tree-walk: fix mode and embedded NUL handling in get_tree_entry_follow_symlinks by inanna-malick · Pull Request #2475 · git/git

inanna-malick · 2026-10-30T05:44:17Z

In get_tree_entry_follow_symlinks(), fix three edge cases when resolving paths and symlink targets:

Initialize *mode = 0 at entry and set *mode = S_IFDIR when an empty path (name = "") resolves directly to the root tree, rather than leaving *mode uninitialized when returning FOUND.
When a symlink target such as .. resolves back to a parent directory and leaves namebuf empty (namebuf.buf[0] == '\0'), set *mode = S_IFDIR instead of leaving the symlink's S_IFLNK mode in *mode.
When reading a symlink blob, check for embedded NUL bytes with memchr(contents, '\0', link_len) and treat such a symlink as DANGLING_SYMLINK. Splicing a target containing an embedded NUL into namebuf previously caused strchr(namebuf.buf, '/') to stop at the NUL and silently discard any remaining path components after the symlink.

Found via agent swarm driven property tests using https://recursion.wtf/posts/agents-and-property-tests/

…w_symlinks In get_tree_entry_follow_symlinks(), fix three edge cases when resolving paths and symlink targets: 1. Initialize `*mode = 0` at entry and set `*mode = S_IFDIR` when an empty path (`name = ""`) resolves directly to the root tree, rather than leaving `*mode` uninitialized when returning `FOUND`. 2. When a symlink target such as `..` resolves back to a parent directory and leaves `namebuf` empty (`namebuf.buf[0] == '\0'`), set `*mode = S_IFDIR` instead of leaving the symlink's `S_IFLNK` mode in `*mode`. 3. When reading a symlink blob, check for embedded NUL bytes with `memchr(contents, '\0', link_len)` and treat such a symlink as `DANGLING_SYMLINK`. Splicing a target containing an embedded NUL into `namebuf` previously caused `strchr(namebuf.buf, '/')` to stop at the NUL and silently discard any remaining path components after the symlink. Found via agent swarm driven property tests using https://recursion.wtf/posts/agents-and-property-tests/ Signed-off-by: Inanna Malick <inanna@recursion.wtf>

gitgitgadget-git · 2026-10-30T05:44:50Z

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gitgitgadget-git · 2026-10-30T05:44:52Z

There is an issue in commit 88c4407:
tree-walk: fix mode and embedded NUL handling in get_tree_entry_follow_symlinks

First line of commit message is too long (> 76 columns)

Copilot

🟡 Changes recommended

Regression tests are missing for embedded-NUL symlink targets and directory object modes under --follow-symlinks, leaving these behavior changes unguarded.

1 open issue

Add tests for NUL symlinks and followed directory modes · New

What changed in this PR

This PR fixes edge cases in Git’s tree-path resolution when following symlinks, ensuring correct directory modes and rejecting malformed symlink targets.

Changes:

Initializes the output mode and returns S_IFDIR when an empty path resolves to the root tree.
Returns S_IFDIR when a symlink resolves back to a parent directory.
Treats symlink blobs containing embedded NUL bytes as dangling instead of silently truncating the path.

File	Description
`tree-walk.c`	Corrects directory modes and rejects embedded-NUL symlink targets in `get_tree_entry_follow_symlinks()`.

_{Review effort: Balanced}

+			if (memchr(contents, '\0', link_len)) {
+				free(contents);
+				goto done;
+			}


Copilot AI balanced review requested due to automatic review settings October 30, 2026 05:44

github-project-automation Bot added this to Op-Amp Frequency Response and Applications Suite Oct 30, 2026

github-project-automation Bot moved this to Todo in Op-Amp Frequency Response and Applications Suite Oct 30, 2026

Copilot started reviewing on behalf of inanna-malick October 30, 2026 05:44

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gitgitgadget-git Bot added the new user label Oct 30, 2026

Copilot AI reviewed Oct 30, 2026

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Comment thread tree-walk.c

Comment on lines +810 to +813

if (memchr(contents, '\0', link_len)) {

free(contents);

goto done;

}

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tree-walk: fix mode and embedded NUL handling in get_tree_entry_follow_symlinks - #2475

tree-walk: fix mode and embedded NUL handling in get_tree_entry_follow_symlinks#2475
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