Examples

[probonopd]

Is your feature request related to a problem? Please describe.

I'd like to consume libsqsh in a Qt based application to extract files from squashfs to files and/or memory. For this reason, I'd like to have it wrapped in a C++ class.

Describe the solution you'd like

Something along those lines with a working .cpp implementation

#ifndef SQSH_FSEXTRACTOR_H
#define SQSH_FSEXTRACTOR_H

#include <QString>
#include <QByteArray>
#include <QList>
#include <QDir>

#include "SqshFSInfo.h" // Include the previously defined SqshFSInfo class

class SqshFSExtractor
{
public:
    SqshFSExtractor(const QString &imagePath);
    ~SqshFSExtractor();

    SqshFSInfo getFileInfo(const QString &filePath) const;
    QList<SqshFSInfo> listFilesRecursively() const; // Recursive listing; like find /
    QList<SqshFSInfo> listFiles() const; // Directory listing, like ls /

    bool extractToFile(const QString &filePath, const QString &outputFilePath);
    bool extractRecursively(const QString &sourceDir, const QString &targetDir);
    QByteArray extractToMemory(const QString &filePath);

private:
    // Add any private members or helper functions here as needed
};

#endif // SQSH_FSEXTRACTOR_H

#ifndef SQSH_FSINFO_H
#define SQSH_FSINFO_H

#include <QString>
#include <QVector>

enum class FileType {
    File,
    Directory,
    Symlink,
    Device,
    Other
};

class SqshFSInfo
{
public:
    SqshFSInfo(const QString &name, FileType type, qint64 size = 0);
    ~SqshFSInfo();

    QVector<SqshFSInfo> getChildren() const;
    QString getName() const;
    FileType getType() const;
    qint64 getSize() const;

private:
    QString name;
    FileType type;
    qint64 size;
    QVector<SqshFSInfo> children;
};

#endif // SQSH_FSINFO_H

Additional context

Unfortunately, I am not able to do this with the current documentation. Do you think it can be done? Would you be able to present a sample implementation?

[Gottox]

I pretty much think, that a C++ wrapper should be achievable. While libsqsh is written in C, the headers are C++ compatible (otherwise consider this a bug and worth reporting).

The implementation stub you provided is a bit naive, as it expects the whole file tree to be loaded into memory, which will not scale with larger archives.

Unfortunately writing a wrapper is out of scope for this project and while I can give you hints, I can't provide you with any good examples, as I'm not experienced with C++.

[probonopd]

Thanks for your quick response. You are right about extractRecursively, it should be done differently.

To get things started, could you point me at working C examples for how to:

• Extract one (small-ish, think icon) known file to memory (following symlinks if needed)
• List all files in one defined directory (e.g., the root directory)

That would be a tremendous help to get me started. Thank you!

[Gottox]

Thanks for the input. That's a great way to improve the documentation!

• Extract one (small-ish, think icon) known file to memory (following symlinks if needed)

sqsh_file_content(archive, path) will do exactly that. It is one of the lesser tested areas in libsqsh, so if you find issues, I'm eager to fix them!

• List all files in one defined directory (e.g., the root directory)

I just wrote an example for this use case. Have a look in examples in the main branch.

[probonopd]

Thanks @Gottox. Very useful indeed!

I am having issues building it. I could not figure out a way to compile just the example using the given meson.build (but I will need to use CMake anyway). Using this

cmake_minimum_required(VERSION 3.0)
project(libsqsh-examples)

# Set the C++ standard to C++11 or higher
set(CMAKE_CXX_STANDARD 11)

# Find libsqsh using pkg-config
find_package(PkgConfig REQUIRED)
pkg_check_modules(LIBSQSH REQUIRED libsqsh)

# Add the include directories for libsqsh
include_directories(${LIBSQSH_INCLUDE_DIRS})

# Build the 'list_files' executable
add_executable(list_files list_files.c)
target_link_libraries(list_files ${LIBSQSH_LIBRARIES})

# Build the 'list_files_ll' executable
add_executable(list_files_ll list_files_ll.c)
target_link_libraries(list_files_ll ${LIBSQSH_LIBRARIES})

it builds :+1: Maybe others will find this information useful, too.

[Gottox]

A few bits and pieces of the API are unstable till v1.0, so if you run into problems, either wait for the 0.6.0 release or use the main branch for now.

[probonopd]

I can confirm that the example works for me using the main branch.

% mksquashfs squashfs-root test.sfs -comp zstd

% /tmp/libsqsh/examples/build/list_files test.sfs 
.DirIcon
AppRun
appimagetool.desktop
appimagetool.png
usr

% /tmp/libsqsh/examples/build/list_files_ll test.sfs 
.DirIcon
AppRun
appimagetool.desktop
appimagetool.png
usr

[probonopd]

The only thing that does not work yet is extracting the data if the file is actually a symlink. Can you point me to a solution for this? E.g., how to (recursively) resolve symlinks. Thanks again for your help, which is tremendous.

[Gottox]

I think that's an actual bug. At least that's a blind spot in the unit tests.

[probonopd]

Should I open a new issue for it?

[Gottox]

Yes please! - I created a unit test for following symlinks, but I cannot reproduce the issue at the moment.

[Gottox]

At least the high level API (sqsh_file_contents, sqsh_directory_list) should work transparently on symlinks.