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7z

7z is the archive format of the 7-Zip utility. Compress4J creates 7z archives and extracts them, including password-protected ones.

Extraction goes through the same guards as every other format: path traversal is rejected, and escapingSymlinkPolicy, maxEntries, maxEntrySize and maxTotalSize apply.

Example Usage

7z Creation

try (SevenZArchiveCreator sevenZCreator =
        SevenZArchiveCreator.builder(Path.of("example.7z")).build()) {
    sevenZCreator.addFile(Path.of("path/to/file.txt"));
    sevenZCreator.addDirectoryRecursively(Path.of("sourceDir"));
}

7z Extraction

try (SevenZArchiveExtractor sevenZExtractor = SevenZArchiveExtractor.builder(Path.of("example.7z"))
        .overwrite(true)
        .stripComponents(1)
        .filter(entry -> entry.name().endsWith(".txt"))
        .errorHandler((entry, exception) -> SKIP)
        .escapingSymlinkPolicy(ArchiveExtractor.EscapingSymlinkPolicy.DISALLOW)
        .build()) {
    sevenZExtractor.extract(Path.of("outputDir"));
}

Extracting a password-protected archive

try (SevenZArchiveExtractor sevenZExtractor = SevenZArchiveExtractor.builder(Path.of("encrypted.7z"))
        .password("secret".toCharArray())
        .maxEntries(10_000)
        .maxTotalSize(1024L * 1024 * 1024)
        .build()) {
    sevenZExtractor.extract(Path.of("outputDir"));
}

Notes

The creator writes to a file path only, because 7z must seek back to patch its header.
The creator does not encrypt. Only extraction accepts a password.
A symbolic link is stored the way p7zip stores it, as a Unix-mode entry whose content is the link target, and is restored as a symlink on extraction.
A wrong or missing password fails with an IOException.

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