libsqsh

libsqsh is a purely 2-Clause BSD Licensed implementation of the squashfs filesystem in C11. It covers the complete squashfs feature set, while still having minimal memory footprint.

Note that libsqsh only supports reading squashfs archives. If you want to create squashfs archives, you can either use squashfs-tools, which provides a command line interface, or squashfs-tools-ng, which provides both a command-line interface and a C library interface.

Features

• Complete feature set: libsqsh supports all features of the squashfs file system.
• Thread-safe: libsqsh is thread-safe and can be used in multi-threaded applications.
• Safe: While we cannot guarantee that libsqsh is bug-free, we have a test suite that covers lots of edge cases and fuzz the library regularly. We trust it enough to use libsqsh to open untrusted squashfs archives. libsqsh runs consistency checks over the squashfs archive to catch loops in the directory trees, invalid file names and a few other error states that are not covered by other implementations.
• Fast: while we need to keep a trade off between safety and speed, we try to keep the performance impact as low as possible. In certain scenarios, libsqsh ranks among the fastest squashfs implementations.
• Modern C11 implementation: Written in modern C11, libsqsh is designed for efficiency and compatibility with C++, C, and other languages.
• Pure 2-Clause-BSD License: libsqsh is licensed under the 2-Clause BSD license. This allows you to use libsqsh in any project, even commercial ones.

Example

This is a simple example that a) prints the content of a file and b) lists the content of a directory.

struct SqshArchive *archive =
        sqsh_archive_open("/path/to/archive.squashfs", NULL, NULL);
assert(archive != NULL);
 
uint8_t *contents = sqsh_easy_file_content(archive, "/path/to/file", NULL);
assert(contents != NULL);
const uint64_t size = sqsh_easy_file_size2(archive, "/path/to/file", NULL);
fwrite(contents, 1, size, stdout);
free(contents);
 
char **files = sqsh_easy_directory_list(archive, "/path/to/dir", NULL);
assert(files != NULL);
for (int i = 0; files[i] != NULL; i++) {
    puts(files[i]);
}
free(files);
 
sqsh_archive_close(archive);

Find further examples in the examples directory.

Note on Deprecation

The sqsh-tools team works hard to keep the API stable. As a result, some functions are marked as deprecated but remain available for the current major version. The replacements for these deprecated functions typically have the same name with a ...2 suffix.

In the next major (at the time of writing v2.0.0) version, the ...2 functions will be renamed to their original names, and the deprecated functions will be removed.

Resource

• https://dr-emann.github.io/squashfs/squashfs.html - A detailed description of the squashfs file format.
• https://github.com/plougher/squashfs-tools/ - The original squashfs-tools implementation.
• https://github.com/AgentD/squashfs-tools-ng/ - A rewrite of the squashfs-tools implementation with library support. In contrast to libsqsh, this library is able to write squashfs archives.
• https://github.com/vasi/squashfuse - A C implementation of the squashfs filesystem.
• https://github.com/wcampbell0x2a/backhand - A Rust implementation of the squashfs filesystem.