[libarchive] Expand fuzzing from 1 to 25 targets

[skypher]

Summary

Update libarchive build configuration to use all 25 fuzz targets now available in upstream libarchive (merged in libarchive/libarchive#2820).

Changes

• Update build.sh to compile all 25 fuzzers from contrib/oss-fuzz/
• Copy dictionaries and options files for guided fuzzing
• Generate seed corpora from libarchive's test files
• Remove local libarchive_fuzzer.cc (now in upstream repo)

New Fuzzers (24 new, 25 total)

Format-specific (13):

• tar, zip, 7zip, rar, rar5, xar, cab, lha, iso9660, cpio, warc, mtree, ar

Security-critical (4):

• encryption, write_disk (path traversal), read_disk (symlinks), entry (ACL)

API coverage (7):

• write, linkify, match, string, seek, roundtrip, filter

Coverage Targets

Previously uncovered functions now targeted:

Function	Complexity	Coverage Before
archive_entry_linkify	775	0%
ACL functions (7 total)	705-713	0%
xar_read_header	1,416	10.11%

Expected coverage improvement: 74% → 85-95%

Testing

• All 25 fuzzers compile with ASan
• All pass check_build validation
• Upstream PR merged: Expand OSS-Fuzz integration: 1 → 25 fuzz targets libarchive/libarchive#2820
• Local testing with python infra/helper.py build_fuzzers libarchive
• Local testing with python infra/helper.py check_build libarchive

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[github-actions]

skypher is a new contributor to projects/libarchive. The PR must be approved by known contributors before it can be merged. The past contributors are: Mrmaxmeier, DonggeLiu, jvoisin, cvediver, Dor1s, mmatuska (unverified)

[skypher]

@mmatuska Companion PR to libarchive/libarchive#2820, your approval is required. Thanks!

[skypher]

Saw we had some conficts and resolved them. Would be great if we could get this merged, thanks!