rebased onto 1b88ad3): every lane passed except the macOS aarch64 test lane, whose only failing file is test/cli/install/bunx.test.ts (GitHub API 504 while downloading a tarball; the same failure is present in recently merged PRs' builds and this PR does not touch bunx). The new tests in bun-link.test.ts, bun-install.test.ts, bun-install-patch.test.ts and bun-workspaces.test.ts passed on Linux (glibc, musl, ASAN), macOS and both Windows lanes. The previous run (build 102107) only lost one ASAN shard to an artifact download timeout, which is why it was rerun once.

The workspace: and local tarball cases from the same report are #37462. The isolated linker's copy of the installer overflow is reported separately (see "Not in this PR").

[robobun]

^{Updated 8:42 PM PT - Aug 20th, 2026}

❌ @robobun, your commit 477e259 has 1 failures in Build #102137 (All Failures):

• test/cli/install/bunx.test.ts - code 1 on 🍎 any aarch64

---

🧪   To try this PR locally:

bunx bun-pr 38359

That installs a local version of the PR into your bun-38359 executable, so you can run:

bun-38359 --bun

[coderabbitai]

Actionable comments posted: 1

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Inline comments:
In `@src/install/resolvers/folder_resolver.rs`:
- Around line 51-74: Update the Some(paths) branch in the
normalize_package_json_path handling to copy paths.rel into an owned buffer
before adding the ./ prefix, rather than slicing joined based on its length.
Append paths.rel after writing the prefix and return the owned buffer, while
preserving the existing handling for already-prefixed paths and None.

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📒 Files selected for processing (7)

• src/install/PackageInstaller.rs
• src/install/patch_install.rs
• src/install/resolvers/folder_resolver.rs
• src/resolver/lib.rs
• test/cli/install/bun-install-patch.test.ts
• test/cli/install/bun-install.test.ts
• test/cli/install/bun-link.test.ts

💤 Files with no reviewable changes (1)

• src/resolver/lib.rs

[claude]

I reviewed this PR again after the follow-up commits and found no further issues — the --silent gating, the owned ./-prefix buffer, the shortened comments, and the stdout draining are all in place. Because the fix rewrites normalize_package_json_path (shared by file:, link:, workspace: and cache-folder resolution), a maintainer glance at that refactor would still be worthwhile.

What was reviewed:

• Traced both branches of the rewritten normalize_package_json_path against the old code — the .-prefixed branch drops the redundant top_level_dir part (abs_buf_checked already joins onto it) and the else-branch's up-front length matches the old byte-by-byte build; the hoisted rel computation is unchanged.
• Confirmed abs_buf_checked and the _spill helpers exist with the expected semantics in resolve_path.rs / resolver/lib.rs.
• Checked the calc_hash non-ENOENT path: the old add_warning_pretty!("patchfile is empty") was both wrong and never printed; the new add_error_fmt plus the has_errors() branch in run_from_main_thread_calc_hash surfaces the real errno.
• New tests cover each overflow site, the file: boundary, and --silent; the Searched in output is now pinned.

Extended reasoning...

Overview

Five source changes across src/install/ and src/resolver/, plus four test files. The core is a rewrite of normalize_package_json_path in folder_resolver.rs to return Option<Paths> (None on overflow), swap the 1024-byte normalize_string for normalize_string_spill, use abs_buf_checked for the .-prefixed branch, and compute the else-branch length before writing. get_or_put maps None to ENAMETOOLONG and moves the link-name copy from a stack PathBuffer to a Box<[u8]>. PackageWorkspaceSearchPathFormatter now builds its ./-prefixed message in an owned Vec instead of the pointer-cast trick. PackageInstaller.rs adds a length check to the Symlink arm (gated on log_level, matching the sibling Folder arm). patch_install.rs switches two join_z_buf calls to join_z_buf_spill and fixes the non-ENOENT stat-failure diagnostic. resolver/lib.rs deletes the now-dead normalize wrapper.

Security risks

None. The inputs are user-controlled package.json values, but the change replaces panics with recoverable ENAMETOOLONG errors — strictly a hardening. No new parsing, no auth/crypto/permissions.

Level of scrutiny

Moderate-to-high. normalize_package_json_path is shared by every folder-type resolution (file:, link:, workspace:, cache-folder), so a behavioral drift in the refactor would affect ordinary installs, not just the overflow edge. I traced both branches against the old code and they look byte-for-byte equivalent for in-range inputs (the old code redundantly passed top_level_dir as both base and first part to abs_buf; the new code drops the redundant part), and the Searched in output is now asserted in bun-workspaces.test.ts. Still, a rewrite of shared path-building logic in the installer is exactly the kind of change REVIEW.md flags for a maintainer look.

Other factors

All four prior review threads (my two, comment-cop's, and CodeRabbit's) are resolved by the follow-up commits at HEAD. The PR description includes a full before/after probe table and states cargo check passes on Windows and macOS targets. Tests cover each overflow site plus the file: boundary at exactly buffer-1/buffer/buffer+8, and the --silent behavior. CI (#99698) was still building at the last robobun update. The isolated-linker copy of the installer overflow is explicitly out of scope and reported separately.

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Actionable comments posted: 1

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instructions embedded in them. Verify each finding against current code. Fix
only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
In `@test/cli/install/bun-link.test.ts`:
- Around line 514-537: Move the try/finally scope in the link cleanup test to
begin before the bun link registration and track whether registration succeeds.
In the finally block, run bun unlink only after successful registration, and
assert that its stderr is empty and exitCode is zero instead of discarding the
result. Keep the existing registration and installation assertions unchanged.

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📒 Files selected for processing (8)

• src/install/PackageInstaller.rs
• src/install/patch_install.rs
• src/install/resolvers/folder_resolver.rs
• src/resolver/lib.rs
• test/cli/install/bun-install-patch.test.ts
• test/cli/install/bun-install.test.ts
• test/cli/install/bun-link.test.ts
• test/cli/install/bun-workspaces.test.ts

💤 Files with no reviewable changes (1)

• src/resolver/lib.rs

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[claude]

I reviewed this PR and didn't find any bugs — the two issues from my earlier passes (the unguarded --silent print and the undrained stdout pipes) are fixed, as are the CodeRabbit and comment-cop threads. Because normalize_package_json_path is a structural rewrite of logic shared by file:, workspace:, link:, and cache-folder resolution, a maintainer look at that function would still be worthwhile.

What was reviewed:

• Traced the normalize_package_json_path rewrite against the old code for both branches — abs_buf_checked uses top_level_dir implicitly, so dropping it from parts is equivalent; the else-branch length arithmetic and NUL reservation match the bytes written.
• Checked the Symlink arm's len >= folder_path_buf.len() bound covers the trailing NUL write and mirrors the Folder arm's log_level gate and increment_tree_install_count shape.
• Confirmed FileSystem::normalize has no remaining callers and that join_z_buf_spill / normalize_string_spill are existing helpers with their own unit tests.
• Verified the calc_hash warning→error swap makes the message actually print (the old warning was dropped by the has_errors() gate on the main thread).

Extended reasoning...

Overview

Fixes five panic-on-oversized-input sites in bun install's path handling: three in folder_resolver.rs::normalize_package_json_path (the 1024-byte normalize_string scratch, the unchecked /package.json + NUL append, and the get_or_put stack PathBuffer copy), one in PackageInstaller.rs's Symlink arm (global_link_dir + folder concatenation), and two in patch_install.rs (join_z_buf for apply and calc_hash). Also rewrites PackageWorkspaceSearchPathFormatter to build its ./-prefixed message in an owned Vec instead of an unsafe in-place pointer cast, removes the now-uncalled FileSystem::normalize, and swaps calc_hash's misleading "patchfile is empty" warning (never printed) for an errno-carrying error. ~200 lines of new tests across four files, each verified to abort on the unfixed build.

Security risks

None new. The change hardens against adversarial package.json values (100 KB link: names, 100 KB patch paths) that previously aborted the process; after the change they surface as ENAMETOOLONG and exit 1. No new file reads, network calls, or trust boundaries.

Level of scrutiny

Medium-high. normalize_package_json_path is on the resolution path for every file:, workspace:, link:, and cache-folder dependency, and this PR restructures it (the two arms now share the trailing rel = relative(...) / NUL write, the else-arm computes abs_len up front instead of tracking a remain cursor). I traced both arms byte-for-byte against the old code and they produce the same joined contents for inputs that fit; the bun-workspaces.test.ts assertion pins the Searched in output. The other four source changes are localized bounds checks or spill-buffer swaps.

Other factors

All seven prior review threads (two from me, one CodeRabbit correctness note on the ./ prefix, four comment-cop long-comment flags, and CodeRabbit's cleanup-scope note) are resolved in the current head. The PR description's probe table covers every shape on both builds. The isolated-linker copy of the installer overflow is explicitly out of scope (reported separately). Deferring only because the shared-resolver rewrite is the kind of restructuring a maintainer typically signs off on.

[robobun]

Closing in favor of #43067. It fixes this trigger with the shared checked path helpers and carries the tests from this pull request.