Fix mkstemp path in setup_mac_metadata

setup_mac_metadata currently concates the template after TMPDIR without
adding a path separator, which causes mkstemp to create a temporary file
next to TMPDIR instead of in TMPDIR. Add a path separator to the
template to ensure that the temporary file is created under TMPDIR.

I hit this while rebuilding libarchive in nixpkgs. Lix recently started
using a dedicated build directory (under /nix/var/nix/builds) instead of
using a directory under /tmp [1]. nixpkgs & Lix support (optional)
on macOS sandboxing. The default sandbox profile allows builds to access
paths under the build directory and any path under /tmp. Because the
build directory is no longer under /tmp, some of libarchive's tests
started to fail as they accessed paths next to (but not under) the build
directory:

cpio/test/test_basic.c:65: Contents don't match
   Description: Expected: 2 blocks
, options=
  file="pack.err"
0000_62_73_64_63_70_69_6f_3a_20_43_6f_75_6c_64_20_6e_bsdcpio: Could n
0010_6f_74_20_6f_70_65_6e_20_65_78_74_65_6e_64_65_64_ot open extended
0020_20_61_74_74_72_69_62_75_74_65_20_66_69_6c_65_0a_ attribute file.

Sandbox: bsdcpio(11215) deny(1) file-write-create /nix/var/nix/builds/nix-build-libarchive-3.8.0.drv-7tar.md.5EUrQu

[1]: https://lix.systems/blog/2025-06-24-lix-cves/

diff --git a/libarchive/archive_read_disk_entry_from_file.c b/libarchive/archive_read_disk_entry_from_file.c
index 19d049770b784bba60215526afe9e62f38964c94..87389642db4ae3fb3eaace7fea348acdb1f6ef46 100644 (file)
--- a/libarchive/archive_read_disk_entry_from_file.c
+++ b/libarchive/archive_read_disk_entry_from_file.c
@@ -364,7 +364,7 @@ setup_mac_metadata(struct archive_read_disk *a,
                tempdir = _PATH_TMP;
        archive_string_init(&tempfile);
        archive_strcpy(&tempfile, tempdir);
-       archive_strcat(&tempfile, "tar.md.XXXXXX");
+       archive_strcat(&tempfile, "/tar.md.XXXXXX");
        tempfd = mkstemp(tempfile.s);
        if (tempfd < 0) {
                archive_set_error(&a->archive, errno,