libarchive returns error on some entries while 7z can extract normally

Question

I'm having trouble with libarchive version 3.3.2. I wrote a program to read selected entries in 7z archives, that look like:

file.7z
    |__ file.xml
    |__ file.fog
    |__ file_1.fog

However, the program failed to read file_1.fog for most of my archives, and failed to read file.fog for some. I tried to use archive_error_string() to see what happens, and the errors were either corrupted archive or truncated RAR archive or Decompressing internal error.

Here's the trouble code:

void list_archive(string name) {
    struct archive *a;
    struct archive_entry *entry;

    // create new archive struct for the file
    a = archive_read_new();
    archive_read_support_filter_all(a);
    archive_read_support_format_all(a);

    // open 7z file
    int r = archive_read_open_filename(a, name.c_str(), 1024);

    if (r != ARCHIVE_OK) {
        cout << "cannot read file: " << name << endl;
        cout << "read error: " << archive_error_string(a) << endl;
    }

    // looping through entries
    for (;;) {
        int status = archive_read_next_header(a, &entry);

        // if there's no more header
        if (status != ARCHIVE_OK) break;

        // print some status messages to stdout
        string pathname(archive_entry_pathname(entry));
        cout << "working on: " << pathname << endl;

        size_t entry_size = archive_entry_size(entry);

        // load the entry's content
        char * content;
        content = (char*)malloc(entry_size);
        r = archive_read_data(a, content, entry_size);

        // check if archive_read_data was successful
        if (r > 0) {
            cout << "read " << r << " of " << entry_size << " bytes successfully\n";
            // we are interested in .fog file only
            if (pathname.back() == 'g') {
                // do something with the .fog file
            }
        }
        else // usually the error happens here
            if (archive_errno(a) != ARCHIVE_OK) cout << "read error: " << archive_error_string(a) << endl;


        // free the content and clear the entry
        archive_read_data_skip(a);
        free(content);
        archive_entry_clear(entry);

        cout << "-----" << endl;
    }

    // we are done with the current archive, free it
    r = archive_read_free(a);
    if (r != ARCHIVE_OK) {
        cout << "Failed to free archive object. Error: " << archive_error_string(a) << endl;
        exit(1);
    }
}

Answer 1

I found the troublemaker and answer here if future users have the same problem.

int r = archive_read_open_filename(a, name.c_str(), 1024);

Apparently 1024 is too small for a buffer size. I increased it to 102400 and was able to read/extract all my archives.